distribution of organism and population size

habitat - where a plant or animal lives

community - organism living in a garden

population - the number present

bio-diversity- variety of plants and animals

organism can be mapped with transect line

quadrat - count animals - assess percentage cover of plants

displays on kite diagram

artificial systems are created by human to benefit them 

population size = number in 1st sample x number in 2nd sample/ number in 2nd sample marked

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The chemistry of photosynthesis

- photosynthesis 6C02 + 6H20 = C6 H12 O6 + 602


- used in respiration to release energy

- convert cellulose to create cell walls

- convert into proteins for growth and repair

- convert into starch, fats and oils for storage

starch used for storage because insoluble doesnt move from storage areas

glucose doesnt affect water concentration and cause osmosis


- water split up, releasing oxygen gas and hydrogen ions

- C02 combines with H2 ions = glucose + water

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Rate of photosynthesis

increased by 

- more C02

- light

- higher temperatures increases enzyme action

photosynthesis takes place in day time but respires all the time releasing energy at all times

respire by taking in oxygen and releasing C02

photosynthesis in day is reverse

rate of gas exchange of photosynthesis is more than respiration, so respiration is noticed in night

limiting factors- photosynthesis needs light, C02 + temp a lack will limit rate of photosynthesis

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lead adaptation for photosynthesis

- broad to get much light as possible

- thin, so gases diffuse easily and light gets to cells

- contain chlorophyll, so they use light from broad range of light spectrums

- have vascular bundles for support and transport chemicals

- have speacilised guard cells, control opening and closing of stomata

- have many pigments such as chlorophyll, carotene and xanthophylls, plants cell maximise suns energy

- each pigment absorbs light of different wave lengths

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leaf structure

- outer eperdermis lacks chloroplasts so is transparents, light can enter

- upper paliside layer contains most chloroplasts, recieves more light

- spongy mesophyll cells are loosly spaced so that diffusion can take place of gases between cells

- arrangement of mesophyll cells create large surface area / volume ratio so that large amount of gases can enter and exit cells

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is a movement of particles in gas or liquid from an area of high and low concentration and results in a random movement

tell us how molecules such as water, oxygen and carbon dioxide can enter and leave through cell membrane. If a plant is using up carbon dioxide there is less of it inside the cell so carbon dioxide will enter through diffusion,

leaves are adapted to increase rate of diffusion of co2 and oxygen

- large surface area

- opening called stamata which are spaced out

- gaps between the mesophyll cells

it can also be increased by

- shorter distance for molecule to travel

- steeper concentration

- greater surface area to molecules to diffuse from

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Osmosis and water in cells

osmosis is a type of diffusion, depends on permeable- membrane that allows the passage of water molecules but not glucose molecules

osmosis is the movement of water across a permeable membrane of an area of high and low concentration and it is the consequence of random movement of water molecules

entry of water into plants cells increases the pressure putting on the cell wall, which is rigid. The turgo pressure supports cell and stops plant from collapsing. When too much water leaves cell it loses pressure and wilts.

A plant cell full of water is rigid when it loses water it becomes plasmolysed and is called a flaccid

Animals cell react to too much water or too little due to osmosis

Animals cells dont have a support cell wall so when it has too much water it swells up and burst but when it has too much water leave it show crenation and shrinks into a scalloped shape

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Xylem and phloem cells

They are made up of speacialised plants. Both types of tissues are continous through the plants. They form vascular bundles in broad leaved plants.

Xylem cells carry water from the roots to the leaves and were involved in transportation

Phloem cells carry food substances for growing and storage tissues. The transport of food substances is called translocation

Xylem cells are called vessels, they are dead cells and lack a cytoplasm leaves a hollow lumen. Their cellulose walls have extra thickening of lignin, giving extra strength and support

Pholem cells are living cells

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Transpiration is the evaporation and diffusion of water in leaves. The loss of water helps to create a continous flow of water from the roots to leaves in xylem cells

Root hairs have a large surface area for water uptake by osmosis

Transpiration means plants have water for cooling by evaporation photosynthesis and support cells from collapsing and transport for minerals

Rate of transpiration is increased by light intensity, temperature and decrease in humidity

The structure of a leaf is adapted to prevent water loss. Water loss is reduced by having a waxy cuticle covering the outer epidermal cells and by most stomatal openings in the lower surface

Plants leave are adapted to photosynthesis. The mesophyll cells are covered with a film of water in which gases dissolve. The water escapes through the stomata

The structure of leaf is adapted to reduce water loss, guard cells are able to change size of the stomatal openings, they contain chloroplasts, so photosynthesis produces sugars, increasing turgo pressure. Guard cells curve opening stomata

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use of minerals

- plants need minerals

- nitrates to make amino acids for protein used for growth

- phosphates to make dna, which contains plant genetic code which is also involved in respiration and growth

- pottassuim compound is used to help enzyme action in respiration and photosynthesis

- magnesium to make chlorophyll which is essential in photosynthesis

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Mineral deficiency

- lack of nitrates causes poor growth

- lack of phosphate causes poor rooth growth

- lack of pottasuim causes poor flower and root growth

- lack of magnesuim causes yellow leaves

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mineral uptake

- minerals are present in low concentration soil

- minerals are taken up by root hair cells by active transport

- a system of carriers transport minerals through cell membrane

- active transport enables minerals from low concentration soils enter root hair cells

- this uptake of minerals against a concentration gradient requires energy for respiration

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- earthworms and maggots are detritivores they feed on decay 

- detritivores increase rate of decay by breaking up detritus to increase SFA for futher microbial breakdown

- rate of decay can be increased by water - allow materials to be digested 

oxygen - bacteria used aerobic respiration to grow and reproduce

 temperature - 37 for bactera and 25 for fungi increase rate of respiration, high temperature denature enzymes

- fungi produce enzymes to digest food outside the cells and the reabsorb soluble substances - extracellular digestion

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Food preservation

- canning, food are heated to kill bacteria and then sealed in vacuum

- cooling and freezing food will slow down bacterial growth 

- drying food removes water so bacteria can't grow

- adding salt and sugar kills bacteria as high osmotic concentration will remove water

- adding vinegar will produce high acid concentration killing bactera and fungi

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pesticides and organic farming and biological cont

- enter food chains causing a lethal dose to predators

- harm organism nearby 

- persistant

- organic farming doesnt use pesticides

- used animal manure and compost

- crops are smaller and are expensive 

- predator may becomes a pest

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hydroponic and intensive farming

- intensive farming makes crop yield cheaply but is animal cruelty as animals are packed into a small space

- plants grow by hydroponic, used water containing minerals

- hydrophonic have no soil, so better control over minerals

- intensive farming improves efficiency of energy transfer in food chains between humans by reducing pests and weed. 

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lisa linsdell


A very useful set of revision cards. This is suitable for Higher papers as well as foundation.



very useful

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