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The following two… (Class 10 Science SQP 2025-26, Q8)

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ScienceCBSE Class 10 · Sample paper, session 2025-26 · 1 mark · Assertion-reason

CBSE Class 10 Science sample paper 2025-26: question 8

From the official CBSE sample question paper for 2025-26, section A, question 8, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q8 · 1 mark · Assertion-reasonCompetency-basedHeredity

The following two questions consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below:
A. Both A and R are true, and R is the correct explanation of A.
B. Both A and R are true, and R is not the correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.

Assertion (A): Tallness of a pea plant is controlled by an enzyme.
Reason (R): The gene for that enzyme makes proteins which help the plant to be tall.

  1. (A)Both A and R are true, and R is the correct explanation of A.
  2. (B)Both A and R are true, and R is not the correct explanation of A.
  3. (C)A is true but R is false.
  4. (D)A is false but R is true.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

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

Hint 1

Recall NCERT's explanation of how a gene controls a trait in peas.

Hint 2

Genes code for proteins, and enzymes are proteins.

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. In Mendel's pea plants, tallness depends on how much growth hormone is made. That amount depends on how efficiently a particular enzyme works. So (A) is true.

  2. The gene for that enzyme carries the information to make the enzyme protein. An efficient enzyme gives more hormone, and the plant grows tall. So (R) is true and it explains (A): option (A).

    1 mark

Answer: Option (A): Both A and R are true, and R is the correct explanation of A

Where the marks are

  • Recognises the gene → protein (enzyme) → hormone → tallness link and chooses (A) (1 mark)

Revise the chapter

  • Chapter: Heredity (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Heredity, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2025-26: 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.