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Answer the following. (Science 2025 31/1/1 Q35b)

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ScienceCBSE Class 10 · Board exam 2025, set 31/1/1 · 5 marks · Long answer

CBSE Class 10 Science 2025: question 35(b)

Set in the CBSE Class 10 board exam of 2025, paper 31/1/1, section D, question 35(b), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q35(b) · 5 marks · Long answerHow do Organisms Reproduce?

Answer the following.

  1. (i)

    Differentiate between self-pollination and cross-pollination.

    0 marks
  2. (ii)

    Identify A, B and C in the diagram given below and write one function of each.

    0 marks

Figure in the paper: A longitudinal section of a flower showing a pistil. Label A points to the stigma at the top. Label B points to the style, a tube running down from the stigma. Label C points to the ovule/embryo sac region at the base inside the ovary, where a pollen tube reaches the ovule. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/1/1.

Hints

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

Hint 1

The difference is about whether pollen stays within one flower or travels to another flower.

Hint 2

Trace the journey of pollen from where it lands, down the tube it grows, to the cell it fertilises.

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. (i) Self-pollination: pollen grains are transferred from the anther (stamen) to the stigma of the same flower, or of another flower on the same plant.

    1 mark

  2. Cross-pollination: pollen grains are transferred from the anther of one flower to the stigma of a flower on a different plant of the same species. Agents such as wind, water, insects or birds carry the pollen.

    1 mark

  3. (ii) A – Stigma: the sticky top of the pistil. It receives the pollen grains and provides a suitable surface for them to germinate.

    1 mark

  4. B – Pollen tube: grows from the germinated pollen grain down through the style. It carries the male germ cells to the female germ cell in the ovule inside the ovary. (If B is read as the style itself: the style connects stigma and ovary and provides the passage through which the pollen tube grows.)

    1 mark

  5. C – Female germ cell (egg cell) in the ovule: it fuses with the male germ cell (fertilisation) to form the zygote, which develops into the embryo.

    1 mark

Answer: (i) Self-pollination: pollen to stigma of same flower; cross-pollination: pollen to stigma of another flower of same species. (ii) A – stigma (receives pollen, helps it germinate); B – pollen tube (carries male gametes to the ovule); C – egg/female germ cell (fuses with male gamete to form zygote).

Where the marks are

  • Correct description of self-pollination (1 mark)
  • Correct description of cross-pollination (1 mark)
  • A identified as stigma with function (1 mark)
  • B identified as pollen tube with function (1 mark)
  • C identified as egg cell/female germ cell with function (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from How do Organisms Reproduce?, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 31/1/1: 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.