Biology Syllabus 0653 Syllabus 2025-2027
Biology
Syllabus 0653 Syllabus
The official CIE syllabus can be found here. It is best to always refer to the original syllabus.
B1. Characteristics of living organisms
1.1 Characteristics of living organisms
·
Describe the characteristics of living organisms by
defining:
·
(a) movement as an action by an organism or part of
an organism causing a change of position or place
·
(b) respiration as the chemical reactions in cells
that break down nutrient molecules and release energy for metabolism
·
(c) sensitivity as the ability to detect and
respond to changes in the internal or external environment
·
(d) growth as a permanent increase in size and dry
mass
·
(e) reproduction as the processes that make more of
the same kind of organism (f) excretion as the removal of waste products of
metabolism and substances in excess of requirements
·
(g) nutrition as the taking in of materials for
energy, growth and development
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Biology
B2.
Cells
2.1 Cell structure
· Describe and compare the structure of a plant cell with an animal
cell, limited to: cell wall, cell membrane, nucleus, cytoplasm, chloroplasts,
ribosomes, mitochondria, vacuoles
· Describe the structure of a bacterial cell, limited to: cell wall,
cell membrane, cytoplasm, ribosomes, circular DNA, plasmids
· Identify the cell structures listed in 2.1.1 and 2.1.2 in diagrams
and images of plant, animal and bacterial cells
· Describe the functions of the structures listed in 2.1.1 in plant
and animal cells
· State that specialised cells have specific functions,
limited to: (a) root hair cells – absorption (b) palisade mesophyll cells –
photosynthesis (c) red blood cells – transport of oxygen *
· Describe the meaning of the terms cell, tissue, organ,
organ system and organism as illustrated by examples given in the syllabus
2.2 Size of specimens
· State and use the formula: magnification = image size/actual
size
· Calculate magnification and size of biological
specimens using millimetres as units
· Convert measurements between millimetres (mm) and
micrometres (μm) *
B3. Movement into and out of cells
· Describe diffusion as the net movement of particles
from a region of their higher concentration to a region of their lower
concentration (i.e. down a concentration gradient), as a result of their random
movement
· State that some substances move into and out of cells
by diffusion through the cell membrane
· Describe the importance of diffusion of gases and
solutes in living organisms
· Investigate the factors that influence diffusion,
limited to: surface area, temperature, concentration gradient and distance *
3.2 Osmosis
· State that water diffuses through partially permeable
membranes by osmosis
· State that water moves into 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
· Describe 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 cells of immersing them in
solutions of different concentrations by using the terms: turgid, turgor
pressure, plasmolysis, flaccid *
3. 3 Active Transport
· Describe active transport as the movement of particles
through a cell membrane from a region of lower concentration to a region of
higher concentration (i.e. against a concentration gradient), using energy from
respiration
· Explain the importance of active transport as a process
for movement of molecules or ions across membranes, including ion uptake by
root hairs
B4. Biological Molecules
4.1 Biological Molecules
· List the chemical elements that make up:
carbohydrates, fats and proteins
· State that large molecules are made from smaller
molecules, limited to: (a) starch, glycogen and cellulose from glucose (b)
proteins from amino acids (c) fats and oils from fatty acids and glycerol
· Describe the use of: (a) iodine solution test for
starch (b) Benedict’s solution test for reducing sugars (c) biuret test for
proteins (d) ethanol emulsion test for fats and oils
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Biology
B5. Enzymes
5.1 Enzymes
· Describe enzymes as proteins that are involved in all
metabolic reactions, where they function as biological catalysts
· Investigate and describe the effect of changes in
temperature and pH on enzyme activity
· Describe and explain enzyme action with reference to:
the active site, enzyme substrate complex, substrate and product *
· Describe and
explain the specificity of enzymes in terms of the complementary shape and fit
of the active site with the substrate*
Biology
B6. Plant Nutrition
6.1 Photosynthesis
· Describe photosynthesis as the process by which plants
synthesise carbohydrates from raw materials using energy from light
· State the word equation for photosynthesis as: carbon
dioxide + water → glucose + oxygen in the presence of light and chlorophyll
· State that chlorophyll is a green pigment that is
found in chloroplasts
· Investigate and understand the need for chlorophyll,
light and carbon dioxide for photosynthesis
· State the balanced symbol equation for photosynthesis
as: 6CO2 + 6H2O → C6H12O6 + 6O2 *
· State that chlorophyll transfers energy from light into
energy in chemicals, for the synthesis of carbohydrates *
· Understand and describe the effect of varying light
intensity, carbon dioxide concentration and temperature on the rate of
photosynthesis *
· Understand and describe the effect of light and dark conditions
on gas exchange in an aquatic plant using hydrogencarbonate indicator solution
*
Biology
6.2 Leaf Structure
· Identify in diagrams and images the following
structures in the leaf of a dicotyledonous plant: chloroplasts, cuticle, guard
cells and stomata, upper and lower epidermis, palisade mesophyll, spongy
mesophyll, air spaces, vascular bundles, xylem and phloem
B7.
