Chapter 46, Problem 1MC

Summary Introduction

Introduction:

Light is the crucial part of a plant life, plants perform photosynthesis to capture and store light energy as chemical energy. The onset of flowering in many plants described as a long day or short day plants, which is stimulated by the consistent seasonal changes in day length. Long day plants are flower only when uninterrupted darkness is shorter than a specific length of time that varies with the species of plant. Short day plants flower when uninterrupted darkness exceeds species-specific duration.

Answer to Problem 1MC

Correct answer:

Short day plants a flower in response to a minimum duration of uninterrupted darkness. Therefore, option (b) is correct.

Option (b) is given as “flower in response to a minimum duration of uninterrupted darkness”.

Explanation of Solution

Justify reason for the correct statement:

Plants have a different response to different environmental stimuli and have adapted physiological changes in response to that stimulus. Short day plants such as cockleburs, chrysanthemums, and potatoes, flower when uninterrupted darkness exceeds species-specific duration.

Hence, option (b) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “flower in response to the maximum duration of uninterrupted light”.

Short day plants do not flower in response to the maximum duration of uninterrupted light, but it requires a minimum duration of uninterruptedly light. Hence, it is a wrong answer.

Option (c) is given as “are likely to be common in the tropics”.

Short day plants are likely to be common in habitats prone to adverse environmental conditions and they do not occur in tropics. Hence, it is a wrong answer.

Option (d) is given as “are stimulated to flower by ${\text{P}}_{\text{fr}}$”

Short day plants are not stimulated to flower by ${\text{P}}_{\text{fr}}$ but more from the exposure of uninterrupted light for a minimum duration. Hence, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.

Conclusion

Short day plants have adapted to flower in response to uninterrupted darkness for a minimum duration.