Seed germination

Question 1

What happens when the seed absorbs water?

Answer 1

• the embryo is activated
• it begins to produce gibberellins

Question 2

How does the embryo produce energy?

Answer 2

• enzymes are released which break down the food stores found in the seed
  
  • the food store is in the cotyledons in dicot seeds and the endosperm in monocot seed
• use food stores to produce ATP for building materials so it can grow and break out through the seed coat

Question 3

What other role do gibberellins have in the germination of seeds?

Answer 3

• swtich on genes which code for amylases and proteases
  
  • digestive enzymes required for germination

Question 4

What is the experimental evidence for the role of gibberellins in the germination of seeds?

Answer 4

• mutant varieties of seeds that are unable to make gibberellins
  
  • don’t germinatie
  • if gibberelins are applied externally, they germinate normally
• if gibberellin biosynthesis inhibitors are applied to seed, they do not germinate as they cannot make the gibberellins needed for them to break dormancy
  
  • if inhibitors is removed, or gibberellins applied, they germinate normally

Question 5

What does the seed contain?

Answer 5

• seed coat
• layer containing storage proteins
• starchy food store
• embryo