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3 ADAPTIONS FOR GAS EXCHANGE > SIZE > Flashcards

Flashcards in SIZE Deck (10):
1

Respiratory surface

Site of gas exchange

2

Gas Exchange

Diffusion of gases down a concentration gradient

3

Criteria for a respiratory surface (4 points)

- Large SA/V ratio
- Thin, short diffusion pathways
- Permeable
- Have a method of creating a steep concentration gradient

4

Unicellular

Single-celled organisms

5

Unicellular properties (3) and therefore they can (2)...

- Large SA/V ratio
- Thin cell membrane so rapid diffusion
- Short diffusion distance

-Absorb O2 across cell membrane to meet respiration needs
- Remove CO2 fast enough to prevent making the cytoplasm too acidic

6

Multicellular

made up of many cells

7

Multicellular flaws (2)

- lower SA/V ratio
- diffusion is not efficient enough for gas exchange

8

Flatworms property + explanation

- Flat so larger SA/V than spherical organism

9

Earthworm properties + explanation (5)

- Cylinder shape so lower SA/V
- Skin kept moist by secreting mucus so has to stay in damp soil
- low O2 requirement bc slow-moving with a low metabolic rate
- Capillaries carry O2 away from surface maintaining gradient
- CO2 diffuses out skin down a gradient

10

Multicellular properties + explanation (4)

- Higher metabolic rate so need more O2/remove more CO2
- cells are bigger w/ more specialisation so more independent
- have a ventilation mechanism to maintain steep gradient
- respiratory surface is thin so they are fragile and have to be protected inside organism