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100+ Free Higher Biology Practice Questions

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Selection that favours individuals with one extreme of a trait and shifts the population mean in that direction is called:

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B
C
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Key Facts: Higher Biology Exam

120 marks

Question paper total

Qualifications Scotland course specification

2h 30min

Question paper duration

Qualifications Scotland course specification

3 units

DNA and the Genome, Metabolism and Survival, Sustainability and Interdependence

Qualifications Scotland

100

Free practice questions here

OpenExamPrep

Qualifications Scotland Higher Biology is assessed through a 2h30 question paper (120 marks) and a 20-mark assignment. The course covers molecular biology, metabolism and ecology and is graded A-D on the 2026 specification.

Sample Higher Biology Practice Questions

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

1In a DNA double helix, which base pairs with cytosine through three hydrogen bonds?
A.Guanine
B.Thymine
C.Adenine
D.Uracil
Explanation: In DNA, cytosine (C) pairs with guanine (G) by three hydrogen bonds, while adenine (A) pairs with thymine (T) by two hydrogen bonds. This complementary base pairing maintains the constant width of the double helix.
2The two strands of a DNA double helix are described as antiparallel because they run in:
A.Opposite directions, one 5' to 3' and the other 3' to 5'
B.The same direction, both 5' to 3'
C.The same direction, both 3' to 5'
D.Perpendicular directions at right angles to each other
Explanation: The two sugar-phosphate backbones of DNA run in opposite directions: one strand is oriented 5' to 3' while its partner runs 3' to 5'. This antiparallel arrangement is essential for complementary base pairing and for replication.
3Which components make up the sugar-phosphate backbone of a single DNA strand?
A.Deoxyribose sugars linked by phosphate groups
B.Ribose sugars linked by phosphate groups
C.Deoxyribose sugars linked by hydrogen bonds
D.Nitrogenous bases linked by phosphate groups
Explanation: Each DNA nucleotide contains a deoxyribose sugar, a phosphate group and a base. The backbone is formed when the phosphate of one nucleotide bonds to the deoxyribose of the next, producing alternating sugar-phosphate units along each strand.
4DNA replication is described as semi-conservative because each new DNA molecule contains:
A.One original strand and one newly synthesised strand
B.Two newly synthesised strands
C.Two original strands held together
D.A random mix of fragments from both parent strands
Explanation: Semi-conservative replication, demonstrated by Meselson and Stahl, produces two daughter molecules each containing one parental strand acting as a template and one newly synthesised complementary strand. This was confirmed by density gradient centrifugation of bacterial DNA.
5What is the role of a primer in DNA replication?
A.A short nucleotide sequence that provides a 3' end for DNA polymerase to add to
B.An enzyme that unwinds the double helix
C.A protein that joins Okazaki fragments together
D.A long template strand for the new strand to copy
Explanation: A primer is a short single-stranded nucleotide sequence (often RNA in cells, DNA in PCR) that binds to the template and provides a free 3' hydroxyl group for DNA polymerase to extend. Without a primer, DNA polymerase cannot begin synthesis.
6DNA polymerase can only add nucleotides to the:
A.3' end of the growing strand
B.5' end of the growing strand
C.Either end of the growing strand
D.Middle of the growing strand
Explanation: DNA polymerase catalyses the formation of a phosphodiester bond between the 3' hydroxyl of the last nucleotide on the growing strand and the 5' phosphate of the incoming nucleotide. Synthesis therefore proceeds only in the 5' to 3' direction.
7Which statement correctly describes the leading and lagging strands during DNA replication?
A.The leading strand is synthesised continuously, the lagging strand in Okazaki fragments
B.Both strands are synthesised continuously towards the replication fork
C.The lagging strand is synthesised continuously, the leading strand in fragments
D.Both strands are synthesised in short fragments joined by ligase
Explanation: Because DNA polymerase only synthesises 5' to 3', the leading strand can be made continuously towards the replication fork. The lagging strand runs in the opposite direction and is built as short Okazaki fragments away from the fork, each later joined by DNA ligase.
8Short DNA segments synthesised on the lagging strand and later joined together are called:
A.Okazaki fragments
B.Exons
C.Telomeres
D.Plasmids
Explanation: Okazaki fragments are short stretches of DNA synthesised discontinuously on the lagging strand. Each starts at a new primer, is extended by DNA polymerase, and is then sealed to the next fragment by DNA ligase.
9Which enzyme joins Okazaki fragments together to produce a continuous lagging strand?
A.DNA ligase
B.DNA polymerase
C.Helicase
D.Primase
Explanation: DNA ligase catalyses the formation of a phosphodiester bond between the 3' OH of one Okazaki fragment and the 5' phosphate of the next, sealing the sugar-phosphate backbone and producing a continuous lagging strand.
10In PCR, the high-temperature step at approximately 95 degrees Celsius is used to:
A.Denature the DNA by breaking hydrogen bonds between strands
B.Allow primers to anneal to the template
C.Activate Taq polymerase
D.Extend the new strand from each primer
Explanation: At about 95 degrees Celsius the hydrogen bonds between complementary bases are broken, separating the double-stranded DNA into two single strands. Cooling then allows primers to anneal and Taq polymerase to extend the new strands.

