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IGCSE Revision Checklist

Revision checklists can be used to help you to focus on your revision. The checklist provides you with an overview of the skills and knowledge from
the syllabus that you should revise.

BIOLOGY (0610)

The table headings for International Mathematics are explained below:

You should be able to R A G Comments

This is what you should Tick the ‘R’, ‘A’, and ‘G’ column to record your progress. You can use the Comments column to:
be able to do or know The ‘R’, ‘A’ and ‘G’ represent different levels of • add more information about the details for each
for each part of the confidence, as follows: point
syllabus
• include a reference to a useful resource
R = RED: means you are really unsure and lack
• add further information of your own, such as
confidence in that area; you might want to focus your
names of case studies needed
revision here and possibly talk to your teacher for help.
• add learning aids, such as rhymes, poems or
A = AMBER: means you are reasonably confident in a word play
topic but need some extra practice. • pinpoint areas of difficulty you need to check
further with your teacher or textbooks.
G = GREEN: means you are very confident in a topic.

As your revision progresses, you can concentrate on the

RED and AMBER topics, in order to turn them into
GREEN topics.

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1. Characteristics and classification of living organisms

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1.1 Characteristics of living organisms
 Describe the characteristics of living organisms by defining the terms:
– movement as an action by an organism causing a change of position or place
– respiration as the chemical reactions in cells that break down nutrient
molecules and release energy
– sensitivity as the ability to detect and respond to changes in the environment
– growth as a permanent increase in size
– reproduction as the processes that make more of the same kind of organism
– excretion as removal from organisms of toxic materials and substances in
excess of requirements
– nutrition as taking in of materials for energy, growth and development
Extended Material
 Define the terms:
– movement as an action by an organism or part of an organism causing a
change of position or place
– respiration as the chemical reactions in cells that break down nutrient
molecules and release energy for metabolism
– sensitivity as the ability to detect or sense stimuli in the internal or external
environment and to make appropriate responses
– growth as a permanent increase in size and dry mass by an increase in cell
number or cell size or both
– excretion as removal from organisms of the waste products of metabolism
(chemical reactions in cells including respiration), toxic materials, and
substances in excess of requirements
– nutrition as taking in of materials for energy, growth and development;
plants require light, carbon dioxide, water and ions; animals need organic
compounds and ions and usually need water

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1.2 Concept and use of a classification system
 State that organisms can be classified into groups by the features that they
share
 Define species as a group of organisms that can reproduce to produce fertile
offspring
 Define and describe the binomial system of naming species as an
internationally agreed system in which the scientific name of an organism is
made up of two parts showing the genus and species
Extended Material
 Explain that classification systems aim to reflect evolutionary relationships
 Explain that classification is traditionally based on studies of morphology
and anatomy
 Explain that the sequences of bases in DNA and of amino acids in proteins
are used as a more accurate means of classification
 Explain that organisms which share a more recent ancestor (are more
closely related) have base sequences in DNA that are more similar than
those that share only a distant ancestor
1.3 Features of organisms
 List the features in the cells of all living organisms, limited to cytoplasm,
cell membrane and DNA as genetic material
 List the main features used to place animals and plants into the appropriate
kingdoms
 List the main features used to place organisms into groups within the
animal kingdom, limited to:
– the main groups of vertebrates: mammals, birds, reptiles,
amphibians, fish
– the main groups of arthropods: myriapods, insects, arachnids,
crustaceans

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1.3 Features of organisms
Extended Material
 List the features in the cells of all living organisms, limited to ribosomes
for protein synthesis and enzymes involved in respiration
 List the main features used to place all organisms into one of the five
kingdoms: Animal, Plant, Fungus, Prokaryote, Protoctist
 List the main features used to place organisms into groups within the plant
kingdom, limited to ferns and flowering plants (dicotyledons and
monocotyledons)
 List the features of viruses, limited to protein coat and genetic material
1.4 Dichotomous keys
 Construct and use simple dichotomous keys based on easily identifiable
features
. There is no extended content for ‘1.4 Dichotomous keys’.
2. Organisation of the organism
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2.1 Cell structure and organisation
 Describe and compare the structure of a plant cell with an animal cell, as
seen under a light microscope, limited to cell wall, nucleus, cytoplasm,
chloroplasts, vacuoles and location of the cell membrane
 State the functions of the structures seen under the light microscope in the
plant cell and in the animal cell
Extended Material
 State that the cytoplasm of all cells contains structures, limited to
ribosomes on rough endoplasmic reticulum and vesicles
 State that almost all cells, except prokaryotes, have mitochondria and
rough endoplasmic reticulum
 Identify mitochondria and rough endoplasmic reticulum in diagrams and
images of cells
 State that aerobic respiration occurs in mitochondria
 State that cells with high rates of metabolism require large numbers of
mitochondria to provide sufficient energy

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2.2 Levels of organisation
 Relate the structure of the following to their functions:
– ciliated cells – movement of mucus in the trachea and bronchi
– root hair cells – absorption
– xylem vessels – conduction and support
– palisade mesophyll cells –photosynthesis
– nerve cells – conduction of impulses
– red blood cells – transport of oxygen
– sperm and egg cells –reproduction
 Define tissue as a group of cells with similar structures, working together
to perform a shared function
 Define organ as a structure made up of a group of tissues, working
together to perform specific functions
 Define organ system as a group of organs with related functions, working
together to perform body functions
 State examples of tissues, organs and organ systems from sections 6 to 16
 Identify the different levels of organisation in drawings, diagrams and
images of familiar material
Extended Material
 Identify the different levels of organisation in drawings, diagrams and
images of unfamiliar material
2.3 Size of specimens
 Calculate magnification and size of biological specimens using millimetres
as units
Extended Material
 Calculate magnification and size of biological specimens using millimetres
and micrometres as units

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3. Movement in and out of cells

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3.1 Diffusion
 Define diffusion as the net movement of particles from a region of their
higher concentration to a region of their lower concentration down a
concentration gradient, as a result of their random movement
 Describe the importance of diffusion of gases and solutes
 State that substances move into and out of cells by diffusion through the
cell membrane
Extended Material
 State that the energy for diffusion comes from the kinetic energy of
random movement of molecules and ions
 Investigate the factors that influence diffusion, limited to surface area,
temperature, concentration gradients and distance
3.2 Osmosis
 State that water diffuses through partially permeable membranes by
osmosis
 State that water moves in and out of cells by osmosis through the cell
membrane
 Investigate and describe the effects on plant tissues of immersing them in
solutions of different concentrations
 State that plants are supported by the pressure of water inside the cells
pressing outwards on the cell wall
Extended Material
 Define osmosis as the net movement of water molecules from a region of
higher water potential (dilute solution) to a region of lower water potential
(concentrated solution), through a partially permeable membrane
 Explain the effects on plant tissues of immersing them in solutions of
different concentrations by using the terms turgid, turgor pressure,
plasmolysis and flaccid

