Chromosomes, DNA & Mitosis

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CognitoDNA, genes and chromosomes

CognitoMitosis and the cell cycle

Key facts & methods

DNA and chromosomes — fill in the table

Term	Definition
DNA
Chromosomes
Gene
Allele
Genome
Diploid & haploid

The cell cycle and mitosis

Cell cycle: growth (G1) → DNA replication (S phase) → growth (G2) → mitosis (M) → cell division.
Mitosis: cell division producing two genetically identical daughter cells.
Used for: growth, repair, asexual reproduction.
Before mitosis: DNA is copied so each cell gets a complete set of chromosomes.
Result: 2 daughter cells, same chromosome number as parent (diploid → diploid).
Uncontrolled mitosis = cancer (cells divide without regulation).

Meiosis (contrast with mitosis) — fill in the table

Term	Definition
Meiosis
Gametes
Chromosome number
Crossing over
Fertilisation

DNA replication and protein synthesis (Higher) — fill in the table

Term	Definition
DNA replication
Complementary base pairing
Semi-conservative replication
Genes & codons
Mutations

Exam questions — 5 questions · 12 marks · AQA 8461 style

1 markMitosis productAQA 8461 style

How many cells are produced by mitosis and what is their genetic relationship to the parent cell?

A Four genetically different cells

B Two genetically identical cells

C Two genetically different cells

D Four genetically identical cells

1 markChromosome numberAQA 8461 style

A human body cell has 46 chromosomes. How many chromosomes does a human egg cell contain?

A 46

B 92

C 23

D 22

3 marksCell cycleAQA 8461 P2 style

Describe the stages of the cell cycle that occur before mitosis takes place. (3 marks)

Hint: Think about what a cell needs to do to prepare for division: grow, duplicate organelles, copy its DNA.

+30 XP

4 marksMeiosis vs mitosisAQA 8461 P2 style

Compare mitosis and meiosis in terms of: (a) the number of daughter cells produced, (b) whether they are genetically identical, (c) where each process occurs in the human body. (4 marks)

Hint: Three paired comparisons. Each comparison earns a mark. Be specific about location for meiosis.

+40 XP

1 markRole of mitosisAQA 8461 style

Which of the following is NOT a role of mitosis in humans?

A Growth of the organism

B Repair of damaged tissue

C Production of gametes

D Replacement of worn-out cells

Quick recall flashcards

Chromosomes, DNA & Mitosis

DNA and chromosomes — fill in the table

The cell cycle and mitosis

Meiosis (contrast with mitosis) — fill in the table

DNA replication and protein synthesis (Higher) — fill in the table

Module complete! 🎉