Chemical Coordination in Plants

These flashcards cover key concepts related to chemical coordination in plants, focusing on plant hormones, their functions, and movements.

What are plant hormones?

Chemical compounds that work as messengers in plants to respond to stimuli.

Who first used the term 'hormone'?

William Bayliss and Ernest Starling in 1902.

What are phytohormones?

Plant hormones that are produced in one area and transported around the plant.

How are hormones transported in plants?

Through xylem and phloem.

What are the five main types of plant hormones?

Auxins, Gibberellins, Cytokinins, Abscisic acid, Ethylene.

What is the function of auxins?

Cell division, cell elongation, and promoting growth.

What do gibberellins help with?

Growth of stem and branches, seed germination.

What is the main role of cytokinins?

Stimulate cell division and formation of fruits and seeds.

What does abscisic acid do?

Inhibits growth and affects wilting of leaves.

What effect does ethylene have on plants?

Aids in flowering and ripening of fruits.

What is apical dominance?

Suppression of lateral buds by apical buds due to auxin.

What is parthenocarpy?

Fruit formation without fertilization.

Where are auxins synthesized?

In growing regions like shoot apex and root apex.

What is the main natural auxin found in plants?

Indole 3-acetic acid (IAA).

What is the role of gibberellins in horticulture?

Used to increase fruit length and improve shape.

Who discovered cytokinins?

Skoog and Miller in 1950.

What do cytokinins prevent?

Aging of plant parts.

What are the primary sites of ethylene synthesis?

Ripening fruits, senescent leaves, and germinating seeds.

What role does abscisic acid play in stomata?

Stimulates closure of stomata.

What is the effect of auxins on lateral buds?

Inhibits their growth.

What type of movements are tropic movements?

Growth movements in response to unidirectional external stimuli.

What is phototropism?

Growth towards light.

What is hydrotropism?

Growth movement towards water.

What do roots exhibit in response to gravity?

Positive geotropism.

What do climbing plants exhibit as a response to touch?

Thigmotropism.

What is the response of plants to chemicals called?

Chemotropism.

What is the primary action in positive phototropism?

Growth of stems towards light.

How does ethylene affect fruit ripening?

Accelerates the ripening process.

What happens to lateral buds if the apical bud is removed?

Lateral buds can grow.

What is the main effect of gibberellins on seed dormancy?

Break dormancy.

What is the effect of auxins on leaf abscission?

Delays the falling of leaves.

What does apical dominance result in?

Dominance of the apical bud over lateral buds.

How are nastic movements different from tropic movements?

Nastic movements respond to diffused stimuli, not unidirectional.

What is one example of a nastic movement?

Seismonastic movements, like those in the touch-me-not plant.

Define tropic movements.

Growth movements caused by a stimulus in one direction.

What is the role of auxins in fruit development?

Induces parthenocarpy for fruit formation without fertilization.

What is the primary synthesis site for gibberellins?

Meristematic regions such as stem-apex and root-apex.

What is the primary site of cytokinin synthesis?

Root tips.

What is one major commercial use of gibberellins in food industry?

Enhancing the length and shape of grapes.

What hormonal function does ethylene serve beside ripening?

Promoting root growth and root-hair formation.

What triggers the closure of stomata in response to stress?

Abscisic acid (ABA).

What common trait do all plant hormones share?

They regulate growth and response to environmental stimuli.

What process do auxins influence to support plant growth?

Cell elongation and apical dominance.

In what condition do roots show negative geotropism?

When growing away from gravity.