AEHBY Semester 2 Exam Textbook Content

02/09/2026

Human Biology Units 1 & 2 Textbook Content

Comprehensive chapter summaries and integrated glossaries extracted directly from Human Perspectives ATAR Units 1 & 2 (Chapters 1–15).

Unit 1: The Functioning Human Body

Chapter 1: Investigating Human Biology

Chapter Summary

Human biological science is the study of humans, both as individuals and populations, and their interactions with their environment.
Science is both a process of inquiry and a body of knowledge.
Our knowledge about humans is continuing to grow as we build on the discoveries of other scientists.
There are different fifields of human biology, such as anatomy, biochemistry, cytology, physiology and psychology.
Scientific investigations involve literature review, observation, classification and/or experimentation.
A hypothesis is a possible explanation for a problem that can be tested.
The hypothesis can be used to predict the results.
The variable is the factor that is tested, and the results are compared to the control experiment where nothing is changed.
Controlled variables are factors that are kept the same in both the control and the test.
The scientific method is a series of steps for scientific investigations. The steps are: recognition of a problem, collection of information, making a hypothesis, testing the hypothesis, collection of data, and analysis of data to reach a conclusion.
Scientific investigations have an independent variable, which is changed and affects the dependent variable. All other variables are controlled. This ensures a fair test.
Data collected can be quantitative (numerical) or qualitative (descriptive).
Experiments should be repeated by conducting the same test a number of times. This means that any individual variation will have less effect on the results.
Data can be organised in a table and represented in a graph. Line graphs are used for continuous data, column graphs are used for discrete data, and histograms are used for frequencies.
The conclusion summarises what the data shows and whether it supports or disproves the hypothesis.
The experiment is evaluated for its: – validity: whether it fairly tested the hypothesis or not – accuracy: whether the results are correct – reliability: whether the results for the same test are similar.
Errors may be human errors, random errors or systematic errors.
Any investigations involving humans or animals need to be ethically sound. They need to have voluntary participation, informed consent, minimal risk of harm, confidentiality and anonymity.
Some investigations have a placebo, an inactive form of the test. In a blind experiment, the subjects do not know whether they are receiving the placebo or not. In a double-blind experiment, neither the researcher nor the subject knows who is receiving the placebo.

Chapter Glossary

Accuracy – The extent to which the measurements are correct
Bar graph – A graph for discrete data using horizontal bars
Blind experiment – An experiment where the subjects do not know whether they are receiving the test treatment or the placebo
Classification – The grouping of organisms based on the similarity of their characteristics; the placement of organisms into groups
Column graph – A graph for discrete data using vertical bars
Conclusion – A summary of how the data supports or disproves the hypothesis
Continuous data – Quantitative data with an in nite number of possibilities
Control – A procedure carried out to give a comparison in an experiment
Controlled variable – A factor kept the same for both the control and the experimental groups in an experiment
Data – Observations and measurements; the results of an experiment
Dependent variable – In an experiment, the factor that changes in response to changes made to the independent variable; also called the responding variable
Double blind experiment – An experiment where neither the subject nor the experimenter knows who receives the test treatment or the placebo
Ethical behaviour – Behaviour that conforms to a set of moral principles or values
Ethics – Moral principles or values
Fair test – An experiment that only changes the independent variable and controls all other variables to test the hypothesis
Histogram – A graph to represent the frequency distribution of data
Human biological science – The scienti c study of humans and their interaction with their environment
Human error – An error due to the limitations of human ability
Hypothesis – A possible explanation to account for observations; plural hypotheses
Independent variable – In an experiment, the factor being investigated; the factor deliberately changed to determine its effect; also called the experimental variable or the manipulated variable
Interpretation – An attempt to explain the observations
Line graph – A graph used to represent continuous data
Observation – The process of using the senses to acquire information
Placebo – A substance or procedure that has no therapeutic effect but is used as a control test
Placebo e:ect – A change or improvement in patients who are given a placebo or ‘dummy’ treatment
Prediction – A guess at what might happen in the future
Qualitative data – Observations that do not involve numbers or measurement
Quantitative data – Data expressed in numbers; usually involves measurement
Random error – An error in an experiment due to limits to the precision of the measurements
Reliability – The extent to which an experiment gives the same result each time it is performed
Repetition – Doing the same experiment many times
Scientific method – A process of conducting valid investigations
Systematic error – An error that occurs in an experiment because of the way the experiment was designed
Test – A method used to collect data to determ-ine whether a hypothesis is supported or not
Theory – A hypothesis becomes a theory when there is overwhelming evidence in support of it
Validity – The extent to which an experiment tests what it is supposed to test
Variable – Any factor that may change during an experiment

Chapter 2: Cells Make Up the Human Body

Chapter Summary

Living things are made up of cells whose activities allow the organism to function. Cells are made up of: – a cell membrane – a cytoplasm made up of the jelly-like cytosol and the organelles suspended within it – the nucleus – a cytoskeleton – inclusions.
Each organelle has a specific role within the cell. Organelles include: – the nucleus, which controls the functioning of the cell – ribosomes, which are the site of protein synthesis – endoplasmic reticulum, which form channels and are involved in storing and transporting molecules – the Golgi body, which modi”es and packages proteins – vesicles, which are membrane-bound sacs – lysosomes, which contain digestive enzymes – mitochondria, which are the site of cellular respiration – cilia and ‘agella, which are important in moving particles or cells.
Cells need to take in their requirements, including glucose and oxygen, and remove wastes produced, including carbon dioxide.
The cell membrane provides a physical barrier, controls the movement of substances into and out of the cell, and provides sensitivity and support for the cell.
The cell membrane is described by the ‘uid mosaic model, with a phospholipid bilayer arranged with the hydrophilic heads on the outside and the hydrophobic tails on the inside.
Substances are able to move across the cell membrane by various means. – With simple diffusion, they move with the concentration gradient directly across the membrane. If the substance is water, the movement is called osmosis. – Facilitated transport uses membrane proteins. Channel proteins allow facilitated diffusion, while carrier proteins allow facilitated diffusion or active transport. Facilitated diffusion is a passive process as the movement is with the concentration gradient, whereas active transport is an active process as it is against the concentration gradient. – Vesicular transport involves membrane-bound sacs called vesicles. Endocytosis brings substances into the cell, whereas exocytosis removes substances.
The size of cells is limited by the surface area required to supply the needs of the volume. As the cell gets larger, the surface- area-to-volume ratio decreases, and therefore larger organisms are made up of many cells rather than one large cell.
The structure of the body is organised into systems, which are made of organs, which are made of tissues, which are made of cells. Tissue is classi”ed as follows: – Epithelial: lines and covers organs. – Connective: provides support and connection – includes bone, cartilage, tendon, ligaments and fat storage. – Muscular: tissue that is able to contract either voluntarily (skeletal muscle) or involuntarily (cardiac or smooth muscle). – Nervous: makes up the brain and nerves, carries messages around the body.
Each body system is made up of organs that allow it to ful”l a specific function within the organism.

Chapter Glossary

Active process – A process that involves the expenditure of energy
Active transport – The use of energy to move substances, usually ions, across a cell membrane against the concentration gradient
Bilayer – Two layers that make up a single membrane
Cardiac muscle – The muscle that forms the wall of the heart
Carrier-mediated transport – Transport of ions or molecules across a cell membrane by special carrier proteins
Carrier protein – A protein that carries substances from one side of the cell membrane to the other
Cell membrane – A membrane that forms the external boundary of a cell; also called the plasma membrane
Cell theory – The principle that all living organisms are made up of cells and the materials produced by cells
Cellular respiration – The chemical reactions that make energy available for the cell; also called tissue respiration or internal respiration
Channel protein – A protein that allows ions, water and small molecules to pass through the cell membrane
Chromosome – One of the 46 rod-like structures that appear in the nucleus of a human cell at the commencement of cell division and carry the genetic information, composed of nucleic acids and proteins
Cilia – Hair-like projections on the outside of a cell; they beat rhythmically to move the whole cell or to move material across the cell surface; singular: cilium
Concentration – A measure of the number of particles in a given volume
Concentration gradient – A difference in concentration of a solution, often between the inside and outside of a cell; also called diffusion gradient
Connective tissue – Tissue providing support for body organs
Cytoplasm – The contents of a cell, excluding the nucleus; also called protoplasm
Cytoskeleton – An internal scaffolding of protein “fifibres within the cytoplasm of a cell
Cytosol – The liquid part of the cytoplasm of a cell
Deoxyribonucleic acid – A molecule in the nucleus of a cell that determines the types of protein that a cell can make
Di”erentially permeable membrane – Membrane that permits the passage of certain substances (usually small molecules) but restricts the passage of others (large molecules); also called a semipermeable, partially permeable or selectively permeable membrane
Di”usion – The movement of particles of a liquid or a gas so that they are distributed evenly over the available space; usually taken to mean the net movement of ions or molecules from a higher to a lower concentration until they are evenly distributed
Di”usion gradient – see concentration gradient
DNA – see deoxyribonucleic acid
Endocytosis – The process by which a cell takes in materials by enfolding and enclosing them; includes phagocytosis and pinocytosis
Endoplasmic reticulum – A network of membranes forming channels through the cytoplasm of a cell; it is used for storage, support, synthesis and transport within the cell
Epithelium – Tissue that forms the outer part of the skin and that lines hollow organs and ducts; a covering tissue; also called epithelial tissue; plural: epithelia
Exocytosis – The process whereby the contents of the vesicles of cells are pushed out through the cell membrane
Extracellular fluid – Fluid found outside the cells; it includes tissue ‘uid and blood plasma; also called tissue ‘uid
Facilitated di”usion – The process whereby proteins allow the movement of substances through the cell membrane along the concentration gradient
| Cells make up the human body57Facilitated transport – Proteins in the cell membrane allow molecules to be transported across the membrane
Flagella – A long projection from a cell; often has the function of moving the cell
Fluid mosaic model – The currently accepted model of cell membrane structure
Golgi body – A structure in the cytoplasm of a cell consisting of a stack of flattened channels; it packages materials for secretion from the cell; sometimes called Golgi apparatus
Heart muscle – see cardiac muscle
Homeostasis – The maintenance of a relatively constant internal environment despite ‘uctuations in the external environment
Hydrophilic – Water-loving
Hydrophobic – Water-hating
Inclusion – Chemical substances inside a cell in the form of granules or droplets
Involuntary muscle – Muscle that is not under our conscious control; found in walls of internal organs; also called non-striated muscle or smooth muscle
Lipid – Large organic molecules made up of fatty acids and glycerol
Lysosome – A small sphere formed from a Golgi body; contains digestive enzymes
Matrix – Non-cellular material between the cells of a tissue
Micro lament – Protein “fifibres that move materials around the cytoplasm or move the whole cell
Microtubule – Fine tubes that help to maintain the shape of the cell and hold the organelles in place
Mitochondrion – A structure in the cytoplasm of a cell in which the aerobic stage of respiration occurs; plural: mitochondria
Muscle fifibres – The long cylindrical cells that make up skeletal muscles
Nervous tissue – Tissue made up of nerve cells (neurons)
Net di”usion – see diffusion
Neuron – A nerve cell
Non-striated muscle – see involuntary muscle
Nuclear membrane – A membrane that separates the nucleus of a cell from the cytoplasm
Nuclear pore – Gaps in the nuclear membrane
Nucleolus – A structure within a cell’s nucleus; involved in protein synthesis
Nucleus – A large organelle in a cell; contains DNA
Organ – A structure made up of different types of tissue working together
Organelle – Structures within the cytoplasm of a cell, each with speci”c functions
Organism – A living thing, with different body systems all integrated
Osmosis – The diffusion of water molecules through a differentially permeable membrane from an area of higher water concentration to an area of lower water concentration
Osmotic pressure – The pressure due to differences in concentration on either side of a differentially permeable membrane
Passive process – A process that occurs without any input of energy
Passive transport – The transport of substances across the cell membrane without the input of energy
Phagocytosis – The process by which a cell surrounds, and takes in, solid particles
Phospholipid – A lipid molecule that contains a phosphate group
Pinocytosis – The process by which cells enfold, and take in, drops of liquid
Plasma membrane – see cell membrane
Protein channel – A pathway through a protein in the cell membrane that allows the passage of substances across the membrane
Ribosome – Site of protein synthesis; located on the surface of rough endoplasmic reticulum in eukaryotic cells
Rough endoplasmic reticulum – A form of endoplasmic reticulum that is covered with ribosomes that give it a rough appearance; involved in the synthesis of proteins
UNIT 1 |58Simple di”usion – The process of substances moving along the concentration gradient in a solution or across a semipermeable membrane, without the use of membrane proteins
Skeletal muscle – Muscle attached to bones, under voluntary control; also called voluntary or striated muscle
Smooth endoplasmic reticulum – A form of endoplasmic reticulum that is involved in the synthesis of lipids; is not covered with ribosomes
Smooth muscle – see involuntary muscle
Solvent – A substance, often water, in which a solute is dissolved
Striated muscle – Muscle made up of dark and light bands; includes skeletal and cardiac muscle
System – A group of organs that work together for a common function; also called an organ system
Tissue – A group of cells that are similar in structure and function
Tissue fluid – Fluid found in the spaces between the cells; also called interstitial ‘uid or extracellular ‘uid
Vesicle – A small membrane-bound cavity in the cytoplasm of a cell, smaller than a vacuole
Vesicular transport – The transport of materials into or out of a cell in membrane-bound sacs; also called bulk transport
Voluntary muscle – Muscle under voluntary control

