Plant Responses to Signals

A set of flashcards based on the lecture notes regarding plant responses to various signals and stimuli.

What is phototropism in plants?

Phototropism is the growth of plants towards light.

What hormone is primarily involved in phototropism?

Auxin is the hormone primarily involved in phototropism.

How do statoliths influence gravitropism?

Statoliths fall to the bottom of root cap cells, stimulating auxin production and causing downward bending.

What is de-etiolation?

De-etiolation refers to the changes a plant undergoes when exposed to light after growing in the dark.

What is the role of auxin in cell elongation?

Auxin stimulates proton pumps that acidify the cell wall, activating enzymes that loosen cell wall materials and allow elongation.

What is apical dominance?

Apical dominance is the phenomenon where the apical bud inhibits the growth of axillary buds, allowing the main stem to grow.

How does gibberellin affect seed germination?

Gibberellin stimulates cell division and elongation, promoting seed germination.

What is the role of ethylene in fruit ripening?

Ethylene promotes fruit ripening and can spread its effects to surrounding fruits.

Describe the hypersensitive response in plants during pathogen attack.

The hypersensitive response involves local cell death at the infection site, production of defense enzymes, and changes in cell walls to confine the pathogen.

What is systemic acquired resistance?

Systemic acquired resistance is a plant-wide defense mechanism that activates genes to protect against diverse pathogens.

What types of stimuli can plants sense?

Plants can sense heat, light, gravity, touch, chemical signals, and environmental stresses such as drought and flooding.

How do plants respond to mechanical disturbances?

Plants exhibit thigmomorphogenesis, altering growth patterns in response to mechanical disturbances, such as rubbing.

What is the significance of the flowering hormone called florigen?

Florigen is a protein that signals flowering in response to photoperiod changes.

How does auxin affect leaf abscission?

Leaf abscission occurs when ethylene production prevails over auxin, leading to the death of leaf cells.

What is thigmotropism?

Thigmotropism is the growth response of plants to touch, often seen in climbing plants.