TCE Biology — Level 3
Meiosis — Flashcards & Quiz
Meiosis is a specialised form of cell division that produces haploid gametes from diploid parent cells. TCE Biology Level 3 expects you to describe the two sequential divisions, explain how crossing over and independent assortment generate genetic variation, and compare meiosis with mitosis. Non-disjunction errors and their consequences (e.g. Down syndrome) are standard application content.
Key Points
- Meiosis is a reduction division: one diploid cell (2n) produces four haploid cells (n).
- Meiosis I separates homologous chromosome pairs (reduction step); meiosis II separates sister chromatids (like mitosis).
- Crossing over in prophase I exchanges segments between homologous chromosomes at chiasmata, creating new allele combinations.
- Independent assortment in metaphase I: homologous pairs align randomly, giving 2ⁿ possible chromosome combinations (n = haploid number).
- Random fertilisation adds further variation: any sperm can meet any egg.
- Non-disjunction errors (failure to separate) cause aneuploidy — e.g. trisomy 21 (Down syndrome).
Common Mistakes to Avoid
- Stating meiosis produces two haploid cells — it produces FOUR.
- Forgetting crossing over happens in prophase I, not II.
- Confusing independent assortment (different genes) with crossing over (same gene, different alleles).
- Mixing up haploid and diploid when labelling diagrams.
- Missing one of the three sources of variation (crossing over, independent assortment, random fertilisation).
Exam Strategy
TASC Level 3 meiosis questions usually ask you to compare meiosis with mitosis or explain how meiosis generates variation. Structure: (1) state purpose (gamete production vs growth/repair), (2) outline the two divisions, (3) name all three sources of variation with mechanisms, (4) link to evolution and natural selection. Diagrams with labelled stages strengthen responses.
Sample Flashcards
Q1: Explain how meiosis produces genetic variation.
Meiosis is a reduction division producing four genetically unique haploid cells from one diploid cell. Genetic variation arises through: 1) Crossing over — exchange of segments between homologous chromosomes during prophase I. 2) Independent assortment — random orientation of homologous pairs at metaphase I. 3) Random fertilisation — any sperm can fuse with any egg.
Sample Quiz Questions
Q1: Crossing over during meiosis I increases genetic variation by exchanging segments between homologous chromosomes.
Answer: TRUE
Crossing over occurs during prophase I when non-sister chromatids of homologous chromosomes exchange genetic material, creating new allele combinations.
Revision Tip
The mitosis/meiosis comparison is high-yield — drill a Revizi flashcard deck with rows for purpose, divisions, daughter cells, ploidy, variation, and genetic outcome.
Related Concepts
Last updated: March 2026 · 1 flashcards · 1 quiz questions