gaseous exchange in plants

Question 1

what part of the plant allows very little gaseous exchange?

Answer 1

a waxy cuticle covers leaves and allows very little gaseous exchange

Question 2

what are the main structures involved in gaseous exchange in plants?

Answer 2

stomata, mesophyll cells and the air spaces between them

Question 3

what are the stomata?

Answer 3

stomata are pores in the epidermis of leaves and are surrounded by two guard cells. gases diffuse in and out of leaves through the stomata.

Question 4

how are plants adapted for gaseous exchange?

Answer 4

short diffusion pathway : leaves are thin

large surface area : numerous mesophyll cells lining the intercellular air spaces in the leaf

Question 5

when do plants respire and photosynthesise?

Answer 5

plants respire 24 hours a day. at night only respiration occurs. in daylight, the cells still respire but they also carry out photosynthesis. normally during daylight, the rate of photosynthesis is greater than the rate of respiration so there is a net uptake of carbon dioxide and loss of oxygen.

Question 6

how does respiration and photosynthesis maintain diffusion gradients?

Answer 6

respiration and photosynthesis maintain diffusion gradients by using and producing oxygen and carbon dioxide

Question 7

how do gases enter the plant cell?

Answer 7

gases diffuse in, through the stomata between the guard cells, down a concentration gradient and rapidly through the intercellular air spaces.

the gases dissolve in the moist cell walls of the mesophyll cells.

gases diffuse across the thin cell wall and cell membrane of mesophyll cells.