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During the early stage… (Class 12 Biology SQP 2026-27, Q3)

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BiologyCBSE Class 12 · Sample paper, session 2026-27 · 1 mark · MCQ

CBSE Class 12 Biology sample paper 2026-27: question 3

From the official CBSE sample question paper for 2026-27, section A, question 3, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q3 · 1 mark · MCQHuman Reproduction

During the early stage of human embryonic development, the blastomeres are arranged into an outer layer and an inner group of cells known as the Inner Cell Mass (ICM). What is the fundamental significance of the outer layer, the trophoblast?

  1. (A)It is responsible for forming the primary germ layers (ectoderm, mesoderm, endoderm).
  2. (B)It provides essential nutrients to developing embryo and helps in its implantation.
  3. (C)It secretes colostrum which contains antibodies.
  4. (D)It gives rise to all the organs of the future embryo (organogenesis).

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Which layer of the blastocyst touches the uterine wall?

Hint 2

The inner cell mass forms the embryo proper.

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 trophoblast layer of the blastocyst attaches to the endometrium, which brings about implantation.

  2. The trophoblast also forms chorionic villi that help nourish the embryo. The germ layers and organs arise from the inner cell mass, not from the trophoblast. Option (B).

    1 mark

Answer: (B) It provides nutrients to the developing embryo and helps in implantation

Where the marks are

  • Identifies the role of the trophoblast in implantation and nourishment (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 paperSample paper 2026-27: 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.