Q.26 Determine the correctness or otherwise of the following Assertion (a) and the Reason (r)

Assertion (a): Somatic embryogenesis in plants is a two step process comprising of embryo initiation followed by embryo production.

Reason (r): Embryo initiation is independent of the presence of 2,4-dichlorophenoxyacetic acid whereas embryo production requires a high concentration of 2,4-dichlorophenoxyacetic acid.

• (A) Both (a) and (r) are true and (r) is the correct reason for (a)
• (B) Both (a) and (r) are true and (r) is not the correct reason for (a)
• (C) (a) is true but (r) is false
• (D) (a) is false but (r) is true

  Somatic embryogenesis is a key process in plant tissue culture where embryos develop from somatic cells. This article analyzes a common exam question on its steps and 2,4-D role to clarify the correct option.

  Assertion (a) Analysis

  Assertion states somatic embryogenesis is a two-step process: embryo initiation followed by embryo production. This is largely true as standard descriptions highlight initiation (induction of embryogenic cells) and production (further embryo development).

  Many sources confirm it involves embryo initiation from explants or callus, followed by embryo maturation and production.​

  However, detailed protocols often expand it to 3-5 steps like initiation, proliferation, maturation, and germination, but the core matches the two-step view.​

  Reason (r) Evaluation

  Reason claims embryo initiation is independent of 2,4-D, while embryo production requires high 2,4-D. This is false.

  Embryo initiation depends on high auxin like 2,4-dichlorophenoxyacetic acid (2,4-D) to induce pro-embryogenic masses from somatic cells.

  Embryo production or maturation occurs after transfer to low/no 2,4-D media, allowing bipolar embryo development.

  Correct Answer: Option (C)

  Option (C) is correct: Assertion (a) is true but Reason (r) is false.​

  The two-step framing holds in simplified models, but r misstates 2,4-D dependence—initiation requires it, not production.​

  Options Breakdown

  Option	Description	Correctness	Explanation
  (A)	Both true, r explains a	False	r is false, so cannot explain a.​
  (B)	Both true, r does not explain a	False	r is false despite a being true.​
  (C)	a true, r false	True	Matches evidence: two steps valid, but 2,4-D role reversed.
  (D)	a false, r true	False	a true, r false.​

  This table summarizes why (C) fits exam patterns in biotech questions.​

  Exam Preparation Tips

  Focus on plant tissue culture protocols: 2,4-D induces callus/embryogenic competence, then withdrawal promotes embryo formation.​

  Practice similar assertion-reason questions from GATE/NEET biotech syllabi for molecular biology and bioprocess engineering.