Double Science (Biology) Retrospective Revision guide

Instructions

(a) Characteristics of living organisms

2

1.1
understand how living organisms share the following characteristics:
• they require nutrition
• they respire
• they excrete their waste
• they respond to their surroundings
• they move
• they control their internal conditions
• they reproduce
• they grow and develop.

(b) Variety of living organisms

2

1.2
describe the common features shown by eukaryotic organisms: plants, animals, fungi
and protoctists
Plants: these are multicellular organisms; their cells contain chloroplasts and are able
to carry out photosynthesis; their cells have cellulose cell walls; they store
carbohydrates as starch or sucrose. Examples include flowering plants, such as a
cereal (for example, maize), and a herbaceous legume (for example, peas or beans).
Animals: these are multicellular organisms; their cells do not contain chloroplasts and
are not able to carry out photosynthesis; they have no cell walls; they usually have
nervous co-ordination and are able to move from one place to another; they often
store carbohydrate as glycogen. Examples include mammals (for example, humans)
and insects (for example, housefly and mosquito).
Fungi: these are organisms that are not able to carry out photosynthesis; their body
is usually organised into a mycelium made from thread-like structures called hyphae,
which contain many nuclei; some examples are single-celled; their cells have walls
made of chitin; they feed by extracellular secretion of digestive enzymes onto food
material and absorption of the organic products; this is known as saprotrophic
nutrition; they may store carbohydrate as glycogen. Examples include Mucor, which
has the typical fungal hyphal structure, and yeast, which is single-celled.
Protoctists: these are microscopic single-celled organisms. Some, like Amoeba, that
live in pond water, have features like an animal cell, while others, like Chlorella, have
chloroplasts and are more like plants. A pathogenic example is Plasmodium,
responsible for causing malaria.

2

1.3
describe the common features shown by prokaryotic organisms such as bacteria
Bacteria: these are microscopic single-celled organisms; they have a cell wall, cell
membrane, cytoplasm and plasmids; they lack a nucleus but contain a circular
chromosome of DNA; some bacteria can carry out photosynthesis but most feed off
other living or dead organisms. Examples include Lactobacillus bulgaricus, a
rod-shaped bacterium used in the production of yoghurt from milk, and
Pneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia.

2

1.4 understand the term pathogen and know that pathogens may include fungi, bacteria,
protoctists or viruses
Viruses: these are not living organisms. They are small particles, smaller than
bacteria; they are parasitic and can reproduce only inside living cells; they infect
every type of living organism. They have a wide variety of shapes and sizes; they
have no cellular structure but have a protein coat and contain one type of nucleic
acid, either DNA or RNA. Examples include the tobacco mosaic virus that causes
discolouring of the leaves of tobacco plants by preventing the formation of
chloroplasts, the influenza virus that causes ‘flu’ and the HIV virus that causes AIDS.

(a) Level of organisation

2

2.1
describe the levels of organisation in organisms: organelles, cells, tissues, organs and
systems

(b) Cell structure

2

2.2
describe cell structures, including the nucleus, cytoplasm, cell membrane, cell wall,
mitochondria, chloroplasts, ribosomes and vacuole

2

2.3
describe the functions of the nucleus, cytoplasm, cell membrane, cell wall,
mitochondria, chloroplasts, ribosomes and vacuole

2

2.4
know the similarities and differences in the structure of plant and animal cells

(c) Biological molecules

2

2.7
identify the chemical elements present in carbohydrates, proteins and lipids
(fats and oils)

2

2.8
describe the structure of carbohydrates, proteins and lipids as large molecules made
up from smaller basic units: starch and glycogen from simple sugars, protein from
amino acids, and lipid from fatty acids and glycerol

2

2.9
practical: investigate food samples for the presence of glucose, starch, protein and fat

2

2.10
understand the role of enzymes as biological catalysts in metabolic reactions

2

2.11
understand how temperature changes can affect enzyme function, including changes
to the shape of active site

2

2.12
practical: investigate how enzyme activity can be affected by changes in temperature

