5.1.5 Plant Responses

Question 1

Auxins

Answer 1

Cause cell elongation in stems
Inhibits growth in roots
Prevents leaves from dropping/abscission
Maintains apical dominance
Stimulates ethene (fruit ripening)

Question 2

Ethene

Answer 2

Fruit ripening
Promotes abscission in deciduous trees

Question 3

Gibberellin

Answer 3

Stimulates seed germination
Stem elongation
Pollen tube growth in fertilisation

Question 4

Abscisic acid (ABA)

Answer 4

Stimulates stomatal closing
Maintains dormancy of seeds
Stimulates cold protective responses (antifreeze)

Question 5

Pheromones

Answer 5

Chemical made by an organism which affects the social behaviour of other members of the same species

Question 6

Tannins

Answer 6

Bitter taste
Puts animals off eating the leaves
Toxic to insects

Question 7

Alkaloids

Answer 7

Bitter taste nitrogenous compounds
- Caffeine, nicotine, morphine