Question

The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of

(A) far-red light during the night.

(B) red light during the night.

(C) red light followed by far-red light during the night.

(D) far-red light during the day.

Short answer

1. The statement "far-red light during the night" isfalse.

2. The statement "red light during the night" istrue.

3. The statement "red light followed by far-red light during the night" is false.

4. The statement "far-red light during the day" is false.

Step-by-step solution

Flower

The specialized structure that reproduces sexually by developing their seeds and located in flowering plants is called flower. The four distinct parts found in flowers are carpels, sepals, stamens, and petals.

Explanation of option '(A)'

The plant's behavioral response towards light duration in day or night that influences seed germination and flowering is called photoperiodism.

Thus, the phytochrome activity is inhibited by far-red light.

Therefore, the given statement is false.

Explanation of option '(B)'

The molecules that convey information among plant cells and are responsible for producing plant stress response under a stressful environment are called signaling molecules.

Thus, when short-night flowering plants are exposed to the red light during the night, light-absorbing pigments (phytochrome) will be converted to their active form. This results in the regulation of seed germination.

Therefore, the given statement is true.

Explanation of option '(C)'

The term long-day plants refers to those plants which require a long period of daylight. Examples of long-day plants include spinach, potato, hibiscus, and radish.

Thus, red and far-red light accelerate flowering in long-day plants.

Therefore, the given statement is false.

Explanation of option '(D)'

The action of a plant to bear a flower is called flowering. Examples of the flowering plant include the daisy family, nightshade, buttercups, and dogbanes.

Thus, flowers releasing signaling molecules are exposed with red light during the day rather than during the day with far-red light.

Therefore, the given statement is false.