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Answer the following. (Science 2023 31/4/1 Q35)

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ScienceCBSE Class 10 · Board exam 2023, set 31/4/1 · 5 marks · Long answer

CBSE Class 10 Science 2023: question 35

Set in the CBSE Class 10 board exam of 2023, paper 31/4/1, 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?

Answer the following.

  1. (i)

    Name and explain the two modes of asexual reproduction observed in hydra.

    3 marks
  2. (ii)

    What is vegetative propagation ? List two advantages of using this technique.

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/4/1.

Hints

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

Hint 1

One mode of hydra involves a small outgrowth, and the other involves cut pieces.

Hint 2

Vegetative parts are the parts of a plant other than flowers and seeds.

Hint 3

Think of speed of fruiting, and of plants like banana that do not 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. (i) Mode 1: Budding.

    ½ mark

  2. In budding, a bud develops as an outgrowth from the body of hydra because of repeated cell division at one specific site. The bud grows into a tiny individual. When fully mature, it detaches from the parent and becomes a new independent hydra.

    1 mark

  3. (i) Mode 2: Regeneration.

    ½ mark

  4. In regeneration, hydra can be cut into many pieces. Each piece grows into a complete organism through specialised cells that proliferate and differentiate into the different tissues.

    1 mark

  5. (ii) Vegetative propagation is the method of growing new plants from a vegetative part of the parent plant, such as the root, stem or leaf, without seeds.

    1 mark

  6. Advantage 1: plants grown this way bear flowers and fruits earlier than plants raised from seeds.

    ½ mark

  7. Advantage 2: it allows propagation of plants that have lost the capacity to produce seeds, such as banana, orange, rose and jasmine. (Also accepted: the new plants are genetically similar to the parent, so they keep all its desirable characters.)

    ½ mark

Answer: (i) Budding and regeneration; (ii) vegetative propagation is raising new plants from roots, stems or leaves. Advantages: earlier flowering and fruiting; propagates seedless plants such as banana and rose (also retains parental characters).

Where the marks are

  • Names budding (½ mark) and explains it (1 mark)
  • Names regeneration (½ mark) and explains it (1 mark)
  • Defines vegetative propagation (1 mark)
  • Gives any two advantages (½ + ½ 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 31/4/1: 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.