gas exchange in plants (dicotyledonus plants)

Question 1

explain how leaves of dicotyledonous plants are adapted for gas exchange.

Answer 1

many stomata - large surface area for gas exchange.
spongy mesophyll contains air spaces - large surface area for gasses to diffuse through.
thin - short diffusion distance.

Question 2

describe palisade mesophyll.

Answer 2

located near top surface and packed full of chloroplasts for photosynthesis
- loads of cells packed together so large surface area for co2 gas exchange.

Question 3

describe spongy mesophyll.

Answer 3

have air spaces around for gasses to reach palisade mesophyll but also have large surface area for o2 exchange.

Question 4

describe guard cells and stomata.

Answer 4

guard cells control opening and closing of stomata to allow gasses in and out.

Question 5

whats a xerophyte?

Answer 5

plant adapted to live in very dry conditions.

Question 6

explain structural and functional features in xerophytic plants that allow efficient gas exchange while limiting water loss.

Answer 6

thicker waxy cuticle - increases diffusion distance so less evaporation.
sunken stomata in pits - traps water vapour so reduced WP gradient so less evaporation.
spines - reduces surface area to volume ratio.