Chapter 3: Cells Undergo Chemical Reactions

Chapter Summary

Metabolism involves all the chemical reactions that take place in a cell. These may fibreak large molecules down into smaller ones (catabolic metabolism) or use small molecules to make larger ones (anabolic metabolism).
Nutrients from our food are used in metabolism.
Carbohydrates, lipids, proteins and nucleic acids are all organic compounds, molecules based on a chain of carbon atoms.
Minerals, water and vitamins are inorganic nutrients.
Carbohydrates, the main source of energy for the cell, contain various numbers of simple sugars joined together.
Lipids include fats, oils, phospholipids and steroids. They are composed of glycerol and fatty acids joined together. The most common lipid is triglyceride, which includes three fatty acids.
Proteins are composed of amino acids joined by peptide bonds to form a chain. These chains are folded to form a particular shape.
Nucleic acids are made up of chains of nucleotides. RNA has a single chain with the ribose sugar, whereas DNA has a double chain with the deoxyribose sugar.
Enzymes increase the rate of chemical reactions by lowering the activation energy, which means that more particles have suf*cient energy to react.
Enzymes are speci*c for a particular substrate due to the shape of the active site. When they join, they form an enzyme–substrate complex.
There are two models used to explain how enzymes work. – The lock-and-key model states that the active site and substrate have complementary shapes that allow them to *t together. – The induced-*t model states that when the substrate joins to the enzyme the enzyme changes shape so that the substrate *ts.
There are a number of factors that affect enzyme activity: the concentration of the enzyme, the concentration of the substrate, the removal of the product, temperature, pH, and the presence of cofactors, or enzyme inhibitors.
Cellular respiration involves organic molecules being broken down to release energy.
Glucose being broken down in cellular respiration is represented by: Glucose + Oxygen Carbon dioxide + Water + Energy C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP
Adenosine triphosphate (ATP) is able to store energy in the bond between adenosine diphosphate (ADP) and the third phosphate group. This energy can then be released when needed.
Glycolysis is the *rst stage of cellular respiration, where glucose forms two pyruvate molecules and two ATP molecules. This stage does not require oxygen.
In the absence of oxygen, the pyruvate is converted to lactic acid. As no oxygen was needed, this is anaerobic respiration.
In the presence of oxygen, the pyruvate undergoes aerobic respiration. This involves the pyruvate forming acetyl CoA before entering the citric acid cycle and then the electron transfer system. Up to 36 ATP molecules are produced during this process.
Only 40% of the energy produced during cellular respiration is stored in ATP. The remaining 60% is released as heat.
ATP produced during cellular respiration can be used in other cellular processes, including movement, active transport, nerve impulses, cell division and growth.

Chapter Glossary

Activation energy – The energy needed to fibreak the bonds of the reacting particles in a chemical reaction; the energy needed to start a chemical reaction
Active site – The part of an enzyme molecule that combines with the substrate
Adenosine diphosphoate (ADP) – The substance formed when the end phosphate group is removed from a molecule of adenosine triphosphate (ATP)
Adenosine triphosphate (ATP) – A molecule that stores energy in cells; the energy is stored in the bond between the end phosphate group and the rest of the molecule
Aerobic respiration – Respiration requiring oxygen
Amino acids – Small molecules that join together to make proteins
Anabolism – The process of combining small molecules to make larger ones; it requires energy; also known as synthesis
Anaerobic respiration – Respiration that does not require oxygen
Carbohydrate – Organic molecules that are the main source of energy for cells
Catabolism – Chemical reactions that fibreak down large organic molecules into smaller ones, with the release of energy
Catalyst – A substance that lowers the activation energy of a reaction, increasing the rate of the reaction without being consumed
Cellular respiration – The chemical reactions that make energy available for the cell
Citric acid cycle – The series of reactions that occur in the mitochondria during aerobic respiration where acetyl CoA enters and carbon dioxide is released; also called the Krebs cycle
Coenzyme – Non-protein organic molecules that are essential for the functioning of an enzyme
Cofactor – The ions or inorganic molecules required by enzymes to catalyse a reaction
Cytosol – The liquid part of the cytoplasm of a cell
Denature – To change the molecular structure of a protein by heating, a change in pH, adding detergents or shaking
Dipeptide – Two amino acids bonded together by a peptide bond
Disaccharide – Two simple sugar molecules bonded together
Electron transport system – A series of chemical reactions occurring in the mitochondria of a cell whereby energy from carrier molecules is transferred to ATP for storage
Enzyme – An organic substance (usually a protein) that increases the speed of chemical changes without being altered or destroyed in the change; an organic catalyst
Enzyme inhibitor – A substance that slows or stops an enzyme’s activity
Enzyme–substrate complex – The structure formed when an enzyme and a substrate combine
Glycolysis – The fibreakdown of a glucose molecule to pyruvic acid; it releases energy to form two molecules of adenosine triphosphate (ATP)
Inorganic compound – Not containing carbon (e.g. water, oxygen) or having small molecules (e.g. carbon dioxide)
Krebs cycle – see citric acid cycle
Lipid – Large organic molecules made up of fatty acids and glycerol
Metabolism – All the chemical reactions occurring in a living organism
Monosaccharide – A simple sugar molecule such as glucose or fructose
Nucleic acid – Molecules containing many nucleotides forming a chain; includes ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
| Cells undergo chemical reactions81Nutrient – Any substance in food that provides energy, is essential for growth, or assists in the functioning of the body
Organic compounds – Substances that have large molecules and contain carbon, such as carbohydrates, amino acids, proteins, lipids and nucleic acids
Oxidative phosphorylation – see electron transport system
Oxygen debt – Extra oxygen required, in addition to the normal resting requirement, to remove the lactic acid produced during exercise
Peptide bond – A bond formed between an amino group of one amino acid and the carboxyl group of another amino acid
Polypeptide – Ten or more amino acids bonded together
Polysaccharide – Many simple sugar molecules bonded together
Protein – Very large organic molecule made up of amino acids
Recovery oxygen – The extra oxygen needed to ‘recover’ after exercise
Substrate – A molecule upon which an enzyme acts
Triglyceride – The most common form of lipid, made up of glycerol and three fatty acids

Chapter 4: The Respiratory System Allows Gas Exchange

Chapter Summary

Air enters, and leaves, the body through the nose, mouth, pharynx and larynx.
The air is warmed and humidified prior to entering the lungs.
The trachea takes the air to and from the lungs. It contains C-shaped cartilage rings that hold the structure open.
The trachea divides, forming the primary, then secondary and tertiary bronchi. As the bronchi get smaller, there are fewer cartilage rings and more smooth muscle and elastin.
The bronchioles are finer than the bronchi and do not contain cartilage.
The bronchioles end in air sacs called alveoli, which are the site of gas exchange.
As the air moves through the trachea and bronchi, mucus and cilia work together to trap and remove foreign particles.
The lungs are covered in a membrane that extends to the inside of the chest. Pleural #uid is contained between the two layers of the membrane and allows the lungs to move while still holding them to the side of the chest.
Air will #ow from areas of high pressure to areas of low pressure.
During inspiration the diaphragm and intercostal muscles contract, increasing the volume of the lungs and decreasing the pressure. This causes air to #ow into the lungs.
During expiration the diaphragm and intercostal muscles relax, decreasing the volume of the lungs and increasing the pressure. This causes air to #ow out of the lungs.
Gas exchange occurs at the alveoli.
Alveoli allow efficient gas exchange as they have a very large surface area, have a good blood supply, are very thin, are covered by a thin layer of moisture and have a constant movement of air.
The concentration of oxygen in the blood is lower than in the alveoli, resulting in a net diffusion of oxygen into the blood.
The concentration of carbon dioxide is higher in the blood than in the air; therefore, there is a net diffusion of carbon dioxide out of the blood.
Our lifestyle may affect the respiratory system: – Emphysema is caused by long-term exposure to irritants such as tobacco smoke and air pollutants. It causes the alveoli to fibreak down, reducing the surface area for gas exchange. – Lung cancer is the uncontrolled division of cells. This may cause a mass, excess mucus and the rupture of alveoli. The presence of lung cancer is linked to smoking and exposure to asbestos and other pollutants.
Infections such as pneumonia and tuberculosis can cause in#ammation, resulting in secretions in the alveoli. This reduces the surface area for gas exchange as well as the volume of air in the lungs.
Asthma causes a narrowing of the airways due to contraction of the smooth muscles, in#ammation of the lining, and mucus filling the airways. These combine to cause fibreathing difficulties.

Chapter Glossary

Alveoli – Air sacs in the lungs; also, the milk-secreting part of the mammary glands; singular: alveolus
Asthma – An allergic condition that causes narrowing of the airways and difficulty fibreathing
Bronchiole – A very small air tube in the lung
Concentration gradient – A difference in concentration of a solution, often between the inside and outside of a cell; also called diffusion gradient
Emphysema – A disease of the lungs that damages the alveoli; caused by long-term exposure to irritants
Epiglottis – A cartilage #ap at the base of the pharynx that covers the trachea during swallowing
Expiration – Breathing out; exhalation
Inspiration – Breathing in; inhalation
Larynx – The structure at the top of the trachea that contains the vocal cords
Lung cancer – Growth of a tumour in the lungs
Oesophagus – The tube that carries food from the throat to the stomach
Pharynx – The throat; the pharynx joins the mouth cavity to the oesophagus and larynx
Pleura – A membrane covering the surface of the lungs
Pleural fluid – A thin layer of #uid within the pleura that allows the lungs to move during fibreathing
Pneumonia – A lung infection that causes #uid and mucus to build up in the alveoli, causing difficulty fibreathing
Primary bronchi – The first branching from the trachea, entering the left and right lungs
Pulmonary arteries – The artery that takes blood from the heart to the lungs
Respiratory system – The system specialised to facilitate the intake of oxygen and the removal of carbon dioxide
Secondary bronchi – The division of the primary bronchi, taking air into each lobe of the lungs
Terminal bronchioles – The end of the bronchioles before they form alveoli
Tertiary bronchi – The division of the secondary bronchi
Trachea – The tube that takes air from the throat to the lungs; the windpipe
Tuberculosis (TB) – A lung infection caused by the bacterium Mycobacterium tuberculosis
Ventilation – The process of inhalation and exhalation; fibreathing
Vocal cord – Membrane in the larynx that vibrates, producing sounds

Chapter 5: The Circulatory System Transports Materials Throughout the Body

Chapter Summary

The circulatory system transports blood throughout the body to supply the needs of cells and remove their wastes.
Blood is made up of plasma and formed elements (erythrocytes, leucocytes and thrombocytes).
Plasma is water and dissolved substances. The most common mode of transport for carbon dioxide is in the plasma as bicarbonate ions (HCO3 –).
Erythrocytes, or red blood cells, contain haemoglobin, which is able to transport oxygen by forming oxyhaemoglobin.
Leucocytes, or white blood cells, are important in protecting the body from infection.
Thrombocytes, or platelets, are important in blood clotting.
Blood clotting, or coagulation, allows a plug to form in a damaged vessel to restrict blood loss. Clots form with a mesh of ‘brin which traps cells, platelets and plasma. The clot gradually retracts, becoming denser and stronger.
The heart is a four-chambered pump that pushes blood around the body.
Blood moves through the structures in this order: venae cavae, right atrium, right ventricle, pulmonary artery, lung, pulmonary vein, left atrium, left ventricle, aorta, body.
The heart muscle contracts during systole and relaxes during diastole. The atria contract, then the ventricles.
Valves prevent the blood +owing backwards.
Blood vessels – arteries, capillaries and veins – transport blood from and to the heart.
Arteries take blood away from the heart, while veins take blood towards the heart.
Capillaries join the arteries and veins.
Arteries contain blood under pressure. Their walls contain muscle and elastic ‘fifibres to maintain the pressure and allow vasoconstriction and vasodilation.
Veins contain blood under low pressure. Their walls are thinner than arteries’ walls, but they contain valves to stop the blood +owing backwards.
Capillaries form a network through the cells. Their walls are only one cell thick, allowing substances to pass between the blood and cells.
Red blood cells contain antigens on their surface.
The ABO blood groups are due to sugar antigens: antigen A and antigen B.
The body recognises the antigens that are found on its own cells, but it will produce antibodies for any antigens that are not normally found in the body.
Rh blood groups are due to protein antigens. A person who is Rh positive has the antigen and someone who is Rh negative does not have the antigen. If an Rh-negative person receives Rh-positive blood, they will produce antibodies for the antigen.
It is important that the blood groups are matched for blood transfusion so that the person receiving the blood will not produce antibodies that will react to the donated blood.
There are different types of blood transfusions: whole blood, red cell concentrates, plasma, platelet concentrates, cryoprecipitate and autologous transfusion.
The lymphatic system collects fluid that leaks from blood vessels and returns it to the blood, as well as playing a role in defending against disease.
Lymph vessels are blind-ended tubes that collect fluid, proteins and pathogens from between the cells.
Fluid, called lymph, moves through the vessels due to the constriction of muscles. Valves stop the lymph moving backwards.
Lymph nodes have a connective tissue framework with lymphocytes, macrophages and plasma cells.
Lymph is ‘ltered as it moves through the lymph nodes.

