B1.2.3 Control in plants

Question 1

What 3 factors are plants sensitive to?

Answer 1

light, moisture and gravity.

Question 2

What affects the direction in which shoots grow? (2 marks)

Answer 2

shoots grow towards light

and against the force of gravity

Question 3

What affects the direction in which roots grow? (2 marks)

Answer 3

Roots grow towards moisture

and in the direction of the force of gravity.

Question 4

What is the name for plant hormones that coordinate and control growth?

Answer 4

Auxins

Question 5

What is the response towards light more scientifically known as?

Answer 5

phototropism

Question 6

What is the response towards gravity more scientifically known as?

Answer 6

gravitropism (geotropism).

Question 7

What causes plants roots and shoots response to gravity, light and moisture?
(2 marks)

Answer 7

• The unequal distribution of hormones,

- causing unequal growth rates.

Question 8

Which way do auxins move in a plant root?

Answer 8

Towards gravity

Question 9

What effect do auxins have on root cells?

Answer 9

They cause the cells to slow down their growth (elongation)

Question 10

Which way do auxins move in a plant shoot?

Answer 10

Away from light (towards the shaded part)

Question 11

What effect do auxins have on shoot cells?

Answer 11

They cause the cells to speed up their growth (elongation)

Question 12

How might plant growth hormones be used in agriculture and horticulture? (2 marks)

Answer 12

As weed killers

As rooting hormones.