$$\text{Signal} \rightarrow \text{Receptor} \rightarrow \text{Second Messenger} \rightarrow \text{Response}$$

Question 1

Which of the following best describes the sequence of events in a typical plant signal transduction pathway?

Accepted Answer

Reception → Transduction → Response

Question 2

A potato kept in the dark develops long stems and pale leaves. After exposure to sunlight, it becomes green and short. What is this process called?

Accepted Answer

De-etiolation

Question 3

Which plant hormone is primarily responsible for stimulating cell elongation and regulating branching?

Accepted Answer

Auxin

Question 4

In the classic experiment by Frits Went (1926), what was demonstrated about the tip of a plant shoot?

Accepted Answer

It produces a growth-promoting chemical that diffuses downward

Question 5

Which hormone is most closely associated with promoting seed germination and breaking seed dormancy?

Accepted Answer

Gibberellin

Question 6

A scientist applies gibberellin to a rosette plant. What is the most likely outcome?

Accepted Answer

The plant will bolt, producing a tall flowering stalk

Question 7

Which of the following is a correct description of a hormone in plants?

Accepted Answer

A signaling molecule produced in one part of the body and transported to another, where it triggers a specific response

Question 8

Which plant hormone is most likely to promote lateral bud growth and slow organ death?

Accepted Answer

Cytokinin

Question 9

During de-etiolation, which molecule acts as a receptor for light and initiates the signal transduction pathway?

Accepted Answer

Phytochrome

Question 10

Which of the following best explains the role of second messengers in plant signal transduction?

Accepted Answer

They relay signals from receptors to target proteins, amplifying the response

Question 11

A plant exposed to drought conditions increases the production of which hormone to promote stomatal closure?

Accepted Answer

Abscisic acid

Question 12

Which hormone is most directly involved in mediating fruit ripening?

Accepted Answer

Ethylene

Question 13

If a plant’s tip is removed and replaced with an agar cube containing auxin, what will happen to the plant’s growth?

Accepted Answer

The plant will continue to grow towards the light

Question 14

Which of the following is a major function of brassinosteroids in plants?

Accepted Answer

Promote cell elongation and division

Question 15

Which hormone is most likely to regulate seed germination and mycorrhizal associations?

Accepted Answer

Strigolactone

Question 16

A plant cell receives a hormone signal. Which equation best represents the general process of signal transduction in the cell?

Accepted Answer

$$	ext{Signal} ightarrow 	ext{Receptor} ightarrow 	ext{Second Messenger} ightarrow 	ext{Response}$$

Question 17

Which hormone would you expect to be elevated in a plant that is experiencing water stress and needs to conserve water?

Accepted Answer

Abscisic acid

Question 18

Which of the following best explains why gibberellin-treated grapevines produce larger grapes than untreated vines?

Accepted Answer

Gibberellin promotes cell elongation and division, resulting in larger fruit size

Question 19

Which hormone is most likely to be involved in the process of leaf abscission?

Accepted Answer

Ethylene

Question 20

A plant cell is exposed to light, activating phytochrome. Which of the following is the most immediate cellular response?

Accepted Answer

Activation of second messengers such as Ca$$^{2+}$$ and cGMP

Plant Responses to Internal and External Signals: Signal Transduction and Plant Hormones

Study Guide - Practice Questions