SAFOLO — 2j.2 — Coordination/hormones in plants

Question 1

Auxin?

Answer 1

A plant hormone involved in tropisms and other growth responses

Question 2

Geo/Gravitropism?

Answer 2

Growth responses to the direction of gravity

Question 3

Phototropism?

Answer 3

Growth responses to light

Question 4

Tropism?

Answer 4

A directional growth responses
Positive: towards stimulus
Negative: away from stimulus

Question 5

4 important facts about auxin?

Answer 5

1. produced at the tip of shoots and roots
2. shoots - causes cell elongation (growth)
3. roots - prevents cell elongation (slows growth)
4. build up away from light (in shaded areas)

Question 6

How does auxin cause phototropism?

Answer 6

• shoots of plant contain auxin
• auxin diffuses equally down the shoot
• growth is equal in the shoot
• shoot will grow upwards
• since auxin builds up away from light growth will be unequal (shoot will bend)

Question 7

How does auxin cause geotropism?

Answer 7

• auxin prevents elongation
• auxin builds up in the lower part due to gravity
• in the shoot, auxin causes elongation so it grows faster and grows upwards
• but auxin prevents elongation in roots so it grows slower and bends down

Question 8

How can auxin be used as a weed killer?

Answer 8

It stimulates uncontrolled growth. Excess auxin can prevent elongation

Question 9

Positive and negative phototropism?

Answer 9

Positive: shoots grow towards light
Negative: roots grow away from light

Question 10

Positive and negative geotropism?

Answer 10

Positive: roots grow in direction of gravity
Negative: shoots grow opposite the direction of gravity

Question 11

Phototropism experiment variables?

Answer 11

Independent: direction of light
Dependent: if plant grows towards or away from light
Control: species of plant, temperature, spacing of seeds

Question 12

Geotropism experiment variables?

Answer 12

Independent: position of seed
Dependent: if the plant grows towards or away from gravity
Control: species of plant, temperature, volume of water