8 Transport In Plants

Question 1

xylem

Answer 1

transport of water and mineral ions

Question 2

phloem

Answer 2

transport of amino acids and sucrose

Question 3

structure of xylem vessel

Answer 3

walls thickened and strengthened by lignin
no cell contents
cells joined end to end with no cross walls to form a long continuous tube

Question 4

adaptations of root hair cells

Answer 4

large surface area - increases the uptake of water and mineral ions
lots of mitochondria - energy for active transport
large vacuole - helps maximise water absorption, storage until its transport takes place

Question 5

pathway of water in plant

Answer 5

root hair cells –> root hair cortex cells –> xylem cells –> mesophyll cells

Question 6

Transpiration

Answer 6

loss of water vapour from leaves
water evaporates from the surface of the spong y mesophyll cells and then diffuses out of the leaves through the stomata as water vapour

Question 7

mechanism of water movement from the roots up the tree to the leaves

Answer 7

a transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules

Question 8

why does wilting occur?

Answer 8

When theres more transpiration than water intake. the cells lose their turgidity and becomes flaccid, so stems can no longer remain erect and the plant begins to wilt

Question 9

how is wilting useful

Answer 9

• results in the loss of turgidity of guard cells which causes the closing of stomatas. This prevents further loss of water.
• reduces the rate of transpiration
• reduces surface area, less light absorption = less photosynthesis = less usage of water = reduced water loss

Question 10

translocation

Answer 10

movement of sucrose and amino acids in phloem from sources to sinks

Question 11

sources

Answer 11

parts of plants that release sucrose or amino acids

Question 12

sinks

Answer 12

parts of plants that use or store sucrose or amino acids

Question 13

what part of a plant can act as a sink and source at times

Answer 13

Roots:
When photosynthesis cannot occur/plant needs energy = source = roots break down starch stores and provide glucose to the plant for respiraiton
When roots need energy for active transport = sink = need sugar/energy from the plant for respiration to release energy

Question 14

Adaptations of xerophyte leaves

Answer 14

sunken stomata
hairs
fleshy leaves
thick cuticle
small surface area
lower stomata density

Question 15

function of stomata

Answer 15

movement of gases into and out of leaf:
For photosynthesis or respiration;
Allows tranpiration;
Enables water to be pulled up the plant;