Test: Phytohormones - JAMB MCQ

Gibberellins are plant hormones that promote cell elongation and growth. They are involved in stem elongation, seed germination, and flowering. Gibberellins stimulate the production of enzymes that break down cell walls, allowing cells to elongate. This hormone is important for regulating plant height and overall growth.

Phytohormones, also known as plant hormones, are chemical messengers produced by plants that regulate various aspects of plant growth and development. They control processes such as seed germination, root and shoot growth, flowering, fruit development, and response to environmental stimuli.

Cytokinins are plant hormones that promote cell division and lateral bud growth. They are involved in various developmental processes, such as promoting the growth of shoots, stimulating cell division in roots, and preventing aging in plant tissues. Cytokinins work in conjunction with other hormones to regulate plant growth.

Abscisic acid (ABA) is a phytohormone that plays a crucial role in seed dormancy and drought tolerance. ABA inhibits seed germination under unfavorable conditions, such as water scarcity or high salinity, to ensure that seeds only germinate when suitable conditions are present. It also promotes closure of stomata in leaves during water stress, reducing water loss through transpiration.

Auxins are the primary hormones responsible for phototropism, the bending of plant shoots towards light. When light shines on one side of a plant shoot, auxins accumulate on the shaded side, causing cell elongation and bending towards the light source. This helps plants maximize their exposure to sunlight for photosynthesis.

Ethylene is a plant hormone that plays a key role in fruit ripening and senescence (aging). It triggers the ripening process by stimulating the production of enzymes that break down cell walls, softening the fruit. Ethylene is also involved in leaf senescence, flower wilting, and the abscission (shedding) of leaves and fruits.

Auxins are plant hormones that inhibit lateral bud growth and maintain apical dominance. Apical dominance refers to the phenomenon where the growth of the main shoot tip (apical bud) is favored over the growth of lateral buds. Auxins produced by the apical bud suppress the growth of lateral buds, allowing the main shoot to grow taller.

Phytohormones are primarily synthesized in the shoot tips of plants. Shoot tips contain actively growing tissues, such as apical meristems, where cell division and hormone synthesis occur. From the shoot tips, these hormones are transported to various parts of the plant to regulate growth and development.

Auxins are responsible for promoting root growth and development. They stimulate cell elongation in the root region, leading to root elongation. Auxins also play a role in root initiation during vegetative propagation, where new roots are induced to form from stem or leaf cuttings.

Gibberellins are involved in seed germination and breaking seed dormancy. They promote the synthesis of enzymes that break down stored nutrients in the seed, providing energy for seedling growth. Gibberellins also stimulate the elongation of the embryonic stem, pushing the shoot out of the soil during germination.