Other pages in this set

Page 2

Preview of page 2

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
12.1 Animal and Plant Cells
Cells
Cells are the smallest unit of life.
All living things are made of cells.
Most human cells, like most other animal cells, have the following parts:
o nucleus
o cytoplasm
o cell membrane
o mitochondria
o ribosomes
Plant cells also have:
o cell wall
o chloroplasts
o permanent vacuole
What do these structures do?
Nucleus ­ controls the activities of the cell.…read more

Page 3

Preview of page 3

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
Permanent vacuole filled with cell sap in plant cells.
Other facts:
The chemical reactions inside cells are controlled by enzymes.
Examples:
o Enzymes for respiration are in the mitochondria.
o Enzymes for photosynthesis are in the chloroplasts.
o Enzymes for protein synthesis are on the ribosomes.
Cells may be specialised to carry out a particular function.
Examples:
Tissues, organs and systems
A tissue is a group of similar cells carrying out a particular function.…read more

Page 4

Preview of page 4

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
12.2 Movement into and out of cells
To get into or out of cells, dissolved substances have to cross the cell membranes.
Solutes = particles in solution eg glucose, sodium ions, chloride ions.
Solvent = liquid in which the particles are dissolved eg water.
Solute and solvent molecules move around randomly.
Solutes can move into and out of cells by diffusion and osmosis.…read more

Page 5

Preview of page 5

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
Osmosis in animal cells:
If animal cells are placed in a solution that has a higher solute concentration
than the cytoplasm, then water will leave the cell by osmosis, until it shrinks
and dies.
If animal cells are placed in a solution that has a lower solute
concentration than the cytoplasm, then water will enter the cell by osmosis
until it bursts.…read more

Page 6

Preview of page 6

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
12.3 Photosynthesis
Photosynthesis
Photo = light
Synthesis = making of (glucose)
Photosynthesis = making glucose using light
Complex definition:
A process in green plants that produces complex organic chemicals (glucose) from simple
inorganic chemicals (carbon dioxide and water) using light energy.
More detail:
Light energy is absorbed by a green substance called chlorophyll.
Plants look green because chlorophyll reflects green wavelengths of light.
The plant then uses this energy for photosynthesis.…read more

Page 7

Preview of page 7

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
A palisade mesophyll cell:
Factors that limit the rate of photosynthesis
1) Temperature
A low temperature will limit the rate as the molecules will move less and therefore the reaction
happens slower
2) Carbon dioxide
A shortage of CO2 will limit the rate as fewer molecules will be available for the reaction.
3) Light intensity
A shortage of light means there is less energy to power the reaction.…read more

Page 8

Preview of page 8

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
Farmers artificially manipulate the environment in which they grow plants.
They grow plants in greenhouses or in polythene tunnels.
They can control the temperature in greenhouses using heaters and ventilation.
They can artificially increase the carbon dioxide levels.
They can control the light using fluorescent lamps.
By doing all of this, their plants grow faster and certain plants can be grown in this country
out of their natural growth season.…read more

Page 9

Preview of page 9

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
12.4 Energy flow in ecosystems
Food Chains
Radiation from the Sun is the source of energy for most communities of living organisms.
Green plants capture a small part of the solar energy which reaches them.
This energy is stored in the substances which make up the cells of the plants.
Food chain = a diagram to represent feeding relationships between organisms, showing
direction of energy flow.…read more

Page 10

Preview of page 10

Here's a taster:

AQA GCSE Biology ­ Unit 2 summary notes
Diagrams that display the numbers of organisms at each trophic level in a food chain
Each block is drawn to scale.
These do not necessarily represent amount of biomass:
Pyramids of biomass
The biomass at each stage can be drawn to scale and shown as a pyramid of biomass.
Biomass = mass of living material
All pyramids of biomass are pyramid shaped.…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »