8.1: Responses In Plants And Natural Selection

Question 1

Why can plants can respond to light?

Answer 1

• because photosynthesis is critical to a plant’s survival

Question 2

What is phototropism?

Answer 2

• A directional response that allows plants to grow towards (and in some cases away from) a source of
  light - SEE HANDOUT ON AUXINS

Question 3

What is photoperiodism?

Answer 3

• Allows plants to develop in response to day length; plants flower only at certain times of the year.
  ex. Christmas Cactus

Question 4

What are two mechanisms that allow plants to defend themselves against herbivory?

Answer 4

Physical and chemical defenses

Question 5

What are examples of a plant’s physical defenses?

Answer 5

• thorns, trichomes (small, plant-like hair)

Question 6

What are examples of a plant’s chemical defenses?

Answer 6

Production of toxic or distasteful compounds

Question 7

Why can soil composition affect plants? (2)

Answer 7

• the pH of soil can affect flower colouring in some plants

- nutrients are more accessible at certain pH