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3.2 Osmosis Extended Material Continues…
 Explain the importance of water potential and osmosis in the uptake of
water by plants
 Explain the importance of water potential and osmosis on animal cells and
tissues
 Explain how plants are supported by the turgor pressure within cells, in
terms of water pressure acting against an inelastic cell wall
3.3 Active transport
 Define active transport as the movement of particles through a cell
membrane from a region of lower concentration to a region of higher
concentration using energy from respiration
Extended Material
 Discuss the importance of active transport as a process for movement
across membranes:
– e.g. ion uptake by root hairs and uptake of glucose by epithelial cells of
villi and kidney tubules
 Explain how protein molecules move particles across a membrane during
active transport

4. Biological molecules

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 List the chemical elements that make up:
– carbohydrates
– fats
– proteins

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Biological molecules Continues…
 State that large molecules are made from smaller molecules, limited to:
– starch and glycogen from glucose
– cellulose from glucose
– proteins from amino acids
– fats and oils from fatty acids and glycerol
 Describe the use of:
– iodine solution to test for starch
– Benedict’s solution to test for reducing sugars
– biuret test for proteins
– ethanol emulsion test for fats and oils
– DCPIP test for vitamin C
 State that water is important as a solvent
Extended Material
 Explain that different sequences of amino acids give different shapes to
protein molecules
 Relate the shape and structure of protein molecules to their function,
limited to the active site of enzymes and the binding site of antibodies
 Describe the structure of DNA as:
– two strands coiled together to form a double helix
– each strand contains chemicals called bases
– cross-links between the strands are formed by pairs of bases

5. Enzymes
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 Define the term catalyst as a substance that increases the rate of a chemical
reaction and is not changed by the reaction
 Define enzymes as proteins that function as biological catalysts
 Describe why enzymes are important in all living organisms in terms of
reaction speed necessary to sustain life

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5. Enzymes Continues…
 Describe enzyme action with reference to the complementary shape of an
enzyme and its substrate and the formation of a product (knowledge of the
term active site is not required)
 Investigate and describe the effect of changes in temperature and pH on
enzyme activity
Extended Material
 Explain enzyme action with reference to the active site, enzyme- substrate
complex, substrate and product
 Explain the specificity of enzymes in terms of the complementary shape
and fit of the active site with the substrate
 Explain the effect of changes in temperature on enzyme activity in terms of
kinetic energy, shape and fit, frequency of effective collisions and
denaturation
 Explain the effect of changes in pH on enzyme activity in terms of shape
and fit and denaturation

6. Plant Nutrition

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6.1 Photosynthesis
 Define photosynthesis as the process by which plants manufacture
carbohydrates from raw materials using energy from light
 State the word equation for photosynthesis: carbon dioxide + water →
glucose + oxygen, in the presence of light and chlorophyll
 Investigate the necessity for chlorophyll, light and carbon dioxide for
photosynthesis, using appropriate controls
 Investigate and describe the effects of varying light intensity, carbon
dioxide concentration and temperature on the rate of photosynthesis, e.g. in
submerged aquatic plants

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6.1 Photosynthesis
Extended Material
 State the balanced chemical equation for photosynthesis 6CO2 + 6H2O →
C6H12O6 + 6O2
 Explain that chlorophyll transfers light energy into chemical energy in
molecules, for the synthesis of carbohydrates
 Outline the subsequent use and storage of the carbohydrates made in
photosynthesis
 Define the term limiting factor as something present in the environment in
such short supply that it restricts life processes
 Identify and explain the limiting factors of photosynthesis in different
environmental conditions
 Describe the use of carbon dioxide enrichment, optimum light and
optimum temperatures in glasshouses in temperate and tropical countries
 Use hydrogencarbonate indicator solution to investigate the effect of gas
exchange of an aquatic plant kept in the light and in the dark

6.2 Leaf structure

 Identify chloroplasts, cuticle, guard cells and stomata, upper and lower
epidermis, palisade mesophyll, spongy mesophyll, vascular bundles, xylem
and phloem in leaves of a dicotyledonous plant
Extended Material
 Explain how the internal structure of a leaf is adapted for photosynthesis

6.3 Mineral requirements

 Describe the importance of:
– nitrate ions for making amino acids
– magnesium ions for making chlorophyll
Extended Material
 Explain the effects of nitrate ion and magnesium ion deficiency on plant
growth

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7. Human Nutrition

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7.1 Diet
 State what is meant by the term balanced diet for humans
 Explain how age, gender and activity affect the dietary needs of humans
including during pregnancy and whilst breast- feeding
 Describe the effects of malnutrition in relation to starvation, constipation,
coronary heart disease, obesity and scurvy
 List the principal sources of, and describe the dietary importance of:
– Carbohydrates
– Fats
– Proteins
– vitamins, limited to C and D
– mineral salts, limited to calcium and iron
– fibre (roughage)
– water
Extended Material
 Explain the causes and effects of vitamin D and iron deficiencies
 Explain the causes and effects of protein-energy malnutrition, e.g.
kwashiorkor and marasmus
7.2 Alimentary canal
 Define ingestion as the taking of substances, e.g. food and drink, into the
body through the mouth
 Define mechanical digestion as the breakdown of food into smaller pieces
without chemical change to the food molecules
 Define chemical digestion as the breakdown of large, insoluble molecules
into small, soluble molecules
 Define absorption as the movement of small food molecules and ions
through the wall of the intestine into the blood

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7.2 Alimentary canal Continues…
 Define assimilation as the movement of digested food molecules into the
cells of the body where they are used, becoming part of the cells
 Define egestion as the passing out of food that has not been digested or
absorbed, as faeces, through the anus
 Describe diarrhoea as the loss of watery faeces Outline the treatment of
diarrhoea using oral rehydration therapy
 Describe cholera as a disease caused by a bacterium
 Identify the main regions of the alimentary canal and associated organs,
limited to mouth, salivary glands, oesophagus, stomach, small intestine
(duodenum and ileum), pancreas, liver, gall bladder and large intestine
(colon, rectum, anus)
 Describe the functions of the regions of the alimentary canal listed above,
in relation to ingestion, digestion, absorption, assimilation and egestion of
food
Extended Material
 Explain that the cholera bacterium produces a toxin that causes secretion of
chloride ions into the small intestine, causing osmotic movement of water
into the gut, causing diarrhoea, dehydration and loss of salts from blood
7.3 Mechanical digestion
 Identify the types of human teeth (incisors, canines, premolars and molars)
 Describe the structure of human teeth, limited to enamel, dentine, pulp,
nerves and cement, as well as the gums
 Describe the functions of the types of human teeth in mechanical digestion
of food
 State the causes of dental decay in terms of a coating of bacteria and food
on teeth, the bacteria respiring sugars in the food, producing acid which
dissolves the enamel and dentine
 Describe the proper care of teeth in terms of diet and regular brushing