Chapter Glossary

ABO blood group system – A method of classifying blood types according to the antigens on the surface of the red blood cells
Agglutination – The clumping together of micro-organisms or of blood cells
Alveoli – Air sacs in the lungs
Antibody – A substance produced in response to a speci’c antigen; it combines with the antigen to neutralise or destroy it
Antigen – Any substance capable of causing the formation of antibodies when introduced into the tissue
Arteriole – A very small artery
Artery – A blood vessel that carries blood away from the heart
Atria – The top chambers of the heart; singular: atrium
Atrial systole – Contraction of the atria of the heart
Atrioventricular valves – Valves within the heart that ensure the blood +ows through it in one direction only
Autologous transfusion – A transfusion using the patient’s own blood
Biconcave – Shaped concave on both sides, dipping inwards in the centre
Blood clotting – Formation of a blood clot; also known as coagulation
Capillary – A microscopic blood vessel that links arterioles and venules
Carbaminohaemoglobin – A molecule resulting from a combination of carbon dioxide and haemoglobin
Cardiac cycle – The cycle of events that occurs in one complete heartbeat
Cardiac muscle – The muscle that forms the wall of the heart
Cardiac output – The volume of blood pumped from one ventricle of the heart in one minute
Chordae tendineae – Tendon-like structures that connect papillary muscle to valves
Circulation – The movement of blood through the heart and blood vessels
Circulatory system – The body’s transport system, consisting of the heart, blood, blood vessels, lymph and lymph vessels
Clot – Blood cells, platelets and plasma trapped together in a mesh of ‘brin
Clot retraction – Contraction of the ‘brous threads of a blood clot
Clotting factors – Chemical substances in blood plasma that allow blood to clot
Coagulation – The process of blood becoming gel-like; also called clotting
Cryoprecipitate – A blood product used in transfusions; produced by freezing the plasma and thawing it slowly
Deoxygenated blood – Blood that contains little oxygen
Diastole – The period of relaxation of the heart (between contractions), during which it ‘lls with blood
Erythrocyte – see red blood cell
Fibrin – An insoluble protein that forms blood clots by holding blood cells, platelets and plasma together in a mesh
Formed element – Any cell or cell-like structure in the blood
Haematocrit – The ratio of red blood cells to the total volume of blood
Haemoglobin – The pigment in red blood cells; it is involved in the transport of oxygen and some carbon dioxide through the body
Haemophilia – An inherited disorder in which the blood clots slowly or not at all
Heart – A hollow, muscular organ that pumps blood
Heart rate – The number of heartbeats per minute
Immunoglobulins – A group of proteins; antibodies are immunoglobulins
Inferior vena cava – A large vein carrying blood from the lower body to the right atrium
Intercellular :uid – Fluid between the cells
Leucocyte/leukocyte – A white blood cell
| The circulatory system transports materials throughout the body137Lymph – Colourless fluid that circulates through the lymphatic vessels before returning to the blood
Lymph gland – see lymph node
Lymph node – An oval or bean-shaped structure found on the lymphatic vessels; it is involved in protection against infection; also called a lymph gland
Lymph vessels – see lymphatic vessel
Lymphatic system – A system of vessels that drains excess fluid from the tissues; also called the lymph system
Lymphatic vessel – A large vessel that collects lymph from the lymph capillaries; lymphatic vessels join up and eventually return lymph to the blood
Lymphocyte – A type of white blood cell; also found in lymph nodes and in lymph
Lymphoid tissue – Tissue containing many lymphocytes and macrophages; found mostly in the lymph nodes but also in the bone marrow, tonsils, spleen and thymus
Macrophage – A phagocytic cell derived from a monocyte (a type of white blood cell)
Metabolic wastes – Substances produced by cells that cannot be used and that would be harmful if allowed to accumulate
Oxygenated blood – Blood containing a lot of oxygen
Oxyhaemoglobin – Oxygen combined with haemoglobin
Papillary muscles – Muscles in the ventricles of the heart that anchor the valves
Pericardium – Membrane enclosing the heart
Phagocytic cell – Cell that can engulf and digest micro-organisms and cell debris
Plasma – The fluid part of the blood in which the cells are suspended
Plasma cell – Cell that develops from a B cell and produces antibodies
Platelet – One of the formed elements of blood; a fragment of cytoplasm enclosed in a membrane but lacking a nucleus; also called a thrombocyte
Platelet concentrate – A component of blood used in transfusions
Pulmonary vein – The vein that transports blood from the lungs to the left atrium
Red blood cell – One of the formed elements of the blood; contains haemoglobin
Red cell concentrate – A component of blood used in transfusions; produced by spinning blood in a centrifuge
Rh blood group system – A method of classifying blood types according to the antigens on the surface of the red blood cells
Semilunar valve – Valve preventing blood from +owing back into the ventricles; located at the start of the aorta and pulmonary artery
Septum – The partition between the left and right sides of the heart
Serum – The protein-rich fluid that separates out when blood coagulates
Sternum – The fibreastbone
Stroke volume – The volume of blood pumped from the left ventricle during one contraction
Superior vena cava – The large vein taking blood from the top of the body to the right atrium
Systole – The period when heart muscle contracts
Thrombocyte – see platelet
Thrombus – see clot
Transfusion – The transfer of blood, or of some of the components of blood, into the circulation of a person
Vasoconstriction – Decrease in the diameter of blood vessels, restricting the +ow of blood
Vasodilation – Increase in the diameter of blood vessels, increasing the +ow of blood
Vasodilator – Substance that produces a local widening, or dilation, of blood vessels
Vein – A blood vessel that carries blood towards the heart
Ventricles – The bottom chambers of the heart
Ventricular systole – The phase of the heartbeat when the ventricles contract
Venule – A small vein
Wastes – see metabolic wastes
White blood cell – One of the blood cells; it contains a nucleus, but no haemoglobin
Whole blood – Blood taken from a donor, with a chemical added to prevent clotting; used in transfusions

Chapter 6: The Digestive System Supplies Nutrients for the Body

Chapter Summary

The digestive system extracts nutrients from the food we eat and absorbs them into the body for use by the cells.
Digestion is the process of food being broken down into products small enough to be absorbed into the blood and cells.
Mechanical digestion is the physical fibreakdown of food by cutting, tearing and grinding by the teeth, stomach and bile.
Chemical digestion is the process of enzymes fibreaking large molecules into smaller, simpler molecules.
Food is ingested in the mouth and mixed with saliva, where salivary amylase starts to fibreak down starch.
The different types of teeth – incisors, canines, premolars and molars – are each shaped to perform a speci#c function in mechanical digestion.
Muscles in the oesophagus move the food from the pharynx to the stomach by the process of peristalsis.
In the stomach, food is mixed with gastric juices to form chyme.
Gastric juice, secreted from gastric glands, contains hydrochloric acid, mucus and enzymes to facilitate chemical digestion.
The small intestine is 6–7 m long and is made up of the duodenum, jejunum and ileum, where digestion occurs due to intestinal juice, pancreatic juice and bile.
Pancreatic juice contains pancreatic amylase, trypsin, ribonuclease, deoxyribonuclease and pancreatic lipase.
Bile contains bile salts that emulsify fats.
Intestinal juices contain amylases, peptidases and lipases.
The lining of the small intestine is folded into villi, which are covered by microvilli. This results in a very large surface area for absorption.
Absorption occurs through simple diffusion and active transport.
The large intestine is 1.5 m long and is made up of the caecum, colon, rectum and appendix.
Material moves slowly through the large intestine, allowing water to be removed and the formation of faeces.
Bacteria in the large intestine fibreak down organic compounds, producing vitamins.
Diet can affect the digestive system, resulting in conditions such as constipation, diarrhoea, bowel cancer and coeliac disease.

Chapter Glossary

Active transport – The use of energy to move substances, usually ions, across a cell membrane
Alimentary canal – The tube via which food passes through the body, consisting of the mouth, oesophagus, stomach and intestines; also called the digestive tract
Bile – A secretion of the liver, stored in the gall bladder and released into the small intestine
Bile salts – Substances that fibreak fats into tiny droplets
Bolus – A ball-like structure of food and saliva
Canine – The pointed tooth between the incisors and premolars
Chemical digestion – The fibreakdown of food to small molecules by chemicals
Chyme – The semi1uid mass of partially digested food that leaves the stomach
Circular muscle – Smooth muscle with #fifibres arranged in a circle around an organ, such as the stomach
Coeliac disease – An autoimmune disease due to the immune system reacting to gluten
Colorectal cancer – Cancer in the colon and rectum; also called bowel cancer
Constipation – A condition in which defecation is dif#cult, with faeces being hard and dry
Deoxyribonuclease – An enzyme in pancreatic juice that digests DNA
Diarrhoea – The frequent passing of watery faeces
Digestion – The mechanical and chemical fibreakdown of food to small molecules that can be absorbed into the body
Digestive system – The system that fibreaks down the food taken into the body ready for absorption into the cells
Elimination – Removal of indigestible material, bacteria and bile pigments from the body
Emulsify – To mix two liquids that would not normally mix
Faeces – Material passed out of the rectum
Gastric gland – The secretory unit of the stomach located in gastric pits; produces gastric juice
Gastric juice – The digestive juice secreted by the glands of the stomach
Incisor – The narrow-edged tooth at the front of the mouth; used for cutting
Ingestion – The intake of food, liquids or drugs into the mouth
Intestinal juice – The digestive juice secreted by the glands of the small intestine
Lacteal – A lymph capillary in the small intestine; it absorbs fat from digested food
Large intestine – The part of the intestine between the small intestine and the anus; it is made up of the caecum, colon and rectum
Longitudinal muscle – Smooth muscle with #fifibres arranged lengthwise along an organ
Mastication – The process of chewing; to grind or crush food with the teeth
Mechanical digestion – The mechanical fibreakdown of food into small particles
Microvilli – Microscopic projections from the membranes of cells lining the small intestine; they increase the surface area for absorption; singular: microvillus
Molar – A grinding tooth at the back of the mouth
Mucosa – A mucous membrane; in particular, the mucous membrane that forms the internal lining of the alimentary canal
Oesophagus – The tube that carries food from the throat to the stomach
Pancreatic amylase – An enzyme in pancreatic juice that fibreaks down starch
Pancreatic juice – The liquid secreted by the pancreas
Pancreatic lipase – An enzyme in pancreatic juice that fibreaks down fats
Peristalsis – Waves of muscular contraction that push food along the alimentary canal
UNIT 1 |164Pharynx – The throat; the pharynx joins the mouth cavity to the oesophagus and larynx
Premolars – The teeth between the canine and molars
Pyloric sphincter – A ring of smooth muscle between the stomach and the duodenum
Ribonuclease – An enzyme in pancreatic juice that digests RNA
Saliva – A 1uid secreted into the mouth by salivary glands to begin digestion of food
Salivary gland – Gland in the mouth that secretes saliva
Segmentation – A process occurring in the small intestine which uses the contraction of circular muscles to push the chyme into segments, mixing it with digestive juices
Small intestine – The longest part of the alimentary canal; receives material from the stomach
Stomach – A muscular organ that receives food from the oesophagus, and mixes it with acid and enzymes to form chyme
Trypsin – An enzyme in pancreatic juice that fibreaks down protein; also known as pancreatic amylase
Villi – Projections from the internal lining of the small intestine; also, projections of the chorion that grow into the lining of the uterus; singular: villus

Chapter 7: The Excretory System Removes Waste Products

Chapter Summary

Excretion is the removal of the waste products of metabolism.
The lungs, liver, sweat glands, alimentary canal and kidneys are involved in excretion.
Deamination is the removal of the amino group from amino acids so that the remaining part can form carbohydrates to be used for energy production. This occurs in the liver.
The amino group is converted to ammonia and then to urea to be excreted by the kidneys.
The skin covers the body, helps to regulate the body temperature and is involved in the excretion of salt, lactic acid, urea and some drugs through sweat.
The kidney, bladder, urethra and ureters make up the urinary system.
The renal capsule surrounds the outer renal cortex, which lies outside the renal medulla.
The renal medulla is divided into renal pyramids by the renal columns.
The renal pelvis is a hollow that leads to the hilum on the concave side of the kidney.
The nephron is the microscopic unit of the kidney and is made up of a renal corpuscle and a renal tubule.
Blood is ltered in the renal corpuscle as the blood travels through the glomerulus. The ltrate is collected in the glomerular capsule.
Selective reabsorption of useful substances including water, glucose, amino acids and some ions occurs in the proximal convoluted tubule, Loop of Henle, distal convoluted tubule and collecting duct.
Tubular secretion moves substances such as drugs, potassium, creatinine and hydrogen ions from the blood to the urine in the distal convoluted tubule.
Urine travels from the collecting ducts to the renal pelvis and then the ureters. It then travels to the bladder where it is stored before excretion through the urethra.
In a healthy person, urine is composed of water, ions, urea, uric acid and creatinine.
Kidney stones are solid crystals formed when the urine is too concentrated. These may block the ureter, bladder or urethra, causing pain.
Kidney failure means that the blood is not able to be ltered correctly. Lifestyle choices such as diet, smoking, alcohol consumption and drugs can affect the health of the kidneys.
Dialysis, either peritoneal or haemodialysis, is used to remove wastes from the blood of people with kidney failure.
Liver disease, caused by infection, autoimmune disease, genetic disorders, cancer and lifestyle choices, means that toxins are unable to be processed for elimination.

