adaptations and hormones

Question 1

Describe the root system of a plant in the desert

Answer 1

Widespread, deep root system

Question 2

Why do plants in the desert have longer roots?

Answer 2

To collect water from over a larger area

Question 3

Why do plants in the desert have smaller leaves or spines?

Answer 3

Minimising surface area, reducing the number of stomata and therefore water loss. Spines might also protect from predators

Question 4

Why do plants in the desert have thicker, waxy cuticles?

Answer 4

To reduce water loos by evaporation.

Question 5

Why are there usually more stomata on the bottom of a leaf than on the top?

Answer 5

to reduce water loss by transpiration. The underside of a leaf is shaded from the sun and usually cooler.

Question 6

How can you measure how many stomata are on a leaf?

Answer 6

make a layer of clear nail polish on the leaf and peel off onto a microscope slide. Use a microscope to count the number of stomata in a part of the leave. Work out the area you have sampled and the total area of the leaf. Then area of leaf / sampled area x number of stomata. Take repeat readings.

Question 7

What is a phototropism

Answer 7

When a plant grows in response to light

Question 8

What is the difference between a positive tropism and a negative tropism?

Answer 8

A positive tropism means the plant is growing towards a stimulus (e.g. light) whereas a negative tropism means the plant is growing away from the stimulus.

Question 9

What is gravitropism?

Answer 9

A plant grows in response to gravity

Question 10

Which part of the plant has a positive phototropism?

Answer 10

stem

Question 11

Which part of the plant has a negative phototropism?

Answer 11

roots

Question 12

What effect does auxin have on stems?

Answer 12

cells grow more

Question 13

What effect does auxin have on roots?

Answer 13

cells grow less

Question 14

How does auxin cause positive phototropism in shoots?

Answer 14

the sunlight breaks down auxin on the side of the shoot facing the sun. On the shaded side, the auxin causes the cells to elongate. The unequal growth on both sides of the shoot causes the shoot to bend towards the light.

Question 15

Which part of a plant has a negative gravitropism?

Answer 15

Stems- they grow away from gravity

Question 16

Which part of the plant has a positive gravitropism?

Answer 16

Roots- they grow towards gravity

Question 17

How does auxin cause positive gravitropism in roots?

Answer 17

Gravity means the auxin gathers in the part of the root facing downward. Auxin slows the growth of these cells meaning the root curve downwards

Question 18

What are some uses of auxins in agriculture?

Answer 18

Weed killers and rooting powders

Question 19

What is the function of gibberellins?

Answer 19

causing seed germination and stimulating cell elongation

Question 20

What are some uses of gibberellins in agriculture?

Answer 20

causing seeds to germinate at the correct time, making plants grow taller, making plants flower at a certain time and increasing fruit size. Giberellins are also used to produce seedless fruit.

Question 21

What is the function of ethene in plants?

Answer 21

Causing fruit to ripen

Question 22

What is a use for ethene in agriculture?

Answer 22

Causing fruit to ripen at a certain time, meaning it is fresh in shops