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7.4 Chemical digestion
 State the significance of chemical digestion in the alimentary canal in
producing small, soluble molecules that can be absorbed
 State the functions of enzymes as follows:
– amylase breaks down starch to simpler sugars
– protease breaks down protein to amino acids
– lipase breaks down fats to fatty acids and glycerol
 State where, in the alimentary canal, amylase, protease and lipase are
secreted
 State the functions of the hydrochloric acid in gastric juice, limited to
killing bacteria in food and giving an acid pH for enzymes
Extended Material
 Describe the digestion of starch in the alimentary canal:
– amylase is secreted into the alimentary canal and breaks down
starch to maltose
– maltose is broken down by maltase to glucose on the membranes of
the epithelium lining the small intestine
 Describe pepsin and trypsin as two protease enzymes that function in
different parts of the alimentary canal:
– pepsin in the stomach
– trypsin in the small intestine
 Explain the functions of the hydrochloric acid in gastric juice, limited to
the low pH:
– denaturing enzymes in harmful microorganisms in food
– giving the optimum pH for pepsin activity
 Outline the role of bile in neutralising the acidic mixture of food and
gastric juices entering the duodenum from the stomach, to provide a
suitable pH for enzyme action
 Outline the role of bile in emulsifying fats to increase the surface area for
the chemical digestion of fat to fatty acids and glycerol by lipase

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7.5 Absorption
 Identify the small intestine as the region for the absorption of digested food
 State that water is absorbed in both the small intestine and the colon, but
that most absorption of water happens in the small intestine
Extended Material
 Explain the significance of villi and microvilli in increasing the internal
surface area of the small intestine
 Describe the structure of a villus
 Describe the roles of capillaries and lacteals in villi

8. Transport in plants

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8.1 Transport in plants
 State the functions of xylem and phloem
 Identify the position of xylem and phloem as seen in sections of roots,
stems and leaves, limited to non-woody dicotyledonous plants
There is no Extended material for ‘8.1 Transport in plants’
8.2 Water uptake
 Identify root hair cells, as seen under the light microscope, and state their
functions
 State the pathway taken by water through root, stem and leaf as root hair
cell, root cortex cells, xylem and mesophyll cells
 Investigate, using a suitable stain, the pathway of water through the above
ground parts of a plant
Extended Material
 Explain that the large surface area of root hairs increases the rate of the
absorption of water by osmosis and ions by active transport

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8.3 Transpiration
 State that water is transported from the roots to leaves through the xylem
vessels
 Define transpiration as loss of water vapour from plant leaves by
evaporation of water at the surfaces of the mesophyll cells followed by
diffusion of water vapour through the stomata
 Investigate and describe the effects of variation of temperature and
humidity on transpiration rate
Extended Material
 Explain how water vapour loss is related to the large surface area of cell
surfaces, interconnecting air spaces and stomata
 Explain the mechanism by which water moves upwards in the xylem in
terms of a transpiration pull that draws up a column of water molecules,
held together by cohesion
 Explain how and why wilting occurs
 Explain the effects of variation of temperature and humidity on
transpiration rate
8.4 Translocation
There is no Core material for ‘8.Translocation’
Extended Material
 Define translocation in terms of the movement of sucrose and amino acids
in phloem:
– from regions of production (source)
– to regions of storage OR to regions where they are used in
respiration or growth (sink)
 Explain that some parts of a plant may act as a source and a sink at
different times during the life of a plant

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9. Transport in animals
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9.1 Transport in animals
 Describe the circulatory system as a system of blood vessels with a pump
and valves to ensure one- way flow of blood
Extended Material
 Describe the single circulation of a fish
 Describe the double circulation of a mammal
 Explain the advantages of a double circulation
9.2 Heart
 Name and identify the structures of the mammalian heart, limited to the
muscular wall, the septum, the left and right ventricles and atria, one-way
valves and coronary arteries
 State that blood is pumped away from the heart into arteries and returns to
the heart in veins
 State that the activity of the heart may be monitored by ECG, pulse rate
and listening to sounds of valves closing
 Investigate and state the effect of physical activity on the pulse rate
 Describe coronary heart disease in terms of the blockage of coronary
arteries and state the possible risk factors as diet, stress, smoking, genetic
predisposition, age and gender
Extended Material
 Name and identify the atrioventricular and semilunar valves in the
mammalian heart
 Explain the relative thickness:
– of the muscle wall of the left and right ventricles
– of the muscle wall of the atria compared to that of the ventricles
 Explain the importance of the septum in separating oxygenated and
deoxygenated blood
 Describe the functioning of the heart in terms of the contraction of muscles
of the atria and ventricles and the action of the valves

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9.2 Heart Extended Material Continues…
 Explain the effect of physical activity on the heart rate
 Discuss the roles of diet and exercise in the prevention of coronary heart
disease
 Describe ways in which coronary heart disease may be treated, limited to
drug treatment with aspirin and surgery (stents, angioplasty and by-pass)
9.3 Blood and lymphatic vessels
 Describe the structure and functions of arteries, veins and capillaries
 Name the main blood vessels to and from the:
– heart, limited to vena cava, aorta, pulmonary artery and pulmonary vein
– lungs, limited to the pulmonary artery and pulmonary vein
– kidney, limited to the renal artery and renal vein
Extended Material
 Explain how the structures of arteries, veins and capillaries are adapted for
their functions
 State the function of arterioles, venules and shunt vessels
 Outline the lymphatic system in terms of lymphatic vessels and lymph
nodes
 Describe the function of the lymphatic system in the circulation of body
fluids and the protection of the body from infection
9.4 Blood
 List the components of blood as red blood cells, white blood cells, platelets
and plasma
 Identify red and white blood cells, as seen under the light microscope, on
prepared slides and in diagrams and photomicrographs
 State the functions of the following components of blood:
– red blood cells in transporting oxygen, including the role of
haemoglobin
– white blood cells in phagocytosis and antibody production
– platelets in clotting (details are not required)
– plasma in the transport of blood cells, ions, soluble nutrients,
hormones and carbon dioxide

