(todo 8.8-12) Exchange and Transport in Animals - Paper 2 Flashcards
1
Q
Why must organisms take in and get rid of substances?
A
- Cells need oxygen for aerobic respiration, producing carbon dioxide as a waste product, both moving between cells and the environment by diffusion.
- Cells take up water in osmosis, alongside (in animals) dissolved food molecules and mineral ions.
- Cells produce urea as a waste product, which is removed from the body by the kidneys.
2
Q
Why don’t single-celled organisms need exchange surfaces and transport systems?
A
- In single-celled organisms, substances can diffuse in and out of the cell across the cell membrane.
- They have a large surface area to volume ratio.
- Therefore enough substances can be exchanged across the membrane to supply the volume of the cell.
3
Q
Why do multicellular organisms need exchange surfaces and transport systems?
A
- Multicellular organisms have a small surface area to volume ratio.
- Therefore they cannot exchange enough substances to supply their entire volume across their outside surface alone.
- They need some exchange surface for efficient diffusion and a transport system to move substances between the exchange surface and the rest of the body.
4
Q
Explain adaptations for gas exchange by diffusion between air in the lungs and blood in capillaries.
A
5
Q
Describe the factors affecting rate of diffusion
A
- Surface area:
- Concentration gradient:
- Diffusion distance:
6
Q
What is Fick’s Law?
A
7
Q
How is the structure of red blood cells related to their function?
A
8
Q
How is the structure of white blood cells related to their function?
A
9
Q
What is the function of blood as a plasma?
A
10
Q
What is the function of platelets in blood?
A
11
Q
How is the structure of blood vessels related to their function?
A
