Skip to content

Give reason for the… (Class 10 Science 2023, Q35)

questionbuddy.in/q/cbse-10-science-2023-31-6-1-q35-give-during-reproduction-inheritance-different

ScienceCBSE Class 10 · Board exam 2023, set 31/6/1 · 5 marks · Long answer

CBSE Class 10 Science 2023: question 35

Set in the CBSE Class 10 board exam of 2023, paper 31/6/1, section D, question 35, for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q35 · 5 marks · Long answerHow do Organisms Reproduce?

Give reason for the following:
(a) During reproduction inheritance of different proteins will lead to altered body designs.
(b) Fertilization cannot take place in flowers if pollination does not occur.
(c) All multicellular organisms cannot give rise to new individuals through fragmentation or regeneration.
(d) Vegetative propagation is practised for growing only some type of plants.
(e) The parents and off-springs of organisms reproducing sexually have the same number of chromosomes.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/6/1.

Hints

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

Hint 1

For (a) and (e), think about what DNA does and what happens to the chromosome number in gametes.

Hint 2

For (b)–(d), ask what pollination delivers, why complex bodies cannot regrow from a piece, and which plants cannot form seeds.

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. (a) DNA is the information source for making proteins. If the DNA copy changes, different proteins are made. Proteins control body structures, so this leads to an altered body design.

    1 mark

  2. (b) Pollination brings pollen grains to the stigma. Without it, no male gametes reach the ovule, so fusion with the female gamete (fertilisation) cannot occur.

    1 mark

  3. (c) In many multicellular organisms, the body is made of specialised cells organised into tissues and organs at definite positions. A simple broken piece cannot reorganise into a complete organism, so fragmentation or regeneration is not possible for them.

    1 mark

  4. (d) Vegetative propagation is used for plants such as banana, orange, rose and jasmine, which have lost the capacity to produce seeds. It also gives flowers and fruits earlier, and plants genetically like the parent. Plants that set seed easily do not need it, so it is used only for some plants.

    1 mark

  5. (e) During gamete formation the chromosome number is reduced to half. At fertilisation, the fusion of male and female gametes restores the original number in the zygote, so offspring have the same number of chromosomes as the parents.

    1 mark

Answer: (a) Changed DNA gives different proteins, so altered body design; (b) no male gametes reach ovule; (c) specialised cells organised into tissues/organs cannot regenerate from a piece; (d) used for plants that have lost the ability to produce seeds (banana, rose, etc.); (e) gametes have half the chromosomes and fusion restores the full number.

Where the marks are

  • DNA → protein → body design link (1 mark)
  • No male gametes without pollination (1 mark)
  • Specialised cells/tissues/organs in complex organisms (1 mark)
  • Valid reason for vegetative propagation, e.g. seedless plants (1 mark)
  • Halving at gamete formation and restoration at fertilisation (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 paper2023 board paper, set 31/6/1: 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.