Plant Hormones Overview

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Questions and Answers

What is the primary role of ethylene in plant physiology?

Promoting root development

Enhancing nutrient absorption

Facilitating leaf abscission (correct)

Stimulating chlorophyll production

In what way can ethylene be used in agriculture for apple trees?

To increase leaf area

To enhance photosynthesis

To reduce water loss

To promote fruit thinning (correct)

What is a bioassay primarily used for in the context of ethylene?

To evaluate the effectiveness of irrigation systems

To determine ripening rates in fruits (correct)

To assess fruit color changes

To measure soil moisture levels

Which hormone was originally discovered in Brassica rapa pollen and promotes plant growth?

Brassinosteroids Signup and view all the answers

What effect does ethylene have on fruit ripening?

It promotes rapid ripening and can affect other fruits. Signup and view all the answers

What is the effect of treating cotton plants with ethylene before mechanical harvesting?

Encouraging senescence for easier harvesting Signup and view all the answers

Which of the following is NOT a way to control ethylene levels in plants?

Declining light exposure Signup and view all the answers

What is the primary influence of gibberellins (GA) on plants?

Elongation of plant stems. Signup and view all the answers

What is a defining characteristic of brassinosteroids compared to auxin?

Brassinosteroids have a similar effect on elongation as auxin Signup and view all the answers

Which stage of leaf abscission is characterized by low auxin levels and increased sensitivity to ethylene?

Abscission induction. Signup and view all the answers

How do auxin and ethylene interact during leaf maintenance?

Auxin reduces leaf sensitivity to ethylene. Signup and view all the answers

What method is used to measure gas concentrations of ethylene?

Gas chromatography Signup and view all the answers

What role does jasmonic acid (JA) primarily serve in plants?

It is involved in plant defense responses. Signup and view all the answers

What is a critical factor for the initiation of leaf abscission?

Decreased auxin levels. Signup and view all the answers

Which enzymes are primarily involved in the abscission phase of leaves?

Cellulases and pectinases. Signup and view all the answers

What condition is required for the effectiveness of 1-Methylcyclopropene (MCP) in delaying ethylene effects?

Application before day 30. Signup and view all the answers

Which two active forms of brassinosteroids are recognized?

Castasterone and Brassinolide Signup and view all the answers

What physiological processes are brassinosteroids involved in?

Seed germination and cell division Signup and view all the answers

Where is Jasmonic Acid synthesized initially?

Chloroplast Signup and view all the answers

What is the primary role of Jasmonic Acid in plants?

Act as a signaling molecule in plant defense Signup and view all the answers

What compound is synthesized in response to insect herbivory that leads to increased Jasmonic Acid production?

Systemin Signup and view all the answers

Which statement about Jasmonic Acid is false?

JA is a steroidal compound easily absorbed by plants. Signup and view all the answers

What specific proteins are enhanced by Jasmonic Acid in response to insect herbivory?

Defense proteins Signup and view all the answers

How does JA interact with ethylene regarding plant responses to herbivores?

JA enhances the response when combined with ethylene. Signup and view all the answers

Which of the following statements best describes the synthesis and movement of Jasmonic Acid?

JA is synthesized in the wounded leaves and moves to unaffected leaves via the phloem. Signup and view all the answers

What role does JA play in the interaction between plants and insect herbivores?

Acts as a deterrent to herbivore feeding. Signup and view all the answers

Study Notes

Plant Hormones

Plant hormones regulate numerous processes like growth, development, and responses to environmental stimuli.
There are five major classes of plant hormones: auxins, gibberellins, cytokinins, abscisic acid, and ethylene.

Auxins

Auxins promote cell elongation and affect root development, apical dominance, tropic responses, and fruit growth.

Gibberellins

Gibberellins influence stem elongation, seed germination, and flowering.

Cytokinins

Cytokinins promote cell division and affect apical dominance, differentiation, and senescence.

Abscisic Acid (ABA)

ABA promotes stomatal closure, seed dormancy, and drought tolerance.

Ethylene

Ethylene promotes fruit ripening, senescence, and abscission.

Other plant hormones

Other plant hormones include jasmonic acid, salicylic acid, and brassinosteroids, which influence various plant responses.

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Description

This quiz explores the essential functions and classes of plant hormones, including auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Delve into how these hormones regulate growth, development, and responses to environmental stimuli. Test your knowledge and understanding of plant physiology!