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Explain the process of… (Class 12 Biology SQP 2023-24, Q17)

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BiologyCBSE Class 12 · Sample paper, session 2023-24 · 2 marks · Very short answer

CBSE Class 12 Biology sample paper 2023-24: question 17

From the official CBSE sample question paper for 2023-24, section B, question 17, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q17 · 2 marks · Very short answerHuman Reproduction

Explain the process of hormonal regulation of spermatogenesis.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

Start from the brain: which gland starts the hormonal signal at puberty?

Hint 2

Two pituitary hormones are involved. Each acts on a different cell type in the testis.

Hint 3

Match LH with Leydig cells and FSH with Sertoli cells, and say what each cell type does.

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. At puberty, the hypothalamus sharply increases its secretion of gonadotropin releasing hormone (GnRH), and this starts spermatogenesis.

    ½ mark

  2. GnRH acts on the anterior pituitary. The pituitary then secretes two gonadotropins: luteinising hormone (LH) and follicle stimulating hormone (FSH).

    ½ mark

  3. LH acts on the Leydig (interstitial) cells, which make and release androgens (testosterone). Androgens stimulate spermatogenesis.

    ½ mark

  4. FSH acts on the Sertoli cells, which release factors that help in spermiogenesis (conversion of spermatids into sperms).

    ½ mark

Answer: Hypothalamic GnRH → anterior pituitary releases LH and FSH; LH → Leydig cells → androgens → spermatogenesis; FSH → Sertoli cells → factors aiding spermiogenesis.

Where the marks are

  • GnRH from hypothalamus rises at puberty (0.5 mark)
  • GnRH stimulates anterior pituitary to release LH and FSH (0.5 mark)
  • LH acts on Leydig cells to secrete androgens that stimulate spermatogenesis (0.5 mark)
  • FSH acts on Sertoli cells to secrete factors that help spermiogenesis (0.5 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 2023-24: 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.