B9 Transport In Plants

Question 1

Lignin

Answer 1

What lines and strengthens the cellulose walls of xylem. It also makes the cells waterproof

Question 2

Why do the xylem cells need to be strengthened?

Answer 2

It’s needed to cope with tension forces created as large volumes of water evaporate from the leaves and also to provide support for the plant

Question 3

Phloem

Answer 3

The specialized tissue in a plant which transports soluble compounds such as sugars (e.g sucrose) and amino acids to sites of growth and storage

Question 4

What is phloem tissue made up of?

Answer 4

Sieve tubes and companion cells

Question 5

Use of companion cells

Answer 5

They provide energy for the movement of soluble substances through the sieve tubes in the phloem

Question 6

What process causes water to enter the root hair cell from the soul water?

Answer 6

Osmosis

Question 7

What process causes mineral ions to enter the root hair cell from the water?

Answer 7

Active transport

Question 8

How does the root hair cell help the plant bring water and mineral ions into it?

Answer 8

Osmosis- there’s concentrated cell sap in the cell
ATP
Lots of root hairs- large surface area
Water in the xylem is continuously flowing upward by transpiration pull- this maintains a steep concentration gradient

Question 9

Transpiration

Answer 9

The evaporation of water at the surfaces of the mesophyll cells followed by loss of water vapour from plant leaves, through the stomata

Question 10

Adhesion

Answer 10

The attraction of water molecules to the wall of xylem

Question 11

Cohesion

Answer 11

The attraction between water molecules

Question 12

Xylem

Answer 12

The specialized tissue in plants that transports water and inorganic ions.

Question 13

Transpiration stream

Answer 13

The flow of water from the roots to the stem and then to the leaves through the xylem tubes

Question 14

How do the columns of water in the xylem tubes not break?

Answer 14

There are strong cohesive forces between the water molecules

Question 15

Water potential gradient

Answer 15

The movement of water from an area where it is at a high concentration to an area where it is at a lower concentration

Question 16

Features of the plant that help decrease the rate of transpiration

Answer 16

1) Waxy cuticle covering the upper and lower epidermis- waterproof, so water can’t evaporate through the epidermis
2) Hairs in the surface of the leaf- traps moisture and water molecules, this makes a humid area around the leaf, allowing for a more gradual concentration and slower diffusion
3) Low stomatal density and very few stomata on the upper surface of the leaf- less stomata= slower transportation rate
4) Sunken stomata- makes it harder for water to evaporate
5) Small volume of air space in the spongy mesophyll layer- there’s less water in the air space

Question 17

Translocation

Answer 17

The movement of manufacturer food through the tissues of the phloem.

Question 18

Where is food manufactured in plants?

Answer 18

The leaves

Question 19

Capillarity

Answer 19

The ability of water molecules to move through the tubes by cohesion and adhesion. The thinner the tube, the higher the water level in the tube

Question 20

Xylem vessels

Answer 20

The dead empty xylem cells which form continuous columns and a system of pipes