2

2.13
understand how enzyme function can be affected by changes in pH altering the active
site

(d) Movement of substances into and out of cells

2

2.15
understand the processes of diffusion, osmosis and active transport by which
substances move into and out of cells

2

2.16
understand how factors affect the rate of movement of substances into and out of
cells, including the effects of surface area to volume ratio, distance, temperature and
concentration gradient

2

2.17
practical: investigate diffusion and osmosis using living and non-living systems

(e) Nutrition

Flowering Plants

2

2.18
understand the process of photosynthesis and its importance in the conversion of
light energy to chemical energy

2

2.19
know the word equation and the balanced chemical symbol equation for
photosynthesis

2

2.20
understand how varying carbon dioxide concentration, light intensity and temperature
affect the rate of photosynthesis

2

2.21
describe the structure of the leaf and explain how it is adapted for photosynthesis

2

2.22
understand that plants require mineral ions for growth, and that magnesium ions are
needed for chlorophyll and nitrate ions are needed for amino acids

2

2.23
practical: investigate photosynthesis, showing the evolution of oxygen from a water
plant, the production of starch and the requirements of light, carbon dioxide and
chlorophyll

Humans

2

2.24
understand that a balanced diet should include appropriate proportions of
carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

2

2.25
identify the sources and describe the functions of carbohydrate, protein, lipid
(fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and
dietary fibre as components of the diet

2

2.26
understand how energy requirements vary with activity levels, age and pregnancy

2

2.27
describe the structure and function of the human alimentary canal, including the
mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine
(colon and rectum) and pancreas

2

2.28
understand how food is moved through the gut by peristalsis

2

2.29
understand the role of digestive enzymes, including the digestion of starch to glucose
by amylase and maltase, the digestion of proteins to amino acids by proteases and
the digestion of lipids to fatty acids and glycerol by lipases

2

2.30
understand that bile is produced by the liver and stored in the gall bladder

2

2.31
understand the role of bile in neutralising stomach acid and emulsifying lipids

2

2.32
understand how the small intestine is adapted for absorption, including the structure
of a villus

(f) Respiration

2

2.34
understand how the process of respiration produces ATP in living organisms

2

2.35
know that ATP provides energy for cells

2

2.36
describe the differences between aerobic and anaerobic respiration

2

2.37
know the word equation and the balanced chemical symbol equation for aerobic
respiration in living organisms

2

2.38
know the word equation for anaerobic respiration in plants and in animals

2

2.39
practical: investigate the evolution of carbon dioxide and heat from respiring seeds or
other suitable living organisms

(g) Gas exchange

Humans

2

2.46
describe the structure of the thorax, including the ribs, intercostal muscles,
diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes

2

2.47
understand the role of the intercostal muscles and the diaphragm in ventilation

2

2.48
explain how alveoli are adapted for gas exchange by diffusion between air in the
lungs and blood in capillaries

2

2.49
understand the biological consequences of smoking in relation to the lungs and the
circulatory system, including coronary heart disease

2

2.50
practical: investigate breathing in humans, including the release of carbon dioxide
and the effect of exercise

(h) Transport

2

2.51
understand why simple, unicellular organisms can rely on diffusion for movement of
substances in and out of the cell

2

2.52
understand the need for a transport system in multicellular organisms

Flowering plants

2

2.53
describe the role of phloem in transporting sucrose and amino acids between the
leaves and other parts of the plant

2

2.54
describe the role of xylem in transporting water and mineral ions from the roots to
other parts of the plant

Humans

2

2.59
describe the composition of the blood: red blood cells, white blood cells, platelets and
plasma

2

2.60
understand the role of plasma in the transport of carbon dioxide, digested food, urea,
hormones and heat energy

2

2.61
understand how adaptations of red blood cells make them suitable for the transport of oxygen, including shape, the absence of a nucleus and the presence of haemoglobin

2

2.62
understand how the immune system responds to disease using white blood cells,
illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies
specific to the pathogen

