Pages in this set

Page 1

Preview of page 1
AQA GCSE Biology ­ Unit 3 summary notes















AQA




GCSE Biology




New Unit 3




Summary Notes









Unit 3 Summary
We need to understand how biological and environmental systems operate when they are
working well in order to be able to intervene when things go wrong. Modern developments in
biomedical and…

Page 2

Preview of page 2
AQA GCSE Biology ­ Unit 3 summary notes




Dissolved substances
Dissolved substances move by diffusion and by active transport.

Diffusion (covered in more detail in unit 2):
The movement of particles in a liquid or gas from an area where they are in higher
concentration to an area where they…

Page 3

Preview of page 3
AQA GCSE Biology ­ Unit 3 summary notes




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.


This is why it is vital that we maintain the concentration of our body…

Page 4

Preview of page 4
AQA GCSE Biology ­ Unit 3 summary notes
















Page 4 7/9/2012

Page 5

Preview of page 5
AQA GCSE Biology ­ Unit 3 summary notes




Specialised exchange surfaces
Many organ systems are specialised for exchanging materials.
The effectiveness of an exchange surface is increased by:
o having a large surface area
o being thin, to provide a short diffusion path
o Animals can also maintain high concentration…

Page 6

Preview of page 6
AQA GCSE Biology ­ Unit 3 summary notes




The lungs are in the upper part of the body (thorax).
They are protected by the ribcage.
They are separated from the lower part of the body (abdomen) by the diaphragm.






The breathing system takes air into and out of the body.…

Page 7

Preview of page 7
AQA GCSE Biology ­ Unit 3 summary notes




The moist surface helps oxygen to dissolve so that it can diffuse into the cells.
The capillaries are very close to the alveoli so that the gases have a short distance to
diffuse.
Concentration gradients are maintained by:
o The blood removing…

Page 8

Preview of page 8
AQA GCSE Biology ­ Unit 3 summary notes




Mechanical ventilators:
o Machines can be used that enable air to move into and out of the lungs:
o Negative pressure machines.
Often referred to as iron lungs.
These are used in cases of paralysis, for example, due to polio.
The patient's…

Page 9

Preview of page 9
AQA GCSE Biology ­ Unit 3 summary notes




Exchange systems in plants
Absorption of water by roots
The surface area of the roots is increased by root hairs.
Most of the water and mineral ions are absorbed by root hair cells.
Water is absorbed by osmosis.
Most of the mineral…

Page 10

Preview of page 10
AQA GCSE Biology ­ Unit 3 summary notes





Transpiration
The process by which plants lose water vapour from the surface of their leaves.
It evaporates into the air spaces in the leaf, and then diffuses out through the stomata.





Transpiration is more rapid in hot, dry and windy conditions:
o…

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »