Example of artficial auxins are:-

(a) IPA

(b) PAA

(c) NAA

(d) 2, 4, 5 - T

(e) 2, 4 - D

• Please note that there are 2 sets of information given in the question.
• The first set (options a-e) mentions the names of compounds.
• The second set (options 1-4) mentions the combinations of first set of options.

Key Points

• Auxin refers to a group of plant hormones that regulate plant growth.
• Based on their origin, auxins can be divided into:
  • Natural Auxins - They occur naturally in the plant and affect physiological functions. E.g. - IAA, IBA.
  • Artificial Auxins - These are synthetically-derived chemical compounds that resemble IAA in biological activity. E.g. - NAA.
• Artificial auxins are widely used in horticultural practices, as weedicides, rooting agents and defoliating agents.

Important Points

• IPA
  • Indole-3-pyruvic acid (IPA) is an intermediate in the IAA biosynthesis pathway.
  • Hence, it is not an artificial auxin.
• PAA
  • Phenylacetic acid (PAA) is a natural auxin.
• NAA
  • Naphthalene acetic acid (NAA) is a artificial auxin that is used as a rooting agent.
• 2,4,5-T
  • 2,4,5 - Trochlorophenoxyacetic acid is an artificial auxin that is used as a herbicide.
• 2,4-D
  • 2,4 - Dichlorophenoxy acetic acid (2,4-D) is a artificial auxin that is widely used as a herbicide.
• Thus the answer will be (c), (d) and (e).