4.7 Transport In Plants

Question 1

Describe the structure of the xylem

Answer 1

Transports water and minerals providing structural support
Made of dead cells forming a continuous hollow tube
Contains pits enabling water to move between vessels
Contain lignin
One way
No cytoplasm

Question 2

Describe structure of phloem

Answer 2

Made of living cells
Has sieve tubes and companion cells
Sieve tubes transport sugars in the form of sap
And companion cells are involved in the ATP production for active processes
Plasmodesmata are gaps between cell walls allowing substnaces to flow and move
Both ways

Question 3

Process of transpiration

Answer 3

Humidity in the atmosphere causes water to diffuse out of the leaf via the stomata due too wp being lower outside of leave then inside water then moves into mesophyll cells via osmosis taking water from neighbouring cells.

Question 4

Cohesion tension theory

Answer 4

Water molecules form hydrogen bonds with each other sticking together via cohesion allowing water to form a continuous column down xylem evaporation causes hydrostatic pressure in the xylem the tension moves the column upwards due to cohesion.

Question 5

Describe the process of translocation

Answer 5

Movement of nutrients that store organs and parts of a plant

Question 6

Movement in the phloem(translocation)

Answer 6

Sucrose moves from the source to the sink via diffusion decreasing the water potential of the phloem allowing water to move into the phloem from the xylem via osmosis generating a hydrostatic pressure in the phloem so water moves down the sieve tube towards the sink down a pressure gradient as sucrose moves out of the phloem tue water potential of the phloem increases and water moves out by osmosis back to the xylem.

Question 7

Factors affecting transpiration

Answer 7

Air - increases the rate of transpiration
Humidity- decreases the concentration gradient
Temperature- rate of evaporation, water vapour
Light intensity - stomata opens