Phototropism

Concept: Signal Transduction and Response

8m

Concept: Photomorphogenesis

14m

Concept: Auxin

11m

Concept: Photoderiodism

6m

Phototropism Additional Practice Problems

Guanylyl cyclase:

A. is linked with angina.

B. like adenylyl cyclase, converts NTPs to CNTPs.

C. causes a cGMP cascade that activates protein kinase C.

D. and adenylyl cyclase can bind extracellular signal molecules.

Watch Solution

You may have observed plants rotate towards a light source, thereby increasing the plant's ability to intercept light energy and increase photosynthesis. You, however, are given the task of preventing grass seedlings from rotating toward the light. Using your knowledge of phototropism, which of the following experimental procedures would you use to complete your task?

a. Cover the growing tip of the grass seedling with black paper.

b. Supply the seedlings with very dim light (red light does not induce a bend).

c. Cover the portion of the seedling below the tip with a black shield.

d. Supply the seedling with nutrient-rich fertilizer solution.

Watch Solution

Phytochrome plays a critical role in seed germination. Which of the colors maximizes the seed germination?

a. red

b. blue

c. violet

d. orange

Watch Solution

Which of the colors of visible light induces curvature in coleoptile most effectively?

a. red

b. blue

c. violet

d. orange

Watch Solution

Upon exposure to blue light, plants not only begin to grow toward the light, but move their chloroplasts to the sunny side of each cell. The adaptive advantage of moving chloroplasts to the sunny side of each cell ________.

a. maximizes light absorption by the chloroplasts for photosynthesis

b. increases production of phototropic hormones

c. maximizes heat absorption by the chloroplasts for cellular respiration

d. increases adenosine triphosphate (ATP) production during the light-independent reactions

Watch Solution