6.8 Structures of the xylem and phloem

Question 1

Name the two plant transport tissues

Answer 1

Xylem

Phloem

Question 2

What is the function of Xylem?

Answer 2

Xylem is made of
tubes of dead cells
that are adapted to
carry water through
the plant.

Question 3

Describe how the xylem is adapted to its function

Answer 3

● Cell walls strengthened with
lignin to prevent bursting or
colanse

● Tiny pores allow water and mineral
ions to enter and leave the xylem
vessels.

● The dead cells have no cytoplasm
and so form an empty tube for
water to flow through.

-One cell thick, the lack of cell walls between the cells means that water flow is not slowed down.

Question 4

What is the function of the phloem?

Answer 4

Transports sucrose up and down the stem from mature green leaves to non-photosynthetic tissues developing seeds via translocation

Question 5

What are the two cell types that make up the phloem?

Answer 5

Sieve tube elements

Companion cells

Question 6

Describe how the phloem is adapted to its function?

Answer 6

● Sieve tube elements are long, thin cells, laid end-to-end with perforated end plates to enable the flow of sugars. They contain no nucleus and little cytoplasm to allow sugars to flow easily.

● Companion cells (adjacent to sieve tube elements) contain a dense cytoplasm, nucleus and mitochondria. They provide energy for processes in both cell types

Question 7

Is transpiration or translocation through the XYLEM?

Answer 7

Transpiration

Question 8

Is transpiration or translocation through the PHLOEM?

Answer 8

Translocation

Question 9

Is transpiration or translocation through a passive process?

Answer 9

transpiration

Question 10

Is transpiration or translocation through an active process?

Answer 10

Translocation

Question 11

Is transpiration or translocation the movement of water?

Answer 11

Transpiration

Question 12

Is transpiration or translocation the movement of sucrose?

Answer 12

Translocation

Question 13

Where does transpiration transport water?

Answer 13

Mainly to the roots to the leaves

Question 14

Where does translocation transport sucrose?

Answer 14

Mainly leaves to the other parts

Question 15

What is the purpose of Transpiration?

Answer 15

Transpiration is the process that transports water and mineral ions through a plant, providing water to leaf
cells for photosynthesis and mineral ions to other
cells for growth.

Question 16

Explain how transpiration happens, and how plants are adapted for this process.

Answer 16

Transpiration is the flow of water through a plant. It starts at the roots where water is absorbed through root hair cells. These cells have thin cell walls and long extensions out into the soil that increase the surface area for absorption, making it easier for the plant to absorb water quickly.

Inside the plant, water moves into xylem tissue. Xylem is made of long empty tubes, because the cells that formed the tubes have died and the cytoplasm and walls between the cells have gone. This makes it easier for water to move quickly from the roots to all parts of the plant. The walls of xylem tubes are thickened with lignin so they don’t collapse or burst easily as water passes through them.

Water moves out of xylem in the leaves and diffuses out through tiny pores called stomata in the leaf surface. Each stoma is surrounded by two guard cells that can change shape. This enables stomata to open during the day, but close at night to reduce water loss from the plant.

Water continually flows through the plant because water molecules are attracted to each other. As water diffuses out of stomata, it pulls more water into the leaf from xylem, which causes more water to be absorbed in the roots.

Question 17

Label the structure of a plant

Answer 17

A-
waxy cuticle

B-
Air Space

C-
Stoma

D-
Lower Epidermis

E-
Xylem and Phloem vessels

F-
Palisade layer

G-
Upper epidermis

Question 18

Define Phototropism

Answer 18

The growth response of the shoot to light