Topic 10 random

Question 1

unlinked genes

Answer 1

• genes located on different chromosomes
• they segregate independently in meiosis

Question 2

allele frequency definition

Answer 2

the proportion a particular allele within a population

Question 3

gene pool definition

Answer 3

represents the sum total of alleles present for all genes present in a sexually reproducing population

Question 4

a large gene pool indicates what?

Answer 4

high amounts of genetic diversity, increasing the chances of biological fitness & survival

Question 5

a small gene pool indicated what?

Answer 5

low amounts of genetic diversity, reducing biological fitness & increasing chances of extinction

Question 6

can gene pools be used to determine allele frequency?

Answer 6

yes

Question 7

what causes changes to allele frequencies in a gene pool?

Answer 7

• mutation
• gene flow
• sexual reproduction
• genetic drift
• natural selection

Question 8

evolution

Answer 8

the cumulative change in the heritable characteristics of a population across successful generations
- this requires that allele frequencies change within the gene pool of the population to reflect these evolving characteristics

Question 9

what is genetic drift?

Answer 9

the change in the composition of a gene pool as a result of chance or random events
- It will occur faster and be more significant in smaller populations, where chance events have a bigger impact on the gene pool

Question 10

what are the circumstances preventing interbreeding known as?

Answer 10

reproductive isolating mechanisms

Question 11

3 ways in which populations can be isolated to prevent reproduction

Answer 11

• temporal isolation
• behavioural isolation (only affects animals)
• geographic isolation

Question 12

Speciation

Answer 12

• an evolutionary process that results in the formation of a new species from pre-existing species
  
  • it occurs when reproductive isolating mechanisms prevent 2 breeding organisms from producing fertile, viable offspring

Question 13

2 basic mechanisms in which speciation may occur

Answer 13

• allotropic speciation
• sympatric speciation

Question 14

when does allotropic speciation occur?

Answer 14

when a geographical barrier physically isolates populations of an ancestral species
- the 2 species begin to evolve separately as a result of cumulative mutation, genetic drift, and natural selection
- eventually, the 2 populations reach a degree of genetic divergence whereby they can no longer interbreed (speciation)

Question 15

what promotes genetic variation?

Answer 15

crossing over (prophase 1), random orientation (metaphase 1), fusion of gametes from different parents (sexual reproduction)

Question 16

How does crossing over promote genetic variation?

Answer 16

during the lining up of homologous chromosomes, during this lining up, DNA sequences can be exchanged between the homologous chromosomes which allows the daughter cells to be genetically unique from one another

Question 17

when do cells become haploid?

Answer 17

after meiosis 1, they can no longer perform crossing over bc crossing over can only occur in homologous chromosomes

Question 18

crossing over occurs before bivalents are aligned along the equator

Answer 18

….

Question 19

what structures exchange genetic material during crossing over?

Answer 19

non sister chromatids of homologous chromosomes

Question 20

zygote

Answer 20

A diploid cell formed as a result of the fusion of two haploid gametes.

Question 21

what is meiosis

Answer 21

the process by which sex cells are made in the reproductive organisms