IGCSE Biology glossary
Chromosome
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A thread-like structure made of DNA and protein, found in the nucleus of a cell. Chromosomes carry genes in a specific order along their length. Humans have 46 chromosomes (23 pairs), including one pair of sex chromosomes (XX in females, XY in males).
What to include in an exam answer
Each chromosome is a long molecule of DNA. Genes are sections of a chromosome. Humans have 23 pairs: 22 pairs of autosomes and 1 pair of sex chromosomes. Be precise with numbers.
Example in context
State the number of chromosomes in a human body cell and in a human gamete (2 marks): A body cell has 46 chromosomes (23 pairs). A gamete has 23 chromosomes.
Related syllabus topic
Inheritance