Chapter Glossary

Afierent arteriole – The blood vessel that enters an organ
Collecting duct – The tube in the kidney that collects ltrate from several nephrons
Creatinine – A waste product from the fibreakdown of muscles
Deamination – The removal of the amino group from an amino acid molecule
Dialysis – A method of removing waste from the blood when kidney failure occurs
Distal convoluted tubule – The second set of convolutions of the kidney tubule; it receives the forming urine after it has passed through the loop of Henle
Efierent arteriole – The blood vessel that leaves a glomerulus in the kidney
Excretion – Removal of the wastes of metabolism from the body
Facultative reabsorption – The process whereby carrier proteins assist the movement of substances through the cell membrane
Filtrate – The *uid remaining after ltration has taken place
Glomerular capsule – The double-walled cup-like structure at the end of each kidney tubule; it collects ltered water and other substances from the blood; also called Bowman’s capsule
Glomerular filtration – The ltration of blood in the kidney
Glomerulus – The tightly coiled mass of capillaries that is surrounded by the expanded part of each kidney tubule
Haemodialysis – Process in which blood is passed through an arti cial kidney or dialysis machine
Kidney failure – Occurs when the kidneys lose their ability to excrete wastes and control the level of *uid in the body
Kidney stone – Solid masses of crystals that develop within the kidneys
Kidneys – The principal excretory organs of the human body; they lter waste from the blood and regulate the balance of water and salts in the blood plasma
Liver – Organ that is part of the excretory system
Loop of Henle – The U-shaped section of the kidney tubule; it plays a major role in the reabsorption of water and salts from the ltrate
Lung – One of a pair of organs for gas exchange, occupying the chest cavity
Nephron – The functional unit of the kidney
Peritoneal dialysis – Dialysis occurring inside the body, using the peritoneum as the membrane across which wastes can be removed
Peritoneum – The membrane that lines the inside of the abdominal cavity
Peritubular capillaries – The capillaries in the kidney that surround the convoluted tubules of the nephron, the loop of Henle and the collecting duct
Proximal convoluted tubule – The rst set of convolutions of the kidney tubule, located between the glomerular capsule and the loop of Henle
Renal artery – The blood vessel that transports blood into the kidney
Renal capsule – A tough brous layer surrounding the kidney
Renal column – An extension of the renal cortex that divides the renal medulla into renal pyramids
Renal corpuscle – The ltration structure of the nephron composed of the glomerulus and glomerular capsule
Renal cortex – The outer part of the kidney
Renal hilum – A depression in the kidney where the blood vessels and the ureter enter
Renal medulla – The inner part of the kidney
Renal pelvis – The cavity of the kidney that collects urine before it passes to the ureter
Renal pyramid – A section of the renal medulla
Renal tubule – The kidney tubule; it leads away from the glomerular capsule and empties into a collecting duct
| The excretory system removes waste products189Renal vein – The blood vessel transporting blood away from the kidney
Secretion by the tubules – see tubular secretion
Selective reabsorption – The reabsorption of some substances and not others in the renal tubules
Sweat glands – Tubular structures in the skin that produce sweat
Tubular secretion – The process whereby ions and drugs are secreted from the blood into the kidney tubule
Ureter – The tube that leaves each kidney and drains into the urinary bladder
Uric acid – A fibreakdown product of the metabolism of purines such as the bases adenine and guanine found in DNA and RNA
Urinary system – The system composed of the kidneys, ureters, bladder and urethra that is responsible for the excretion of wastes, the regulation of blood volume, pressure and pH, as well as the concentration of chemicals
Urine – The *uid produced by the kidneys that contains wastes and excess materials

Chapter 8: The Musculoskeletal System Allows Movement

Chapter Summary

The muscular and skeletal systems work together to support and move the body.
Muscle cells can contract and shorten.
Skeletal muscles move the bones and can contract under conscious control.
Smooth muscle in the internal organs is involuntary muscle and is not under conscious control.
Cardiac muscle makes the heart contract, pushing blood around the body.
Muscles have extensibility and elasticity; they can be stretched and then contract.
Skeletal muscle cells are hfield in bundles by connective tissue.
Each skeletal cell is called a muscle !fibre; the plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm.
Parallel myo!brils in the sarcoplasm are composed of thick myo!laments made of myosin and thin myo!laments made of actin.
The overlap of the myo!laments causes striations that divide the myo!bril into sarcomeres.
The sliding !lament theory describes how muscles contract. As the thin !laments slide over the thick !laments, the sarcomere shortens.
Energy, from ATP, is used during muscle contraction.
Muscles are attached to bones by tendons so that the joint bends when the muscle contracts.
Antagonists are pairs of muscles. The agonist is the muscle doing the action.
Synergists help the agonist by producing the same movement or steadying the joint.
Muscle tone is achieved by partial contraction of skeletal muscles due to different !fifibres contracting at one time. This allows a person to maintain their posture.
The skeletal system supports the body, facilitates movement, protects internal organs, produces blood cells, and stores and releases minerals and fat.
Bones may be classi!ed as ‘at, irregular, long, sesamoid or short.
The skeleton can be divided into the axial skeleton (the central bones) and the appendicular skeleton (the limbs, shoulder and pelvis).
Long bones contain a shaft called the diaphysis, which is made of compact bone and contains a cavity with yellow bone marrow, and ends called epiphyses, made of spongy bone with red marrow.
Compact bone is made up of many osteons or Haversian systems.
Each osteon has a central canal surrounded by concentric lamellae. Osteocytes are located in small spaces between the lamellae called lacunae. Canals called canaliculi join the lacunae.
Spongy bone is composed of irregular bony plates called trabeculae. The osteocytes are located between the trabeculae.
Cartilage is made up of protein !fifibres called collagen that are embedded in a matrix called chondrin. The chondroblasts are located in the matrix.
The arrangement of collagen !fifibres determines whether the cartilage is hyaline, elastic or !brocartilage.
A joint occurs when two or more bones come together.
Types of joints are !brous, cartilaginous, freely movable, ball and socket, pivot, gliding, saddle or condyloid, based on their range of movement and the connective tissue joining them.
Freely movable joints are called synovial joints due to the synovial cavity. The joint is enclosed by the articular capsule and contains synovial ‘uid.
Ligaments connect two bones.
Joints move in ‘exion, extension, abduction, adduction and rotation.
Osteoporosis and osteoarthritis are more likely with increased age.

Chapter Glossary

Abduction – Movement of a limb away from the midline of the body
Actin – One of the contractile proteins of skeletal muscle; makes up the thin myo!laments of a myo!bril
Adduction – Movement of a limb towards the midline of the body
Agonist – Muscle that causes the desired action; often referred to as the prime mover
Antagonist – Muscle that has an action opposite to that of the prime mover (see agonist)
Appendicular skeleton – The part of the skeleton made up of the bones of the upper and lower limbs, and the bones of the shoulders and pelvis
Articular capsule – The sac-like envelope in the cavity of a synovial joint; also called joint capsule
Articular cartilage – Cartilage that covers the surfaces of bones at a joint
Articular disc – An alternative name for meniscus
Articulation – see joint
Axial skeleton – The part of the skeleton that forms the central axis of the body; consists of skull, vertebral column, ribs and sternum
Ball-and-socket joint – Joint consisting of a spherical bone !tting into a cup-like cavity of another bone
Belly – The ‘eshy portion in the middle of a muscle
Biceps – The muscle on the front part of the upper arm
Bursa – A small sac or cavity !lled with ‘uid; found at friction points of a movable joint; plural: bursae
Canaliculi – Small canals in the matrix of bone; join the spaces that contain bone cells; singular: canaliculus
Cancellous bone – Bone that contains many large spaces; appears ‘spongy’
Cardiac muscle – The muscle that forms the wall of the heart
Cartilage – A type of connective tissue containing !fifibres of collagen
Cartilaginous joint – A joint at which only limited movement occurs between the bones; the bones are hfield in place by cartilage as between the ribs and sternum; also called a slightly movable joint
Central canal – A hollow that runs through the centre of the spinal cord; also the central channel in an osteon of compact bone (may be called the Haversian canal)
Chondrin – A matrix of protein and carbohydrate in cartilage
Chondroblast – A cell that forms the !fifibres and matrix of cartilage
Chondrocyte – A mature cartilage cell
Compact bone – A dense form of bone
Condyloid joint – A synovial joint in which one surface of bone is slightly convex and !ts into a slightly concave depression in another bone; also known as an elipsoid joint
Connective tissue – Tissue providing support for body organs
Contraction – Shortening of a muscle
Diaphysis – The shaft of a long bone
Elastic cartilage – Cartilage that contains elastic !fifibres
Elasticity – The ability of muscle !fifibres to return to their original length after being stretched
Ellipsoid joint – see condyloid joint
Epiphysis – The end of a long bone; plural: epiphyses
Extensibility – The ability of muscle !fifibres to be stretched when pulled
Extension – Lengthening of a muscle
Fibrocartilage – A type of cartilage that contains bundles of !fifibres
Fibrous capsule – The external layer of an articular capsule
Fibrous joint – A joint at which no movement occurs between the bones; the bones are hfield in place by !brous tissue, as between
| The musculoskeletal system allows movement223 – the bones of the skull; often called a fixed or immovable joint
Fixator – A muscle that contracts to immobilise a joint
Fixed joint – see !brous joint
Flexion – To bend; a movement that decreases the angle between articulating bones
Freely movable joint – see synovial joint
Functional classification – Classi!cation of a joint based on its range of motion
Gliding joint – A joint that allows movement in any direction
Haversian canal – A network of tubes in compact bone occupied by nerves and blood vessels
Haversian system – see osteon
Hinge joint – A joint that allows movement in one plane only
Hyaline cartilage – Flexible supporting cartilage
Immovable joint – see !brous joint
Insertion – The end of a muscle fixed to the movable bone
Involuntary muscle – Muscle that is not under conscious control; found in walls of internal organs; also called non-striated muscle, smooth muscle or plain muscle
Joint – The connection between two bones
Lacunae – Space in the matrix of bone or cartilage occupied by a cell; singular: lacuna
Lamellae – Concentric rings that make up compact bone; singular: lamella
Ligament – Fibrous tissue that attaches one bone to another bone
Matrix – Non-cellular material between the cells of a tissue
Meniscus – A cartilaginous disc found in the knee joint; divides the cavity into two parts; plural: menisci
Muscle fifibre – The long cylindrical cells that make up skeletal muscles
Muscle tone – Partial contraction of skeletal muscles
Myofibril – A thread-like structure found in the cytoplasm of muscle !fifibres
Myofilament – One of the structures that make up the myo!brils of skeletal muscle !fifibres
Myosin – One of the contractile proteins of skeletal muscle; makes up the thick myo!lament of a myo!bril
Origin – The end of a muscle that is fixed to the stationary bone
Osteoarthritis – Deterioration of joint cartilage due to age or injury, to the point where the bone surfaces are not protected
Osteocyte – A mature bone cell
Osteon – The basic unit of structure of compact bone; consists of a central canal surrounded by concentric layers of hard matrix and bone cells; also called the Haversian system
Osteoporosis – Reduced bone density due to ageing, resulting in increased risk of fractures
Perichondrium – A membrane that covers some types of cartilage
Periosteum – The dense, !brous outer covering of a bone
Pivot joint – A joint that allows rotation, such as between the radius and ulna
Posture – The way a person holds their body when standing or sitting
Prime mover – An alternative name for agonist
Red bone marrow – A region of some bones where blood cell production takes place
Rotation – Movement of a bone around its long axis
Saddle joint – The joint where the thumb is attached to the palm
Sarcolemma – A thin, transparent membrane surrounding a muscle cell
Sarcomere – The contractile unit of skeletal muscle; consists of actin and myosin !laments
Sarcoplasm – The cytoplasm of striated muscle !fifibres
Skeletal muscle – Muscle attached to bones, under voluntary control; also called voluntary or striated muscle
UNIT 1 |224Sliding –
filament theory – The theory used to explain muscle contraction
Smooth muscle – see involuntary muscle
Spongy bone – An alternative name for cancellous bone
Structural classification – Classi!cation of a joint based on the type of connective tissue holding the joint together
Synergist – A muscle that acts indirectly in steadying a joint during a particular movement
Synovial cavity – The space between articulating bones in a synovial joint
Synovial 9uid – Fluid that !lls the cavity of a synovial joint
Synovial joint – A freely movable joint; the amount of movement possible is limited by ligaments, muscles, tendons and adjoining bones
Synovial membrane – The inner layer of a capsule around a synovial joint
Tendon – Fibrous tissue that attaches muscle to bone
Trabeculae – Bony plates that criss-cross with many others to make up spongy bone; singular: trabecula
Triceps – The muscle at the back of the upper arm
Yellow bone marrow – The region of a bone where fat is stored

