GCSE AQA Biology Additional 2(i) Life Processes REVISION NOTES

These detailed notes provide everything you need to know for additional biology 2(i) including:

  • animal and plant cells
  • specialised cells
  • diffusion
  • osmosis
  • photosynthesis
  • the rate of photosynthesis
  • how plants use glucose
  • minerals for healthy growth
  • pyramids of number and biomass
  • energy transfer and decay
  • managing food production
  • the carbon cycle

They are explained clearly though designed for revision not initial learning.

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  • Created by: LissT
  • Created on: 25-04-10 18:57
Preview of GCSE AQA Biology Additional 2(i) Life Processes REVISION NOTES

First 166 words of the document:

Life and Cells
Animal & Plant cells
Animal Cells
Most animal cells have the following
Structure Function
1. Nucleus · Controls all the activities of the cell
· Contains genetic material for making new cells and
2. Cytoplasm · A liguid gel in which most of the chemical reactions take
3. Cell membrane · Controls the passage of substances in and out of the
4. Mitochondria · Where most of the respiration takes place
5. Ribosomes · Where protein synthesis takes place
Plant cells
Most plant cells have all the features of a typical
animal cell. They also have:
Structure Function
1. Cell Wall · Made of cellulose
· Strengthens the cell and gives it
2. Chloroplasts · Found in all the green parts of a
· Contain chlorophyll which absorbs
light energy for photosynthesis
3. Permanent Vacuole · Contains cell sap, keeps the cells
rigid to support the plant

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Enzymes control the chemical reactions inside cells
· Enzymes are found throughout the structure of a cell but particularly in the
cytoplasm and mitochondria (and chloroplasts in plants)
· Enzymes are proteins and they act as biological catalysts
Cells, Tissues, Organs and Systems
· Cells have structures that are specialised to suit their function.
· A group of similar cells is called a tissue.
· Different tissue work together as an organ.
· Groups of organs working together make up an organ system (e.g.…read more

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Specialised Cells
Fat Cells
Fat cells are storage cells­ if you eat more food than you need, your body makes
fat and stores it in these cells
1. Very little normal cytoplasm­ leaves room
for large amounts of fat
2. Very few mitochondria as it uses very little
3.…read more

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· Diffusion is the passive movement of particles from places of high
concentration to places of low concentration
· Diffusion occurs in liquids and gases, because the particles are free to move
about randomly
· Cell membranes hold the cell together, but let materials pass in and out of
the cell as well
· Only very small molecules can diffuse through cell membranes
· Big molecules like starch and proteins can't fit through
· Particles flow through the membrane from where there is a…read more

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Osmosis is a special case of diffusion
Osmosis is the movement of water across a partially permeable membrane from
a region of high water concentration to a region of low water concentration
· A partially permeable membrane is one with very small holes in it, so only
tiny molecules, like water, can pass through it
· The water molecules can pass through it both ways because they move
· There is a steady net flow of water into the region of low water…read more

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Carbon dioxide + Water Glucose + Oxygen
Photosynthesis is the process by which plants produce their "food". The "food" is
glucose. It occurs in al the leaves of green plants.
Photosynthesis occurs in the chloroplasts, which are found in all the green parts
of the plant. Chloroplasts contain chlorophyll which absorbs light energy from the
sun, and uses it to form glucose and oxygen from carbon dioxide and water.
Four Vital Things needed for Photosynthesis
1.…read more

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The Effect of Carbon Dioxide
Carbon dioxide is one of the raw materials needed for photosynthesis, so as the
amount of carbon dioxide in the air increases, so does the rate of photosynthesis.
But as with light intensity, it only increases up to a certain point, where either light
intensity or temperature becomes the limiting factor.…read more

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How plants use glucose
The glucose produced by photosynthesis is used in the following ways:
1. For Respiration
Some of the glucose produced is used for respiration. This releases energy
which allows them to convert the rest of the glucose into other useful
2. Making Fruits
Glucose (and another sugar called fructose) is converted into sucrose for
storing in fruits. This makes fruits taste nice so animals will eat them and
spread the seeds in their faeces
3.…read more

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Minerals for Healthy Growth
Plants also need mineral salts in order to grow healthily. There are two important
minerals to learn.
Why are nitrates needed?
Nitrates are needed from the soil in order to make amino acids, which are then
used to make proteins. Proteins act as enzymes, and make up a large part of the
cytoplasm and cell membrane.
Where do nitrates come from?
Nitrates are absorbed from the soil through the roots.…read more

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Pyramids of number and biomass
Both of these pyramids show food chains at their various stages. Pyramids of
number show the number of organisms at each stage. The problem with this is
that sometimes, for example, there are many organisms feeding on one tree. This
would make the pyramid look like this:
Blue tits
Oak tree
This is why we prefer to use pyramids of biomass, as they always give a
conventional pyramid shape.…read more


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