Question 1

Which of the following best describes the process of de-etiolation in plants?

Accepted Answer

The process by which plants resume normal growth under light conditions, activating enzymes for photosynthesis and chlorophyll production.

Question 2

A plant biologist removes the apical bud from a growing plant. Which hormonal changes and physiological response would most likely occur?

Accepted Answer

Decreased auxin and strigolactone levels, increased sugar availability, and initiation of axillary bud growth.

Question 3

Which of the following is a direct result of auxin stimulating proton pumps in the plasma membrane of plant cells?

Accepted Answer

Lowering of cell wall pH, activation of expansins, and loosening of the cell wall for elongation.

Question 4

A scientist exposes seeds to alternating flashes of red and far-red light. According to the study materials, which statement best explains the effect on seed germination?

Accepted Answer

The final light exposure determines the germination result; red inhibits and far-red promotes germination.

Question 5

Which hormone is primarily responsible for enabling plants to withstand drought by causing rapid stomatal closure?

Accepted Answer

Abscisic acid (ABA)

Question 6

A mutant rice plant infected with a pathogenic fungus grows excessively tall and falls over. Which hormone is most likely overproduced due to the infection?

Accepted Answer

Gibberellin

Question 7

Which of the following best describes the role of phytochromes in plant responses to light?

Accepted Answer

They absorb red and far-red light, regulating processes such as seed germination and shade avoidance.

Question 8

Which of the following is an example of thigmotropism?

Accepted Answer

A vine coiling around a trellis after contact with it.

Question 9

A plant is exposed to mechanical stress, such as wind or touch. Which hormone is most likely to be produced in response, and what is the typical growth response?

Accepted Answer

Ethylene; triple response with slowed stem elongation, thickening, and horizontal growth.

Question 10

Which of the following best explains why blue light is effective in initiating stomatal opening in plants?

Accepted Answer

Blue light is absorbed by cryptochromes and phototropins, which mediate stomatal opening.

Question 11

A plant is genetically modified to lack functional protein phosphatases. What is the most likely consequence for its signal transduction pathways?

Accepted Answer

Proteins will remain phosphorylated, leading to prolonged or unregulated cellular responses.

Question 12

Which of the following best describes the action spectrum in plant biology?

Accepted Answer

A graph depicting the relative response of a physiological process to different wavelengths of light.

Question 13

Which hormone is most directly involved in promoting cell division and differentiation in conjunction with auxin, and is also known for its anti-aging properties?

Accepted Answer

Cytokinin

Question 14

A plant is exposed to a long night interrupted by a brief flash of red light. What is the most likely effect on a short-day plant's flowering?

Accepted Answer

Flowering is inhibited because red light interrupts the critical night length.

Question 15

Which of the following is a unique feature of plant cell communication compared to animal cells?

Accepted Answer

Plants can transport macromolecules such as proteins cell-to-cell through plasmodesmata.

Question 16

Which hormone is chemically similar to animal cholesterol and sex hormones, and is involved in promoting cell elongation, slowing leaf abscission, and promoting xylem differentiation?

Accepted Answer

Brassinosteroids

Question 17

A seed requires both a period of cold and a specific photoperiod to flower. What is the term for the cold pretreatment, and what is the likely flowering response if only the photoperiod is provided?

Accepted Answer

Vernalization; the plant will not flower without the cold treatment.

Question 18

Which of the following best describes the role of jasmonates in plants?

Accepted Answer

They play important roles in plant defense, nectar secretion, fruit ripening, and response to wounding.

Question 19

A plant's roots grow downward while its shoots grow upward. Which terms best describe these responses?

Accepted Answer

Roots: positive gravitropism; Shoots: negative gravitropism

Question 20

Which of the following best explains how circadian rhythms are entrained to a 24-hour cycle in plants?

Accepted Answer

Light, detected by phytochromes and blue-light photoreceptors, resets the biological clock to 24 hours.

Plant Responses to Internal and External Signals

Study Guide - Practice Questions

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