Plant Hormones (5.4) (M)

Question 1

Why are plant hormones released?

Answer 1

to coordinate and control growth and responses to light (phototropism) and gravity (gravitropism or geotropism)

Question 2

(…) distributions of auxin - a plant hormone - cause (…) growth rates in plant roots and shoots

Answer 2

Unequal (uneven)

unequal

Question 3

What are three plant hormones?

Answer 3

• auxin
• ethene
• gibberellins

Question 4

What effect does auxin have on plant shoots?

Answer 4

Stimulates growth

Question 5

What effect does auxin have on plant roots?

Answer 5

inhibits growth

Question 6

Why do shoots grow towards the light?

Answer 6

Because when exposed to sunlight, auxin (produced from the tip) moves to the shaded side, causing unequal distribution.

As auxin stimulates growth in shoots, the side with auxin grows at a faster rate (upwards) than the other, causing cell elongation

Question 7

Why do roots grow down?

Answer 7

Because gravity pulls auxin (produced at tip) down, auxin inhibits growth in roots, so the lower side won’t grow,, the other side will elongate downwards due to unequal distribution.

Question 8

What do gibberellins do?

Answer 8

initiate seed germination (so can grow)

Question 9

What does ethene do?

Answer 9

controls cell division and ripening of fruits

Question 10

Why do shoots grow upwards? (ignore light)

Answer 10

Because gravity pulls auxin (produced at tip) down, auxin promotes growth in roots, so the lower side will grow at a faster rate than the upper side, causing cell elongation due to unequal distribution