Module 5: Plant hormones and growth in plants

Question 1

What are the 4 main plant hormones

Answer 1

auxins
gibberellin
ethene
ABA

Question 2

Plant hormones and seed germination:

When a seed absorbs water , the embryo is activated and begins to produce which hormone?
What is the role of this hormone in seed germination?

Answer 2

gibberellins - these stimulate the production of enzymes that break down food stores within the seed

Question 3

Plant hormones and seed germination:

What are the food stores within the embryo of seeds used for?

Answer 3

the production of ATP which is then used for building materials so that the embryo can grow and break out through the seed coat

Question 4

Make 1 point about what evidence suggests about the role of gibberellins in seed germination

What is the role of ABA in seed germination?

make 1 more point about the effect of these 2 hormones combined

Answer 4

-gibberellins switches on genes which code for amylases and proteases which are the digestive enzymes required for germination

ABA-acts as an antagonist to gibberellins

(the relative levels of both hormones determine when a seed will germinate)

Question 5

Give 2 pieces of experimental evidence that support the role of gibberellins in seed germination

Answer 5

1)varieties of seeds have been bred that lack the gene enabling them to make gibberellins , these seeds don’t germinate but if gibberellins is then applied they do germinate

2)if gibberellin biosynthesis inhibitors are applied to seeds they do not germinate , if the inhibitors are removed they do germinate

Question 6

Where in plants are auxins produced?

Name the 2 ways that auxins can be transported around plants

Answer 6

in cells at the tip of roots and shoots and in the meristems

they can move down the stem and up the root in transport tissue or just from cell to cell

Question 7

Make 6 points explaining the steps of how auxins stimulate growth of the apical shoot of plants