2

2.65
describe the structure of the heart and how it functions

2

2.66
explain how the heart rate changes during exercise and under the influence of
adrenaline

2

2.67
understand how factors may increase the risk of developing coronary heart disease

2

2.68
understand how the structure of arteries, veins and capillaries relates to their function

2

2.69
understand the general structure of the circulation system, including the blood
vessels to and from the heart and the lungs, the liver and the kidneys

(i) Excretion

Flowering plants

2

2.70
understand the origin of carbon dioxide and oxygen as waste products of metabolism
and their loss from the stomata of a leaf

Humans

2

2.71
know the excretory products of the lungs, kidneys and skin (organs of excretion)

(j) Co-ordination and response

2

2.80
understand how organisms are able to respond to changes in their environment

2

2.81
understand that homeostasis is the maintenance of a constant internal environment,
and that body water content and body temperature are both examples of homeostasis

2

2.82
understand that a co-ordinated response requires a stimulus, a receptor and an
effector

Flowering plants

2

2.83
understand that plants respond to stimuli

2

2.84
describe the geotropic and phototropic responses of roots and stems

2

2.85
understand the role of auxin in the phototropic response of stems

Humans

2

2.86
describe how nervous and hormonal communication control responses and
understand the differences between the two systems

2

2.87
understand that the central nervous system consists of the brain and spinal cord and
is linked to sense organs by nerves

2

2.88
understand that stimulation of receptors in the sense organs sends electrical impulses
along nerves into and out of the central nervous system, resulting in rapid responses

2

2.89
understand the role of neurotransmitters at synapses

2

2.90
describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object

2

2.91
describe the structure and function of the eye as a receptor

2

2.92
understand the function of the eye in focusing on near and distant objects, and in
responding to changes in light intensity

2

2.93
describe the role of the skin in temperature regulation, with reference to sweating,
vasoconstriction and vasodilation

2

2.94
understand the sources, roles and effects of the following hormones: adrenaline,
insulin, testosterone, progesterone and oestrogen

a) Reproduction

2

3.1
understand the differences between sexual and asexual reproduction

2

3.2
understand that fertilisation involves the fusion of a male and female gamete to
produce a zygote that undergoes cell division and develops into an embryo

Flowering plants

2

3.3
describe the structures of an insect-pollinated and a wind-pollinated flower and
explain how each is adapted for pollination

2

3.4
understand that the growth of the pollen tube followed by fertilisation leads to seed
and fruit formation

2

3.5
practical: investigate the conditions needed for seed germination

2

3.6
understand how germinating seeds utilise food reserves until the seedling can carry
out photosynthesis

2

3.7
understand that plants can reproduce asexually by natural methods
(illustrated by runners) and by artificial methods (illustrated by cuttings)

Humans

2

3.8
understand how the structure of the male and female reproductive systems are
adapted for their functions

2

3.9
understand the roles of oestrogen and progesterone in the menstrual cycle

2

3.11
describe the role of the placenta in the nutrition of the developing embryo

2

3.12
understand how the developing embryo is protected by amniotic fluid

2

3.13
understand the roles of oestrogen and testosterone in the development of secondary
sexual characteristics

(b) Inheritance

2

3.14
understand that the genome is the entire DNA of an organism and that a gene is a
section of a molecule of DNA that codes for a specific protein

2

3.15
understand that the nucleus of a cell contains chromosomes on which genes are
located

2

3.19
understand how genes exist in alternative forms called alleles which give rise to
differences in inherited characteristics

2

3.20
understand the meaning of the terms: dominant, recessive, homozygous,
heterozygous, phenotype, and genotype

2

3.22
understand that most phenotypic features are the result of polygenic inheritance
rather than single genes

2

3.23
describe patterns of monohybrid inheritance using a genetic diagram

2

3.24
understand how to interpret family pedigrees

2

3.25
predict probabilities of outcomes from monohybrid crosses

2

3.26
understand how the sex of a person is controlled by one pair of chromosomes, XX in a
female and XY in a male

