Auxin MCQs

Q1. Application of which of the following can delay abscission of leaves & fruits at the early stages?

1. 1. Gibberellic Acid

   2. Cytokinin

   3. Auxin

   4. None of these

Ans. Auxin is the right answer.

Auxin, a plant growth regulator (PGR) or plant hormone, can be used to reduce fruit and leaf loss in the early stages of development (IIA or Indole-3 – Acetic Acid). They also encourage mature and older leaves to fall off. They also start rooting stem cuttings. Growing root and shoot tips contain auxin as well.

Q2. Flowering is induced in pineapple by the application of which of the following?

1. 1. Abscisic acid

   2. NAA, 2,4-D

   3. Cytokinin

   4. None of the above

Ans. NAA, 2,4-D is the correct answer.

Both NAA and 2,4-D are auxin hormones, however NAA and 2,4-D are synthetic versions. Naphthalene acetic acid is the complete name, and 2,4-D stands for 2,4 dichlorophenoxyacetic acid.

These are utilised as rooting hormones in agriculture and gardening, and they aid in plant propagation. They also encourage blooming in plants such as pineapple.

Q3. Uneven distribution of which of the following results in the phototropic curvature?

1. 1. Phytochrome

   2. Cytokinin

   3. Gibberellin

   4. Auxin

Ans. Auxin is the right answer.

The unequal distribution of auxin causes phototropic curvature. The coleoptiles of the canary grass reacted to unilateral illumination by the growing towards light source, as Charles Darwin & his son Francis Darwin noticed. The tip of the coleoptile contains auxin, which causes the entire coleoptile to bend in response to the direction of light, according to a series of investigations.

Q4. Avena Curvature Test is an accurate bioassay for determining the activity of which of the following?

1. 1. Gibberellins

   2. Auxin

   3. Cytokinin

   4. Ethylene

Ans. Auxin is the correct answer.

Avena curvature test is the bioassay for determining auxin activity. Went devised a method for measuring auxin in 1928. His findings revealed that stem curvatures were proportional to auxin levels in agar (in 1928). Avena curvature test was the name of this exam. Auxin’s applications have provided us with a lot of information.

Q5. Which one of the following is mostly used synthetic Auxin?

1. 1. NAA

   2. Abscisic Acid

   3. 2, 4 – D

   4. IBA

Ans. 2, 4 – D is the right answer.

Auxin, also known as 2, 4 – D, is a synthetic auxin that is extensively employed in callus and suspension cultures. Continuous administration of these growth regulators was found to be beneficial to cell proliferation as well as embryo differentiation. As a result, a considerable time of growth regulator-free media was required before embryo differentiation could resume.

Q6. Which of the following is the application of synthetic auxin?

1. 1. Killing the weeds.

   2. Ripening the fruits.

   3. Preventing the elongation of the internodes.

   4. None of these

Ans. Killing the weeds is the right answer.

Weedicides consist of synthetic auxins such as 2,4-dichlorophenoxy acetic acid & 2, 4,5 -Trichloro -phenoxy acetic acid. Auxin is a protein that these herbicides resemble. Because they disrupt the plant’s natural hormone balance, they’re referred to as growth regulators. Synthetic auxins are largely utilised in grass crops, pastures, and turf to suppress broadleaf weeds.  2,4-dichloro weeds can be found in pastures, grass crops, and turf, among other places.

Q7. Auxin is transported in polarised form. Most of the time, the movement of auxin is

1. 1. Acropetal

   2. Centripetal

   3. Basipetal

   4. Both (a) & (b)

Ans. Basipetal is the correct answer.

Auxin is a phytohormone that promotes growth. It primarily goes from apical to basal end of the cell (basipetally). Polar transport is the name given to this sort of unidirectional travel. Auxin is only plant growth hormone that is known to be polarly transported. A considerable percentage of auxin transport occurs acropetally in the root, which has only recently been discovered.

Q8. Which of the following is the result of removal of the apical bud?

1. 1. Formation of more Axillary Buds

   2. Formation of more Lateral Branches

   3. Death of the plants

   4. None of these

Ans. Formation of more Lateral Branches is the right answer.

Apical dominance occurs when the core stem takes precedence over the lateral stems. Plant hormones produced at the shoot’s tip are to blame. Apical dominance is caused by the auxin hormone. When the apical bud is removed, the lateral bud grows. As a result, lateral branching develops. This results in a bushy plant.

Q9. Which of the following is the commonly used hormone in the tea plantation?

1. 1. Abscisic Acid

   2. Ethylene

   3. Indole butyric acid & Indole – 3 – Acetic Acid

   4. Zeatin

Ans. Indole Butyric Acid & Indole – 3 – Acetic Acid is the correct answer to this question.

Synthetic plant hormones such as Indole butyric acid & Indole – 3 – Acetic Acid are useful in tea plantations. When mixed with a proportion of 1.0mg per litre, Indole Butyric Acid & Indole – 3 – Acetic Acid are 2 distinct kinds of synthetic auxin that stimulate rooting. These synthetic hormones were also discovered to have a variety of impacts in tea plants, including the development of adventitious roots.

Q10. Lateral buds are not able to grow in the presence of an apical bud during the apical dominance phase. This is because of

1. 1. The amount of cytokinin in the lateral buds is more.

   2. The amount of cytokinin in the lateral buds is Less.

   3. The amount of Auxin in the lateral buds is more.

   4. The amount of Auxin in the lateral buds is Less.

Ans. The amount of Auxin in the lateral buds is more is the right answer.

An apical bud is found at the end of a shoot and is where the shoot grows. Auxin sensitivity is higher in the lateral buds than in the apical buds. The growth of apical buds is promoted at a certain concentration of auxin, and they are unable to grow above that concentration. Hence, Lateral buds are not able to grow in the presence of an apical bud during the apical dominance phase.