3.4.3 Genetic diversity can arise as a result of mutation or during meiosis

Question 1

Describe how crossing over introduces variation

Answer 1

Occurs during mitosis one
Homologous pair of chromosomes associate forming a bivalent
Chiasma forms
Equal tenths of the non sister chromatids are exchanged
Producing new combinations of alleles

Question 2

Describe how independent segregation introduces variation

Answer 2

Homologous chromosomes align opposite at the equator
It random which side the parental and maternal chromosomes are
these separate into daughter cells and large combination of chromosome in daughter cells

Question 3

What two factors can influence genetic diversity ?

Answer 3

Meiosis
Mutations

Question 4

Homologous chromosomes carry the same genes but they are not genetically identical. Explain why

Answer 4

Homologous chromosomes carry different alleles

Question 5

Explain the two ways in which the behaviours of chromosomes during meiosis produces genetic variation in gametes

Answer 5

Crossing over - different combinations of alleles
Independent segregation - different combination of maternal and parental chromosomes/ independent assortment of chromosomes

Question 6

Give four differences between meiosis and mitosis

Answer 6

1. Reduce number of chromosomes, maintains the same number of chromosomes as parent nucleus
2. Homologous chromosomes associate in pairs, homologs chromosomes do not associate in pairs
3. Crossing over, no crossing over
4. Genetically different, genetically identical

Question 7

What is the term used to describe a pair of homologous chromosomes

Answer 7

Bivalent

Question 8

Give a process other than crossing over and independent segregation that results in genetic variation

Answer 8

Mutation - leads to different allele produced by different sequence of bases

Question 9

What affects the rate of mutation

Answer 9

Environment

Question 10

Why can different mutations not be passed onto different species

Answer 10

Different species do not interbreed as cannot produce fertile offspring
So mutations cannot be passed on from one species to another