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Question 1

What is tropism?

Answer 1

The response of an organism (plants) to a stimulus.

Question 2

What are the 2 types of tropism?

Answer 2

1. Phototropism (response towards light)
2. Geotropism/gravitropism (response towards gravity)

Question 3

What are auxins?

Answer 3

The plant hormone responsible for phototropism and gravitropism.

Question 4

Where is an auxin found and how does it work?

Answer 4

Auxin is found at the tip of coleoptiles (seedlings/shoots). As light shines on the plant, the auxin diffuses to the shaded part of the shoot. The auxin then causes the cells to elongate causing the shoot to bend towards the light, in order to receive more light energy and do more photosynthesis.

Check book page 136 and notebook “Plant Hormones” for diagram.

Question 5

How do auxins work in roots?

Answer 5

Roots grow by positive gravitropism and negative phototropism. Auxins in roots are located at the bottom part of the root due to gravity and inhibit cell elongation. At the top part, cells elongate naturally causing the root to bend towards the soil.

Check book page 137 and teacher notes/notebook “Plant Hormones”.

Question 6

What are 2 other plant hormones, their purpose and where they are found?

Answer 6

Ethene/ethylene (gas): Produced in fruits as they ripen and speeds up the ripening process.

Gibberellins: Formed in seeds and young leaves, promote stem elongation and germination.

Question 7

What are 2 artificial uses of auxins?

Answer 7

Artificial hormones used as:
1. Selective weedkillers
2. Rooting powder

Question 8

What do selective weedkillers do?

Answer 8

Can only kill plants with broad leaves, which can be used in fields containing crops with narrow leaves.

Question 9

What does rooting powder do?

Answer 9

Plant cuttings are dipped into rooting powder, causing roots to develop a lot faster for planting.

Question 10

What are 3 uses of gibberellins?

Answer 10

1. Used to create seedless fruit
2. Used to make fruits bigger in size
3. Spraying gibberellins causes the plant to override their photoperiodism and they will flower whenever we want them

Question 11

What is the use of ethene?

Answer 11

Used to ripen fruits so they reach the market just-ripped.

Question 12

What is photoperiodism?

Answer 12

The response of plants/organisms to the number of daylight hours during a 24-hour period.

Question 13

What is the flowering of plants?

Answer 13

The number of hours in continuous darkness that determines whether a plant will flower or not.

Question 14

What are the 2 different types of plants?

Answer 14

1. Short-day plants (need many hours in darkness)
2. Long-day plants (need few hours in darkness)