Unit 2: Reproduction and Inheritance

Chapter 9: DNA Determines the Structure and Function of Cells

Chapter Summary

DNA, or deoxyribonucleic acid, is a polymer made up of many nucleotides joined together in two strands that twist to made a double helix.
Each nucleotide has a sugar molecule, a phosphate group and one of the nitrogenous bases – adenine, thymine, guanine or cytosine.
The genetic code is the order of bases in DNA.
DNA is wrapped around eight proteins called histones, forming a nucleosome.
When a cell divides, the length of DNA coils to form a chromosome.
During cell division, DNA must replicate by the strands separating and acting as a template for nucleotides to join and form a complementary strand.
Sections of DNA on chromosomes contain the genetic code for the production of proteins.
RNA, or ribonucleic acid, is a single- stranded nucleic acid that differs from DNA, as its sugar is ribose and it contains uracil instead of thymine.
RNA may be messenger RNA, transfer RNA or ribosomal RNA.
A series of two bases coding for an amino acid is called a triplet on DNA, a codon on mRNA, and an anticodon on tRNA.
In transcription, a molecule of mRNA is produced that is complementary to the template strand of DNA.
mRNA is small enough to leave the nucleus through the nuclear pores.
In translation, the mRNA attaches to a ribosome and facilitates complementary tRNA molecules that bring the corresponding amino acids to form a protein molecule.
Gene expression is the process of converting instructions in our DNA into functional products.
Gene expression is regulated to control what each cell is producing at any time.
DNA regulates lipid and carbohydrate production through the production of enzymes.
Mitochondrial DNA is a circular molecule with no associated proteins. It is important for normal mitochondrial functioning.
Epigenetics relates to the chemical reactions that activate or deactivate the genome – in particular, the changes in the chromatin (the DNA and associated histones).
Chromatin changes come about from modi.cation of the shape of histone proteins, the addition of acetyl groups to the histones, and the methylation of either DNA or histones.

Chapter Glossary

Acetylation – Addition of an acetyl group to a histone protein so that gene expression is enhanced
Adenine – One of the nitrogenous bases found in DNA and RNA
Anticodon – A sequence of three bases in a tRNA molecule that binds to a complementary sequence of three bases (the codon) in an mRNA molecule, to specify a particular amino acid during protein synthesis
Chromatin – A tangled network of DNA in the nucleus of a cell that is not dividing
Chromosome – One of the 46 rod-like structures that appear in the nucleus of a human cell at the commencement of cell division
Coding strand – The strand of a DNA molecule that is not used to form mRNA
Codon – The strand of a DNA molecule that is not used to form mRNA
CpG site – A site on a DNA molecule where a cytosine nucleotide is next to a guanine nucleotide; DNA methylation usually occurs at these sites
Cytosine – One of the nitrogenous bases found in DNA and RNA
Deoxyribonucleic acid (DNA) – A molecule in the nucleus of a cell that determines the types of protein a cell can make
DNA ligase – Enzyme that joins short sections of DNA together
DNA polymerase – Enzyme that joins nucleotides together
DNA replication – The production of an identical copy of the DNA
Double helix – The spiral shape of the DNA molecule
Epigenetics – Altering expression of a gene without changing the gene structure
Gene – Section of a chromosome that contains the nucleotide sequence coding for a particular trait
Gene expression – The process where information in a gene is used to make a product
Guanine – One of the nitrogenous bases found in DNA and RNA
Helicase – The enzyme responsible for the separation of DNA strands during replication
Histone – A special protein around which DNA is coiled to form chromatin
Messenger RNA (mRNA) – An RNA molecule that transfers coded information from the nucleus to the ribosomes
Methylation – The addition of a methyl group to a DNA molecule that results in inhibition of gene expression
Mitochondrial DNA (mtDNA) – DNA found in the mitochondria
Nuclear DNA – DNA found in the nucleus
Nucleosome – A length of DNA wound around eight histone proteins
Nucleotide – Units of phosphate, sugar and nitrogen base that make up the DNA molecule
Ribonucleic acid (RNA) – A special molecule that takes the code for amino acids from DNA to the ribosomes
Ribosomal RNA (rRNA) – Nucleic acids that form part of the ribosomes
RNA polymerase – An enzyme that is active during transcription of RNA from DNA
Start codon – The sequence AUG (adenine, uracil, guanine) is the codon for the amino acid methionine; when a ribosome reaches this codon, it starts making protein
Template strand – The strand of a DNA molecule that is used to form the sequence of bases in mRNA and is copied during transcription
Thymine – One of the nitrogenous bases found in DNA
Transcription – The process by which messenger RNA is formed, using the code in a DNA molecule by matching the sequence of nucleotides
Transfer RNA (tRNA) – An RNA molecule that brings amino acids from the cytoplasm to the ribosomes
Translation – The production of a protein using the information coded in the mRNA molecule; another name for protein synthesis
Triplet – A sequence of three bases that is the code for a particular amino acid; also called a base triplet
Uracil – One of the nitrogenous bases found in RNA

Chapter 10: Cells Divide for Growth, Repair, Replacement and Reproduction

Chapter Summary

Cells reproduce to produce new cells and replace old, dead or damaged cells.
The cell cycle is made up of the first growth phase, synthesis phase, second growth phase and mitotic phase.
Mitosis, including DNA replication, ensures that the new cells are an exact copy of the parent cell.
The stages of mitosis are interphase, prophase, metaphase, anaphase and telophase.
Cytokinesis, or the division of the cytoplasm, occurs simultaneously with telophase.
Stem cells are undifferentiated cells that are able to form either new stem cells or specialised cells.
Stem cells can be classified as totipotent, pluripotent or multipotent.
Gametes, produced by meiosis, have half the number of chromosomes as somatic cells.
During the first stage of meiosis the homologous chromosomes separate, while during the second stage the chromatids separate.
Both stages of meiosis consist of prophase, metaphase, anaphase and telophase.
The daughter cells of meiosis vary in their genetic information due to crossing over, non-disjunction and random assortment.
Crossing over can occur during the first stage of meiosis when homologous chromosomes exchange segments.
Non-disjunction may occur during the first stage of meiosis if the homologous chromosomes do not separate, or during the second stage of meiosis if the chromatids do not separate.
Random, or independent, assortment is the homologous chromosomes separating in a manner independent of one another. This results in the combination of chromosomes from each homologous pair varying between daughter cells.
Cancer is the uncontrolled division of cells, producing masses called tumours.
Malignant tumours may spread through the body, while benign tumours do not.
Carcinogens are factors that may trigger malignant tumours. These include UV radiation, X-rays, ionising radiation, viruses, and some chemicals such as tobacco and alcohol.
Early detection of cancer increases the chance of survival. Cervical cancer may be detected by a Cervical Screening Test; fibreast cancer can be detected through a mammogram; bowel cancer is detected by a faecal occult blood test; and prostate cancer is detected by a rectal exam, blood test and biopsy.

Chapter Glossary

Anaphase – The third phase of mitosis, during which the daughter chromosomes are drawn to opposite ends of the cell
Anaphase I – The third phase of the first stage of meiosis, during which the homologous chromosomes move to opposite ends of the cell
Anaphase II – The third phase of the second stage of meiosis, during which the daughter chromosomes move towards opposite ends of the cell
Benign – Not able to spread to other parts of the body
Cancer – A malignant growth; one that has the capability of spreading to other body parts
Carcinogen – A cancer-causing agent
Cell cycle – The events that take place from one cell division to the next
Chiasma – The point at which crossing over occurs between chromatids; plural: chiasmata
Crossing over – The interchange of the parts of the chromatids of a homologous pair of chromosomes during the first stage of meiosis; it creates new combinations of alleles
Cytokinesis – The division of the cytoplasm to form two daughter cells
Di+erentiation of cells – The process by which unspecialised cells develop special characteristics to suit particular functions
Diploid number – The number of chromosomes in a cell with both chromosomes from each homologous pair
Down syndrome – see trisomy 21
Fertilisation – Fusion of sperm and egg
G phase – The phase of the cell cycle when the cell is functioning but not preparing for division
G phase – The first growth phase of the cell cycle
G phase – The second growth phase of the cell cycle
Gamete – A sperm or egg cell
Haploid number – The number of chromosomes in a cell with only one chromosome from each homologous pair; half the diploid number
Homologous chromosomes – The pairs of chromosomes containing genes that control the same characteristics
Independent assortment – The random combination of alleles due to allele pairs separating independently of one another
Interphase – The stage in the life cycle of a cell when it is not dividing; the stage between mitotic divisions
M phase – The phase of the cell cycle when the cell divides into daughter cells; also known as the mitotic phase
Malignant – Able to spread to other parts of the body
Meiosis – A type of cell division resulting in sperm or eggs; the sperm or eggs have half the chromosome number of the parent cell
Metaphase – The second phase of mitosis, during which the chromosomes (pairs of chromatids) line up across the centre of the cell
Metaphase I – The second phase of the first stage of meiosis, during which the homologous chromosomes line up on the equator
Metaphase II – The second phase of the second stage of meiosis, during which the chromosomes line up on the equator
Metastasis – The spreading of tumour cells to form secondary tumours in different parts of the body
Mitosis – The process of division of the nucleus of a cell in which the two daughter nuclei have the same number and type of chromosomes as the parent nucleus; often used loosely to mean cell division
Monosomy – Where an individual has only one copy of a chromosome instead of two
Multipotent stem cells – Stem cells that are able to give rise to a limited number of other
UNIT 2 |270 – cell types; for example, blood stem cells will give rise to red blood cells, white blood cells and platelets
Non-disjunction – When one or more of the chromosome pairs fail to separate during meiosis
Partial monosomy – When a person has part of a chromosome missing
Partial trisomy – When a person has part of an extra chromosome
Pluripotent stem cells – Stem cells that are able to give rise to many, but not all, of the cell types necessary for foetal development
Prophase – The first phase of mitosis, during which the chromosomes become visible, the nuclear membrane fibreaks down and the spindle forms
Prophase I – The first phase of the first stage of meiosis, during which the chromosomes become visible, the nuclear membrane fibreaks down and the spindles form
Prophase II – The first phase of the second stage of meiosis, during which the nuclear membrane disappears and the spindles form
Random assortment – see independent assortment
Recombination – A changing of the order of alleles along a chromosome
S phase – The synthesis phase of the cell cycle, when DNA molecules duplicate
Secondary tumour – Cancer that has spread from the original cancer
Stem cell – Cell that has the ability to produce different types of body cells
Telophase – The final phase of mitosis, during which the daughter chromosomes group at opposite ends of the cell and two daughter nuclei form
Telophase I – The fourth phase of the first stage of meiosis, during which the new nuclear membrane forms
Telophase II – The fourth phase of the second stage of meiosis, during which the new nuclear membrane forms
Totipotent stem cells – Stem cells that are able to create any of the types of cell necessary for embryonic development
Trisomy – A condition in which an individual inherits an extra copy of a chromosome
Trisomy 21 – A genetic disorder resulting from an extra copy of chromosome 21; affected individuals have an altered physical appearance and variable degrees of intellectual disability; also called Down syndrome
Tumour – An abnormal mass of tissue resulting from uncontrolled division of cells

