Plant hormones auxin and gibberellin notes

What is auxin?

Auxin is a plant hormone that regulates growth and development by promoting cell elongation, apical dominance, and root formation.

Role of auxin in phototropism?

Auxin redistributes in response to light, promoting growth on the darker side of the plant, leading to bending toward the light source.

True or False: Auxin is only active in stems.

False. Auxin is active in various plant tissues, including roots, stems, and leaves.

What does auxin promote in roots?

Auxin promotes root formation and growth, enhancing the plant's ability to absorb water and nutrients.

Fill in the blank: Auxin promotes __________ of plant cells.

elongation

Cause of apical dominance?

The presence of auxin in the apical bud inhibits lateral bud growth, maintaining a dominant central stem.

How does auxin affect fruit development?

Auxin promotes fruit development by stimulating cell division and expansion, leading to larger fruit.

What is the main source of auxin in plants?

The main source of auxin is the apical meristem, primarily located at the tips of roots and shoots.

Comparison: Auxin vs. Gibberellin.

Auxin primarily regulates cell elongation and tropisms, while gibberellin is involved in seed germination and stem elongation.

Function of auxin in leaf abscission?

Auxin levels decrease, triggering senescence and the eventual shedding of leaves by disrupting the balance of growth hormones.

How does auxin help in tissue culture?

Auxin is used to induce root formation in plant tissue culture, facilitating cloning and propagation.

What is the effect of auxin on lateral roots?

Auxin promotes the formation of lateral roots by stimulating new root meristem formation.

True or False: Auxin only acts in high concentrations.

False. Auxin can have significant effects even in low concentrations, demonstrating the sensitivity of plant responses.

Role of auxin in gravitropism?

Auxin redistributes in response to gravity, promoting growth in the direction of gravity for roots and stems.

What is the relationship between auxin and cell division?

Auxin indirectly promotes cell division by stimulating the production of other hormones like cytokinin.

Auxin's role in seed development?

Auxin influences seed development by regulating cell expansion and differentiation, impacting overall seed size and viability.

What are gibberellins?

Gibberellins are a group of plant hormones that promote growth and development, influencing processes such as seed germination, stem elongation, and flowering.

How do gibberellins affect seed germination?

Gibberellins stimulate the production of enzymes that break down starches, aiding in seed germination and providing energy for the growing plant.

True or False: Gibberellins inhibit stem elongation.

False. Gibberellins promote stem elongation by stimulating cell division and elongation.

Fill in the blank: Gibberellins are primarily produced in __________.

young tissues, seeds, and roots.

Comparing auxins and gibberellins: role in growth?

Auxins primarily promote cell elongation, while gibberellins enhance both cell division and elongation.

What is the effect of gibberellins on fruit development?

Gibberellins promote fruit enlargement and development, often leading to larger fruits.

Cause → Effect: Gibberellin application on dwarf plants?

Cause: Gibberellin application. Effect: Increased height and growth due to enhanced cell elongation.

What is the role of gibberellins in flowering?

Gibberellins regulate flowering time by acting on specific genes, promoting the transition from vegetative to flowering stages.

True or False: Gibberellins are involved in leaf abscission.

False. Gibberellins do not promote leaf abscission; they support growth processes.

What are the main functions of gibberellins?

Key functions include promoting seed germination, stimulating stem elongation, inducing flowering, and enhancing fruit growth.

Gibberellins and enzyme production: explain.

Gibberellins trigger the synthesis of enzymes like amylase, which break down stored food, facilitating seed germination.

How do gibberellins interact with other hormones?

Gibberellins can work in conjunction with auxins to promote growth, but their effects can vary based on concentration and tissue type.

Fill in the blank: Gibberellin levels can be affected by __________.

environmental factors, such as light and temperature.

What is the significance of gibberellins in agriculture?

Gibberellins are used to enhance crop yield, improve fruit size, and synchronize flowering, benefiting agricultural practices.

Gibberellins and root growth: what’s the relationship?

Gibberellins generally have a minor influence on root growth compared to their strong effects on stems and fruits.

What are some examples of gibberellin types?

Examples include GA1, GA3 (gibberellic acid), and GA4, each with specific biological roles in plant growth.