Question

Through their effect on plant growth regulators, what do the temperature and light control in plants?
A. Flowering
B. Closure of stomata
C. Fruit elongation
D. Apical dominance

Answer 1

The plant growth regulators are some organic chemicals that are used by plants to induce growth, etc. Moreover, temperature and light greatly influence plant growth, food production, and blooming in plants.

Complete step by step answer: The plant growth regulators are like supplementary factors with nutrients, water, and sunlight required by the plant for its growth and maintenance. The plant growth regulators are the chemical synthesis of hormones that are responsible to govern the development and plant growth.
-The various factors affect plant growth. Two of the major factors are light and temperature. Light is required by the plant for photosynthesis whereas temperature regulates the germination process, transpiration, etc. Except for these major roles both the temperature and light influence the working of plant growth hormones.
-Now let us study each given option to know which is the result of the effects of temperature and light.
-Option A is flowering. Light and temperature control flowering in plants by the process of photoperiodism and vernalization respectively. The developmental response of plants concerning lengths of light and dark periods is termed as photoperiodism. Photoreceptor proteins such as cryptochrome or phytochrome are used by various angiosperms to detect seasonal changes. This sensing acts as a signal for flowers to bloom. The cold temperature during winters leads to vernalization after which the plants acquire the ability to flower in the spring.
-Option B is the closure of the stomata. The inhibiting plant growth factor Abscisic acid is the key regulator for stomata closing in the epidermis. Light and temperature have very less or no role in this.
-Option C is Fruit elongation. Gibberellins are the plant growth promoters that are majorly involved in fruit elongation. This can be seen in apples. The gibberellins also work to enhance the shape of the fruits.
-Option D is apical dominance. Apical dominance refers to the longitudinal growth of apical structures like stem tips in plants. This is regulated by Auxins.
Therefore, the right answer is option A.

Note: Plants are very versatile organisms and they are easily adaptable to their habitats. Different light and temperature conditions induce plants to undergo several genetic changes so that they can adapt to their surroundings. Also, the role of light can be studied clearly in phototropism shown by growing plants.