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9.4 Blood
Extended Material
 Identify lymphocyte and phagocyte white blood cells, as seen under the
light microscope, on prepared slides and in diagrams and
photomicrographs
 State the functions of:
– lymphocytes – antibody production
– phagocytes – phagocytosis
 Describe the process of clotting as the conversion of fibrinogen to fibrin to
form a mesh
 State the roles of blood clotting as preventing blood loss and preventing the
entry of pathogens
 Describe the transfer of materials between capillaries and tissue fluid
(details of the roles of water potential and hydrostatic pressure are not
required)

10. Diseases and immunity

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 Define pathogen as a disease- causing organism
 Define transmissible disease as a disease in which the pathogen can be
passed from one host to another
 State that the pathogen for a transmissible disease may be transmitted
either through direct contact, e.g. through blood or other body fluids, or
indirectly, e.g. from contaminated surfaces or food, from animals, or from
the air
 State that the body has defences:
– mechanical barriers, limited to skin and hairs in the nose
– chemical barriers, limited to mucus and stomach acid
– cells, limited to phagocytosis and antibody production by white
blood cells which can be enhanced by vaccination

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 Explain the importance of hygienic food preparation, good personal
hygiene, waste disposal and sewage treatment in controlling the spread of
disease
Extended Material
 State that antibodies lock on to antigens leading to direct destruction of
pathogens, or marking of pathogens for destruction by phagocytes
 Explain how each pathogen has its own antigens, which have specific
shapes, so specific antibodies which fit the specific shapes of the antigens
are needed
 Define active immunity as defence against a pathogen by antibody
production in the body
 Explain that active immunity is gained after an infection by a pathogen, or
by vaccination
 Explain the process of vaccination:
– harmless pathogen given which has antigens
– antigens trigger an immune response by lymphocytes which
produce antibodies
– memory cells are produced that give long-term immunity
 Explain the role of vaccination in controlling the spread of diseases
 Explain that passive immunity is short-term defence against a pathogen by
antibodies acquired from another individual, e.g. mother to infant
 State that memory cells are not produced in passive immunity
 Explain the importance of passive immunity for breast-fed infants
 State that some diseases are caused by the immune system targeting and
destroying body cells, limited to Type 1 diabetes

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11. Gas exchange in humans

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 List the features of gas exchange surfaces in humans, limited to large
surface area, thin surface, good blood supply and good ventilation with air
 Name and identify the lungs, diaphragm, ribs, intercostal muscles, larynx,
trachea, bronchi, bronchioles, alveoli and associated capillaries
 State the differences in composition between inspired and expired air,
limited to oxygen, carbon dioxide and water vapour
 Use limewater as a test for carbon dioxide to investigate the differences in
composition between inspired and expired air
 Investigate and describe the effects of physical activity on rate and depth of
breathing
Extended Material
 Name and identify the internal and external intercostal muscles
 State the functions of the cartilage in the trachea
 Explain the role of the ribs, the internal and external intercostal muscles
and the diaphragm in producing volume and pressure changes in the thorax
leading to the ventilation of the lungs
 Explain the differences in composition between inspired and expired air
 Explain the link between physical activity and rate and depth of breathing
in terms of the increased carbon dioxide concentration in the blood,
detected by the brain, causing an increased rate of breathing
 Explain the role of goblet cells, mucus and ciliated cells in protecting the
gas exchange system from pathogens and particles

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12. Respiration

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12.1 Respiration
 State the uses of energy in the body of humans: muscle contraction, protein
synthesis, cell division, active transport, growth, the passage of nerve
impulses and the maintenance of a constant body temperature
 State that respiration involves the action of enzymes in cells
There is no Extended material for ‘12.1 Respiration’
12.2 Aerobic respiration
 Define aerobic respiration as the chemical reactions in cells that use
oxygen to break down nutrient molecules to release energy
 State the word equation for aerobic respiration as glucose + oxygen →
carbon dioxide + water
 Investigate the uptake of oxygen by respiring organisms, such as
arthropods and germinating seeds
Extended Material
 State the balanced chemical equation for aerobic respiration as C6H12O6 +
6O2 → 6CO2 + 6H2O
 Investigate the effect of temperature on the rate of respiration of
germinating seeds
12.3 Anaerobic respiration
 Define anaerobic respiration as the chemical reactions in cells that break
down nutrient molecules to release energy without using oxygen
 State the word equations for anaerobic respiration in muscles during
vigorous exercise (glucose lactic acid) and the microorganism yeast
(glucose alcohol + carbon dioxide)
 State that anaerobic respiration releases much less energy per glucose
molecule than aerobic respiration
Extended Material
 State the balanced chemical equation for anaerobic respiration in the
microorganism yeast as C6H12O6 → 2C2H5OH + 2CO2

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12.3 Anaerobic respiration Extended Material Continues…
 State that lactic acid builds up in muscles and blood during vigorous
exercise causing an oxygen debt
 Outline how the oxygen debt is removed during recovery, limited to:
– aerobic respiration of lactic acid in the liver
– continuation, after exercise, of fast heart rate to transport lactic acid
in blood from muscles to the liver
– continuation, after exercise, of deeper breathing supplying oxygen
for aerobic respiration of lactic acid
13. Excretion in humans

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 State that urea is formed in the liver from excess amino acids
 State that carbon dioxide is excreted through the lungs
 State that the kidneys excrete urea and excess water and salts
 Explain that the volume and concentration of urine produced is affected by
water intake, temperature and exercise
 Identify on drawings, diagrams and images, the ureters, bladder and urethra
Extended Material
 Describe the role of the liver in the assimilation of amino acids by
converting them to proteins, including plasma proteins, e.g. fibrinogen
 Define deamination as the removal of the nitrogen-containing part of
amino acids to form urea
 Explain the need for excretion, limited to toxicity of urea and carbon
dioxide
 Outline the structure of the kidney, limited to the cortex, medulla and
ureter
 Outline the structure and functioning of a kidney tubule, including:
– the role of the glomerulus in the filtration from the blood of water,
glucose, urea and salts

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– the role of the tubule in the reabsorption of all of the glucose, most
of the water and some salts
– back into the blood, leading to the concentration of urea in the urine
– as well as loss of excess water and salts (details of these processes
are not required)
 Explain dialysis in terms of salt balance, the maintenance of glucose
concentration and the removal of urea
 Describe the use of dialysis in kidney machines
 Discuss the advantages and disadvantages of kidney transplants, compared
with dialysis

14. Coordination and response

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14.1 Nervous control in humans
 Describe a nerve impulse as an electrical signal that passes along nerve
cells called neurones
 Describe the human nervous system in terms of:
– the central nervous system consisting of brain and spinal cord
– the peripheral nervous system
– coordination and regulation of body functions
 Identify motor (effector), relay (connector) and sensory neurones from
diagrams
 Describe a simple reflex arc in terms of receptor, sensory neurone, relay
neurone, motor neurones and effector
 Describe a reflex action as a means of automatically and rapidly integrating
and coordinating stimuli with the responses of effectors (muscles and
glands)
 Define a synapse as a junction between two neurones

