1What are gametes?
Sperm and egg cells.
2How many chromosomes do gametes have?
23 chromosomes.
3What happens during fertilisation?
Gametes fuse to form a zygote.
4What does the zygote develop into?
An embryo.
5What ensures genetic diversity during fertilisation?
Random fertilisation.
6What type of cell division forms gametes?
Meiosis.
7Where does meiosis occur?
Reproductive organs.
8What does meiosis halve in gametes?
Chromosome number.
9How many divisions occur in meiosis?
Two divisions.
10What happens before meiosis starts?
DNA replicates.
11What does each chromosome consist of after replication?
Two chromatids.
12What happens in meiosis I?
Homologous chromosomes are separated.
13What happens in meiosis II?
Sister chromatids are separated.
14What cells are produced by meiosis?
Four haploid cells.
15What are homologous chromosomes?
Pairs of chromosomes with the same genes.
16What happens in crossing over?
Chromatids swap genetic material.
17What does crossing over increase?
Genetic variation.
18What happens in independent segregation?
Chromosomes randomly separate.
19How many chromosomes do daughter cells have after meiosis?
23 chromosomes.
20What type of variation does meiosis cause?
Genetic variation.
21What is the chromosome mutation called when chromosomes fail to separate?
Non-disjunction.
22What condition is caused by an extra chromosome 21?
Down's syndrome.
23How does non-disjunction occur?
Chromosomes fail to separate in meiosis.
24What does a zygote with an extra chromosome have?
Three copies of chromosome 21.
25What does haploid mean?
One set of chromosomes.
26What does diploid mean?
Two sets of chromosomes.
27What are the differences between mitosis and meiosis?
Mitosis produces identical cells, meiosis does not.
28How many daughter cells are produced in mitosis?
Two daughter cells.
29How many daughter cells are produced in meiosis?
Four daughter cells.
30What are chromatids?
Strands of a replicated chromosome.
31What process ensures no two gametes are identical?
Independent segregation.
32What process results in genetic diversity in offspring?
Crossing over and random fertilisation.