Unit 4

Question 1

Evolution

Answer 1

Change in gene and allele frequencies within a population or species

Question 2

Genetic drift

Answer 2

When populations are small chance can change allele frequencies, can lead to a fixation of alleles. Change in a population resulting in chance

Question 3

Bottleneck effect

Answer 3

When a severe event results in a drastic reduction in numbers. Very small sample alleles survives to establish a new population

Question 4

Founder effect

Answer 4

When a few individuals from a large population leave to establish a new population, the allele frequency of the new population will not be the same as the original population

Question 5

Gene flow

Answer 5

When organisms migrate leaving one population and joining another, they alter the gene frequency of both. Tens to reduce differences. Genetic information is shared

Question 6

Key factors in a change to a gene pool

Answer 6

1) Small population: Chance
2) Nonrandom mating: Preferred individuals pass on some alleles in greater numbers then others
3) Genetic mutations: New alleles are created or alleles are changed
4) Migration: Removes allied from the population
5) Natural selection: Individuals within certain alleles have greater reproductive success than others increasing the relative frequency of their alleles. Can be results of diseases, climate, food, availability, predators, mating preferences

Question 7

Mutations

Answer 7

Point: Changes in a single base pair of DNA
Small insertion and deletions: Produce non functioning harmful genes
Large scale inversions: Often neutral, a tool for biologists
Gene duplications: Unequal crossing over during meiosis results in an additional copy of one or more genes being inserted into a chromosome
Pseudogenes: Duplicated- loose their ability to transcribe

Question 8

Polypoid

Answer 8

Mutation that results in 3 or more sets of chromosomes when diploid gametes join to form a cell containing one or more entire sets of chromosomes

Question 9

Cuvier

Answer 9

Theory- catastrophism. Stated that local catastrophes could cause extinction, extinct forms are then replaced by different migrating species. Determined relative age of fossils

Question 10

Radiometric dating

Answer 10

Calculation of the age through the measurement of the decay of radio isotopes (atoms with unstable nuclear nuclear arrangement that undergoes radioactive decay) in the sample

Question 11

Directional selection

Answer 11

Environments favours individual with more extreme variables of a trait

Question 12

Stabilization selection

Answer 12

Environment favours most common phone type

Question 13

Disruptive selection

Answer 13

Favours individuals with opposite extreme traits

Question 14

Sexual selection

Answer 14

Favours the selection of any trait that influences the mating success of an individual (usually male)

Question 15

Cumulative selection

Answer 15

Evolution of a complex structure in a process

Question 16

Altruistic selection

Answer 16

Increase the fitness of the recipient yet decrease the fitness of the giver. This concerned Darwin

Question 17

Kin selection

Answer 17

Explains the altruistic behaviours of closely related individuals

Question 18

Darwin’s theory

Answer 18

If a population contains variation and if the variation is at least partly heritable and if some variants survive to reproduce at higher rates than others the population will evolve

Question 19

Species

Answer 19

Includes members pf groups or populations that interbreed

Question 20

Microevolution

Answer 20

Evolution that occurs at species level

Question 21

Reproductive isolating mechanisms

Answer 21

Anything that prevents species from reproducing successfully

Question 22

Pre zygotic mechanism

Answer 22

Prevents fertilization. Can be ecological, temporal or behavioural isolation

Question 23

Prevention of fertilization

Answer 23

Mechanical- Structural differences in reproductive organisms
Gametic- prevents fertilization at molecular level