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14.1 Nervous control in humans
Extended Material
 Distinguish between voluntary and involuntary actions
 Describe the structure of a synapse, including the presence of
neurotransmitter containing vesicles, the synaptic cleft and
neurotransmitter receptor molecules
 Describe how an impulse triggers the release of a neurotransmitter from
vesicles into the synaptic gap and how the neurotransmitter diffuses across
to bind with receptor molecules, in the membrane of the neurone after the
synaptic gap, causing the impulse to continue
 State that in a reflex arc the synapses ensure that impulses travel in one
direction only
 State that many drugs, e.g. heroin act upon synapses
14.2 Sense organs
 Define sense organs as groups of receptor cells responding to specific
stimuli: light, sound, touch, temperature and chemicals
 Identify the structures of the eye, limited to cornea, iris, pupil, lens, retina,
optic nerve and blind spot
 Describe the function of each part of the eye, limited to:
– cornea – refracts light
– iris – controls how much light enters pupil
– lens – focuses light onto retina
– retina – contains light receptors, some sensitive to light of different
colours
– optic nerve – carries impulses to the brain
 Explain the pupil reflex in terms of light intensity and pupil diameter only
 Explain the pupil reflex in terms of light intensity and pupil diameter only

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14.2 Sense organs
Extended Material
 Explain the pupil reflex in terms of light intensity and antagonistic action
of circular and radial muscles in the iris
 Explain accommodation to view near and distant objects in terms of the
contraction and relaxation of the ciliary muscles, tension in the suspensory
ligaments, shape of the lens and refraction of light
 State the distribution of rods and cones in the retina of a human
 Outline the function of rods and cones, limited to greater sensitivity of rods
for night vision and three different kinds of cones absorbing light of
different colours for colour vision
 Identify the position of the fovea
14.3 Hormones in humans
 Define a hormone as a chemical substance, produced by a gland and
carried by the blood, which alters the activity of one or more specific target
organs
 Identify specific endocrine glands and their secretions, limited to adrenal
glands and adrenaline, pancreas and insulin, testes and testosterone and
ovaries and oestrogen
 Describe adrenaline as the hormone secreted in ‘fight or flight’ situations
and its effects, limited to increased breathing and pulse rate and widened
pupils
 Give examples of situations in which adrenaline secretion increases
 State the functions of insulin, oestrogen and testosterone
Extended Material
 Discuss the role of the hormone adrenaline in the chemical control of
metabolic activity, including increasing the blood glucose concentration
and pulse rate
 Compare nervous and hormonal control systems in terms of speed and
longevity of action

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14.4 Homeostasis
 Define homeostasis as the maintenance of a constant internal environment
 Name and identify on a diagram of the skin: hairs, hair erector muscles,
sweat glands, receptors, sensory neurones, blood vessels and fatty tissue
 Describe the maintenance of a constant internal body temperature in
humans in terms of insulation, sweating, shivering and the role of the brain
(limited to blood temperature receptors and coordination)
Extended Material
 Explain that homeostasis is the control of internal conditions within set
limits
 Explain the concept of control by negative feedback
 Describe the control of the glucose concentration of the blood by the liver
and the roles of insulin and glucagon from the pancreas
 Outline the symptoms and treatment of Type 1 diabetes (detail of cells is
not required)
 Describe the maintenance of a constant internal body temperature in
humans in terms of vasodilation and vasoconstriction of arterioles
supplying skin surface capillaries
14.5 Tropic responses
 Define gravitropism as a response in which parts of a plant grow towards
or away from gravity
 Define phototropism as a response in which parts of a plant grow towards
or away from the direction from which light is coming
 Investigate gravitropism and phototropism in shoots and roots
Extended Material
 Explain phototropism and gravitropism of a shoot as examples of the
chemical control of plant growth
 Explain the role of auxin in controlling shoot growth, limited to:
– auxin made in shoot tip (only)
– auxin spreads through the plant from the shoot tip
– auxin is unequally distributed in response to light and gravity
– auxin stimulates cell elongation
 Describe the use in weed killers of the synthetic plant hormone 2,4-D

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15. Drugs
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15.1 Drugs
 Define a drug as any substance taken into the body that modifies or affects
chemical reactions in the body
There is no Extended material for ’15.1 Drugs’
15.2 Medicinal drugs
 Describe the use of antibiotics for the treatment of bacterial infection
 State that some bacteria are resistant to antibiotics which reduces the
effectiveness of antibiotics
 State that antibiotics kill bacteria but don’t affect viruses
Extended Material
 Explain how development of resistant bacteria such as MRSA can be
minimised, limited to using antibiotics only when essential and ensuring
treatment is completed
 Explain why antibiotics kill bacteria, but don’t affect viruses
15.3 Misused drugs
 Describe the effects of excessive alcohol consumption and abuse of heroin,
limited to:
– powerful depressant drugs
– effect on reaction times and self-control
– addiction and withdrawal symptoms
– negative social implications, e.g. crime
 State that injecting heroin can cause infections such as HIV
 State that excessive alcohol consumption can cause liver damage
 State that tobacco smoking can cause chronic obstructive pulmonary
disease (COPD), lung cancer and coronary heart disease
 Describe the effects on the gas exchange system of tobacco smoke and its
major toxic components, limited to carbon monoxide, nicotine and tar
 State that the liver is the site of breakdown of alcohol and other toxins

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15.3 Misused drugs
Extended Material
 Explain how heroin affects the nervous system, limited to its effect on the
function of synapses
 Discuss the evidence for the link between smoking and lung cancer
 Discuss the use of hormones to improve sporting performance, limited to
testosterone and anabolic steroids

16. Reproduction
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16.1 Asexual reproduction
 Define asexual reproduction as a process resulting in the production of
genetically identical offspring from one parent
 Identify examples of asexual reproduction from information provided
Extended Material
 Discuss the advantages and disadvantages of asexual reproduction:
– to a population of a species in the wild
– to crop production
16.2 Sexual reproduction
 Define sexual reproduction as a process involving the fusion of the nuclei
of two gametes (sex cells) to form a zygote and the production of offspring
that are genetically different from each other
 Define fertilisation as the fusion of gamete nuclei
Extended Material
 State that the nuclei of gametes are haploid and that the nucleus of a zygote
is diploid
 Discuss the advantages and disadvantages of sexual reproduction:
– to a population of a species in the wild
– to crop production