Human Nutrition
7.1 Diet
· Describe what is meant by a balanced diet
· State the principal dietary sources and describe the importance
of: (a) carbohydrates (b) fats and oils (c) proteins (d) vitamins, limited to C
and D (e) mineral ions, limited to calcium and iron (f) fibre (roughage) (g)
water
7.2 Digestive system
· Identify in diagrams and images the main organs of the
digestive system limited to: (a) alimentary canal; mouth, oesophagus, stomach,
small intestine (duodenum and ileum) and large intestine (colon, rectum and
anus) (b) associated organs; salivary glands, pancreas, liver and gall bladder
· Describe the functions of the organs of the digestive
system listed in 7.2.1, in relation to: (a) ingestion – the taking of
substances, e.g. food and drink, into the body (b) digestion – the breakdown of
food (c) absorption – the movement of nutrients from the intestines into the
blood (d) assimilation – uptake and use of nutrients by cells (e) egestion –
the removal of undigested food from the body as faeces
7.2 Digestion
· Describe physical digestion as the breakdown of food
into smaller pieces without chemical change to the food molecules
· Describe chemical digestion as the breakdown of large
insoluble molecules into small soluble molecules
· State that physical digestion increases the surface area
of food for the action of enzymes in chemical digestion *
· State the role of chemical digestion in producing small
soluble molecules that can be absorbed*
· Describe the functions of enzymes as follows: (a)
amylase breaks down starch to simple reducing sugars (b) proteases break down
protein to amino acids (c) lipase breaks down fats and oils to fatty acids and
glycerol *
· State where, in the digestive system, amylase, protease
and lipase are secreted and where they act*
· Describe the functions of hydrochloric acid in gastric
juice, limited to killing harmful microorganisms in food and providing an
acidic pH for optimum enzyme activity of proteases in the stomach *
B8. Transport in Plants
8.1 Xylem and phloem
· State the functions of xylem and phloem: (a) xylem –
transport of water and mineral ions, and support (b) phloem – transport of
sucrose and amino acids
· Identify in diagrams and images the position of xylem
and phloem as seen in sections of roots, stems and leaves of non-woody
dicotyledonous plants
8.2 Water Uptake
· Identify in diagrams and images root hair cells and
state their functions
· State that the large surface area of root hairs
increases the uptake of water and mineral ions*
· Outline the pathway taken by water through the root
hair cells, root cortex cells, xylem and mesophyll cells
8.2 Transpiration
·
Describe transpiration as the loss of water vapour from leaves
·
Investigate and describe the effects of variation of temperature and
wind speed on transpiration rate*
B9. Transport in animals
Biology 9.1 Circulatory systems
· Describe the circulatory system as a system of blood
vessels with a pump and valves to ensure one-way flow of blood
9.2 Heart
· Identify in diagrams and images the structures of the
mammalian heart, limited to: muscular wall, septum, left and right ventricles,
left and right atria, one-way valves and coronary arteries
· State that blood is pumped away from the heart in
arteries and returns to the heart in veins
· State that the activity of the heart may be monitored
by: ECG (electrocardiogram), pulse rate and listening to sounds of valves
closing
· Describe the functioning of the heart in terms of the
contraction of muscles of the atria and ventricles and the action of the valves
*
·
Investigate and describe the effect of physical activity
on heart rate
· Explain the effect of physical activity on the heart
rate *
· Describe coronary heart disease in terms of the blockage
of coronary arteries and state the possible risk factors including: diet, lack
of exercise, stress, smoking, genetic predisposition, age and sex *
· Discuss the roles of diet and exercise in reducing the
risk of coronary heart disease *
9.3 Blood vessels
· Describe the structure of arteries, veins and
capillaries, limited to: relative thickness of wall, diameter of the lumen and
the presence of valves in veins
· Explain how the structure of arteries and veins is
related to the pressure of the blood that they transport*
·
List the components of blood as: red blood cells, white
blood cells, platelets and plasma
·
Identify red and white blood cells in photomicrographs
and diagrams
·
State the functions of the following components of blood:
(a) red blood cells in transporting oxygen, including the role of haemoglobin
(b) white blood cells in phagocytosis and antibody production (c) platelets in
clotting (details are not required) (d) plasma in the transport of blood cells,
ions, nutrients, urea, hormones and carbon dioxide
· State the roles of blood clotting as preventing: blood
loss and the entry of pathogens*
B 10. Diseases and immunity
10.1 Diseases and immunity
· Describe a pathogen as a disease-causing organism
· Describe a transmissible disease as a disease in which
the pathogen can be passed from one host to another
· State the features of viruses, limited to a protein coat
and genetic material *
· State that a pathogen is transmitted: (a) by direct
contact, including through blood and other body fluids (b) indirectly,
including from contaminated surfaces, food, animals and air
· Describe the body defences against pathogens, limited
to: skin, hairs in the nose, mucus, stomach acid and white blood cells
· Explain the importance of the following in controlling
the spread of disease: (a) a clean water supply (b) hygienic food preparation
(c) good personal hygiene (d) waste disposal (e) sewage treatment (details of
the stages of sewage treatment are not required) *
· Describe active immunity as defence against a pathogen
by antibody production in the body *
·
State
that active immunity is gained after an infection by a pathogen or by
vaccination *
B11.
