5.2

Question 1

Is variation always visible?

Answer 1

no because it is not always expressed in its phenotypes

Question 2

What are three causes of variation

Answer 2

mutation

meiosis

sexual reproduction

Question 3

what is a mutation

Answer 3

any change to the DNA sequence is classified as a mutation, it can range from a single base change to the removal of one segment of a chromosome.

Question 4

what is meiosis

Answer 4

produces games with unique combinations of alleles, thus increasing the genetic variation of individuals within the species

Question 5

what is sexual reproduction and random fertilization

Answer 5

the combination of gametes is random and results in a zygote that has genes from both of its parents

Question 6

what is the only way asexual species can increase variation

Answer 6

through mutation because they only produce identical genetic copies of themselves

Question 7

what are mutations

Answer 7

any change in the genome of an organism

Question 8

what are harmful mutations

Answer 8

those which cause a gene to not function properly or not to function at all

these are nonsense mutations

Question 9

what are non-sense mutations

Answer 9

harmful mutations

Question 10

what are missense mutations

Answer 10

they can cause variations which benefit the organisms by changing a codon that alters a protein

Question 11

what are silent mutations

Answer 11

those in which the codon still codes for the same amino acid so there is no actual change in the protein - have no effect on variation

Question 12

how does meiosis increase variation

Answer 12

it helps create new combinations of genes in the organism’s gametes through crossing over and independent assortment of chromosomes

Question 13

when does crossing over occur and where

Answer 13

on homologous chromosomes between non-sister chromatids during prophase 1

Question 14

when can natural selection occur

Answer 14

if there is variation among members of the same species

Question 15

name examples of adaptations that have arisen through natural selection

Answer 15

development of special hair structures in the fur coat of polar bears that insulate them from the intense cold and provide camouflage with the snow and ice

development of intricate and subtle forms of orchids to entice certain insects to pollinate them

Question 16

what is said about species when the more offspring they produce

Answer 16

the higher chance that there is some that will survive

Question 17

what is a consequence of overproduction of offspring

Answer 17

not all offspring will survive, there is a power struggle within the population and indirectly ensures that those individuals best adapted to the environment will survive. Struggles could include, finding food, hiding from predators,

Question 17

what is a consequence of overproduction of offspring

Answer 17

not all offspring will survive, there is a power struggle within the population and indirectly ensures that those individuals best adapted to the environment will survive. Struggles could include, finding food, hiding from predators,

Question 18

what does natural selection mean

Answer 18

only the best adapted will pass on their genes to the next generation, and has nothing to do with the acquired characteristics.

Question 19

Describe the pathway of evolution

Answer 19

a change occurs, not all individuals can cope and do not survive, well-adapted individuals do survive and can produce offspring, they have a different set of alleles from the non survivors and as a result the gene pool changes

Question 20

what is a change in the allele frequency in a gene pool known as

Answer 20

a genetic drift

Question 21

what is a genetic drift

Answer 21

a change in the allele frequency of a gene pool

Question 22

what decreases variation

Answer 22

natural selection as it can increase the allele frequency of the favored characteristic

Question 23

why did the Galapagos finches evolve

Answer 23

due to food availability and other selectional pressures from a variety of the different niches they occupied

Question 24

What did the Finches do

Answer 24

they evolved to adapt particular food sources available on their islands which changes their beaks.

This adaptive radiation allowed them to survive because of food specialization

Question 25

How did the Galapagos finches beaks change

Answer 25

their beak length increased while the black width decreased

Question 26

What are Methicillin and vancomycin

Answer 26

they are antibiotics used to treat various infections but resistance to them is growing among bacteria

Question 27

what bacteria is resistant to methicillin

Answer 27

methicillin-resistant staphylococcus aureus (MRSA or Golden staph)

Question 28

what bacteria is resistant to vancomycin

Answer 28

vancomycin-resistant Enterococcus (VRE)

Question 29

why has antibiotic resistance spread so widely and rapidly

Answer 29

1. bacterial generation times are short, ranging from 20 minutes to several hours, meaning evolution can progress rapidly
2. there has been widespread use of antibiotics in the general population and they do not finish a Course, leaving residual populations of bacteria in their system that have been exposed and are likely to have developed partial or full resistance.
3. Antibiotic resistance is often coded for by a gene located on plasmids
4. there is lots of selective pressure on bacteria in the hospitals as they treat so much with high doses of antibiotics.

Question 30

where are variations mostly present

Answer 30

in bacterial populations which leads to natural selection

Question 31

what happens when bacterial populations are exposed to antibiotics

Answer 31

bacterial mutations can occur leading to more variation within the population.

bacteria with variations that are resistant to the antibiotic are the most fit for their environment and will survive to pass on their resistant genes to their offspring or through plasmids. Those bacteria that are susceptible to the antibiotics will die. The allele for the antibiotic resistant characteristic will increase in frequency in the gene pool and the bacteria will become more resistant.

Question 32

what causes the struggle for survival. in populations

Answer 32

overproduction of offspring