2

3.27
describe the determination of the sex of offspring at fertilisation, using a genetic
diagram

2

3.28
understand how division of a diploid cell by mitosis produces two cells that contain
identical sets of chromosomes

2

3.29
understand that mitosis occurs during growth, repair, cloning and asexual
reproduction

2

3.30
understand how division of a cell by meiosis produces four cells, each with half the
number of chromosomes, and that this results in the formation of genetically different
haploid gametes

2

3.31
understand how random fertilisation produces genetic variation of offspring

2

3.32
know that in human cells the diploid number of chromosomes is 46 and the haploid
number is 23

2

3.33
understand that variation within a species can be genetic, environmental, or a
combination of both

2

3.34
understand that mutation is a rare, random change in genetic material that can be
inherited

2

3.38
explain Darwin’s theory of evolution by natural selection

2

3.39
understand how resistance to antibiotics can increase in bacterial populations, and
appreciate how such an increase can lead to infections being difficult to control

(a) The organism in the environment

2

4.1
understand the terms population, community, habitat and ecosystem

2

4.2
practical: investigate the population size of an organism in two different areas using
quadrats

2

4.5
understand how abiotic and biotic factors affect the population size and distribution of
organisms

(b) Feeding relationships

2

4.6
understand the names given to different trophic levels, including producers, primary,
secondary and tertiary consumers and decomposers

2

4.7
understand the concepts of food chains, food webs, pyramids of number, pyramids of
biomass and pyramids of energy transfer

2

4.8
understand the transfer of substances and energy along a food chain

2

4.9
understand why only about 10% of energy is transferred from one trophic level to the
next

(c) Cycles within ecosystems

2

4.10
describe the stages in the carbon cycle, including respiration, photosynthesis,
decomposition and combustion

(d) Human influences on the environment

2

4.12
understand the biological consequences of pollution of air by sulfur dioxide and
carbon monoxide

2

4.13
understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are
greenhouse gases

2

4.14
understand how human activities contribute to greenhouse gases

2

4.15
understand how an increase in greenhouse gases results in an enhanced greenhouse
effect and that this may lead to global warming and its consequences

2

4.16
understand the biological consequences of pollution of water by sewage

2

4.17
understand the biological consequences of eutrophication caused by leached minerals
from fertiliser

(a) Food production
Crop plants

2

5.1
describe how glasshouses and polythene tunnels can be used to increase the yield of
certain crops

2

5.2
understand the effects on crop yield of increased carbon dioxide and increased
temperature in glasshouses

2

5.3
understand how the use of fertiliser can increase crop yield

2

5.4
understand the reasons for pest control and the advantages and disadvantages of
using pesticides and biological control with crop plants

Micro-organisms

2

5.5
understand the role of yeast in the production of food including bread

2

5.6
practical: investigate the role of anaerobic respiration by yeast in different conditions

2

5.7
understand the role of bacteria (Lactobacillus) in the production of yoghurt

2

5.8
understand the use of an industrial fermenter and explain the need to provide
suitable conditions in the fermenter, including aseptic precautions, nutrients,
optimum temperature and pH, oxygenation and agitation, for the growth of micro-organisms

(b) Selective breeding

2

5.10
understand how selective breeding can develop plants with desired characteristics

2

5.11
understand how selective breeding can develop animals with desired characteristics

(c) Genetic modification (genetic engineering)

2

5.12
understand how restriction enzymes are used to cut DNA at specific sites and ligase
enzymes are used to join pieces of DNA together

2

5.13
understand how plasmids and viruses can act as vectors, which take up pieces of
DNA, and then insert this recombinant DNA into other cells

2

5.14
understand how large amounts of human insulin can be manufactured from
genetically modified bacteria that are grown in a fermenter

2

5.15
understand how genetically modified plants can be used to improve food production

2

Double Science (Biology) Retrospective Revision guide

(a) Characteristics of living organisms

1.1 understand how living organisms share the following characteristics:• they require nutrition• they respire• they excrete their waste• they respond to their surroundings• they move• they control their internal conditions• they reproduce• they grow and develop.

