5B:Plant Vascular Tissues

Question 1

How does the structure of a root assist it to uptake water for photosynthesis?

Answer 1

root hairs - tiny hairs that increase SA for mineral & water absorption from soil

meristem - region where new cells are produced by mitosis

root cap - large cells that protect tip of growing root as it grows into soil

Question 2

Name the transport system for water transport.
In which direction is water transported in this transport system?

Answer 2

XYLEM: transport water via osmosis upwards into the stem

Question 3

Describe the structure of the xylem.

Answer 3

XYLEM VESSELS - dead cells that become hollow tubes which carry the water up to leaves
LIGNIN - rings which strengthen the xylem vessels keeping them open to allow easy water flow

Question 4

What is the transpiration stream?

Answer 4

continuous stream of water molecules which adhere to sides of vessel and stick to each other aiding in the upward movement of water

Question 5

What is the difference in the forces of cohesion and adhesion which relate to water transport in a plant?

Answer 5

• water adheres to the sides of the vessel
• whilst cohesion occurs in the attachment of the water molecules sticking them together

Question 6

What is a vascular bundle and what does it contain?

Answer 6

• organised group of xylem vessels
• contains xylem and phloem

Question 7

How are vascular bundles arranged in the root, stem and the leaf?

Answer 7

?

Question 8

Know the structure of a leaf and how the layers assist
photosynthesis – cuticle, palisade cells, spongy cells,
air spaces, vascular bundles, bundle sheath cells, stomata with guard cells.

Answer 8

cuticle - waxy layer covering upper surface, protects leaf against water loss
palisade cells - contain chloroplast, tightly packed, maximise energy production during photosynthesis
spongy cells - allow CO2 to diffuse in and O2 to diffuse out of cells
vascular bundles - transport water, nutrients and food, contains phloem and xylem
stomata - opening where water and gases enter and exit
guard cells - surround stoma, open and close

Question 9

What is the function of stomata in photosynthesis?
When do they open and close and why?
What is the role of potassium ions in stomatal opening and closing?

Answer 9

• most water evaporates out of the leaf through the stomata
• open to allow carbon dioxide in/oxygen out
• open at day, close at night
• k+ irons are actively pumped into cell to make it hypertonic, forcing open stomata speeding transpiration and photosynthesis

Question 10

What factors increase the rate of transpiration in a plant?

Answer 10

temp, humidity, light, wind, water

Question 11

Name the transport system which transports food in a plant?

Answer 11

PHLOEM:
- made of living cells separated by sieve plates
- surrounded by companion cells w/t nucleus which control movement of sugars

Question 12

In what direction is this food transported? What form is food transported?

Answer 12

• two way flow, up and down
• food in the form of sugar(sucrose)

Question 13

What is translocation?

Answer 13

the movement of food(sucrose)

Question 14

How is food stored in a plant? Where is food stored?

Answer 14

• if sucrose is not used it can be stored as starch
• starch can be stored in leaves, roots, fruits, flowers(sink)

Question 15

What are the steps of translocation?

Answer 15

1) Glucose made in leaf cells is
pumped into a companion cell.

2) It then diffuses into the sieve
cells of the phloem.

3) Increased glucose concentration causes water to
enter (osmosis) from nearby
xylem.

4) The increased pressure in the phloem, pushes the liquid in the phloem throughout the plant.

5) Glucose is actively transported into the required cells (sinks – root and fruit cells)

6) Once glucose is unloaded, concentration in phloem is reduced and water diffuses back into the xylem.