GCSE AQA Additional Biology all units

These revision cards are short notes, including Higher Tier material, that cover all of the topics needed for the AQA additional biology exam. 

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Osmosis = movement of water

  • random, requries no energy
  • through/across semi-permeable membrane
  • dilute solution --> more concentrated solution
    • larger difference of concentration, faster rate of osmosis

Water needed to 

  • support cells

Chemical reaction take place in SOLUTION

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Ribosomes + Mitochondria


synthesised proteins made here


where energy is released during aerobic respiration

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Plant roots

Plant roots take up

(1) Nitrates

  • used to make amino acids
  • too little nitrate = stunted growth

(2) Magnesium Ions

  • used to produce chlorophyll
  • no chlorophyll = yellow leaves
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Energy in foodchains

There is energy loss between EACH STAGE of a foochain

not all energy taken by organism = growth

energy --> used up not lost

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Energy in animals

energy used in

  • faeces (poo)
  • respiration
  • movement
  • keeping temperature constant (homeostasis)
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plants AND animals respire

energy released in respiration:

  • builds large molecules from small ones
  • enables muscle contraction in animals
  • keeps contant body temp. (in mammals+birds)
  • allows sugars, nitrates + nutrients to turn into amino acids then into protein


glucose + oxygen --> CO2 + water [+energy]

mostly takes place in MITOCHONDRIA

returns CO2 to atmosphere

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carbon dioxide + water (+light energy) --> glucose + oxygen

removes CO2 from atmosphere

lack of light       > 

cold weather     >  slows down photosynthesis

too little CO2    >

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  • used for respiration
  • combines with nutrients by plants = make new materials
  • stored by some plants as insoluble starch  --> no effect on osmosis
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Uses of things by plants in photosynthesis

carbon dioxide = taken in by leaves 

water = taken in by roots

chlorophyll = traps energy needed for photosynthesis

oxygen = given off as a waste gas

glucose sugar = made by/during photosynthesis

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Contents of animal cells

Animal cells            mnemonic for help remembering

nucleus                      nude

cytoplasm                  cyclists

cell membrane            cycle

mitochondria               my

ribosomes                   road

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Contents of plant cells

Plant cells            mnemonic for help remembering

nucleus                      nude

cytoplasm                  cyclists

cell membrane            cycle

mitochondria               my

ribosomes                   road

cell wall                      casually

chloroplasts                colouring

permanent vacuole       pavements

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Decay organisms = micro organisms

(types of worm)       (bacteria and funghi)

decay = fast if warm and wet

ALL materials from waste + dead organisms are recycled

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Stem cells

stem cells = unspecialised cells

develop into specialised cells

stem cells found in 

  • embryo
  • adult bone marrow

stem cells from adult bone marrow = limited use

as different types of specialised cells = limited

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Embryonic stem cells

embryonic stem cells researched on from:

  • aborted embryos
  • 'spare' fertility treatment embryos

ethical issues and debate over

destroying life for research

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Genes and Alleles

Genes = short lengths of DNA

Alleles = genes controlling the SAME characteristic

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Amino acids

SOME amino acids we take in = not used up

not used up = converted to UREA in LIVER

excreted by KIDNEYS in URINE

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Water and ion content of cells

Water and ion content of cells = carefully controlled

if not

too much or too little = water movement in OSMOSIS

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homeostasis is processes in your body that maintain a constant internal environment

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Core temperature

Core temp. rises

blood vessels near skin surface dilate 

more blood flows through skin capillaries

heat = lost via radiation

sweat glands make more sweat

Core temp. falls

blood vessels near skin surface constrict

less blood flows through capillaries keeping internal organs warm

heat = LESS loss via radiation

'shivering' = muscles contracting quickly

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Pancreas monitors and controls blood sugar level

blood sugar too high = insulin produced

when insulin produced = excess insulin stored in LIVER as glycogen

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Enzymes (1)

Enzymes = biological catalysts 

Enyzmes ---> large proteins = different shape each

area where other molecules fit called active site

conditions too hot?

denatured enzymes --> change shape

enzymes = sensitive to pH levels

too high/too low = denatured enzymes

optimum temp. = temp. enzymes work best as

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Enzymes (2)


  • catalyses build up of SMALL molecules into LARGE molecules
  • break down of LARGE molecules into SMALL molecules

enzymes LOWER energy needed for reaction

this energy = activation energy

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Protease made in



small intestine

catalyses proteins into amino acids in stomach and small intestine

works best in acidic stomach

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Lipase made in

small intestine 


catalyses lipids (fats and oils) into fatty acids and glycerol

works best in slightly alkaline small intestine

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Amylase made in

small intestine 


salivary glands

catalyses starch into sugars in mouth and small intestine

works best in slightly alkaline small intestine

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  • made by liver
  • stored in gall bladder 
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Use of enzymes

carbohydrases = make starch into sugar syrup --> use in foods

protease = pre-digests proteins in some baby foods

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Pyramid of biomass

pyramids of biomass are more accurate than a food chain

as they present MASS not quantity

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Thanx thats really helpful revision cards! :D

Aspiring Medic


Any chance you can do B3

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