(b) Variety of living organisms

(a) Level of organisation

2.1 describe the levels of organisation in organisms: organelles, cells, tissues, organs and systems

(b) Cell structure

2.2 describe cell structures, including the nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes and vacuole

2.3 describe the functions of the nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes and vacuole

2.4 know the similarities and differences in the structure of plant and animal cells

(c) Biological molecules

2.7 identify the chemical elements present in carbohydrates, proteins and lipids (fats and oils)

2.8 describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugars, protein from amino acids, and lipid from fatty acids and glycerol

2.9 practical: investigate food samples for the presence of glucose, starch, protein and fat

2.10 understand the role of enzymes as biological catalysts in metabolic reactions

2.11 understand how temperature changes can affect enzyme function, including changes to the shape of active site

2.12 practical: investigate how enzyme activity can be affected by changes in temperature

2.13 understand how enzyme function can be affected by changes in pH altering the active site

(d) Movement of substances into and out of cells

2.15 understand the processes of diffusion, osmosis and active transport by which substances move into and out of cells

2.16 understand how factors affect the rate of movement of substances into and out of cells, including the effects of surface area to volume ratio, distance, temperature and concentration gradient

2.17 practical: investigate diffusion and osmosis using living and non-living systems

(e) Nutrition

2.18 understand the process of photosynthesis and its importance in the conversion oflight energy to chemical energy

2.19 know the word equation and the balanced chemical symbol equation for photosynthesis

2.20 understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis

2.21 describe the structure of the leaf and explain how it is adapted for photosynthesis

2.22 understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids

2.23 practical: investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll

2.24 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

2.25 identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the diet

2.26 understand how energy requirements vary with activity levels, age and pregnancy

2.27 describe the structure and function of the human alimentary canal, including the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas

2.28 understand how food is moved through the gut by peristalsis

2.29 understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases

2.30 understand that bile is produced by the liver and stored in the gall bladder

2.31 understand the role of bile in neutralising stomach acid and emulsifying lipids

2.32 understand how the small intestine is adapted for absorption, including the structure of a villus

(f) Respiration

2.34 understand how the process of respiration produces ATP in living organisms

2.35 know that ATP provides energy for cells

2.36 describe the differences between aerobic and anaerobic respiration

2.37 know the word equation and the balanced chemical symbol equation for aerobic respiration in living organisms

2.38 know the word equation for anaerobic respiration in plants and in animals

2.39 practical: investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms

(g) Gas exchange

2.46 describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes

2.47 understand the role of the intercostal muscles and the diaphragm in ventilation

2.48 explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

2.49 understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart disease

2.50 practical: investigate breathing in humans, including the release of carbon dioxide and the effect of exercise

(h) Transport

2.51 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell

2.52 understand the need for a transport system in multicellular organisms

2.53 describe the role of phloem in transporting sucrose and amino acids between the leaves and other parts of the plant

2.54 describe the role of xylem in transporting water and mineral ions from the roots to other parts of the plant

2.59 describe the composition of the blood: red blood cells, white blood cells, platelets and plasma

2.60 understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy

2.61 understand how adaptations of red blood cells make them suitable for the transport of oxygen, including shape, the absence of a nucleus and the presence of haemoglobin

2.62 understand how the immune system responds to disease using white blood cells, illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies specific to the pathogen

2.65 describe the structure of the heart and how it functions

2.66 explain how the heart rate changes during exercise and under the influence of adrenaline

2.67 understand how factors may increase the risk of developing coronary heart disease

2.68 understand how the structure of arteries, veins and capillaries relates to their function

2.69 understand the general structure of the circulation system, including the blood vessels to and from the heart and the lungs, the liver and the kidneys

(i) Excretion

2.70 understand the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf

2.71 know the excretory products of the lungs, kidneys and skin (organs of excretion)

(j) Co-ordination and response

2.80 understand how organisms are able to respond to changes in their environment

