Phototrophism in Plants

Phototrophism is the movement of plants in response to light, with stems showing positive phototrophism by growing towards light, and roots showing negative phototrophism by growing away. Light receptor molecules in plant cells respond to light, triggering the hormone auxin to act. Auxin accumulates on the shaded side of stems, causing them to bend towards light. Different plant parts respond to different light wavelengths; stems grow upwards in blue light, while roots grow downwards. Both stems and roots grow upwards in red light.

What is the term for plant movement towards a light source?

• Lateral phototropism

• Negative phototropism

• Positive phototropism

• Neutral phototropism

Which molecule is primarily responsible for the plant's response to light?

• Auxin

• Chlorophyll

• Starch

• Glucose

How does auxin affect the cells on the shady side of a plant stem?

• It hardens the cell walls

• It causes the cells to shrink

• It stops cell growth

• It softens and elongates the cell walls

What is the phototropic response of plant stems to blue light?

• They grow sideways

• They stop growing

• They grow downwards

• They grow upwards

How do roots respond to red light exposure?

• They grow sideways

• They stop growing

• They exhibit negative phototropism

• They exhibit positive phototropism