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Answer the following. (Science 2024 31/3/1 Q35a)

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ScienceCBSE Class 10 · Board exam 2024, set 31/3/1 · 5 marks · Long answer

CBSE Class 10 Science 2024: question 35(a)

Set in the CBSE Class 10 board exam of 2024, paper 31/3/1, section D, question 35(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.

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

Answer the following.

  1. (i)

    What are spores ? On which structures are they formed ? How do they overcome unfavourable conditions ? Name the organism which multiplies with the help of these structures.

    0 marks
  2. (ii)

    Give two reasons why some plants are grown by the method of vegetative propagation. List two methods used to grow plants vegetatively.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/3/1.

Hints

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

Hint 1

Recall the fungus that grows on moist bread and the black dots on its threads.

Hint 2

What protects a spore until it reaches a moist surface?

Hint 3

For (ii), think of plants like banana or rose that do not form seeds, and about how quickly vegetatively grown plants flower.

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) Spores: Spores are tiny, single-celled reproductive bodies. They are released from the parent and each one can grow into a new individual when it lands on a moist, suitable surface.

    ½ mark

  2. (i) Where they form: Spores are formed inside blob-like structures called sporangia (singular: sporangium), at the tips of thin hyphae.

    ½ mark

  3. (i) Surviving unfavourable conditions: Each spore is covered by a thick protective wall. This wall protects the spore from drying out and from harsh conditions until it reaches a moist surface and can germinate.

    ½ mark

  4. (i) Organism: Rhizopus (bread mould) reproduces by spore formation.

    ½ mark

  5. (ii) Reason 1: Some plants have lost the ability to produce seeds, for example banana, orange, rose and jasmine. Such plants can only be multiplied vegetatively.

    1 mark

  6. (ii) Reason 2: Plants raised vegetatively flower and fruit earlier than plants grown from seeds. Also, all the new plants are genetically similar to the parent, so useful characters are kept.

    1 mark

  7. (ii) Two methods of vegetative propagation: (1) Layering and (2) Grafting. Stem cutting is also accepted.

    1 mark

Answer: (i) Spores are single-celled reproductive bodies; formed in sporangia; thick protective walls help them survive; Rhizopus. (ii) Seedless plants (banana, rose) can be grown, and plants flower/fruit earlier and are genetically similar to the parent; methods: layering and grafting

Where the marks are

  • Correct meaning of spores (½ mark)
  • Formed in sporangia (½ mark)
  • Thick protective wall helps them survive unfavourable conditions (½ mark)
  • Names Rhizopus (½ mark)
  • Two valid reasons for vegetative propagation (1 + 1 marks)
  • Names two methods, e.g. layering and grafting (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 paper2024 board paper, set 31/3/1: 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.