CBSE Class 12 Biology sample paper 2026-27: question 19
From the official CBSE sample question paper for 2026-27, section B, question 19, for 2 marks. Try it first; the hints and our step-by-step solution are below.
Q19 · 2 marks · Very short answerCompetency-basedHuman Health and Disease
The following is a realistic example dataset and not a real world patient dataset:
| Sample ID | Tumor size (mm) | Glucose level mM/litre | Oxygen level (mmHg) | Neighboring cell's viability/ vitality (%) |
|---|---|---|---|---|
| 1 | 150 | 2.0 | 15 | 60 |
| 2 | 50 | 4.5 | 30 | 85 |
| 3 | 200 | 1.3 | 10 | 50 |
| 4 | 100 | 3.0 | 20 | 70 |
| 5 | 250 | 0.9 | 7 | 40 |
A. Interpret the relationship between tumor size and glucose level.
B. Evaluate the data to determine how tumor progression may affect the viability/vitality of neighboring cells. Provide a brief explanation.
Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.
Hints
Open one hint at a time and try again before the next.
Hint 1
Arrange the samples in increasing order of tumour size and watch the other columns.
Hint 2
Cancer cells divide rapidly: what would they take away from normal cells nearby?
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 mark
A. Tumour size and glucose level are inversely related: as tumour size rises from 50 to 250 mm³, glucose falls from 4.5 to 0.9 mM/L. Larger tumours consume more glucose because their rapidly dividing cells have a high metabolic demand, which suggests more aggressive growth.
- 1 mark
B. As the tumour grows, the viability of neighbouring cells falls from 85% to 40%, and oxygen falls from 30 to 7 mmHg. The growing tumour competes for nutrients and oxygen. This creates a hostile microenvironment that starves and stresses the surrounding normal cells, leading to their death.
Answer: A. Inverse relation: bigger tumours use more glucose. B. Tumour growth lowers neighbouring cell viability (85%→40%) because it competes for nutrients and oxygen.
Where the marks are
- Inverse relation between tumour size and glucose, explained by higher metabolic demand (1 mark)
- Viability of neighbouring cells decreases due to nutrient/oxygen competition (1 mark)
Revise the chapter
- Chapter: Human Health and Disease (notes, formulas, where marks are lost and every past question)
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