definitions of natural selection

Question 1

what is species

Answer 1

the basic unit of biological classification, members of a species are capable of interbreeding and producing fertile offspring

Question 2

what is gene pool

Answer 2

the sum of all the alleles carried by the members of a population

Question 3

what is mutation

Answer 3

a change in a gene or chromosome leading to a new characteristic in an organism

Question 4

what is allele frequencies

Answer 4

how often each allele of a gene occurs

Question 5

what is natural selection

Answer 5

the process by which a species becomes better adapted to its environment, those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations

Question 6

what is random genetic drift

Answer 6

the occurrence of characteristics in a population as a result of chance rather than natural selection occurs only in small populations,

also called genetic drift or seawall wright effect

Question 7

what is gene flow

Answer 7

the transfer of alleles from one population to another through migration

Question 8

what is speciation

Answer 8

the process of new species developing

Question 9

what is selective agent

Answer 9

any factor that causes the death of organisms with certain characteristic, but which has no effect on individuals without those characteristic

Question 10

what is natural selection?

Answer 10

refers to the process by which a species becomes better adapted to its environment, those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations.

Question 11

what is the heterozygote advantage that tay sachs is believed to provide?

Answer 11

increases the percentage of the recessive allele in the gene pools in areas affected by tuberculosis

resistance to tuberculosis

Question 12

founder effect

Answer 12

a type of genetic drift where a small number of individuals forms a new population, the small sample size can cause marked deviations in allele frequencies from the original population

Question 13

bottleneck effect

Answer 13

an extreme form of genetic drift that occurs when the size of a population is severely reduced due to a sudden event such as a natural disaster. the allele frequency of survivors may not reflect that of the original population

Question 14

what is the difference between gene mutations and chromosomal mutations

Answer 14

Gene mutations only affect one gene small section of DNA

Chromosomal mutations affect more than one gene/part of a chromosome/whole chromosome

Question 15

how do mutagens produce mutations

Answer 15

Substances that are known to increase the (rate of) changes to DNA

e.g Includes ionising radiation/mustard gas/some antibiotics/formaldehyde

Question 16

how do DNA replication produce mutations

Answer 16

Errors during the process that alter DNA code

e.g Can be deleting/duplicating/insertions/frameshifts of DNA

Question 17

how do cell divisions produce mutations

Answer 17

Errors during the process that alter the genes or chromosomes in daughter cells formed

e.g Can be non-disjunction/translocation/inversions of DNA

Question 18

isotope

Answer 18

one of two or more atoms of the same element with the same atomic number and number of protons, but different numbers of neautrons

Question 19

half life

Answer 19

the time required for half of any quantity of radioactive material to decay into stable non-radioactive material

Question 20

radioactive decay

Answer 20

occasionally the unstable isotope will change its number of protons, neutrons, or both. This change is called radioactive decay.