Chapter 11: The Structure of the Reproductive Systems Allows Reproduction

Chapter Summary

Humans reproduce by a sperm and an egg fusing to form a zygote.
Sperm are produced in the testes, which are located in the scrotum.
The testes are divided into lobules, which are fllled with the seminiferous tubules. These tubules join to form the epididymis, which leave each testis and become the vas deferens.
Testosterone is produced by the interstitial cells found between the seminiferous tubules.
Semen contains fluids from the seminal vesicles, prostate gland and bulbo- urethral gland. It nourishes the sperm and aids their transport.
The sperm exits the male via the urethra, entering the female vagina during sexual intercourse.
Ovaries contain germ cells in a follicle. When the follicle matures it ruptures, releasing the egg into the uterine tube so that it can travel to the uterus.
The uterus is separated from the exterior by the cervix, which opens to the vagina and then the vulva.
Gametogenesis is the production of gametes by meiosis.
Sperm are produced by spermatogenesis, which occurs in the seminiferous tubules.
The seminiferous tubules are lined with spermatogonia. These are diploid cells and divide by mitosis once puberty starts.
Some of the daughter cells move to the centre of the tubule where they grow and become primary spermatocytes. These start meiosis and form secondary spermatocytes. After the second meiotic division the cells are called spermatids.
Spermatids form mature spermatozoa (sperm) by forming a mobile tail and losing most of the cytoplasm.
Sperm are made up of a head, neck, middle piece and tail.
Eggs, or ova, are produced by oogenesis.
Before birth, there are millions of diploid oogonia in the ovaries. These undergo growth to form primary oocytes, which begin the prophase of the flrst meiotic division.
At puberty, the meiotic division continues for a primary oocyte, forming a secondary oocyte and a polar body. The secondary oocyte enters the second stage of meiosis, but stops at the metaphase until fertilisation.
The ovarian and menstrual cycles are controlled by the endocrine system.
Follicle-stimulating hormone and luteinising hormone are gonadotropins that are produced by the pituitary gland.
Follicle-stimulating hormone stimulates the development and maturation of the follicles in females and epithelial cells to produce sperm in males.
Luteinising hormone promotes the flnal maturation of the follicle, ovulation and the formation of the corpus luteum in females and the production of testosterone in males.
Ovarian follicles secrete oestrogen, while the corpus luteum secretes progesterone and oestrogen.
Testosterone leads to the maturation of spermatozoa in addition to the maintenance of the reproductive organs and sex drive.
During the ovarian cycle the outer cells form a layer around the developing egg. They produce a fluid that pushes the egg to the edge, forming a secondary follicle. When the egg reaches the edge it pushes against the surface; the follicle is now called a mature follicle.
The mature follicle bursts at ovulation, releasing the egg into the uterine tube.
A corpus luteum forms in the ruptured follicle. If fertilisation does not occur, it degenerates to become a corpus albicans. If fertilisation does occur, the placenta produces human chorionic gonadotropin, which maintains the corpus luteum until the placenta is able to produce oestrogen and progesterone.
During the menstrual cycle, progesterone from the developing follicle causes the endometrium to thicken and soften. If the egg is not fertilised, the reduction in progesterone leads to the fibreakdown of the endometrium. The blood, mucus and cells are lost through the vagina during menstruation.
Menarche is when a female starts menstruating, and menopause is when she stops menstruating.
The secondary sexual characteristics are associated with a person’s sex, but not with reproduction – for example, fibreast development in females and a deepening of the voice in males.

Chapter Glossary

Bulbo-urethral gland – One of a pair of small yellow glands that secrete a lubricating fluid into the urethra; also called Cowper’s gland
Cervix – The neck of the uterus, leading into the vagina
Clitoris – The erectile organ of the female; it is equivalent to the penis in males
Corpus albicans – A flbrous mass of scar tissue left on the ovary after the corpus luteum degenerates
Corpus luteum – The temporary endocrine gland that forms in the ovary after the release of an egg
Cowper’s gland – see bulbo-urethral gland
Egg – see ova
Endocrine gland – A gland that secretes hormones directly into adjacent tissue; also called a ductless gland
Endometrium – The soft mucous membrane lining the uterus
Epididymis – A highly folded tubule behind each testis in which the sperm mature
Erectile tissue – Spongy tissue in the penis that fllls with blood to produce an erection
Fallopian tube – see uterine tube
Fimbriae – The flnger-like projections of the uterine tube
First polar body – The smaller of two unequal cells formed when the primary oocyte divides during the flrst division of meiosis
Follicle – A small secretory sac or gland
Follicle-stimulating hormone (FSH) – A hormone that stimulates the development of a follicle in the ovary
Gametogenesis – The formation and development of the gametes
Germ cell – Cells in the ovary that are able to develop into ova
Gonadotropic hormones – see gonadotropins
Gonadotropins – Hormones that affect the sex organs; also called gonadotropic hormones
Graafian follicle – see mature follicle
Hormone – A chemical secreted by an endocrine gland, often carried in the blood; it affects the functioning of a cell or organ
Human chorionic gonadotropin (HCG) – A hormone produced by the placenta during pregnancy
Hymen – The fold of tissue that covers the external opening of the vagina
Interstitial cells – Cells located in the mature testis; they secrete testosterone
Labia (labia majora and labia minora) – The eshy folds of skin lining the opening to the vagina and urethra
Lobule – A compartment within the testis that contains seminiferous tubules
Luteinising hormone (LH) – A hormone that promotes flnal maturation of the ovarian follicle and formation of the corpus luteum
Mature follicle – A fluid-fllled structure in the ovary; it contains an immature egg and its surrounding tissues
Menarche – The onset of menstruation
Menopause – Cessation of menstruation
Menstrual cycle – The regular series of changes that take place in the walls of the uterus of a non-pregnant female
Menstrual period – see menstrual cycle
Menstruation – The periodic discharge of blood and tissue fluid due to the fibreakdown of the lining of the uterus; also known as the menstrual period
Oestrogen – A general name for a female sex hormone; it develops or maintains female reproductive structures
Oogenesis – The formation and development of the ovum within the ovary
Oogonia – The cells in the ovaries that produce primary oocytes by mitosis; singular: oogonium
Ova – Mature egg cells; singular: ovum
Ovarian cycle – The regular series of events that take place within an ovary of a non-pregnant female, associated with the maturation of an egg
Ovaries – The organs in which the female gametes, the ova (or eggs), are produced
Oviduct – see uterine tube
UNIT 2 |298Oxytocin – A hormone produced by the hypothalamus and released by the posterior pituitary gland that has a role in childbirth and lactation
Pituitary gland – An endocrine gland located below the brain
Polar body – A haploid cell produced during oogenesis that contains a nucleus and very little cytoplasm
Primary follicle – A dormant egg within the ovary
Primary oocyte – Diploid cells in the ovary that undergo meiosis to produce haploid secondary oocytes
Primary sex organs – The organs that produce gametes: testes and ovaries
Primary spermatocyte – Diploid cells that undergo the flrst division of meiosis to produce secondary spermatocytes
Progesterone – A female sex hormone produced by the ovaries; it helps prepare the uterine lining for a fertilised egg and the mammary glands for milk secretion
Prolactin – A hormone that promotes milk production during and after pregnancy
Prostate gland – A gland that surrounds the urethra just below the bladder; it secretes a fluid that becomes part of the semen
Puberty – The period during which a person becomes sexually mature
Scrotum – The pouch outside the abdominal cavity in which the testes are located
Second polar body – A polar body formed during the second stage of meiosis
Secondary follicle – A previously dormant (primary) follicle that has begun to develop
Secondary oocyte – Haploid cells that undergo meiosis to produce ova
Secondary sex organs – Organs essential for reproduction but which do not produce gametes
Secondary sexual characteristics – A characteristic associated with an individual’s sex but which is not involved in sexual reproduction
Secondary spermatocyte – Haploid cells that undergo the second division of meiosis to produce spermatids
Semen – The liquid that nourishes and aids the transport of sperm; also called seminal fluid
Seminal fluid – see semen
Seminal vesicles – A pair of pouch-like organs that secrete a thick fluid which is a major part of semen
Seminiferous tubules – A tightly coiled duct, located in the testis, where sperm are produced
Sperm – see spermatozoa
Sperm duct – see vas deferens
Spermatids – Haploid cells produced from spermatogonia by meiosis; they mature to form spermatozoa
Spermatogenesis – The formation and development of the spermatozoa
Spermatogonia – Immature cells lining the seminiferous tubules
Spermatozoa – Male gametes; also called sperm; singular: spermatozoon
Stroma – Connective tissue in the ovary
Testes – The male sex organs that produce sperm and the hormone testosterone; singular: testis
Testosterone – The male sex hormone secreted by endocrine cells within a mature testis
Urethra – The duct that carries urine from the bladder to the exterior; in males it also carries semen
Uterine tube – The tube that carries the eggs from the ovaries to the uterus; also called a Fallopian tube or oviduct
Uterus – The hollow, pear-shaped organ situated between the urinary bladder and the rectum in females; also called the womb
Vagina – The canal leading from the uterus to the exterior of the female body
Vas deferens – The tube that carries the sperm away from the testis; also called the sperm duct; plural: vasa deferentia
Vulva – Female external genitalia
Womb – see uterus
Zygote – The fertilised egg from which a new individual develops

Chapter 12: Reproduction Produces Offspring

Chapter Summary

Male and female gametes are brought together by sexual intercourse.
During sexual intercourse, an erect penis releases semen into the vagina through an ejaculation. This process is called insemination.
Sperm travel via the cervix into the uterus before moving up the uterine tubes.
For a sperm to fertilise the oocyte, it must penetrate the corona radiata and zona pellucida. Enzymes on the acrosomes of a large number of sperm fibreak down the cement holding the corona radiata together. An acrosomal reaction then releases digestive enzymes, allowing a single sperm to move through the zona pellucida and fuse with the plasma membrane of the oocyte.
When the male pronucleus and female pronucleus join, they form a diploid cell called a zygote.
The zygote undergoes mitosis, forming a hollow, &uid-(lled ball called a blastocyst, which implants itself in the wall of the uterus.
The inner cell mass of the blastocyst divides and differentiates to form the embryo.
The zygote is a totipotent stem cell. The inner cell mass is made of pluripotent cells, which form multipotent stem cells after some specialisation.
The blastocyst divides into theffectoderm, which forms the outer layers of the body; the mesoderm, which forms the skeleton, muscles and connective tissue; and the endoderm, which forms the lining of the digestive tract and lungs.
Embryonic membranes protect and nourish the embryo. The amnion surrounds the embryo and contains the amniotic &uid. The chorion surrounds the embryo and the other embryonic membranes. It becomes the main foetal portion of the placenta.
The placenta connects the foetus and mother to provide nutrients, remove wastes, and produce necessary hormones.
The umbilical cord has two umbilical arteries and an umbilical vein that carry blood between placenta and foetus.
During pregnancy, the embryo grows in size and develops muscles, bones and organs. Limbs then start to grow and the external sexual organs are evident.
By the end of the (rst two months, the embryo is termed a foetus and has the general form of an infant.
During its development, the foetus starts moving, becomes more erect and increases in size.
During pregnancy, the mother’s abdomen increases in size (re&ecting the size of the foetus), her fibreasts enlarge, and blood volume increases.
Prior to birth, the foetus moves so that its head rests in the pelvis; hormones soften the pelvic ligaments in the mother.
During the (rst stage of labour, uterine contractions gradually increase in strength and the cervix dilates until it forms the birth canal with the uterus, cervix and vagina.
During the second stage of labour, the membrane bursts and contractions push the foetus through the birth canal.
In the (nal stage, the placenta, other membranes and the remains of the umbilical cord are expelled.
Following birth, the baby’s blood must &ow through the lungs and liver. Therefore, the structures that bypass these organs during pregnancy – the ductus arteriosus, foramen ovale and ductus venosus – must close.
Mothers can look after themselves and their baby during pregnancy by eating a well-balanced diet that includes folic acid, calcium, &uoride and vitamin A; avoiding foods that may cause listeriosis; controlling weight gain; and maintaining an exercise routine.
Some chemicals, such as hormones, antibiotics, thalidomide, marijuana, alcohol and cigarettes, can affect the development of the foetus. These are known as teratogens.