2.81 understand that homeostasis is the maintenance of a constant internal environment, and that body water content and body temperature are both examples of homeostasis

2.82 understand that a co-ordinated response requires a stimulus, a receptor and an effector

2.83 understand that plants respond to stimuli

2.84 describe the geotropic and phototropic responses of roots and stems

2.85 understand the role of auxin in the phototropic response of stems

2.86 describe how nervous and hormonal communication control responses andunderstand the differences between the two systems

2.87 understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

2.88 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

2.89 understand the role of neurotransmitters at synapses

1.1
understand how living organisms share the following characteristics:
• they require nutrition
• they respire
• they excrete their waste
• they respond to their surroundings
• they move
• they control their internal conditions
• they reproduce
• they grow and develop.

2.1
describe the levels of organisation in organisms: organelles, cells, tissues, organs and
systems

2.2
describe cell structures, including the nucleus, cytoplasm, cell membrane, cell wall,
mitochondria, chloroplasts, ribosomes and vacuole

2.3
describe the functions of the nucleus, cytoplasm, cell membrane, cell wall,
mitochondria, chloroplasts, ribosomes and vacuole

2.4
know the similarities and differences in the structure of plant and animal cells

2.7
identify the chemical elements present in carbohydrates, proteins and lipids
(fats and oils)

2.8
describe the structure of carbohydrates, proteins and lipids as large molecules made
up from smaller basic units: starch and glycogen from simple sugars, protein from
amino acids, and lipid from fatty acids and glycerol

2.9
practical: investigate food samples for the presence of glucose, starch, protein and fat

2.10
understand the role of enzymes as biological catalysts in metabolic reactions

2.11
understand how temperature changes can affect enzyme function, including changes
to the shape of active site

2.12
practical: investigate how enzyme activity can be affected by changes in temperature

2.13
understand how enzyme function can be affected by changes in pH altering the active
site

2.15
understand the processes of diffusion, osmosis and active transport by which
substances move into and out of cells

2.16
understand how factors affect the rate of movement of substances into and out of
cells, including the effects of surface area to volume ratio, distance, temperature and
concentration gradient

2.17
practical: investigate diffusion and osmosis using living and non-living systems

2.18
understand the process of photosynthesis and its importance in the conversion of
light energy to chemical energy

2.19
know the word equation and the balanced chemical symbol equation for
photosynthesis

2.20
understand how varying carbon dioxide concentration, light intensity and temperature
affect the rate of photosynthesis

2.21
describe the structure of the leaf and explain how it is adapted for photosynthesis

2.22
understand that plants require mineral ions for growth, and that magnesium ions are
needed for chlorophyll and nitrate ions are needed for amino acids

2.23
practical: investigate photosynthesis, showing the evolution of oxygen from a water
plant, the production of starch and the requirements of light, carbon dioxide and
chlorophyll

2.24
understand that a balanced diet should include appropriate proportions of
carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

2.25
identify the sources and describe the functions of carbohydrate, protein, lipid
(fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and
dietary fibre as components of the diet

2.26
understand how energy requirements vary with activity levels, age and pregnancy

2.27
describe the structure and function of the human alimentary canal, including the
mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine
(colon and rectum) and pancreas

2.28
understand how food is moved through the gut by peristalsis

2.29
understand the role of digestive enzymes, including the digestion of starch to glucose
by amylase and maltase, the digestion of proteins to amino acids by proteases and
the digestion of lipids to fatty acids and glycerol by lipases

2.30
understand that bile is produced by the liver and stored in the gall bladder

2.31
understand the role of bile in neutralising stomach acid and emulsifying lipids

2.32
understand how the small intestine is adapted for absorption, including the structure
of a villus

2.34
understand how the process of respiration produces ATP in living organisms

2.35
know that ATP provides energy for cells

2.36
describe the differences between aerobic and anaerobic respiration

2.37
know the word equation and the balanced chemical symbol equation for aerobic
respiration in living organisms

