Very Short Question and Answers - Coordination in Plants

Plants coordinate their activities mainly through chemical means using plant hormones.

Tropic movement is a growth movement in plants that occurs in response to a directional environmental stimulus.

Phototropism is the growth of a plant part in response to light, such as a stem bending towards a window where light is coming from.

Positive tropism is growth towards the stimulus (e.g., stem towards light in phototropism); negative tropism is growth away from the stimulus (e.g., root away from light).

Geotropism is the response to gravity; roots show positive geotropism by growing downward, and shoots show negative geotropism by growing upward.

Hydrotropism is the growth response to water, such as plant roots growing towards a water source.

Thigmotropism is growth in response to touch; for example, pea plants use tendrils to wind around supports.

Nastic movements are non-directional responses to stimuli; for example, the folding of Mimosa pudica leaves when touched.

Auxins are responsible for phototropism by promoting cell elongation on the shaded side of the stem.

Ethylene is known for promoting fruit ripening, such as in bananas and mangoes.

Gibberellins stimulate stem elongation and seed germination.

Cytokinins delay the aging (senescence) of leaves, keeping cut flowers and vegetables fresh longer.

Abscisic acid promotes the closing of stomata during drought to reduce water loss.

Cytokinins promote the growth of lateral buds, leading to bushier plants.

Auxins are used as rooting hormone powders to promote root formation in plant cuttings.

Sunflower buds exhibit heliotropism, a type of phototropism, by tracking the sun’s movement.

Positive geotropism: roots growing downward; negative geotropism: shoots growing upward.

Abscisic acid induces leaf fall (abscission) in plants.

Photonasty, a nastic movement in response to light, causes dandelion petals to open and close.

Auxins: cell elongation and tropisms; Gibberellins: stem elongation and germination; Cytokinins: cell division and delay aging; Abscisic acid: inhibits growth and induces dormancy/leaf fall; Ethylene: fruit ripening and leaf abscission.