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16.3 Sexual reproduction in plants
 Identify and draw, using a hand lens if necessary, the sepals, petals,
stamens, filaments and anthers, carpels, style, stigma, ovary and ovules, of
an insect- pollinated flower
 State the functions of the sepals, petals, anthers, stigmas and ovaries
 Use a hand lens to identify and describe the anthers and stigmas of a wind-
pollinated flower
 Distinguish between the pollen grains of insect-pollinated and wind-
pollinated flowers
 Define pollination as the transfer of pollen grains from the anther to the
stigma
 State that fertilisation occurs when a pollen nucleus fuses with a nucleus in
an ovule
 Describe the structural adaptations of insect-pollinated and wind-
pollinated flowers
 Investigate and state the environmental conditions that affect germination
of seeds, limited to the requirement for water, oxygen and a suitable
temperature
Extended Material
 Define self-pollination as the transfer of pollen grains from the anther of a
flower to the stigma of the same flower or different flower on the same
plant
 Define cross-pollination as transfer of pollen grains from the anther of a
flower to the stigma of a flower on a different plant of the same species
 Discuss the implications to a species of self-pollination and cross-
pollination in terms of variation, capacity to respond to changes in the
environment and reliance on pollinators
 Describe the growth of the pollen tube and its entry into the ovule followed
by fertilisation (details of production of endosperm and development are
not required)

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16.4 Sexual reproduction in humans
 Identify and name on diagrams of the male reproductive system: the testes,
scrotum, sperm ducts, prostate gland, urethra and penis, and state the
functions of these parts
 Identify and name on diagrams of the female reproductive system: the
ovaries, oviducts, uterus, cervix and vagina, and state the functions of these
parts
 Describe fertilisation as the fusion of the nuclei from a male gamete
(sperm) and a female gamete (egg cell/ovum)
 State the adaptive features of sperm, limited to flagellum and the presence
of enzymes
 State the adaptive features of egg cells, limited to energy stores and a jelly
coating that changes after fertilisation
 Describe the ante-natal care of pregnant women, limited to special dietary
needs and the harm from smoking and alcohol consumption
 Outline the processes involved in labour and birth, limited to:
– breaking of the amniotic sac
– contraction of the muscles in the uterus wall
– dilation of the cervix
– passage through the vagina
– tying and cutting the umbilical cord
– delivery of the afterbirth
Extended Material
 Compare male and female gametes in terms of size, structure, motility and
numbers
 Explain the adaptive features of sperm, limited to flagellum, mitochondria
and enzymes in the acrosome
 Explain the adaptive features of egg cells, limited to energy stores and the
jelly coat that changes at fertilisation
 Describe the function of the placenta and umbilical cord in relation to
exchange of dissolved nutrients, gases and excretory products and
providing a barrier to toxins and pathogens (structural details are not
required)

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16.4 Sexual reproduction in humans Extended Material Continues…
 State that some toxins, e.g. nicotine, and pathogens, e.g. rubella virus, can
pass across the placenta and affect the fetus
 Discuss the advantages and disadvantages of breast-feeding compared with
bottle-feeding using formula milk
16.5 Sex hormones in humans
 Describe the roles of testosterone and oestrogen in the development and
regulation of secondary sexual characteristics during puberty
 Describe the menstrual cycle in terms of changes in the ovaries and in the
lining of the uterus
Extended Material
 Describe the sites of production of oestrogen and progesterone in the
menstrual cycle and in pregnancy
 Explain the role of hormones in controlling the menstrual cycle and
pregnancy, limited to FSH, LH, progesterone and oestrogen
16.6 Methods of birth control in humans
Outline the following methods of birth control:
– natural, limited to abstinence, monitoring body temperature and cervical
mucus
– chemical, limited to IUD, IUS, contraceptive pill, implant and injection
– barrier, limited to condom, femidom, diaphragm
– surgical, limited to vasectomy and female sterilisation
Extended Material
 Outline the use of hormones in contraception and fertility treatments
 Outline artificial insemination (AI)
 Outline in vitro fertilisation (IVF)
 Discuss the social implications of contraception and fertility treatments

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16.7 Sexually transmitted infections (STIs)
 Define sexually transmitted infection as an infection that is transmitted via
body fluids through sexual contact
 State that human immunodeficiency virus (HIV) is an example of an STI
 Explain how the spread of STIs is controlled
 Describe the methods of transmission of HIV
 State that HIV infection may lead to AIDS
Extended Material
 Outline how HIV affects the immune system, limited to decreased
lymphocyte numbers and reduced ability to produce antibodies

17. Inheritance

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17.1 Inheritance
 Define inheritance as the transmission of genetic information from
generation to generation
17.2 Chromosomes, genes and proteins
 Define chromosome as a thread- like structure of DNA, carrying genetic
information in the form of genes
 Define gene as a length of DNA that codes for a protein
 Define allele as a version of a gene
 Describe the inheritance of sex in humans with reference to XX and XY
chromosomes
Extended Material
 Explain that the sequence of bases in a gene is the genetic code for putting
together amino acids in the correct order to make a specific protein
(knowledge of the details of nucleotide structure is not required)
 Explain that DNA controls cell function by controlling the production of
proteins (some of which are enzymes), antibodies and receptors for
neurotransmitters

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17.2 Chromosomes, genes and proteins
Extended Material Continues…
 Explain how a protein is made, limited to:
– the gene coding for the protein remains in the nucleus
– mRNA molecules carry a copy of the gene to the cytoplasm
– the mRNA passes through ribosomes
– the ribosome assembles amino acids into protein molecules
– the specific order of amino acids
– is determined by the sequence of bases in the mRNA (knowledge of
the details of transcription or translation is not required)
 Explain that all body cells in an organism contain the same genes, but
many genes in a particular cell are not expressed because the cell only
makes the specific proteins it needs
 Define a haploid nucleus as a nucleus containing a single set of unpaired
chromosomes, e.g. in gametes
 Define a diploid nucleus as a nucleus containing two sets of chromosomes,
e.g. in body cells
 State that in a diploid cell, there is a pair of each type of chromosome and
in a human diploid cell there are 23 pairs
17.3 Mitosis
 Define mitosis as nuclear division giving rise to genetically identical cells
(details of stages are not required)
 State the role of mitosis in growth, repair of damaged tissues, replacement
of cells and asexual reproduction
Extended Material
 State that the exact duplication of chromosomes occurs before mitosis
 State that during mitosis, the copies of chromosomes separate, maintaining
the chromosome number (details of stages of mitosis are not required)
 Describe stem cells as unspecialised cells that divide by mitosis to produce
daughter cells that can become specialised for specific functions

