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.

Describe the effect of blue light on the phototropic responses of stems and roots.

What happens to stems and roots when exposed to red light?