Plant Transport

Question 1

How is water taken in through the root hairs?

Answer 1

Osmosis

Question 2

Adaptions of root hairs

Answer 2

~ Thin
~ Numerous
~ Not covered by a cuticle

Question 3

Water uptake by roots

Answer 3

~ Water is taken in through the root hairs by osmosis
~ Soil particles are enclosed by a layer of pure water known as capillary water
~ The cytoplasm of root hairs is more concentrated than the water in the soil
~ The capillary water then moves in by osmosis
~ Water then enters the xylem by osmosis

Question 4

Cohesion-tension Model : Upward movement of water

Answer 4

~ Root pressure pushes the water into the xylem
~ Water molecules cling to each other due to cohesion causing a continuous column of water molecules due to hydrogen bonding
~ Adhesion enables the water molecules to cling to the xylem walls
~ Transpiration occurs in the stomata causing the water molecules to be pulled out of the leaf

Question 5

Palisade

Answer 5

Photosynthesis occurs here

Question 6

Guard cells

Answer 6

Control opening and closing of stomata

Question 7

Transpiration

Answer 7

~ Highest rate during : hot and sunny weather
~ Disadvantage : plants can wilt
~ Response : plants close stomata

Question 8

Control of transpiration

Answer 8

~ Leaves have a waxy cuticle on the upper side of leaves which prevents water from evaporating due to sunlight
~ Stomata are normally located on the bottom of leaves as it is cooler which prevents too much water loss
~ The stomata open during the day to allow for gas exchange and close by night to reduce water loss

Question 9

Control of stomata opening and closing

Answer 9

~ High concentrations of carbon dioxide : Causes stomata to close because photosynthesis is not taken place
~ Low concentrations of carbon dioxide : Causes the stomata to open due to photosynthesis happening
~ Other factors : Water loss, high temperatures and high wind speed causes the rate of transpiration to increase which causes the stomata to close during the day

Question 10

Uptake and transport of minerals

Answer 10

Minerals are absorbed into the root hairs by diffusion or active transport

Question 11

Uptake and transport of carbon dioxide

Answer 11

~ Taken in through the stomata by diffusion
~ Produced in leaf by respiration
~ Lenticels are openings in the stems that allow for gas exchange

Question 12

Modified root

Answer 12

Some dicots produce tap roots e.g. carrots

Question 13

Modified stem

Answer 13

Produce an underground stem system e.g. potato

Question 14

Modified leaves

Answer 14

Produce bulbs e.g. onions