IGCSE CO-ORDINATED SCIENCE
NOTES
,Contents INDEX Page number
-B1. Characteristics of living organisms 4
-B2. Cells 4
-B3. Biological Molecules 7
-B4. Enzymes 9
-B5. Plant nutrition 10
-B6. Animal nutrition 12
-B7. Transport 16
-B8. Gas exchange and respiration 21
-B9. Coordination and response 23
-B10. Reproduction 27
-B11. Inheritance 31
-B12. Organisms and their environment 34
-B13. Human influences on ecosystems 35
-C1. The particulate nature of matter 36
-C2. Experimental techniques 37
-C3. Atoms, elements and compounds 39
-C4. Stoichiometry 43
-C5. Electricity and chemistry 45
-C6. Energy changes in chemical reactions 47
-C7. Chemical reactions 48
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,-C8. Acids, bases and salts 49
-C9. The Periodic Table 50
-C10. Metals 51
-C11. Air and water 55
-C12. Sulfur 57
-C13. Carbonates 58
-C14. Organic chemistry 58
-P1. Motion 62
-P2. Work, energy and power 67
-P3. Thermal physics 70
-P4. Properties of waves, including light and sound 73
-P5. Electricity and magnetism 79
-P6. Electric circuits 81
-P7. Atomic physics 83
3
, Biology
Characteristics of Living Organisms
All living things have 7 characteristics:
Movement: An action by an organism or part of an organism causing a change of
position or place.
Reproduction: The process that makes more of the same kind of organism.
Sensitivity: The ability to detect or sense changes in the environment (stimuli) and to
make responses.
Nutrition: The taking of nutrients which are organic substances and mineral ions,
containing raw materials or energy for growth and tissue repair, absorbing and
assimilating them.
Excretion: Removal from organisms of toxic materials, the waste of products of
metabolism (chemical reactions in cells) and substances in excess.
Respiration: The chemical reactions that breakdown nutrient molecules in living cells
to release energy.
Growth: A permanent increase in size and dry mass by an increase in cell number or
cell size.
Cells
Cells: They are the smallest units of living organisms.
Parts of animal and plant cells:
Animal Cell Plant Cell Function
Nucleus Nucleus Contains genetic material (DNA) that
controls the activities of the cell.
Cytoplasm Cytoplasm A gel-like substance where most of the
chemical reactions happen. It contains
enzymes that control this reaction.
Cell Membrane Cell Membrane It is partially permeable. Holds the cell
together and control what goes in and out.
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,Ribosome Ribosome Where proteins are produced.
Mitochondria Mitochondria Here is where most of the reactions of
respiration take place. Respiration releases
the energy the cell needs to work.
Cell Wall Made of cellulose. It is fully permeable.
Supports the cell and strengthens it.
Permanent Vacuole Contains cells sap, a weak solution of
sugars and salts.
Chloroplast This is where photosynthesis occur, which
makes food for the plant. The plant stores
the food as starch. It contains a green
substance called chlorophyll.
Types of Cells:
Red Blood Cells Plant Root Hair Cells
Feature Function Feature Function
No nucleus More space for Cell elongation Large surface area for
molecules of better absorption of
haemoglobin that water (osmosis) and
transport oxygen minerals (active
around the body. transport) from the
soil.
Biconcave shape Large surface area for
better exchange of
gases.
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,Naming Structure:
Organelle: Are structures in the cell with special functions.
Tissues: A group of cells with similar structures, working together to form a specific
function.
Organs: A structure made of a group of tissues, working together to perform a
specific function.
Organ system: A group of organs with related functions, working together to
perform a body function.
Basic Practical Knowledge and Magnification Formula:
Magnification: Is the number of times an item has been enlarged from its actual
size.
Magnification= Size of the drawing/size of the real object.
Diffusion:
Particles in gases, liquids and solutions are in a constant motion. Diffusion is the net
movement of molecules from a region of high concentration to a region of a low
concentration, down a concentration gradient, as a result of a random movement.
Diffusion is important to living organisms and cells as they obtain many of their
requirements, get rid of waste products, for respiration, for digestion…
The rate of diffusion and be increased by: A smaller distance, a greater surface area, at
higher temperatures and a bigger difference of concentration gradient.
Osmosis:
The movement of water molecules, through a partially permeable membrane, from an
area of high-water potential to an area of low water potential of water molecules.
There is also a concentration gradient. Types of partially permeable membranes: the
cell membrane, vising tubing…
Osmosis in animal cells:
Cytoplasm is a solution of proteins and other substances in water. In large animal cells,
cells are surrounded by a tissue fluid. If the solutions are of different concentrations
osmosis will occur. If there is a lower concentration inside the cell than outside, water
will diffuse into the cell and the cell gets bigger. If it absorbs too much the cell will
burst. If there is a higher concentration inside the cell than outside, water will diffuse
out of the cell. The cell would shrink.
