Plant hormones

Question 1

What is the name given to plant response to light?

Answer 1

phototropism

Question 2

What is the name given to a plants response to gravity.

Answer 2

geotropism or gravitropism

Question 3

What is the name of the hormone that controls growth in plants?

Answer 3

The hormone auxin controls growth in plants.

Question 4

Explain how auxin controls phototropism in plants.

Answer 4

Auxin is broken down by sunlight and so concentrates in the unlit side of the shoot. The cells on the unlit side of the shoot elongate and grow causing the shoot to bend towards the light.

Question 5

Explain how auxin controls gravitropism in shoots and roots.

Answer 5

Auxin makes shoot cells grow but inhibits growth in root cells.

Auxin causes unequal growth of cells on one side which causes the shoots and roots to bend

Question 6

What is the role of gibberellins in plants.

Answer 6

Gibberellins are important in initiating seed germination.

Question 7

What is the role of ethene in plants?

Answer 7

Ethene controls cell division and ripening of fruits.

Question 8

Describe how auxins can be used in agriculture and horticulture.

Answer 8

Auxins are used:
• as weed killers
• as rooting powders
• for promoting growth in tissue culture.

Question 9

Describe how ethene can be used in agriculture and horticulture.

Answer 9

Ethene is used in the food industry to control ripening of fruit during storage and transport.

Question 10

Describe how gibberellins can be used in agriculture and horticulture.

Answer 10

Gibberellins can be used to:
• end seed dormancy
• promote flowering
• increase fruit size.