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17.4 Meiosis
 Define meiosis as nuclear division giving rise to cells that are genetically
different (details of stages are not required)
 State that meiosis is involved in the production of gametes
Extended Material
 Define meiosis as reduction division in which the chromosome number is
halved from diploid to haploid resulting in genetically different cells (details of
stages are not required)
 Explain how meiosis produces variation by forming new combinations of
maternal and paternal chromosomes (specific details are not required)
17.5 Monohybrid inheritance
 Define genotype as the genetic make-up of an organism in terms of the alleles
present
 Define phenotype as the observable features of an organism
 Define homozygous as having two identical alleles of a particular gene
 State that two identical homozygous individuals that breed together will be
pure- breeding
 Define heterozygous as having two different alleles of a particular gene
 State that a heterozygous individual will not be pure- breeding
 Define dominant as an allele that is expressed if it is present
 Define recessive as an allele that is only expressed when there is no dominant
allele of the gene present
 Interpret pedigree diagrams for the inheritance of a given characteristic
 Use genetic diagrams to predict the results of monohybrid crosses and
calculate phenotypic ratios, limited to 1:1 and 3:1 ratios
 Use Punnett squares in crosses which result in more than one genotype to work
out and show the possible different genotypes
Extended Material
 Explain how to use a test cross to identify an unknown genotype
 Explain co-dominance by reference to the inheritance of ABO blood groups –
phenotypes being A, B, AB and O blood groups and alleles being IA, IB and Io

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17.5 Monohybrid inheritance Extended Material Continues…
 Define a sex-linked characteristic as a characteristic in which the gene
responsible is located on a sex chromosome and that this makes it more
common in one sex than in the other
 Describe colour blindness as an example of sex linkage
 Use genetic diagrams to predict the results of monohybrid crosses involving
co-dominance or sex linkage and calculate phenotypic ratios

18. Variation and selection

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18.1 Variation
 Define variation as differences between individuals of the same species
 Distinguish between phenotypic variation and genetic variation
 State that continuous variation results in a range of phenotypes between two
extremes, e.g. height in humans
 State that discontinuous variation results in a limited number of phenotypes
with no intermediates, e.g. tongue rolling
 Record and present the results of investigations into continuous and
discontinuous variation
 Define mutation as genetic change
 State that mutation is the way in which new alleles are formed
 State that ionising radiation and some chemicals increase the rate of mutation
Extended Material
 State that phenotypic variation is caused by both genetic and environmental
factors
 State that discontinuous variation is mostly caused by genes alone, e.g. A, B,
AB and O blood groups in humans
 Define gene mutation as a change in the base sequence of DNA
 Describe the symptoms of sickle-cell anaemia
 Explain how a change in the base sequence of the gene for haemoglobin results
in abnormal haemoglobin and sickle- shaped red blood cells

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18.1 Variation Extended Material Continues…
 Use genetic diagrams to show how sickle-cell anaemia is inherited
 State that people who are heterozygous (HbS HbA) for the sickle-cell allele
have a resistance to malaria
 Explain the distribution of the sickle-cell allele in human populations with
reference to the distribution of malarial
18.2 Adaptive features
 Define adaptive feature as an inherited feature that helps an organism to
survive and reproduce in its environment
 Interpret images or other information about a species to describe its
adaptive features
Extended Material
 Define adaptive feature as the inherited functional features of an organism
that increase its fitness
 Define fitness as the probability of an organism surviving and reproducing
in the environment in which it is found
 Explain the adaptive features of hydrophytes and xerophytes to their
environments
18.3 Selection
 Describe natural selection with reference to:
– variation within populations
– production of many offspring
– competition for resources
– struggle for survival
– reproduction by individuals that are better adapted to the
environment than others
– passing on of their alleles to the next generation
 Describe selective breeding with reference to:
– selection by humans of individuals with desirable features
– crossing these individuals to produce the next generation
– selection of offspring showing the desirable features

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18.3 Selection Extended Material
 Describe evolution as the change in adaptive features of a population over
time as the result of natural selection
 Define the process of adaptation as the process, resulting from natural
selection, by which populations become more suited to their environment
over many generations
 Describe the development of strains of antibiotic resistant bacteria as an
example of evolution by natural selection
 State the differences between natural and artificial selection
 Outline how selective breeding by artificial selection is carried out over
many generations to improve crop plants and domesticated animals

19. Organisms and their environment

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19.1 Energy flow
 State that the Sun is the principal source of energy input to biological
systems
Extended Material
 Describe the flow of energy through living organisms including light
energy from the sun and chemical energy in organisms and its eventual
transfer to the environment
19.2 Food chains and food webs
 Define a food chain as showing the transfer of energy from one organism
to the next, beginning with a producer
 State that energy is transferred between organisms in a food chain by
ingestion
 Construct simple food chains
 Define a food web as a network of interconnected food chains
 Define producer as an organism that makes its own organic nutrients,
usually using energy from sunlight, through photosynthesis

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19.2 Food chains and food webs
 Define consumer as an organism that gets its energy by feeding on other
organisms
 State that consumers may be classed as primary, secondary and tertiary
according to their position in a food chain
 Define herbivore as an animal that gets its energy by eating plants
 Define carnivore as an animal that gets its energy by eating other animals
 Define decomposer as an organism that gets its energy from dead or waste
organic material
 Interpret food chains and food webs in terms of identifying producers and
consumers
 Use food chains and food webs to describe the impacts humans have
through over-harvesting of food species and through introducing foreign
species to a habitat
 Draw, describe and interpret pyramids of numbers
Extended Material
 Describe how energy is transferred between trophic levels
 Define trophic level as the position of an organism in a food chain, food
web, pyramid of numbers or pyramid of biomass
 Explain why the transfer of energy from one trophic level to another is
inefficient
 Explain why food chains usually have fewer than five trophic levels
 Explain why there is a greater efficiency in supplying plants as human
food, and that there is a relative inefficiency in feeding crop plants to
livestock that will be used as food
 Identify producers, primary consumers, secondary consumers, tertiary
consumers and quaternary consumers as the trophic levels in food webs,
food chains, pyramids of numbers and pyramids of biomass
 Draw, describe and interpret pyramids of biomass
 Discuss the advantages of using a pyramid of biomass rather than a
pyramid of numbers to represent a food chain

