GAS EXCHANGE IN PLANTS Flashcards Preview

3 ADAPTIONS FOR GAS EXCHANGE > GAS EXCHANGE IN PLANTS > Flashcards

Flashcards in GAS EXCHANGE IN PLANTS Deck (16)
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1
Q

Gas exchange during the day vs night (2)

A
  • During the day respire and photosynthesise

- During the night respire only

2
Q

How does oxygen enter the stem and roots

A
  • via diffusion
3
Q

how do gases travel in a leaf

A
  • down a concentration gradient
  • in substomatal air chambers diffuse through inter cellular spaces between spongy mesophyll into cells
  • direction of diffusion depends on concentration of gases
4
Q

large SA leaf significance for gas exchange and photosynthesis (2)

A
  • room for many stomata

- capture as much light as possible

5
Q

thin leaf significance for gas exchange and photosynthesis (2)

A
  • short diffusion pathway for gases

- light penetrates through leaf

6
Q

transparent cuticle and epidermis significance photosynthesis

A
  • light penetrates to mesophyll
7
Q

elongated palisade cells significance for photosynthesis

A
  • accommodate a large number
8
Q

palisade cells packed with chloroplasts significance for photosynthesis

A
  • capture as much light as possible
9
Q

chloroplasts rotate and move within mesophyll significance for photosynthesis

A
  • move into best positions for maximum absorption of light
10
Q

air spaces in spongy mesophyll significance for gas exchange and photosynthesis? (2)

A
  • allow o2 and co2 to diffuse between stomata and cells

- allow co2 diffuse to photosynthesising cells

11
Q

stomatal pores significance for gas exchange

A
  • allow in and out of leaf
12
Q

stomata (2)

A
  • small pores on bottom of leaves

- where gas exchange occurs

13
Q

guard cell (2)

A
  • epidermal cells with chloroplasts

- unevenly thickened walls - inner > outer

14
Q

how do guard cells work during the day? (2)

A
  • water enters the guard cells they become turgid and swell, opening the pore
  • water leaves the guard cell, they become flaccid and the pore closes
15
Q

guard cells work during the day because… (5)

A
  • chloroplasts in the guard cells photosynthesise producing ATP
  • ATP provides energy for active transport of K+ into the guard cells
  • stored starch converted to malate
  • K+ and malate ions lower water potential in guard cells so water enters via osmosis
  • guard cells are uneven, absorb water in the thin spots, less in the thick areas
16
Q

why do stomata close? (3)

A
  • at night to prevent water loss (bc no LDR)
  • in bright light to prevent water loss due to evaporation
  • if there is excessive water loss