About the Higher Biology Exam

Scottish Higher Biology (course code C807 76) is offered by Qualifications Scotland (formerly SQA) at SCQF Level 6. The course is built around three units — DNA and the Genome, Metabolism and Survival, and Sustainability and Interdependence — and is assessed through a 120-mark question paper plus a 20-mark assignment.

Questions

100 scored questions

Time Limit

2 hours 30 minutes for the question paper

Passing Score

Grade A is the highest pass; A-D count as a pass at SCQF Level 6

Exam Fee

Entry fees set by school/centre; SQA per-subject entry charge applies (Qualifications Scotland (formerly SQA))

Higher Biology Exam Content Outline

Unit 1

DNA and the Genome

DNA structure and replication, PCR, gene expression, cellular differentiation, genome structure, mutations, evolution and genomic sequencing

Unit 2

Metabolism and Survival

Metabolic pathways, cellular respiration, regulation of metabolism, metabolic rate, conformers and regulators, dormancy, migration and micro-organism culture

Unit 3

Sustainability and Interdependence

Food security, photosynthesis and plant productivity, animal welfare, symbiosis, social behaviour and biodiversity

Assessment

Skills of scientific inquiry

Planning, selecting information, analysing experimental data, evaluating procedures and drawing conclusions — assessed in the question paper and assignment

How to Pass the Higher Biology Exam

What You Need to Know

  • Passing score: Grade A is the highest pass; A-D count as a pass at SCQF Level 6
  • Exam length: 100 questions
  • Time limit: 2 hours 30 minutes for the question paper
  • Exam fee: Entry fees set by school/centre; SQA per-subject entry charge applies

Keys to Passing

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

Higher Biology Study Tips from Top Performers

1Work through SQA past papers from 2018 onwards — the multiple-choice and extended-response style is very consistent year on year
2Use the official course specification and Course Reports as your checklist; examiners flag the same misconceptions every diet
3For the assignment, choose a question with a clear independent variable and at least five data points so you can plot a meaningful graph
4Learn the key terminology (e.g. semi-conservative, allosteric, niche, Simpson's index) precisely — examiners reward correct biological language

Frequently Asked Questions

Who awards Scottish Higher Biology?

Higher Biology is awarded by Qualifications Scotland (formerly SQA). The course code is C807 76 and it sits at SCQF Level 6, between National 5 and Advanced Higher.

How is Higher Biology assessed?

Assessment is by a question paper worth 120 marks (25 multiple choice + 95 structured/extended response, 2h 30min) and a 20-mark assignment written up under controlled conditions, giving 140 marks total.

What three units make up Higher Biology?

The three units are DNA and the Genome, Metabolism and Survival, and Sustainability and Interdependence. Each contributes roughly a third of the question paper marks.

When is the Higher Biology exam sat?

The question paper is sat in the May SQA diet at the end of the one-year course, with results released in early August. The assignment is completed earlier in the school year and submitted to SQA for external marking.