Question

Assertion: Dark periods play a more important part in flowering than light periods.
Reason: Flowering occurs in short-day plants if the dark period is interrupted by a light break.
A. If both the assertion and reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false
E. If the assertion is false but the reason is true

Answer 1

Hint:Many flowering plants like angiosperms use photoreceptor protein called phytochrome or cryptochrome, which senses the seasonal changes in the length of the nights or photoperiod which they use as a signal to flower. To flower, plants require a certain duration of light that is day and dark which is at night.

Complete answer:In plants to flower, they require a certain length of day and night which is called photoperiod. The response of the plants for the photoperiod is expressed in the form of flowers and this process is called photoperiodism.
Short day plants- The plants which require short daylight which is usually 8 to 10 hours and need a continuous dark period of 14 to 16 hours are called short-day plants. The dark period for this plant is very critical if it is interrupted the plant will not flower. For an example of short-day plants are tobacco, soybeans, cocklebur, etc.
Long day plants- Plants that require a longer duration of daylight that is 14 to 16 hours and a dark period of 8 to 10 hours is called long-day plants. The light period is very critical for these plants. The light period should not be interrupted or else the plant won’t flower. Some examples of long-day plants are spinach, sugar beet, etc.
Day-neutral plants- Plants that flower in all photoperiods ranging from 5 hours to 24 hours of continuous exposure are called day-neutral plants. Some examples of day-neutral plants are sunflower, cucumbers, tomatoes, etc.
Hence the answer is option C) If the assertion is true but the reason is false.

Note: Plants require more than one inductive cycle for flowering. A period of 24 hours for flowering is one proper inductive cycle. If the flower has received a proper of one inductive cycle is subjected to unfavorable photoperiods, it will still flower