SYI Plant hormones

Plants produce plant hormones called auxins to coordinate and control growth. Which of the following is a function of auxins in shoots?

• Promote cell elongation

• Inhibit cell elongation

• Promote cell division

• Inhibit cell division

Answer explanation

Auxins in shoots promote cell elongation, helping in the growth and development of plant tissues.

In plants, what is the result of a positive phototropic response in shoots?

• Shoots grow upwards towards light

• Shoots grow downwards away from light

• Roots grow upwards towards light

• Roots grow downwards away from light

Answer explanation

A positive phototropic response in shoots causes them to grow upwards towards light, allowing the plant to maximize light absorption for photosynthesis.

In gravitropism or geotropism, how do shoots respond to gravity?

• Positive gravitropic response

• Negative gravitropic response

• Positive phototropic response

• Negative phototropic response

Answer explanation

Shoots exhibit a negative gravitropic response by growing against gravity, allowing them to reach for sunlight and optimize photosynthesis.

How do roots respond to light?

• Positive phototropic response

• Negative phototropic response

• Positive gravitropic response

• Negative gravitropic response

Answer explanation

Roots exhibit a negative phototropic response, meaning they grow away from light sources.

What is the primary effect of auxins in the roots?

• Promote cell elongation

• Inhibit cell elongation

• Promote cell division

• Inhibit cell division

Answer explanation

The primary effect of auxins in the roots is to inhibit cell elongation, not promote it. Auxins help regulate growth by inhibiting elongation in certain areas.

How is the distribution of auxin in shoots affected?

• Primarily by gravity

• Primarily by light

• By both light and gravity

• Neither light nor gravity

Answer explanation

The distribution of auxin in shoots is primarily affected by light, not gravity.

What happens when a shoot or root is placed on its side?

• Auxins accumulate along the upper side

• Auxins accumulate along the lower side

• Auxins are distributed evenly

• Auxins are not affected

Answer explanation

When a shoot or root is placed on its side, auxins accumulate along the lower side, causing that side to grow faster and bend towards the ground.

Which side of the shoot grows faster due to auxin in gravitropism?

• Upper side

• Lower side

• Both sides equally

• Neither side

Answer explanation

In gravitropism, auxin accumulates on the lower side of the shoot, inhibiting growth. This causes the upper side to grow faster, leading to bending towards gravity.

In which part of the shoot is auxin mostly made?

• Middle of the shoot

• Base of the shoot

• Tips of the growing shoots

• Throughout the shoot

Answer explanation

Auxin is mostly made in the tips of the growing shoots, where it plays a crucial role in plant growth and development.

How does auxin affect the cells behind the tip of the shoot?

• Stimulates to inhibit cell elongation

• Stimulates to promote cell elongation

• Inhibits to promote cell elongation

• Inhibits to inhibit cell elongation

Answer explanation

Auxin stimulates cell elongation behind the tip of the shoot, promoting growth.