Auxin_MCQ_Advance Level

Auxin - Advance

Dear Readers,

Auxin is a general name for a group of hormones that are involved with growth responses (i.e., elongate cells, stimulate cell division in callus). Not surprisingly, the term "auxin" is derived from the Greek word "to increase or grow". This was the first group of plant hormones discovered.

Q1. Indole-3-acetic acid called as auxin was first isolated from

•  Human urine
•  Corn germ oil
•  Fusarium
•  Rhizopus

Human urine

Q2. Moving on a grass lawn facilitates better maintenance primarily owing to

•  Removal of apical dominance and promotion of lateral meristem
•  Removal of apical dominance
•  Wounding which stimulate rapid regeneration
•  None of the above

Removal of apical dominance

Q3. A green plant bends towards the source of light when exposed to the light on only one side, it bends towards the source of light as it grows. Which of the following is the best explanation of the phenomenon

•  The apices of their stems are attracted by light
•  They need light for photosynthesis
•  Some auxins accumulates on the shaded side to induce greater cell elongation on that side
•  Light stimulates the cells on the illuminated side to increase in length

Some auxins accumulates on the shaded side to induce greater cell elongation on that side

Q4. The formula of auxin ‘a’ is

•  C₁₈H₃₀
•  C₁₈H₃₂
•  C₁₈H₄₀O₅
•  C₁₈H₄₀O₁₀

C₁₈H₄₀O₅

Q5. The primary precurser of IAA is

•  Phenyl alanine
•  Tyrosine
•  Tryptophan
•  Leucine

Tryptophan

Q6. Antiauxin used in picking cotton bolls is

•   2, 4-D
•  TIBA
•  NAA
•  Both (a) and (b)

TIBA

Q7. An important finding in Went’s experiment was

•  Unequal distribution of elongation promoting substance in Avena coleoptile
•  Presence of elongation factor in all cells of root
•  Curvature of coleoptile is proportional to auxin concentration
•  Curvature occurred due to irregular elongation of cells

Curvature of coleoptile is proportional to auxin concentration

Q8. Apical dominance in higher plants is due to

•  Balance between auxin and cytokinin
•  Enzyme activity and metabolism
•  Carbohydrates
•  Photoperiodism

Photoperiodism

Q9. The number of auxins received from Phaseolus vulgaris is

•  2
•  3
•  4
•  8

8

Q10. Which of the following effects of auxins on plants is the basis for commercial application

•  Callus formation
•  Curvature of stem
•  Induction of root formation in stem cuttings
•  Stem growth

Induction of root formation in stem cuttings