2.8.3 Water Movement in Flowering Plants

Question 1

Root hair cells are adapted for the efficient uptake of, what?

Answer 1

water (by osmosis) and mineral ions (by active transport)

Question 2

What are root hair cells

Answer 2

Root hairs are single-celled extensions of epidermis cells in the root

Question 3

Where do root hair cells grow

Answer 3

They grow between soil particles and absorb water and minerals from the soil

Question 4

Root hairs increase, what?

Answer 4

the surface area to volume ratio significantly

• This increases the rate of the absorption of mineral ions by active transport

Question 5

The high proportion of dissolved minerals and sugars in the cytoplasm (of the root hair cell) give it, what?

Answer 5

a low water potential (less watery)

Question 6

How does water move into the root hair cell

Answer 6

by osmosis

Question 7

Name all of the 8 cells inside a root hair cell

Answer 7

Ribosomes 
Nucleus
Cell Membrane
Cell Wall
Root hair
Vacuole 
Cytoplasm
Mitochondrion

Question 8

The structure of a root specifically allows it to maximise, what?

Answer 8

absorption of water by osmosis and mineral ions by active transport

Question 9

Water moves, by osmosis, into the root hair cells, through, what?

Answer 9

through the root cortex and into the xylem vessels:

Question 10

Once the water gets into the xylem, it is carried up to the leaves where it enters, what?

Answer 10

mesophyll cells

Question 11

What is pathway of water through the plant

Answer 11

root hair cell → root cortex cells → xylem → leaf mesophyll cells

Question 12

Transpiration is defined as, what?

Answer 12

the loss of water vapour from the parts of the plant that are above ground (leaves, stem, flowers)

Question 13

Loss of water occurs through evaporation of water at the surfaces of the, what?

Answer 13

the spongy mesophyll cells followed by diffusion of water vapour through the stomata

Question 14

The many interconnecting air spaces between the mesophyll cells and the stomata create a, what?

Answer 14

large surface area

• This means evaporation can happen rapidly when the stomata are open

Question 15

Describe the effect of transpiration

Answer 15

Water moves through the xylem vessels in a continuous transpiration stream from the roots to the leaves via the stem to replace the water that has been lost due to transpiration

Question 16

Due to cohesion, the water in the xylem creates what?

Answer 16

continuous unbroken column (each individual molecule ‘pulls’ on the one below it)

Question 17

Transpiration produces, what? in the xylem vessels

Answer 17

Transpiration produces tension or ‘pulls’ on the water in the xylem vessels

Question 18

If the rate of transpiration from the leaves increases, what happens?

Answer 18

water molecules are pulled up the xylem vessels quicker

Question 19

Transpiration has several functions (4) in plants, what are they?

Answer 19

1. Transporting mineral ions

Question 20

There are several environmental conditions which have an impact on the rate of transpiration, what are they?

Answer 20

1. Air movement