CGP Diversity

Question 1

How many chromosomes do normal body cells have?

Answer 1

The diploid number (2n) - meaning each cell contains two of each chromosome.

Question 2

How many chromosomes do gametes have?

Answer 2

The haploid number (n) - one copy of each chromosome.

Question 3

Fertilisation is __________.

Answer 3

Random.

Question 4

In one sentence, how does reproduction increase genetic diversity?

Answer 4

Random fertilisation produces zygotes with different combinations of chromosomes to both parents. The mixing of genetic material in sexual reproduction increases genetic diversity within a species

Question 5

In total, humans have ___ chromosomes.

Answer 5

46 chromosomes - 23 pairs.

Question 6

How are gametes formed in meiosis?

Answer 6

1. Before meiosis starts the DNA unravels and replicates so there are two copies of each chromosome (chromatids).
2. The DNA condenses to form double armed chromosomes, each made from two sister chromosomes, joined by a centromere.
3. Meiosis I (first division) - the chromosomes arrange themselves into homologous pairs.
4. These homologous pairs are then separated, halving the chromosome number.
5. Meiosis II (second division) - the pairs of sister chromatids that make up the chromosomes are separated (centromere divides).
6. Four haploid cells (gametes) that are genetically different from each other are produced.

Question 7

Meiosis produces…

Answer 7

4 daughter cells (gametes) with half the number of chromosomes of the parent cell.

Question 8

What events in meiosis lead to genetic variation?

Answer 8

Crossing over of chromatids and independent assortment of chromosomes.

Question 9

Outline the independent assortment of chromosomes.

Answer 9

1.