Cambridge O Level Biology 5090/12 Paper 1 Multiple Choice October/November 2025 PDF

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IB25 11_5090_12/5RP

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Cambridge O Level

BIOLOGY 5090/12

Paper 1 Multiple Choice October/November 2025

1 hour

You must answer on the multiple choice answer sheet.

You will need: Multiple choice answer sheet

Soft clean eraser

Soft pencil (type B or HB is recommended)

INSTRUCTIONS



There are forty questions on this paper. Answer all questions.

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For each question there are four possible answers A, B, C and D. Choose the one you consider correct

and record your choice in soft pencil on the multiple choice answer sheet.



Follow the instructions on the multiple choice answer sheet.



Write in soft pencil.



Write your name, centre number and candidate number on the multiple choice answer sheet in the

spaces provided unless this has been done for you.



Do not use correction fluid.



Do not write on any bar codes.



You may use a calculator.

INFORMATION



The total mark for this paper is 40.



Each correct answer will score one mark.



Any rough working should be done on this question paper.

1 Which row identifies structures X and Y on the plant cell diagram?

structure X structure Y

A chloroplast mitochondrion

B chloroplast ribosome

C nucleus chloroplast

D mitochondrion ribosome

2 Viruses can only replicate inside cells.

A single Herpes simplex virus replicates rapidly inside a living cell and produces 4000 copies in

12 hours.

What is the maximum number of viruses that could be produced in 36 hours from a single

Herpes simplex virus?

A 1.2  10

B 16  10

C 6.4  10

D 2.6  10

3 Which statement about osmosis is correct?

A An animal cell immersed in distilled water will shrink.

B A plant cell immersed in distilled water will become flaccid.

C A plant cell immersed in a strong sodium chloride solution will become turgid.

D A plant cell immersed in a strong sodium chloride solution will become plasmolysed.

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4 Globulin is a substance that can be detected by the biuret test.

Which type of substance is globulin?

A fat

B oil

C protein

D reducing sugar

5 Cellulose and glucose are carbohydrates.

Cellulose is a large molecule made from a long chain of smaller glucose molecules.

One cellulose molecule is 0.01

mm long. One glucose molecule is 0.001 m long.

How many glucose molecules are found in this cellulose molecule?

A 1  10

B 1  10

C 1  10

D 1  10

6 Four test-tubes contain starch solution and amylase. They are placed in water-baths at different

temperatures and provided with different pHs, as shown in the table. All other conditions are kept

the same.

After 30 minutes, iodine solution is added to each test-tube. The contents of three of the

test-tubes turns blue-black.

In which test-tube are the contents yellow-brown?

temperature

/ °C pH

A 35 2.5

B 35 6.9

C 75 2.5

D 75 6.9

Overview

Cambridge O Level Biology 5090/12 Paper 1 Multiple Choice October/November 2025

Cambridge O Level Biology 5090/12 Paper 1 focuses on multiple-choice questions designed for students preparing for their biology examination. This paper includes 40 questions covering various topics in biology, including cell structure, photosynthesis, and human physiology. It is intended for O Level students aiming to enhance their understanding and performance in biology. The exam format allows students to practice their knowledge and application of biological concepts effectively. Key Points Includes 40 multiple-choice questions on key biology topics. Covers essential concepts such as osmosis, cellular respiration, and genetics. Designed for Cambridge O Level students preparing for their biology exams. Helps students practice and reinforce their understanding of biological princ…

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Figures

Which description matches an individual who has this karyotype?

FAQs

What is the maximum number of viruses produced by a single Herpes simplex virus in 36 hours?

A single Herpes simplex virus can replicate rapidly inside a living cell, producing 4000 copies in 12 hours. Therefore, in 36 hours, the maximum number of viruses that could be produced is calculated to be 2.6 × 10^14. This significant multiplication demonstrates the high replication rate of viruses within host cells.

Which structures in a dicotyledonous leaf are almost transparent to aid photosynthesis?

In a dicotyledonous leaf, the structures that are almost transparent to help increase the rate of photosynthesis are identified as structures 1 and 2. Their transparency allows more light to penetrate the leaf, facilitating the photosynthetic process, which is crucial for the plant's energy production.

What happens to plant cells in a strong sodium chloride solution?

When a plant cell is immersed in a strong sodium chloride solution, it becomes plasmolysed. This occurs because the high concentration of salt outside the cell causes water to move out of the cell, leading to the shrinkage of the cell membrane away from the cell wall. This process negatively affects the cell's turgor pressure and overall health.

What is the function of magnesium ions in newly germinated seeds?

Magnesium ions are essential for newly germinated seeds as they are needed to form chlorophyll molecules. Without sufficient magnesium, the seeds may fail to develop into healthy plants, as chlorophyll is crucial for photosynthesis, which provides the energy necessary for growth.

How does the concentration of substance X change during exercise?

During exercise, the concentration of substance X in a person's blood increases significantly. This change typically reflects the production of lactic acid, which is a byproduct of anaerobic respiration that occurs when the body is exerting itself and oxygen levels are insufficient for aerobic respiration.

What does the biuret test detect in biological substances?

The biuret test is used to detect the presence of proteins, such as globulin. When a protein is present, the biuret reagent changes color, indicating the presence of peptide bonds, which are characteristic of proteins. This test is a fundamental method in biochemistry for identifying proteins in various samples.

What is the effect of light intensity on the rate of transpiration?

The document includes a graph illustrating the effect of light intensity on the rate of transpiration. Generally, as light intensity increases, the rate of transpiration also increases, due to the opening of stomata for gas exchange, which is essential for photosynthesis and water regulation in plants.