Hormones and Cell Signaling Pathways Quiz

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Questions and Answers

How do auxins promote root growth in plants?

By increasing the pH of cell walls

By promoting trophic responses to light

By inhibiting the growth of lateral buds

By causing cell elongation through the active transport of hydrogen ions (correct)

What is the main function of auxins in maintaining apical dominance?

To promote lateral bud growth

To inhibit lateral bud growth (correct)

To enhance cell expansion and growth

To facilitate root growth

How do auxins contribute to phototropism in plants?

By suppressing the release of second messengers

By lowering the pH of cell walls

By inhibiting the translocation of nutrients

By promoting the elongation of cells towards light (correct)

What is the role of auxins in cellular metabolism?

Increasing cellular respiration Signup and view all the answers

How do auxins affect the flexibility of cell walls?

By lowering the pH of cell walls Signup and view all the answers

In which process do auxins primarily assist when plants are exposed to light from all directions?

Cell elongation Signup and view all the answers

What is the main purpose of homeostasis in organisms?

To maintain a state of internal dynamic equilibrium Signup and view all the answers

Which of the following is NOT controlled by homeostasis?

Light intensity Signup and view all the answers

What is the role of negative feedback in maintaining homeostasis?

It counteracts any changes in internal conditions Signup and view all the answers

How do hormones affect target organs and cells?

By binding to complementary receptors on plasma membranes Signup and view all the answers

In positive feedback mechanisms, how do responses differ from negative feedback?

Responses amplify the original stimulus Signup and view all the answers

What is the role of auxins when a shoot is illuminated from only one side?

Promote elongation on the shaded side Signup and view all the answers

How do gibberellins stimulate germination?

By triggering the production of amylase in the seed Signup and view all the answers

Which hormone promotes cell division in apical meristems and lateral bud development?

Cytokinins Signup and view all the answers

How do phytochrome levels affect flowering in long-day plants?

Pfr stimulates flowering Signup and view all the answers

What is the relationship between auxins and cytokinins in terms of apical dominance?

Auxins and cytokinins have antagonistic effects on apical dominance Signup and view all the answers

What form of phytochrome exists as the biologically active form, absorbing far red light?

Pfr Signup and view all the answers

Study Notes

Auxins and Plant Growth

Auxins promote root growth by increasing cell elongation and cell division in the root tip.
Auxins maintain apical dominance by inhibiting the growth of lateral buds, allowing the main stem to grow longer and stronger.
Auxins contribute to phototropism by stimulating cell elongation on the side of the stem away from light, causing the stem to bend towards the light source.

Auxins and Cellular Metabolism

Auxins play a role in cellular metabolism by regulating cell wall loosening, allowing for cell expansion and growth.
Auxins affect the flexibility of cell walls by breaking down cellulose and increasing the synthesis of new cell wall components.

Light Response and Homeostasis

Auxins assist in the process of phototropism when plants are exposed to light from all directions.
The main purpose of homeostasis in organisms is to maintain a stable internal environment despite changes in the external environment.
Homeostasis does not control evolutionary processes.
Negative feedback mechanisms help maintain homeostasis by reducing or reversing the response to a stimulus once the desired outcome is achieved.

Hormone Function and Interactions

Hormones affect target organs and cells by binding to specific receptors, triggering a response.
In positive feedback mechanisms, responses amplify or increase the initial stimulus, whereas in negative feedback mechanisms, responses reduce or reverse the initial stimulus.
Auxins promote cell elongation on the side of the stem away from light when a shoot is illuminated from only one side.
Gibberellins stimulate germination by breaking seed dormancy and promoting seedling growth.
Cytokinins promote cell division in apical meristems and lateral bud development, reducing apical dominance.
Phytochrome levels affect flowering in long-day plants by promoting flowering in response to long days.
Auxins and cytokinins have an antagonistic relationship in terms of apical dominance, with auxins promoting apical dominance and cytokinins inhibiting it.
The biologically active form of phytochrome is Pfr, which absorbs far-red light.

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Description

Test your knowledge on how hormones bind to receptors on target cells, trigger intracellular reactions, and affect cell metabolism. Learn about the role of second messengers like cAMP in cellular responses.