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Assertion (A) : The embryo… (Class 12 Biology 2026, Q13)

questionbuddy.in/q/cbse-12-biology-2026-57-5-1-q13-embryo-blastomeres-called-morula-morula

BiologyCBSE Class 12 · Board exam 2026, set 57/5/1 · 1 mark · Assertion-reason

CBSE Class 12 Biology 2026: question 13

Set in the CBSE Class 12 board exam of 2026, paper 57/5/1, section A, question 13, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q13 · 1 mark · Assertion-reasonCompetency-basedHuman Reproduction

Assertion (A) : The embryo with 8 to 16 blastomeres is called a morula.
Reason (R) : The morula continues to divide and transform into trophoblast.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 57/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

What does the morula develop into next?

Hint 2

The structure it forms has two parts. Is it only the trophoblast?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. The assertion is true: an embryo with 8–16 blastomeres is called a morula.

    ½ mark

  2. The reason is false: the morula divides further into a blastocyst (trophoblast plus inner cell mass), not into trophoblast alone. The answer is (C).

    ½ mark

Answer: (C)

Where the marks are

  • States that A is true and R is false (1 mark)

Revise the chapter

  • Chapter: Human Reproduction (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Human Reproduction, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 57/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.