Transpiration and Translocation

Question 1

What are phloem tubes made of?

Answer 1

Columns of elongated living cells with small pores in the end walls to allow cell sap to flow through.

Question 2

What is a phloem tubes job? What is the process called?

Answer 2

They transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use (e.g. in growing regions) or for storage. The transport goes in both directions. This process is called translocation.

Question 3

What are xylem tubes made of?

Answer 3

Dead cells joined end to end with no end walls between them and a hole down the middle. They’re strengthened with a material called lignin.

Question 4

What is a xylem tubes job? What is the process called?

Answer 4

They carry water and mineral ions from the roots to the stem and leaves. The movement of water from the roots, through the xylem and out of the leaves is called the transpiration stream.

Question 5

How is transpiration caused?

Answer 5

1. By the evaporation and diffusion of water from a plant’s surface. (Most transpiration happens at the leaves.) 2. This evaporation creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it. 3. This means more water is drawn up from the roots, and so there’s a constant transpiration stream of water through the plant.