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100+ Free AS-Level Biology Practice Questions

Pass your AS-Level Biology (AQA 7401 / Edexcel 8BN0 / OCR H020) exam on the first try — instant access, no signup required.

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The respiratory quotient (RQ) is defined as:

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Key Facts: AS-Level Biology Exam

A-E

AS grading scale (no A*)

Ofqual

2 papers

Assessment structure

AQA 7401, Edexcel 8BN0, OCR H020

1h 30 min

Time per paper

Specification documents

100

Free practice questions here

OpenExamPrep

AS-Level Biology covers Year 12 content only — biological molecules, cells, exchange, genetics and energy. Two 1h30 papers are sat at the end of Year 12 with AQA, Edexcel or OCR, graded A-E on the 2026 specification.

Sample AS-Level Biology Practice Questions

Try these sample questions to test your AS-Level Biology exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which monomer joins by glycosidic bonds to form starch and glycogen?
A.Alpha glucose
B.Beta glucose
C.Fructose
D.Galactose
Explanation: Starch (in plants) and glycogen (in animals/fungi) are storage polysaccharides built from alpha glucose monomers linked by 1,4 and 1,6 glycosidic bonds. The alpha form allows the chain to coil into a compact helix suitable for storage.
2Which feature of cellulose makes it ideal as a structural component of plant cell walls?
A.Beta glucose chains form straight microfibrils with many hydrogen bonds
B.It contains 1,6 branches that increase rigidity
C.It is a coiled alpha helix that resists stretching
D.It is hydrophobic and waterproof
Explanation: Cellulose is built from beta glucose. Alternate monomers are inverted, producing long straight chains that hydrogen-bond into microfibrils. The many hydrogen bonds collectively give very high tensile strength to the cell wall.
3Triglycerides form when glycerol reacts with three fatty acids. Which bond is produced and what small molecule is released for each bond?
A.Ester bond; water
B.Glycosidic bond; water
C.Peptide bond; carbon dioxide
D.Phosphodiester bond; water
Explanation: Each fatty acid attaches to glycerol via a condensation reaction that forms an ester bond between an -OH on glycerol and -COOH on the fatty acid, releasing one water molecule. Three water molecules are released per triglyceride.
4Why are phospholipids able to form a bilayer in cell membranes?
A.They have a hydrophilic phosphate head and two hydrophobic fatty acid tails
B.They are completely hydrophilic so they dissolve in water
C.They are completely hydrophobic so they float on water
D.They contain ester linkages that lock them in place
Explanation: A phospholipid has a polar phosphate head that interacts with water and two non-polar fatty acid tails that avoid water. In aqueous surroundings the tails point inward and the heads outward, creating a stable bilayer.
5How many different amino acids commonly appear in proteins, and which bond joins them?
A.20; peptide bond
B.20; glycosidic bond
C.64; peptide bond
D.12; ester bond
Explanation: There are 20 standard amino acids in human proteins. They join via condensation between the carboxyl of one amino acid and the amine of another, forming a peptide bond and releasing water.
6Which interactions determine the tertiary structure of a globular protein?
A.Hydrogen bonds, ionic bonds, disulfide bridges and hydrophobic interactions between R-groups
B.Only peptide bonds between adjacent amino acids
C.Only hydrogen bonds between -NH and -CO in the backbone
D.Phosphodiester bonds between amino acid R-groups
Explanation: Tertiary structure is the overall 3D fold of a single polypeptide. It arises from interactions between R-groups: hydrogen bonds, ionic interactions, disulfide bridges (cysteine), and hydrophobic clustering away from water.
7According to the induced-fit model of enzyme action, the active site:
A.Changes shape slightly as the substrate binds, creating an optimal fit
B.Is a rigid pre-formed shape that perfectly matches the substrate
C.Is identical in shape to every possible substrate
D.Becomes permanently denatured after substrate binding
Explanation: Induced fit (Koshland) proposes that substrate binding causes the active site to mould around the substrate, straining bonds and lowering activation energy. This is a refinement of the older lock-and-key model.
8A non-competitive inhibitor of an enzyme would most likely:
A.Decrease Vmax without changing Km
B.Increase Km without changing Vmax
C.Decrease both Vmax and Km
D.Have no effect on either Vmax or Km
Explanation: Non-competitive inhibitors bind to an allosteric site away from the active site, altering enzyme shape so substrate cannot be turned over. Adding more substrate cannot overcome this, so Vmax falls but apparent Km is unchanged.
9Increasing substrate concentration well above Km affects the rate of an enzyme-controlled reaction in what way?
A.Rate plateaus at Vmax because all active sites are occupied
B.Rate increases indefinitely with substrate
C.Rate falls because substrate denatures the enzyme
D.Rate becomes zero because the enzyme is saturated
Explanation: When substrate concentration is high, enzymes work at maximum velocity (Vmax) because active sites are continually occupied. Adding more substrate cannot increase the rate further; enzyme concentration becomes the limiting factor.
10Which best describes the structure of a DNA molecule as proposed by Watson and Crick?
A.Two antiparallel polynucleotide strands wound in a right-handed double helix, held by complementary base pairing
B.A single linear strand of nucleotides with branching
C.Two parallel strands joined by phosphodiester bonds between bases
D.A circular triple helix with A-G and C-T pairing
Explanation: Watson and Crick described two strands running antiparallel (5' to 3' opposite 3' to 5') as a right-handed helix. Complementary base pairs (A-T two H-bonds, C-G three H-bonds) link the strands.

