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Genetics, Variation and Evolution
Practice Questions

96 CXC CSEC Human and Social Biology questions on Genetics, Variation and Evolution, each with instant feedback and a full examiner-style mark scheme.

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✨ Revision guide includes key terms, worked examples and exam technique for Genetics, Variation and Evolution.

Try 2 sample questions on Genetics, Variation and Evolution

Question 1 · 1 mark · Difficulty 1/3

Which type of chromosome abnormality causes Down syndrome?

  1. A deletion of part of chromosome 21
  2. A trisomy of chromosome 21
  3. A monosomy of chromosome 23
  4. A translocation of chromosome 18
Show answer & explanation
✓ Answer: B — A trisomy of chromosome 21
Down syndrome results from trisomy 21, where an individual has three copies of chromosome 21 instead of the normal two. This gives a total of 47 chromosomes rather than the usual 46. It is caused by non-disjunction during meiosis.
Question 2 · 1 mark · Difficulty 1/3

Genetic counselling reveals that a father has Down syndrome. Which of the following best describes the chromosomal composition of his karyotype?

  1. 45 chromosomes with a deletion on chromosome 21
  2. 47 chromosomes with three copies of chromosome 21
  3. 46 chromosomes with an extra segment on chromosome 18
  4. 47 chromosomes with an extra sex chromosome
Show answer & explanation
✓ Answer: B — 47 chromosomes with three copies of chromosome 21
Down syndrome is caused by trisomy 21, in which there are three copies of chromosome 21, giving a total of 47 chromosomes. This is distinct from conditions involving sex chromosome abnormalities or deletions. A karyotype would clearly show the three chromosome 21s.
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CXC CSEC Human and Social Biology: Genetics, Variation and Evolution FAQ

Is Kramizo free for CXC CSEC students preparing for Human and Social Biology?
Yes — completely free. Every student gets 45 questions a day on the free plan, with no card required and no trial countdown. That free quota works across every subject and every topic in our bank, so you can mix Genetics, Variation and Evolution practice with other Human and Social Biology topics or even switch to a totally different CXC subject without paying anything. Kramizo's optional Pro plan removes the daily cap and adds detailed progress analytics, but the free tier is the real product — used by thousands of GCSE, IGCSE and CSEC students.
Are the Genetics, Variation and Evolution questions aligned to the official CXC CSEC Human and Social Biology syllabus?
Every question is written against the published CXC CSEC Human and Social Biology specification, including the exact command words (state, describe, explain, calculate, evaluate, etc.), mark allocations, and difficulty tier you'd see on a real CXC paper. Explanations are written in the style of official examiner mark schemes — they tell you what is being awarded marks and why distractors are wrong, not just whether you got it right. The bank is continually refined to match the latest syllabus updates from CXC.
How is Genetics, Variation and Evolution typically tested on CXC CSEC Human and Social Biology papers?
Genetics, Variation and Evolution appears across multiple question types on real CXC CSEC Human and Social Biology papers — most commonly as multiple-choice questions in the objective section, structured short-answer questions in the main paper, and occasionally as part of an extended response. Kramizo's practice bank reflects that mix: 4-option MCQs, true/false statements, fill-in-the-blank key terms, multi-select questions, and ordering questions. Working through the bank gives you exposure to every question style examiners actually use.

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