Gas Exchange in Plants

Question 1

what are the three key layers of a dicotyledonous leaf

Answer 1

palisade mesophyll
spongy mesophyll
stomata

Question 2

where are the stomata found

Answer 2

on the lower side of the leaf

Question 3

what is the stomata

Answer 3

the site of gas exchange in a leaf

Question 4

what are the cells on either side of the stomata called

Answer 4

guards cells

Question 5

where does carbon dioxide diffuse into through the stomata

Answer 5

spongy mesophyll layer

Question 6

where does carbon dioxide diffuse through to from the spongy mesophyll

Answer 6

palisade mesophyll

Question 7

how do you identify the spongy mesophyll in a diagram

Answer 7

there will be loads of gaps throughout the layer

Question 8

what is the vascular bundle

Answer 8

where the xylem and phloem are

Question 9

how do you identify the palisade mesophyll layer in a diagram

Answer 9

layer of longer, narrower cells

Question 10

why is the palisade mesophyll layer packed with chloroplasts

Answer 10

to maximise the amount of chlorophyll for light absorption

Question 11

what gas diffuses into the stomata

Answer 11

carbon dioxide

Question 12

what gases diffuse out of the stomata

Answer 12

oxygen

Question 13

how do the stomata reduce water loss by evaporation

Answer 13

the guard cells close at night when photosynthesis isnt occuring

Question 14

if the guard cells are swollen the stomata are open/closed

Answer 14

open

Question 15

if the guard cells are shrunken the stomata are open/closed

Answer 15

closed

Question 16

what are xerophytic plants

Answer 16

plants that have to adapt to live in dry arid conditions

Question 17

what structural features do xerophytic plants have to efficiently exchange gases whilst limiting water loss

Answer 17

curled leaves
hair like structures
sunken stomata
thicker cuticle
longer root network

Question 18

how is curled leaves aiding efficient gas exchange in xerophytic plants

Answer 18

water that manages to evaporates, is trapped within the curl so the area becomes very humid > reduces the water potential gradient from inside to outside of plant which reduces further evaporation

Question 19

how do the spikey hair like structures aid efficient gas exchange in xerophytic plants

Answer 19

they help to trap the water within the curl > increases humidity > reduces water potential gradient from the inside to outside of the leaf > reduces further evaporation

Question 20

how is sunken stomata aiding efficient gas exchange in xerophytic plants

Answer 20

helps trap moisture > increase in humidity > reduces water potential gradient from inside to outside of the cell > reduces further evaporation

Question 21

how is a thicker cuticle aiding efficient gas exchange in xerophytic plants

Answer 21

reduces evaporation

Question 22

how does having a longer root network aid efficient gas exchange in xerophytic plants

Answer 22

allows the roots to reach out to longer distances top reach more water