About the AS-Level Biology Exam

AS-Level Biology is the standalone Year 12 qualification covering the first half of A-Level Biology content. It is offered by AQA (7401), Edexcel/Pearson (8BN0 — Biology B and Salters-Nuffield) and OCR (H020 Biology A). Students sit two written papers at the end of Year 12 covering biological molecules, cells, organism exchange, genetic information, energy transfers and required practical skills.

Questions

100 scored questions

Time Limit

Two papers of 1 hour 30 minutes (3 hours total)

Passing Score

Grade E minimum pass; A-E count as a pass (A-B-C-D-E)

Exam Fee

£50-£95 per subject (school-set entry fee) (AQA, Edexcel (Pearson), OCR)

AS-Level Biology Exam Content Outline

~20%

Biological molecules

Monomers and polymers, carbohydrates (alpha/beta glucose, starch, glycogen, cellulose), lipids (triglycerides, phospholipids, ester bonds), proteins (peptide bonds, primary to quaternary structure), enzyme kinetics (Vmax, Km, induced fit, inhibition), DNA/RNA structure and semi-conservative replication, ATP and water properties.

~20%

Cells

Eukaryotic and prokaryotic cells, organelles (nucleus, RER/SER, Golgi, mitochondria, chloroplasts, 70S/80S ribosomes, lysosomes), microscopy and magnification, mitosis and the cell cycle, cancer, membrane transport (diffusion, osmosis, active transport, co-transport) and immunity (phagocytosis, T and B lymphocytes, vaccines, ELISA).

~20%

Organisms exchange substances with their environment

Surface area to volume ratio, gas exchange in single cells, insects, fish (counter-current) and mammals, ventilation mechanics, mass transport in animals (heart, cardiac cycle, blood vessels, tissue fluid, haemoglobin and the Bohr effect) and digestion and absorption.

~20%

Genetic information, variation and relationships between organisms

DNA, genes and chromosomes, transcription and translation, mutations (substitution, insertion, deletion, frameshift), meiosis and sources of genetic variation, classification (domain to species, Woese three-domain system), biodiversity and index of diversity, species concepts and courtship behaviour.

~15%

Energy transfers in and between organisms

Photosynthesis light-dependent reactions (photolysis, photophosphorylation, NADPH) and the Calvin cycle (RuBisCO, GP, TP), limiting factors, respiration (glycolysis, link reaction, Krebs cycle, oxidative phosphorylation and chemiosmosis), anaerobic respiration (lactate, ethanol) and respiratory quotient.

~5%

Required practical skills and apparatus

Use of light microscopes, biological drawings and scale bars, serial dilutions, Benedict's and Biuret tests, iodine test for starch, ethanol emulsion test for lipids, chromatography, dissection and aseptic microbiology technique.

How to Pass the AS-Level Biology Exam

What You Need to Know

  • Passing score: Grade E minimum pass; A-E count as a pass (A-B-C-D-E)
  • Exam length: 100 questions
  • Time limit: Two papers of 1 hour 30 minutes (3 hours total)
  • Exam fee: £50-£95 per subject (school-set entry fee)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

AS-Level Biology Study Tips from Top Performers

1Master required practicals — examiners reuse the same techniques in data-analysis questions every year
2Practise calculations: magnification, water potential, Vmax/Km, index of diversity and ATP yield
3Learn the structure-function links for molecules (starch vs cellulose, haemoglobin, enzymes)
4Use exam-board past papers from 2017 onwards — mark schemes reward specific keywords

Frequently Asked Questions

What exam boards offer AS-Level Biology?

AS-Level Biology is offered by AQA (7401), Edexcel/Pearson (8BN0 — Biology B and 8BN0 Salters-Nuffield) and OCR (H020 Biology A). All follow Ofqual subject content but differ in specification ordering, set practicals and paper structure.

How is AS-Level Biology assessed?

AS Biology is a standalone Year 12 qualification with two written papers, each typically 1 hour 30 minutes and 75 marks. Questions are a mix of short-answer, structured, data-response and extended-response items. There is no coursework, but practical skills are tested in the written papers.

Does AS-Level Biology count towards the full A-Level?

Since 2015 the AS and A-Level are decoupled in England, so AS results no longer feed into the final A-Level grade. The AS gives a separate Year 12 qualification but covers only the first half of the A-Level content.

How is AS-Level Biology graded?

AS-Levels are graded A-E (the AS does not award A*). A is the highest grade and E is the minimum pass. UCAS tariff points are awarded for AS grades but are half those of the equivalent A-Level grade.