Plant Growth and Responses

These flashcards cover the essential concepts of plant growth, responses, and hormones as discussed in the lecture.

What is phototropism in plants?

Phototropism is the growth response of plants towards light, primarily facilitated by auxins that promote elongation on the side of the plant away from the light source.

What role do statoliths play in gravitropism?

Statoliths are specialized cells in plants that help sense gravity, allowing roots to grow downward (positive gravitropism) and shoots to grow upward (negative gravitropism).

What are the main functions of auxins in plants?

Auxins promote cell elongation, regulate phototropism and gravitropism, assist in flowering and fruit development, and prevent leaf drop.

How do cytokinins affect plant growth?

Cytokinins promote cell division and differentiation, delay leaf senescence, and enhance growth, particularly in nutrient-rich tissues such as fruits and roots.

What is the significance of gibberellins in plants?

Gibberellins stimulate seed germination, break dormancy, influence fruit maturation, and are produced in shoot and root meristems to support overall plant growth.

What are the effects of abscisic acid (ABA) in plants?

ABA promotes dormancy, reduces water loss during stress, and works antagonistically to inhibit growth under adverse conditions.

Describe ethylene's role in plants.

Ethylene is a volatile gas that promotes fruit ripening, leaf abscission, and flower senescence, and can influence plant morphology through its effects on nearby fruits.

What is thigmotropism?

Thigmotropism is the growth response of plants to touch stimuli, allowing climbing plants to wrap around supports for stability and protection.

Define nastic responses in plants.

Nastic responses are non-directional movements in plants triggered by stimuli, such as the Venus flytrap closing when touched.

What is figmomorphogenesis?

Figmomorphogenesis refers to long-term morphological changes in plants due to continuous mechanical pressure, helping plants adapt their growth forms over time.

How do plants defend against herbivores and pathogens?

Plants use structural defenses (like thorns), produce secondary metabolites for deterrence, and employ hormonal responses (like ABA, ethylene) to enhance resilience and promote immediate defensive actions.