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,Osmosis in plant cells:
When plant cells absorb a lot of water they don’t burst, as they are surrounded by the
cell wall which protects and supports the cell. As the cell absorbs water the cytoplasm
and vacuole swell but the cell wall resists. A plant cell in this state is turgid, when it is
tight and firm. The turgidity of the cell helps the plant stay upright. When water
diffuses out of the cell, the cytoplasm and vacuole shrink. But the cell wall is too stiff,
so it doesn’t shrink much. When the cell membrane shrinks a lot and tears away from
the cell wall, we say the cell is plasmolysis. When cells plasmolysis they die.
Active Transport:
Sometimes cells need to take substances around them, like minerals or water which
are absorbed by the root hair cells. This water and minerals need to be pushed around
the plant against the diffusion gradient. For that they use active transport, which is the
movement of substance against the diffusion gradient with the use of a lot of energy
released during respiration.
Concentration Gradient: The difference in concentration between areas of high
and low concentration.
Water potential gradient: A difference in the concentration of water molecules
between areas of high and low concentration, down a water potential gradient.
Crenation: When animal cells shrink in concentrated solutions.
Turgid: Plant cells become bigger and tighter in pure water and don’t burst.
Haemolysis: When animal cells burst in pure water.
Biological Molecules
Water: Most of our bodies are made of water. Inside every living organism chemical
reactions are going on all the time, these reactions are called metabolism. These
metabolic reactions can’t take place, if the chemicals that are reacting aren’t dissolved
in water. Water is also used for transport, and to get us get rid of waste products.
Finally, water also helps us to keep us cool and regulate our temperature.
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,Carbohydrates: Carbohydrates include sugars and starches. Their molecules contain 3
kinds of atoms, carbon, hydrogen and oxygen. The simplest kinds of carbohydrates are
the monosaccharides. E.g. Glucose. If 2 monosaccharides join together, they become a
disaccharide. E.g. Sucrose and maltose. If many monosaccharides join together, they
become a polysaccharide. Some polysaccharide molecules form long chains. E.g. of
polysaccharides, cellulose and starch. Most sugars are soluble in water and taste sweet
except the polysaccharides. Carbohydrates are used for energy. Glucose is used in
respiration to produce energy. Energy can be stored in the form of starch for plants
and glycogen for animals.
Fats: They are also known as lipids. They contain carbon, hydrogen and oxygen. A fat
molecule is made by one molecule of glycerol and 3 of fatty acids. Fats are insoluble in
water, and some fats that are liquid at room temperature are called oils. Fats and oils
are used to release energy. And are useful for energy storage.
Proteins: Proteins contain carbon, hydrogen, oxygen, nitrogen and sulfur. Protein
molecules are made of long chains of smaller molecules called amino acids. Some
proteins are soluble in water and others aren’t. Proteins are used for the growth and
repair of the body. They are also needed to produce enzymes, antibodies and other
vital chemicals. They can be used as a source of energy too.
Practical Test:
Benedict’s Test: We use the benedict’s solution to test for reducing sugars. The initial
colour is blue, if it gives a positive result it will turn brick red.
Biuret Test: We use the biuret test for proteins. The initial colour is blue and, if it gives
a positive result it will turn lilac/purple.
Ethanol Emulsion Test: We use the ethanol emulsion test for lipids. The initial colour is
transparent, if it gives a positive result it will turn cloudy/milk.
Iodine Test: We use iodine solution to test for starch. The initial colour is orange, if it
gives a positive result it will turn dark blue/black.
8
, Enzymes
Enzymes: They are proteins that work as biological catalysts. Catalysts are a substance
that speed up chemical reactions and is not changed by the reaction.
Terminology: Enzymes are named according to the substrate on which they act. The
substrate is the substance which is present at the beginning of the reaction. Proteases
act on proteins, carbohydrase’s act on carbohydrates and lipases on fats (lipids).
Structure: An enzyme molecule has a depression called active site, which is exactly the
right shape for the substance to fit in.
Environment of the Enzyme and its effects:
Reactions catalysed by enzymes work faster at higher temperatures, up to an optimum
temperature, which is different for each enzyme. At low temperatures, molecules have
low kinetic energy, so collisions between enzyme and substrate molecules are
infrequent. As temperature rises, they collide more frequently, increasing the reaction
rate. Above the optimum temperature, the vibrations within the enzyme are so great
that it begins to lose its shape. The reaction rate rapidly decreases as the enzyme is
denatured. The substrate doesn’t fit in the enzyme and the reactions stop.
Reactions catalysed by enzymes work faster at a particular pH. The optimum pH for most
enzymes is pH7, neutral. Extremes of pH cause enzymes to lose their shape and become
denatured.
9
, Plant Nutrition
Photosynthesis: The fundamental process by which plants manufacture
carbohydrates from raw materials using energy from light.
Word Equation and symbol equation of photosynthesis:
Carbon dioxide + Water Glucose + oxygen. With the use of sunlight.
6CO2 + 6H2O C6H12O6 + 6O2
Parts of the leaf:
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