Plant Hormones and Their Functions

These flashcards cover the key concepts about plant hormones, including auxin, ethene, and gibberellins, and their roles in plant growth and responses.

What is auxin?

Auxin is a hormone which controls the growth of a plant’s shoots and roots.

What happens when auxin is unevenly distributed in a plant?

The rate of growth will also be unequal.

How do plant shoots show positive phototropism?

Auxin moves to the shaded side, causing the shaded cells to grow more, resulting in the shoot bending towards the light.

What is the result of a shoot bending towards the light?

Photosynthesis can occur at a faster rate.

How do plant shoots show negative gravitropism?

Auxin accumulates on the lower side of a horizontal shoot, causing the shoot to bend away from the direction of gravity.

What is the effect of a shoot bending away from gravity?

More light is usually available for photosynthesis.

How do plant roots show positive gravitropism?

Auxin accumulates in the lower side of a horizontal root, causing less growth on that side and bending the root in the direction of gravity.

What is the effect of a root bending in the direction of gravity?

More water and nutrients are available to the plant roots.

What are the uses of auxins in agriculture?

Weedkillers, rooting powder, and tissue culture.

What is the effect of auxin as a weedkiller?

It causes cells to grow at a rapid rate, leading to plant death.

How is auxin used in rooting powder?

It causes new plants to grow very quickly.

What is the function of auxin in tissue culture?

It promotes growth of roots and shoots.

What is the use of ethene in the food industry?

Control of food ripening.

How does ethene affect fruit ripening?

It allows fruit to be ripened just before they are sold.

What is one of the key uses of gibberellins?

Termination of seed dormancy.

What is another use for gibberellins?

Promotion of flowering.

How do gibberellins affect fruit?

They increase fruit size.

What hormone is involved in phototropism?

Auxin.

How does gravity influence auxin distribution in plants?

It causes auxin to accumulate on the lower side of a horizontal shoot or root.

What is a plant’s response to light called?

Phototropism.

What is a plant’s response to gravity called?

Gravitropism.

What happens to cells on the shaded side of a shoot?

They are stimulated to grow more.

In positive gravitropism, which side of the root grows less?

The lower side.

What promotes the bending of shoots and roots in response to environmental stimuli?

Auxin.