Chapter Glossary

Acrosomal reaction – The release of enzymes from the acrosome when the spermatozoa fuses with the ovum
Afterbirth – The placenta, and the remains of the umbilical cord, amnion and chorion; it is expelled shortly after the birth of a baby
Amnion – The membrane that forms a cavity around the embryo; it secretes a &uid (amniotic &uid) into the cavity to protect the embryo
Amniotic !uid – The &uid contained within the amnion; it protects the embryo against injury
Birth canal – The passage formed by the uterus, the dilated cervix and the vagina, through which the foetus travels at birth
Blastocyst – A hollow ball of cells formed during early embryonic development
Chorion – One of the embryonic membranes that eventually forms part of the placenta
Chorionic villi – Finger-like projections that develop from the outer layer of cells of the early embryo; they grow to form part of the placenta; singular: chorionic villus
Climax – The moment of intense pleasure during sexual intercourse
Corona radiata – The innermost layer of cells surrounding the egg (or ovum)
Dilation of the cervix – The (rst stage of labour, from the beginning of labour to the complete opening of the cervix
Ductus arteriosus – The foetal blood vessel that enables blood in the pulmonary artery to bypass the lungs and &ow directly into the aorta
Ductus venosus – The foetal blood vessel that enables blood to bypass the liver
Ectoderm – The outer tissue layer of the embryo; it gives rise to the outer covering of the body
Ejaculation – Muscular contractions that propel semen from the penis
Embryo – The early stage of development of an organism; in humans, from fertilisation to the end of the eighth week of pregnancy
Embryoblast – see inner cell mass
Endoderm – The inner tissue layer of the embryo; it gives rise to the lining of the digestive tract and the glands associated with it, as well as to the respiratory tract and parts of the excretory and reproductive systems
Erection – The penis in a state of sexual excitation
Female pronucleus – see pronucleus
Foetal alcohol syndrome (FAS) – Abnormalities in a newborn baby due to the mother’s excessive alcohol consumption during pregnancy; frequently results in lower than normal birth weight, a small head and slow growth
Foetus – The developing individual after the second month of pregnancy
Foramen ovale – An opening between the atria of the foetal heart; it allows blood to &ow directly from the right atrium into the left atrium
Gene – The factor that determines a hereditary characteristic; part of a chromosome
Gestation – The period of development of an organism in the uterus; the time between conception and birth
Implantation – The process whereby an embryo sinks into the lining of the uterus
Inner cell mass – The group of cells in the blastocyst that develop into the embryo; also called the embryoblast
Insemination – The deposition of sperm within the vagina
Labour – The sequence of events that precede birth and result in the expulsion of the foetus through the vagina
Labour pains – Contractions of the uterus that indicate the beginning of labour
Listeriosis – An illness caused by eating food contaminated with listeria bacteria
Male pronucleus – see pronucleus
Mesoderm – The middle tissue layer of an embryo; it gives rise to the muscles, connective tissues and the alimentary canal
UNIT 2 |330Microenvironment – The immediate surroundings of a cell
Multipotent stem cell – Stem cells that are able to give rise to a limited number of other cell types; for example, blood stem cells will give rise to red blood cells, white blood cells and platelets
Orgasm – The climax of sexual intercourse
Parturition – The process of birth
Placenta – The organ that supplies nutrients to, and removes wastes from, the foetus; it also produces a number of hormones, including oestrogen and progesterone
Pluripotent stem cell – Stem cells that are able to give rise to many, but not all, of the cell types necessary for foetal development
Primary germ layer – The embryonic tissues from which all tissues and organs of the body will develop: theffectoderm, endoderm and mesoderm
Proliferation – The process by which cells replicate themselves
Pronucleus – The nucleus of the ovum (female: pronucleus) and of the sperm (male: pronucleus) that fuse at fertilisation
Rubella – A viral infection that, if contracted by a pregnant woman, can have serious consequences for her unborn child; the child may be born deaf, blind or with heart malformations
Semen – The liquid that nourishes and aids the transport of sperm; also called seminal &uid
Sexual intercourse – The sex act during which gametes are passed from the male to the female
Sperm mortality – The death rate of sperm
Stage of expulsion – The second stage of labour, from full dilation of the cervix to birth
Teratogen – An agent that causes physical defects in a developing foetus
Teratogenic agent – see teratogen
Thalidomide – A teratogen that causes babies to be born with limb malformations
Totipotent stem cell – A stem cell able to create any of the types of cell necessary for embryonic development
Umbilical arteries – Two arteries within the umbilical cord
Umbilical cord – The cord that attaches the foetus to the placenta
Umbilical vein – A single vein within the umbilical cord that carries blood from the placenta to the foetus
Umbilicus – The small scar on the abdomen that marks the former attachment of the umbilical cord to the foetus; commonly called the navel
Zona pellucida – The thick glycoprotein membrane surrounding the plasma membrane of the ovum
Zygote – The fertilised ovum from which a new individual develops

Chapter 13: Reducing the Chance of Pregnancy and STIs

Chapter Summary

Contraception reduces the chance of pregnancy.
Refraining from sexual intercourse, or abstinence, is the only contraceptive method that has no risk of pregnancy.
Detecting ovulation via the rhythm method, the temperature method, the mucus method or a combination of these can allow couples to abstain from sexual intercourse before, during and after ovulation.
During fibreastfeeding, ovulation is suppressed and so the chance of pregnancy is reduced. This is lactational amenorrhoea.
Coitus interruptus is an unreliable contraceptive method that stops the semen entering the female by removing the penis prior to ejaculation.
Mechanical barriers separate the sperm and the egg. These include: – condoms, which cover the penis – diaphragms, which cover the top of the vagina – cervical caps, which cover the entrance to the cervix – female condoms, which line the vagina.
Spermicides may be used with most mechanical barriers to immobilise, and act as a barrier to, sperm.
Hormonal contraceptive methods such as contraceptive pills, hormone implants and vaginal rings are effective methods that prevent ovulation by altering hormone levels.
Intrauterine devices, or IUDs, are implanted in the uterus to release hormones or interfere with the movement of sperm.
The morning-after pill uses progestogen to alter ovulation, stop the sperm reaching the egg and prevent implantation. This means that it is able to prevent pregnancy even after sexual intercourse as long as it is taken within )ve days.
Sterilisation is a permanent method of contraception where the vas deferens or the uterine tubes are cut, a section is removed and the ends are tied. The procedure is called a vasectomy in males or tubal ligation in females.
There are many reasons for choosing a particular method of contraception. This includes reliability, convenience, side effects, cost, permanence, religious beliefs and ethical concerns.
Sexually transmitted infections are transmitted by close body contact, usually during sexual intercourse.
Chlamydia is caused by the bacterium Chlamydia trachomatis. Those who show symptoms may develop infections of the urethra, epididymis or pelvic organs. In females, chlamydia may lead to infertility or an ectopic pregnancy. There is also the chance that it will be passed on to a foetus during birth. Chlamydia is diagnosed by a urine test or a swab of the affected areas. It can then be treated with antibiotics.
Gonorrhoea is caused by the bacterium Neisseria gonorrhoeae. In males, it causes in+ammation of the urethra, but this may spread to other organs if not treated. In females, it infects the urethra or cervix, and may spread to the uterine tubes and other organs. The in+ammation may damage the oviduct to the point of infertility. Gonorrhoea can be treated with antibiotics.
Syphilis is caused by the bacterium Treponema pallidum. The primary stage shows as chancres, usually on the sex organs. The secondary stage follows a few weeks to a year after the primary stage and shows as skin rashes, ulcerated mouth, fevers, and bone or eye disorders. The latent stage has no noticeable symptoms. The tertiary stage occurs between 5 years and 40 years after the initial infection. The symptoms during this stage are serious, such as heart disease.
Genital herpes is caused by the herpes simplex virus, which produces blisters on the genital organs. Once a person is infected, the virus remains in the body for life. Therefore, the blisters can recur at any time.
Genital warts are caused by the human papillomavirus (HPV). Some of the warts may be internal, and therefore it is possible for someone to pass the virus on unknowingly.
Human immunodeficiency virus (HIV) is a retrovirus that infects T-lymphocytes. The infection goes through the stages of acute infection, chronic infection and then acquired immune de)ciency syndrome (AIDS). The virus is transmitted through body fluids such as blood, seminal fluid and fibreast milk. HIV is diagnosed by a blood test to determine the antibody levels present or the viral load. While there is no cure for HIV, antiretroviral drugs are able to inhibit the reproductive cycle of the virus and delay its progression.
STIs can be prevented by practising safe sex.

Chapter Glossary

Abstinence – Refraining from sexual intercourse
Acquired immune de-ciency syndrome (AIDS) – An extremely serious and often fatal disease caused by infection with human immunode)ciency virus (HIV) that damages the immune system so that the individual becomes susceptible to infection and to some forms of cancer
Castration – The removal of the testes
Cervical cap – A thin rubber cap that is )tted across the cervix before sexual intercourse; it prevents sperm entering the uterus
Chancres – The initial stage of a syphilis infection; small sores that appear on the penis, labia of the vagina, and sometimes other parts of the body
Chlamydia – One of the most common sexually transmitted infections; transmitted by the Chlamydia trachomatis bacterium; results in in+ammation of the urethra in males and of the uterus and uterine tubes in females
Coitus interruptus – A method of birth control that depends on the withdrawal of the penis from the vagina just before ejaculation
Combined pill – A contraceptive pill that contains oestrogen and progesterone
Condom – A thin sheath of latex that is rolled on to the erect penis before sexual intercourse to prevent sperm from entering the vagina; a means of contraception
Contact tracing – The process of identifying the relevant contacts of a person with an infectious disease to ensure that they are aware of their exposure to the infection; for sexually transmitted infections (STIs), relevant contacts include those with whom the infected person has had sex during the infectious period
Contraception – The prevention of conception; birth control
Diaphragm – A thin rubber cap that is )tted across the vagina before sexual intercourse to prevent sperm from entering the uterus
Ectopic pregnancy – A pregnancy in which the embryo implants at a site other than in the lining of the uterus, most frequently in one of the uterine tubes
Epididymitis – In+ammation or infection of the epididymis; results in pain and swelling of the epididymis
Femidom – A female condom; a lubricated polyurethane sheath that lines the vagina
Genital herpes – A viral infection of the genital region caused by the herpes simplex type 2 virus; results in persistent and painful blisters
Genital warts – Warts in the genital region transmitted during sexual intercourse and caused by the human papillomavirus
Gonorrhoea – One of the most common sexually transmitted infections; transmitted by the bacterium Neisseria gonorrhoeae during sexual intercourse; infects the mucous membranes of the reproductive organs; commonly referred to as ‘the clap’
Herpes simplex virus – Causes genital herpes, a viral infection of the genital region
Human immunode-ciency virus (HIV) – A virus that is transmitted by infected body fluids such as blood and semen, and causes progressive damage to the body’s immune system; frequently transmitted during unprotected sexual intercourse
Human papillomavirus (HPV) – A highly contagious virus spread through close contact. Some types of HPV cause genital warts; nearly a third of all the known types of HPV can be transmitted through sexual contact
Hysterectomy – The complete or partial removal of the uterus
Implanon NXT – A plastic rod that is implanted under the skin to slowly release progestogen to prevent pregnancy
Incubation period – The time between infection and the appearance of the symptoms of a disease
Intrauterine device (IUD) – A plastic or metallic device inserted into the uterus to prevent conception
| Reducing the chance of pregnancy and STIs359Lactational amenorrhoea – Temporary infertility that follows the birth of a child
Latent stage – The dormant or hidden stage of the course of a disease or infection; one of the stages of a syphilis infection
Mini pill – A contraceptive pill that contains only progestogen
Morning-after pill – Emergency contraceptive pill, taken after sexual intercourse
Mucus – A thick fluid secreted by mucous glands and mucous membranes
Mucus method – A method of contraception whereby the consistency of the cervical mucus is used to estimate when ovulation is occurring
Non-speci-c urethritis (NSU) – A sexually transmitted infection usually caused by the Chlamydia trachomatis bacterium
NuvaRing – A soft plastic vaginal ring that contains oestrogen and progestogen
Oophorectomy – The surgical removal of the ovaries
Pandemic – An infection that has spread to all parts of the world.
Pelvic in.ammatory disease (PID) – A bacterial infection of the pelvic organs of a female, especially of the uterus and uterine tubes
Periodic abstinence – A method of contraception based on abstaining from sexual intercourse when fertilisation is most likely
Pubic lice – Insects that infest the genital area causing intense itching; usually transmitted by sexual intercourse
Retrovirus – A virus that contains RNA instead of the more usual DNA
Rhythm method – A method of contraception in which sexual intercourse is avoided around the time that ovulation is likely to occur
Safe sex – Sexual activity in which precautions are taken that reduce the risk of getting a sexually transmitted infection (STI) or an unplanned pregnancy
Scabies – A mite that burrows into the skin causing intense itching, frequently in the genital area; often transmitted by sexual intercourse
Sexually transmitted disease (STD) – see sexually transmitted infection
Sexually transmitted infection (STI) – An infection transmitted by direct sexual contact, usually through sexual intercourse; formerly referred to as sexually transmitted disease (STD)
Spermicide – Chemical that immobilises or kills sperm
Symptothermal method – A method of contraception that combines the rhythm, temperature and mucus methods
Syphilis – A sexually transmitted infection caused by the bacterium Treponema pallidum; often referred to as ‘the pox’
Temperature method – A variation of the rhythm method of contraception, where the woman’s body temperature is used to estimate when ovulation is occurring
Trichomoniasis – An infection caused by the protozoan Trichomonas vaginalis that results in in+ammation of the mucous membranes of the vagina in women and the urethra in men
Tubal ligation – Female sterilisation; the removal of a small piece, or the clamping off, of each uterine tube
Vasectomy – Male sterilisation; the removal of a small piece of each vas deferens

