What You Need to Know

Key Concept Diagram

Mitosis produces two genetically identical daughter cells for growth, repair, and asexual reproduction

Meiosis produces four genetically unique haploid gametes (sperm or egg cells) for sexual reproduction

Crossing over during meiosis I exchanges genetic material between homologous chromosomes, increasing variation

Mitosis maintains the chromosome number (diploid); meiosis halves it (haploid) for fertilisation

Errors in cell division can lead to conditions such as Down syndrome (trisomy 21)

Key Vocabulary

Mitosis

Cell division producing two genetically identical diploid daughter cells

Meiosis

Cell division producing four genetically unique haploid gametes

Diploid

A cell containing two complete sets of chromosomes (2n), one from each parent

Crossing over

The exchange of genetic segments between homologous chromosomes during meiosis I, generating genetic variation

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

What is the main purpose of mitosis in multicellular organisms?

To produce genetically identical cells for growth and repair To create genetic variation To produce gametes for sexual reproduction To halve the chromosome number

Question 2

How does meiosis differ from mitosis in terms of chromosome number?

Meiosis doubles the chromosome number Meiosis halves the chromosome number to produce haploid cells Both maintain the same chromosome number Mitosis halves the chromosome number

Question 3

Crossing over during meiosis increases genetic variation by:

Doubling the number of chromosomes Producing identical cells Exchanging segments of genetic material between homologous chromosomes Removing genes from chromosomes

Mitosis and Meiosis