genetic diversity and adaptation

Question 1

what is meant by substitution of bases in mutations

Answer 1

a nucleotide in a DNA molecule is replaced by another nucleotide that has a different base is know as a substitution

Question 2

what is meant by deletion of bases of gene mutation?

Answer 2

when a nucleotide is lost from the normal DNA sequence

Question 3

what are chromosome mutations?

Answer 3

changes in the structure or number of whole chromosomes

Question 4

what two forms of chromosome mutations are there?

Answer 4

– changes in whole sets of chromosomes occur when organisms have three or more sets of chromosomes
– changes in the number of individual chromosomes

Question 5

what are the two kinds of cell division?

Answer 5

– mitosis - produces 2 daughter cells with the same number of chromosomes as parent cells
– meiosis - produced 4 daughter cells with half the number of chromosomes as parent cells

Question 6

what is the importance of meiosis?

Answer 6

two gametes fuse to give rise to new offspring. when two gametes fuse at fertilisation, the diploid number of chromosomes is restored.

Question 7

what is the process of meiosis?

Answer 7

– first division - homologous chromosomes pair up and their chromatids wrap around each other. crossing over may happen.
– the chromatids move apart

Question 8

what are the ways genetic variation may happen?

Answer 8

– independent segregation
– crossing over

Question 9

describe independent segregation of homologous chromosomes

Answer 9

chromosomes line up alongside its homologous partner at random

Question 10

what are the events of crossing over?

Answer 10

– the chromatids of each pair become twisted around one another
– during this twisting process tensions are created and portions of the chromatids break off
– broken portions might then rejoin with the chromatids
– equivalent portions of homologous chromosomes are exchanged
– this way new genetic combinations of maternal and paternal alleles are produced

Question 11

describe genetic diversity

Answer 11

genetic similarities and differences between organisms may be defined in terms of variation in DNA

Question 12

describe the process of allele frequency

Answer 12

– gene pool in any species
– random mutation of alleles
– new allele may posses advantage
– better adapted
– more likely to survive and reproduce
– pass on allele
– carry on

Question 13

what is directional selection?

Answer 13

favour individuals that vary in one direction from the mean of the population

Question 14

what is stabilising selection?

Answer 14

favour average individuals