Gas exchange in humans
11.1 Gas exchange in humans
· Identify in diagrams and images the following parts of
the breathing system: lungs, diaphragm, ribs, intercostal muscles, larynx,
trachea, bronchi, bronchioles, alveoli and associated capillaries
· Investigate and describe the effects of physical activity
on the rate and depth of breathing
· Describe the features of gas exchange surfaces in
humans, limited to: large surface area, thin surface, good blood supply and
good ventilation with air *
B12. Respiration
12.1 Respiration
· State the uses of energy in living organisms,
including: muscle contraction, protein synthesis, cell division, growth and the
maintenance of a constant body temperature
· Describe aerobic respiration as the chemical reactions
in cells that use oxygen to break down nutrient molecules to release energy 3
State the word equation for aerobic respiration as: glucose + oxygen → carbon
dioxide + water
· State the balanced symbol equation for aerobic
respiration as: C6H12O6 + 6O2 → 6CO2 + 6H2O *
B13. Drugs
13.1 Drugs
· Describe a drug as any substance taken into the body
that modifies or affects chemical reactions in the body
· Describe the use of antibiotics for the treatment of
bacterial infections
· State that some bacteria are resistant to antibiotics
which reduces the effectiveness of antibiotics
· State that antibiotics kill bacteria but do not affect
viruses
· Explain how using antibiotics only when essential can
limit the development of resistant bacteria such as MRSA *
B14. Reproduction
14.1 Sexual reproduction in plants
· Identify in diagrams and images and draw the following
parts of an insect-pollinated flower: sepals, petals, stamens, filaments,
anthers, carpels, style, stigma, ovary and ovules
· Identify in diagrams and images and describe the anthers
and stigmas of a wind-pollinated flower *
· State the
functions of the structures listed above
· Describe pollination as the transfer of pollen grains
from an anther to a stigma
· State that fertilisation occurs when a pollen nucleus
fuses with a nucleus in an ovule
· Investigate and describe the environmental conditions
that affect germination of seeds, limited to the requirement for: water, oxygen
and a suitable temperature
·
14.1 Sexual reproduction in humans
· Identify on diagrams and state the functions of the
following parts of the male reproductive system: testes, scrotum, sperm ducts,
prostate gland, urethra and penis
· Identify on diagrams and state the functions of the
following parts of the female reproductive system: ovaries, oviducts, uterus,
cervix and vagina
· Describe fertilisation as the fusion of the nuclei
from a male gamete (sperm) and a female gamete (egg cell)
· Describe the menstrual cycle in terms of changes in
the ovaries and in the lining of the uterus (knowledge of sex hormones is not
required)
B15. Organisms and their environment
15.1 Energy flow
· State that the Sun is the principal source of energy
input to biological systems
· 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
15.2 Food chains and food webs
· Describe a food chain as showing the transfer of
energy from one organism to the next, beginning with a producer
· Construct and interpret simple food chains
· Describe a food web as a network of interconnected
food chains and interpret food webs
· Describe a producer as an organism that makes its own
organic nutrients, usually using energy from sunlight, through photosynthesis
· Describe a 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
· Describe a herbivore as an animal that gets its energy
by eating plants
· Describe a carnivore as an animal that gets its energy
by eating other animals
· Describe a decomposer as an organism that gets its
energy from dead or waste organic material
· Use food chains and food webs to describe the impact
humans have through overharvesting of food species and through introducing
foreign species to a habitat *
15.3 Carbon cycle
· Describe the carbon cycle, limited to: photosynthesis,
respiration, feeding, decomposition, formation of fossil fuels and combustion
B16. Human influences on ecosystems
16.1 Habitat destruction
· Describe an ecosystem as a unit containing the
community of organisms and their environment, interacting together
· Describe biodiversity as the number of different
species that live in an area
· Describe the reasons for habitat destruction,
including: (a) increased area for housing, crop plant production and livestock
production (b) extraction of natural resources (c) freshwater and marine
pollution (a detailed description of eutrophication is not required)
· State the undesirable effects of deforestation as an
example of habitat destruction, to include: reducing biodiversity, extinction,
loss of soil, flooding and increase of carbon dioxide in the atmosphere
· Explain the undesirable effects of deforestation as an
example of habitat destruction, to include: reducing biodiversity, extinction,
loss of soil, flooding and increase of carbon dioxide in the atmosphere *
16.2 Conservation
· Outline why organisms become endangered or extinct,
including: climate change, habitat destruction, hunting, overharvesting,
pollution and introduced species
· Describe how endangered species can be conserved,
limited to: (a) monitoring and protecting species and habitats (b) education
(c) captive breeding programmes (d) seed banks *