Meiosis And Genetic Variation

Question 1

What does haploid and diploid mean

Answer 1

Haploid
When a cell contains one copy of each chromosome

Diploid
When a cell contains two copies of each chromosome

Question 2

What happens during fertilisation

Answer 2

A haploid sperm fuses with haploid egg making a cell with diploid number of chromosomes

Fertilisation is random
This produces zygotes with different combinations of chromosomes in both parents

Question 3

What is meiosis

Answer 3

Type of cell division

Happens in reproductive organs

Question 4

Process of meiosis

Answer 4

DNA unravels and replicates so there are two copies of each chromosome

DNA condensed to form double armed chromosomes

Meiosis one. First division
Chromosomes arrange in homologous pairs

The homologous pairs separate halving the chromosome number

Meiosis two. Second division
Pairs of sister chromatids separate so centromere divided

Four haploid cells genetically different then formed

Question 5

Genetic variation in gametes. Two ways

Answer 5

Crossing over of chromatids
Chromatids twist around eachother and bits of chromatids swap. Now having different combinations of alleles

Independent segregation
The random division of maternal and paternal chromosomes into daughter cells during meiosis

Question 6

Outcomes of meiosis

Answer 6

Produces cells with half the number of chromosomes as the parent cell

Daughter cells genetically different from the parent cells

Produces four daughter cells

Question 7

Outcomes of mitosis

Answer 7

Produces cells same number of chromosomes as parent cell

Daughter cells genetically identical to parent cell

Produces two daughter cells