2.38
know the word equation for anaerobic respiration in plants and in animals

2.39
practical: investigate the evolution of carbon dioxide and heat from respiring seeds or
other suitable living organisms

2.46
describe the structure of the thorax, including the ribs, intercostal muscles,
diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes

2.47
understand the role of the intercostal muscles and the diaphragm in ventilation

2.48
explain how alveoli are adapted for gas exchange by diffusion between air in the
lungs and blood in capillaries

2.49
understand the biological consequences of smoking in relation to the lungs and the
circulatory system, including coronary heart disease

2.50
practical: investigate breathing in humans, including the release of carbon dioxide
and the effect of exercise

2.51
understand why simple, unicellular organisms can rely on diffusion for movement of
substances in and out of the cell

2.52
understand the need for a transport system in multicellular organisms

2.53
describe the role of phloem in transporting sucrose and amino acids between the
leaves and other parts of the plant

2.54
describe the role of xylem in transporting water and mineral ions from the roots to
other parts of the plant

2.59
describe the composition of the blood: red blood cells, white blood cells, platelets and
plasma

2.60
understand the role of plasma in the transport of carbon dioxide, digested food, urea,
hormones and heat energy

2.61
understand how adaptations of red blood cells make them suitable for the transport of oxygen, including shape, the absence of a nucleus and the presence of haemoglobin

2.62
understand how the immune system responds to disease using white blood cells,
illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies
specific to the pathogen

2.65
describe the structure of the heart and how it functions

2.66
explain how the heart rate changes during exercise and under the influence of
adrenaline

2.67
understand how factors may increase the risk of developing coronary heart disease

2.68
understand how the structure of arteries, veins and capillaries relates to their function

2.69
understand the general structure of the circulation system, including the blood
vessels to and from the heart and the lungs, the liver and the kidneys

2.70
understand the origin of carbon dioxide and oxygen as waste products of metabolism
and their loss from the stomata of a leaf

2.71
know the excretory products of the lungs, kidneys and skin (organs of excretion)

2.80
understand how organisms are able to respond to changes in their environment

2.81
understand that homeostasis is the maintenance of a constant internal environment,
and that body water content and body temperature are both examples of homeostasis

2.82
understand that a co-ordinated response requires a stimulus, a receptor and an
effector

2.83
understand that plants respond to stimuli

2.84
describe the geotropic and phototropic responses of roots and stems

2.85
understand the role of auxin in the phototropic response of stems

2.86
describe how nervous and hormonal communication control responses and
understand the differences between the two systems

2.87
understand that the central nervous system consists of the brain and spinal cord and
is linked to sense organs by nerves

2.88
understand that stimulation of receptors in the sense organs sends electrical impulses
along nerves into and out of the central nervous system, resulting in rapid responses

2.89
understand the role of neurotransmitters at synapses

2.90
describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object

2.91
describe the structure and function of the eye as a receptor

2.92
understand the function of the eye in focusing on near and distant objects, and in
responding to changes in light intensity

2.93
describe the role of the skin in temperature regulation, with reference to sweating,
vasoconstriction and vasodilation

2.94
understand the sources, roles and effects of the following hormones: adrenaline,
insulin, testosterone, progesterone and oestrogen

3.1
understand the differences between sexual and asexual reproduction

3.2
understand that fertilisation involves the fusion of a male and female gamete to
produce a zygote that undergoes cell division and develops into an embryo

3.3
describe the structures of an insect-pollinated and a wind-pollinated flower and
explain how each is adapted for pollination

3.4
understand that the growth of the pollen tube followed by fertilisation leads to seed
and fruit formation

3.5
practical: investigate the conditions needed for seed germination

3.6
understand how germinating seeds utilise food reserves until the seedling can carry
out photosynthesis

3.7
understand that plants can reproduce asexually by natural methods
(illustrated by runners) and by artificial methods (illustrated by cuttings)

3.8
understand how the structure of the male and female reproductive systems are
adapted for their functions

3.9
understand the roles of oestrogen and progesterone in the menstrual cycle