A-Level Biology (Edexcel): Free Mock Test & Practice Questions

A-Level Biology (Edexcel)

Biological molecules, cells, exchange, genetics, energy, response. Edexcel board.

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Q1. Water molecules are described as dipolar. What does this mean?

A. The molecule has an unequal distribution of charge, with a slightly negative oxygen and slightly positive hydrogens
B. The molecule carries a full positive charge on one side and a full negative charge on the other
C. The molecule can donate two hydrogen bonds and accept none
D. The molecule has two separate covalent bonds that never break

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✓ Answer: A. The molecule has an unequal distribution of charge, with a slightly negative oxygen and slightly positive hydrogens

Oxygen is more electronegative than hydrogen, so it pulls the shared electrons closer, giving oxygen a slight negative charge (δ−) and each hydrogen a slight positive charge (δ+). This uneven charge distribution, not a full charge, is what makes water polar and able to form hydrogen bonds.

Q2. A cell that secretes large amounts of protein hormones would be expected to have an unusually extensive network of which organelle?

A. Smooth endoplasmic reticulum, because it folds secreted proteins
B. Peroxisomes, because they package proteins into vesicles
C. Rough endoplasmic reticulum, because ribosomes on its surface synthesise and fold secretory proteins
D. Lysosomes, because they synthesise new polypeptides

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✓ Answer: C. Rough endoplasmic reticulum, because ribosomes on its surface synthesise and fold secretory proteins

Rough endoplasmic reticulum is studded with ribosomes that synthesise proteins destined for secretion, and its lumen allows initial folding and processing before the proteins are sent to the Golgi apparatus. Smooth ER lacks ribosomes and instead specialises in lipid synthesis, while lysosomes only contain digestive enzymes and do not synthesise polypeptides.

Q3. Fluid can be drawn into the ends of insect tracheoles during periods of high activity such as flight. What is the functional significance of this?

A. It shortens the diffusion pathway for oxygen by increasing the air-filled volume closer to cells
B. Water is withdrawn from the tracheole tips into surrounding cells, increasing the air-filled length and shortening the diffusion distance for oxygen
C. It creates a countercurrent system that increases the rate of carbon dioxide removal
D. It prevents desiccation of the flight muscles during prolonged activity

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✓ Answer: B. Water is withdrawn from the tracheole tips into surrounding cells, increasing the air-filled length and shortening the diffusion distance for oxygen

During intense activity, anaerobic respiration in the muscles produces solutes that lower the water potential of the cells, drawing fluid out of the tracheole tips. This increases the air-filled portion of the tracheole, shortening the diffusion distance for oxygen to reach respiring cells.

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A-Level Biology (Edexcel) — common questions

Frequently asked

How many questions are in the A-Level Biology (Edexcel)?

The exam has 40 questions. Every Revision Robin mock uses the same 40-question format so your practice matches the real thing.

What is the pass mark for the A-Level Biology (Edexcel)?

You need 24 out of 40 correct to pass, which is about 60%. Our mocks mark you against this exact threshold.

How long do you get?

The test is timed at 60 minutes. Our full mock runs on the same clock so you can practise your pacing.

Are these the real exam questions?

No. Our questions are original and written to match the current syllabus, so they give realistic practice without copying the official paper. Every answer comes with a plain-English explanation. Always confirm current rules and content with Edexcel.