9 - Genetic Diversity and Adaptation

Question 1

mutation

Answer 1

any change to the base sequence or quantity of the DNA of an organism

Question 2

haploid

Answer 2

contains a single copy of each chromosome (one of each homologous pair)

Question 3

diploid

Answer 3

full set of chromosomes (both chromosomes of a homologous pair)

Question 4

process of meiosis

Answer 4

homologous pairs line up
crossing over occurs
pairs are separated and the cell divides
daughter cells containing one set of each homologous pair are formed
each of the daughter cells undergoes another division where the chromatids of each chromosome are pulled apart
4 genetically different daughter cells are formed

Question 5

how meiosis brings about genetic variation

Answer 5

independent segregation of homologous chromosomes

forming new combinations of maternal and paternal alleles through crossing over

Question 6

process of crossing over

Answer 6

chromatids of a homologous pair become twisted around each other as they line up
tensions are created and portions of the chromatids break off
broken portions may rejoin with the chromatids of its homologous partner (RECOMBINATION)
usually equivalent portions of homologous chromosome exchanged

Question 7

possible number of combinations of chromosomes for each daughter cell

Answer 7

2^n

n = number of homologous pairs

Question 8

possible number of chromosome combinations produced from the fertilisation of 2 gametes

Answer 8

(2^n)^2

n = number of homologous pairs

Question 9

genetic variation

Answer 9

number of different alleles of a gene in a population

Question 10

natural selection

Answer 10

1. random mutation can result in new alleles of a gene
2. many mutations are harmful, but in certain environments it may be beneficial to its possessor
3. leads to increased reproductive success
4. advantageous allele is passed onto offspring
5. over many generations, frequency of new allele in the population increases