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19.3 Nutrient cycles
 Describe the carbon cycle, limited to photosynthesis, respiration, feeding,
decomposition, fossilisation and combustion
 Discuss the effects of the combustion of fossil fuels and the cutting down
of forests on the carbon dioxide concentrations in the atmosphere
 Describe the water cycle, limited to evaporation, transpiration,
condensation and precipitation
Extended Material
 Describe the nitrogen cycle in terms of:
– decomposition of plant and animal protein to ammonium ions
– nitrification
– nitrogen fixation by lightning and bacteria
– absorption of nitrate ions by plants
– production of amino acids and proteins
– feeding and digestion of proteins
– deamination
– denitrification
 State the roles of microorganisms in the nitrogen cycle, limited to
decomposition, nitrification, nitrogen fixation and denitrification (generic
names of individual bacteria, e.g. Rhizobium, are not required)
19.4 Population size
 Define population as a group of organisms of one species, living in the
same area, at the same time
 Identify and state the factors affecting the rate of population growth for a
population of an organism, limited to food supply, predation and disease
 Discuss the increase in human population size over the past 250 years and
its social and environmental implications
 Interpret graphs and diagrams of human population growth

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19.4 Population size Extended Material
 Define community as all of the populations of different species in an
ecosystem
 Define ecosystem as a unit containing the community of organisms and
their environment, interacting together, e.g. a decomposing log, or a lake
 Identify the lag, exponential (log), stationary and death phases in the
sigmoid population growth curve for a population growing in an
environment with limited resources
 Explain the factors that lead to each phase in the sigmoid curve of
population growth, making reference, where appropriate, to the role of
limiting factors

20. Biotechnology and genetic engineering

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20.1 Biotechnology and genetic engineering
 State that bacteria are useful in biotechnology and genetic engineering due
to their rapid reproduction rate and their ability to make complex
molecules
Extended Material
 Discuss why bacteria are useful in biotechnology and genetic engineering,
limited to:
– lack of ethical concerns over their manipulation and growth
– genetic code shared with all other organisms
– presence of plasmids
20.2 Biotechnology
 Describe the role of anaerobic respiration in yeast during production of
ethanol for biofuels
 Describe the role of anaerobic respiration in yeast during bread- making
 Investigate and describe the use of pectinase in fruit juice production

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20.2 Biotechnology
 Investigate and describe the use of biological washing powders that contain
enzymes
Extended Material
 Investigate and explain the use of lactase to produce lactose-free milk
 Describe the role of the fungus Penicillium in the production of the
antibiotic penicillin
 Explain how fermenters are used in the production of penicillin
20.3 Genetic engineering
 Define genetic engineering as changing the genetic material of an
organism by removing, changing or inserting individual genes
 State examples of genetic engineering:
– the insertion of human genes into bacteria to produce human insulin
– the insertion of genes into crop plants to confer resistance to
herbicides
– the insertion of genes into crop plants to confer resistance to insect
pests
– the insertion of genes into crop plants to provide additional vitamins
Extended Material
 Outline genetic engineering using bacterial production of a human protein
as an example, limited to:
– isolation of the DNA making up a human gene using
– restriction enzymes, forming sticky ends
– cutting of bacterial plasmid DNA with the same restriction
enzymes, forming complementary sticky ends
– insertion of human DNA into bacterial plasmid DNA using DNA
ligase to form a recombinant plasmid
– insertion of plasmid into bacteria (specific detail is not required)
– replication of bacteria containing recombinant plasmids which
make human protein as they express the gene
 Discuss the advantages and disadvantages of genetically modifying crops,
such as soya, maize and rice

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21. Human influences on ecosystems

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21.1 Food supply
 State how modern technology has resulted in increased food production in
terms of:
– agricultural machinery to use larger areas of land and improve
efficiency
– chemical fertilisers to improve yields
– insecticides to improve quality and yield
– herbicides to reduce competition with weeds
– selective breeding to improve production by crop plants and
livestock, e.g. cattle, fish and poultry
 Describe the negative impacts to an ecosystem of large-scale monocultures
of crop plants
 Describe the negative impacts to an ecosystem of intensive livestock
production
Extended Material
 Discuss the social, environmental and economic implications of providing
sufficient food for an increasing human global population
 Discuss the problems which contribute to famine including unequal
distribution of food, drought and flooding, increasing population and
poverty
21.2 Habitat destruction
 Describe the reasons for habitat destruction, limited to:
– increased area for food crop growth, livestock production and housing
– extraction of natural resources
– marine pollution
 State that through altering food webs and food chains, humans can have a
negative impact on habitats
 List the undesirable effects of deforestation as an example of habitat
destruction, to include extinction, loss of soil, flooding and increase of
carbon dioxide in the atmosphere

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21.2 Habitat destruction
Extended Material
 Explain the undesirable effects of deforestation on the environment
21.3 Pollution
 State the sources and effects of pollution of land and water, e.g. rivers,
lakes and the sea, by insecticides, herbicides and by nuclear fall-out
 State the sources and effects of pollution of water (rivers, lakes and the
sea) by chemical waste, discarded rubbish, untreated sewage and fertilisers
Extended Material
 Explain the process of eutrophication of water in terms of:
– increased availability of nitrate and other ions
– increased growth of producers
– increased decomposition after death of producers
– increased aerobic respiration by decomposers
– reduction in dissolved oxygen
– death of organisms requiring dissolved oxygen in water
 Discuss the effects of non-biodegradable plastics in the environment, in
both aquatic and terrestrial ecosystems
 Discuss the causes and effects on the environment of acid rain
 State the measures that are taken to reduce sulfur dioxide pollution and
reduce the impact of acid rain
 Explain how increases in carbon dioxide and methane concentrations in the
atmosphere cause an enhanced greenhouse effect that leads to climate
change
 Describe the negative impacts of female contraceptive hormones in water
courses, limited to reduced sperm count in men and feminisation of aquatic
organisms
21.4 Conservation
 Define a sustainable resource as one which is produced as rapidly as it is
removed from the environment so that it does not run out
 Explain the need to conserve non- renewable resources, limited to fossil
fuels

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21.4 Conservation
 State that some resources can be maintained, limited to forests and fish
stocks
 State that products can be reused or recycled, limited to paper, glass,
plastic and metal
 Outline how sewage is treated to make the water that it contains safe to
return to the environment or for human use
 Explain why organisms become endangered or extinct, limited to climate
change, habitat destruction, hunting, pollution and introduced species
 Describe how endangered species can be conserved, limited to monitoring
and protecting species and habitats, education, captive breeding
programmes and seed banks
Extended Material
 Define the term sustainable development as development providing for the
needs of an increasing human population without harming the environment
 Explain how forests and fish stocks can be sustained using education, legal
quotas and re-stocking
 Explain that sustainable development requires:
– management of conflicting demands
– planning and co-operation at local, national and international levels
 Explain the risks to a species if the population size drops, reducing
variation (knowledge of genetic drift is not required)
 Explain reasons for conservation programmes, to include:
– reducing extinction
– protecting vulnerable environments
– maintaining ecosystem functions, limited to nutrient cycling and
resource provision, e.g. food, drugs, fuel and genes

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