Plant Hormones

Question 1

[ ] is a plant hormone that controls growth near the tips of [ ] and [ ].

Answer 1

Auxin
Shoots
Roots

Question 2

What does Auxin do?

Answer 2

It controls the growth of a plant in response to light (Phototropism), gravity (Gravi/Geotropism) and moisture

Question 3

Where is Auxin produced? Where does it go? What does it cause?

Answer 3

Produced in the tips and moves backwards to stimulate the cell elongation (enlargement) process which occurs in the cells just behind the tips

Question 4

What happens if the tip of a shoot is removed?

Answer 4

No auxin is available and the shoot may stop growing

Question 5

Auxin [ ] in a plant’s shoots

Answer 5

Promotes growth

Question 6

Shoots grow towards [ ]

Answer 6

Light

Question 7

Describe the process that makes shoots grow towards light

Answer 7

1) When a shoot tip is exposed to light, more auxin accumulates on the side that’s in the shade than the side that’s in the light
2) This makes the cells grow (elongate) faster on the shaded side, so the shoot bends towards the light.

Question 8

Describe the process that makes Shoots grow away from gravity

Answer 8

1) When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side.
2) This causes the lower side to grow faster bending the shoot upwards

Question 9

Shoots grow away from [ ]

Answer 9

Gravity

Question 10

Auxin [ ] in a plant’s roots

Answer 10

Inhibits growth

Question 11

Describe the process that makes Roots grow towards moisture

Answer 11

1) An uneven amount of moisture either side of a root produces more more auxin on the side with more moisture
2) This inhibits growth on that side, causing the root to bend in that direction, towards the moisture

Question 12

Describe the process that makes Roots grow towards gravity

Answer 12

1) A root growing sideways will have more auxin on it’s lower side (because of gravity)
2) But in a root the extra auxin INHIBITS growth. This means the cells on top elongate faster and the root bends downwards.

Question 13

Make sure you can draw diagrams for auxin elongation etc.

Answer 13

Do it!!

Question 14

Plant hormones can be [ ], or [ ] versions can be made

Answer 14

extracted

artificial

Question 15

How do weed-killers work?

Answer 15

Most weeds in crop fields are broad-leaved, unlike the crops. Selective weedkillers are made of plant growth hormones - they only effect the brad-leaved plants. They disrupt their normal growth patterns, which soon kill them

Question 16

Why use rooting powder?

Answer 16

Plant cutting won’t always work in soil. If you had rooting powder, which contain the plant hormone auxin, they’ll produce roots rapidly and start growing as new plants.
This helps growers to produce lots of clones of a really good plant quickly