Skip to content

Observe the contents… (Class 12 Biology SQP 2023-24, Q12)

questionbuddy.in/q/cbse-12-biology-2023-24-sqp-q12-observe-contents-soil-samples-graph

BiologyCBSE Class 12 · Sample paper, session 2023-24 · 1 mark · MCQ

CBSE Class 12 Biology sample paper 2023-24: question 12

From the official CBSE sample question paper for 2023-24, section A, question 12, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q12 · 1 mark · MCQCompetency-basedEcosystem

Observe the contents 1,2,3 and 4 of soil samples A,B and C shown in the graph. If the temperature and soil moisture of all soil samples are identical, which soil sample (s) will show faster decomposition?

  1. (A)Soil Sample A
  2. (B)Soil Sample B
  3. (C)Soil Samples A and B both
  4. (D)Soil Sample C

Figure in the paper: Bar graph of Content (%) (0-20) for Soil A, B, C, each with bars 1-4. 1 indicates lignin content, 2 indicates chitin, 3 indicates Nitrogen content and 4 indicates sugar content. Approx. values: Soil A: 8, 15, 5, 20; Soil B: 15 (10), 20, 7, 11.5; Soil C: 8, 10, 17, 20. See it in the official paper.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2023-24.

Hints

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

Hint 1

Lignin and chitin slow decomposition down.

Hint 2

Look for the sample with the highest nitrogen and sugar.

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. Decomposition is faster when the detritus is rich in nitrogen and water-soluble sugars, and slower when it contains more lignin and chitin.

    ½ mark

  2. Soil C has the lowest lignin and chitin together with the highest nitrogen and sugar, so it will decompose fastest.

    ½ mark

Answer: (D) Soil Sample C

Where the marks are

  • States the factors that speed up or slow down decomposition (0.5 mark)
  • Applies them to choose Soil C (0.5 mark)

Revise the chapter

  • Chapter: Ecosystem (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Ecosystem, one at a time, marked against the answer key and marking points.Back to the full paperSample paper 2023-24: 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.