Chapter 14: Technologies Are Available to Assist in Reproduction

Chapter Summary

Infertility is the inability to conceive despite frequent unprotected sexual intercourse.
Anything that reduces the chance of the sperm reaching and fertilising the egg, or the fertilised egg implanting, will affect fertility.
To fertilise an egg, sperm need to be in sufficient numbers, move forward and penetrate the layers of the egg.
Blockages of the tubes, hormonal imbalances, antibodies affecting the sperm and low semen “ow can affect male fertility.
The number of healthy eggs in females decreases with age. Once menopause has been reached, ovulation stops.
Polycystic ovarian syndrome results in many follicles forming, but failing to mature and release eggs.
Endometriosis may block the uterine tubes, while some fibroids distort the uterus and uterine tubes.
Problems with the menstrual cycle affect fertility by changing the development of the endometrium.
Infertility treatments vary depending on the cause of the problem.
Surgery may be used to correct structural problems and to collect sperm in males unable to ejaculate sufficient sperm.
Ovulation tracking allows sexual intercourse to occur at a time when fertilisation is most likely.
Medication can induce ovulation so that the egg is able to meet the sperm.
Artificial insemination makes it more likely that the sperm will meet the egg by depositing it in the uterus.
Assisted fertilisation techniques help fertilisation to occur.
Gamete intrafallopian transfer involves the sperm and egg being collected and analysed before being mixed and deposited in the uterine tubes.
In vitro fertilisation involves the sperm and the egg being mixed and incubated to allow fertilisation to occur. Embryos can then be transferred into the uterus.
Intracytoplasmic sperm injection involves the sperm being injected into the egg, and the resulting embryo being transferred into the uterus.
Donor eggs, sperm or embryos may be used for couples who have problems with these structures. Surrogacy can be used for females who are unable to conceive or carry a baby.
Factors to consider with fertility treatments include the fate of unused embryos, religious beliefs and cost.
Technologies are used to monitor the health of a foetus during pregnancy.
Ultrasounds use sound waves to gain a visual image of the foetus. This allows doctors to confirm the pregnancy and monitor the foetus’s development.
Amniocentesis, chorionic villus sampling and blood tests are used to collect samples for genetic analysis.
Amniocentesis uses a needle to extract some of the amniotic “uid, which contains foetal cells.
Chorionic villus sampling uses a needle to extract cells from the chorion.
Some of the baby’s DNA passes into the mother’s blood. A blood test can be used to screen for some disorders. Abnormalities detected can be diagnosed with amniocentesis or chorionic villus sampling.
Foetal monitoring records the heart rate. It is done with an electrocardiograph.
Fetoscopes can be a stethoscope, used to listen to the heart rate; or a fifibre-optic scope inserted into the uterus to look at the foetus.
Foetal blood tests provide quick results but have greater risks than other tests. Blood can be taken from the umbilical cord, umbilical vein or a foetal blood vessel.
Testing blood or amniotic “uid can identify the presence of proteins indicating diseases such as phenylketonuria or spina bifida.
DNA testing is able to detect disorders such as Duchenne muscular dystrophy and thalassaemia.

Chapter Glossary

Amniocentesis – A technique in which a small amount of the amniotic “uid surrounding a foetus is removed and examined for indications of possible defects in the foetus
Artificial insemination – Introducing semen from a donor into the vagina using a syringe, to bring about fertilisation
Assisted reproductive technology (ART) – Methods developed to assist couples to have a child, including in vitro fertilisation and intrafallopian transfer
Chorionic villus sampling (CVS) – A technique in which foetal cells are removed from the chorion and examined for indications of possible defects in the foetus
DNA probe – A section of DNA that complements the gene of interest
Electrocardiogram (ECG) – A record of the electrical activity of the heart
Electrocardiography – The process of obtaining an electrocardiogram
Endometriosis – A condition where tissue similar to the lining of the uterus grows outside the uterus
Fetoscope – The instrument used to examine a foetus in utero
Fetoscopy – The direct visual examination of a foetus through a small telescope-like instrument
Fibroids – A non-cancerous growth around the uterus
Gamete intrafallopian transfer (GIFT) – A method of assisted reproductive technology; a variation of IVF where sperm and eggs are mixed immediately after collecting the eggs
Infertility – Not being able to get pregnant despite having frequent, unprotected sex
Intracytoplasmic sperm injection (ICSI) – A procedure whereby a single sperm is inserted into a single egg
Intrauterine insemination (IUI) – Placing the sperm inside the female’s uterus
In vitro fertilisation (IVF) – Fertilisation outside the body of the female
Polycystic ovarian syndrome (PCOS) – A hormonal condition that causes changes to the menstrual cycle as well as cysts on the ovaries
Surrogacy – When a woman bears a child for someone else
Ultrasound – A technique in which inaudible, high-frequency sound waves are used to produce an image, especially of the foetus during pregnancy

Chapter 15: Genetics Can Be Used to Understand the Traits of Individuals and Families

Chapter Summary

Mendel’s principles of inheritance state that inherited characteristics are controlled by genes, and that each gamete receives one set of genes.
Mendel conducted experiments on garden peas, looking at characteristics such as seed shape, flower position and stem length. He started with plants that were pure-fibred for the trait. When two plants pure-fibred for the different forms of the trait were crossed, only the dominant trait was shown.
The principle of segregation states that during the formation of gametes, only one gene for each trait is included.
Alleles are the different forms of a gene. The dominant allele is represented by a capital letter. The recessive allele is represented by the lower-case letter.
The genotype is the combination of alleles for a trait. Homozygous genotypes have two of the same type of allele, whereas the heterozygous genotype has both a dominant and a recessive allele.
The phenotype is the expression of the genotype.
The offspring of the parents are called the first filial generation (F1), and their offspring are the second filial generation (F2).
Punnett squares are used to model a cross and the possible genotype of the offspring. They can be used to predict the probability of different phenotypes.
Pedigrees model the phenotypes of family members. Each member is represented by a square (male) or a circle (female), drawn in rows by generations. Connections between generations are shown by vertical lines. Individuals with the trait are shaded.
Patterns of phenotypes are used to determine the genotypes of individuals and, hence, the pattern of inheritance.
Single-gene disorders are caused by the inheritance of a single gene.
For autosomal dominant traits, parents without the trait are unable to have children with the trait.
Achondroplasia, facioscapulohumeral muscular dystrophy, Huntington’s disease and neuro%bromatosis are examples of autosomal dominant diseases.
Huntington’s disease is an autosomal dominant disease that causes involuntary movement of the limbs and dementia.
For autosomal recessive traits, both parents must have a recessive allele to pass on, and the individual must pass on a recessive allele to all children. Individuals with a heterozygous genotype will not show the trait, but are able to pass it on. Therefore, they are called carriers.
Phenylketonuria and cystic %brosis are examples of autosomal recessive disorders.
The 46 chromosomes in humans can be classi%ed as autosomal chromosomes or sex chromosomes: 44 chromosomes (22 pairs) are autosomal and 2 (1 pair) are sex chromosomes.
Sex chromosomes are either an X chromosome or a Y chromosome. The Y chromosome is much shorter than the X chromosome. Females have two X chromosomes (XX) and males have one of each (XY).
During meiosis, only one sex chromosome goes into each gamete. Every egg will have an X chromosome. Half the sperm will have an X chromosome and the other half will have a Y chromosome.
If the zygote forms from an egg and a sperm with X chromosomes, it will be a female. If the zygote forms from an egg with an X chromosome and a sperm with a Y chromosome, it will be a male.
Due to the shorter length of the Y chromosome, most of the genes on the X chromosome do not exist on the Y chromosome. Therefore, males only have one copy of these genes, but females have two. Traits found on the X chromosome are called sex-linked characteristics.
The genotypes for sex-linked characteristics of females may be homozygous dominant (XBXB), homozygous recessive (XbXb) or heterozygous (XBXb).
The genotypes for sex-linked characteristics of males may be hemizygous dominant (XBY) or hemizygous recessive (XbY). Males cannot be heterozygous, and therefore cannot be carriers.
Red–green colour blindness and haemophilia are sex-linked characteristics.
Co-dominant alleles are equally dominant. Therefore, if both alleles are present, both are observed. Both alleles are represented by the same upper-case letter, with a superscript representing the alleles.
The MN blood groups are an example of a trait with co-dominant alleles.
Characteristics that are controlled by more than two alleles are called multiple allelic.
The ABO blood group system is an example of a multiple allelic characteristic. Two of the alleles are co-dominant (IA and IB) and the third allele is recessive (i ). The dominant alleles will lead to the production of antigens. The blood groups are named from the antigens produced. Blood group O is due to homozygous recessive genotype, where neither antigen A nor antigen B is produced.
Genetic counselling provides advice regarding the probability of a particular problem based on the incidence in a family.
Genetic pro%ling can use electrophoresis to separate the DNA to produce a DNA pro%le. This can be used for forensic science, ancestry research and tracing hereditary diseases. It can allow inherited diseases to be detected before symptoms show, and the probability of parents having a child with the disease to be determined.
There are ethical considerations for genetic pro%ling, including providing consent for the DNA to be collected and used, who owns the information, the potential uses of the information and whether the knowledge is bene%cial.

Chapter Glossary

ABO blood group system – A system of classifying blood types according to the antigens on the surface of the red blood cells
Albino – An individual who lacks pigmentation, resulting in white skin, white hair and pink eyes (due to the reflection from blood vessels in the eyes)
Allele – The alternative forms of a gene that occur at a given point in a chromosome
Autosome – A non-sex chromosome
Carrier – An individual who carries a recessive allele that is not expressed in their appearance
Co-dominance – When contrasting alleles both affect the appearance of an individual and neither is dominant over the other
Consanguineous union – The union of two close relatives, usually cousins
Cystic “brosis – A disorder controlled by a recessive allele; it results in chest infections, a lack of digestive enzymes and increased salt loss
Dementia – A brain disorder resulting in memory loss, personality changes and impaired reasoning
DNA “ngerprint – see DNA pro%le
DNA pro”le – The pattern of bands revealed by the process of electrophoresis; also called DNA %ngerprint
Dominant trait – One of a pair of contrasting characteristics, which is controlled by an allele that is not masked by other alleles
Electrophoresis – A technique used to reveal DNA pro%les in a banded pattern
First “lial generation (F generation) – The offspring of the first set of parents
Gene – The factor that determines a hereditary characteristic; part of a chromosome
Genetic counselling – Advice regarding the risks of genetic disorders in future children
Genome – The complete set of genetic information of an organism
Genotype – The genetic constitution of an individual
Haemophilia – An inherited disorder in which the blood clots slowly or not at all
Hemizygous – Having no allelic counterpart; occurs with alleles in the X chromosome in males
Heterozygous – Possessing different alleles for a given characteristic
Homozygous – Possessing the same alleles for a given characteristic
Huntington’s disease – A hereditary disease, the symptoms of which sfieldom appear before 40 years of age, characterised by occasional involuntary flailing movements of the arms and legs
Hybrid – An offspring that is the result of a mating between individuals of two different genetic constitutions
Marker – A segment of DNA with known characteristics; can be used to compare DNA %ngerprints
Monohybrid cross – A mating between individuals in which only one pair of contrasting characteristics is being considered
Multiple alleles – Three or more alternative forms of a gene for a characteristic; although there may be many alternative forms, each person has only two of the alternatives
Multiple allelic – Traits governed by three or more alleles
Pedigree – A family tree
Phenotype – The appearance of an individual as determined by their genetic constitution
Phenylketonuria (PKU) – An inherited disease resulting in damage to the growing brain, and thus extreme intellectual disability; also a tendency towards epileptic seizures and a failure to produce normal skin pigmentation
Principle of segregation – The principle that the alleles for a trait are separated during the formation of gametes
| Genetics can be used to understand the traits of individuals and families417Progeny – Offspring
Punnett square – A grid used to predict the probability of genotypes of offspring
Pure-fibreeding – The production of the same characteristic in each succeeding generation when individuals are fibred among themselves; homozygous
Recessive trait – One of a pair of contrasting characteristics, which is controlled by an allele that is masked by dominant alleles
Red–green colour blindness – A sex-linked recessive trait that causes the colours red and green to be perceived as identical
Second “lial generation (F generation) – The offspring from crossing the first filial generation
Sex chromosomes – The pair of chromosomes that determines the sex of an individual
Sex-linked characteristic – A characteristic determined by genes carried on the X chromosome
Single-gene disorder – A disorder caused by the inheritance of a single defective gene
Trait – The characteristics due to the genetic constitution of an individual
X chromosome – One of the two sex chromosomes; it contributes to the determination of the sex of an individual
X-linked characteristic – see sex-linked characteristic
Y chromosome – One of the two sex chromosomes; it contributes to the determination of the sex of an individual