Xylem and Phloem - Translocation

Question 1

What is a xylem?

Answer 1

A continuous tube in a plant composed of dead cells with a hole down the middle.

Question 2

What is the function of a xylem?

Answer 2

Takes up water from the soil to the leaves through osmosis (passive)

Question 3

Give 3 structural features of a xylem?

Answer 3

1. Walls are impermeable due to a protein called lignin
2. No cytoplasm to maximise volume of water
3. There are lots of xylems in a plant to maximise the rate of photosynthesis.

Question 4

What is a phloem?

Answer 4

A column composed of elongated living cells with perforated end walls to allow cell sap to flow through.

Question 5

What is the function of a phloem?

Answer 5

Transports sugars i.e glucose and other food substances down the stem for use in growing regions or for storage in the roots via active transport (active).

Question 6

Give a structural feature of a phloem.

Answer 6

Has a cytoplasm

Question 7

What is translocation?

Answer 7

The transports of food subtances.

Question 8

Give the 6 stages of translocation.

Answer 8

1. Photosynthesis occurs in the leaves and glucose is produced.
2. The glucose is then transported into the phloem via active transport.
3. Water is then drawn into the phloem via osmosis.
4. This causes an increase in pressure in the phloem, which pushes the substances along its tube.
5. The glucose is then unloaded at the sink where it’s needed.
6. The xylem reabsorbs the water via osmosis back up the plant for photosynthesis.

Question 9

What are sources and sinks for glucose in a plant?

Answer 9

Source - leaves

Sinks - roots and stem

Question 10

Why is glucose stored as starch in plants?

Answer 10

1. It increases the total amount of glucose stored.
2. It’s a long-term energy store.
3. Starch cannot dissolve whereas glucose can.