inherited change

Question 1

what is the definition for genotype

Answer 1

genetic constitution of an organism ( the alleles it has)

Question 2

what is the definition for phenotype

Answer 2

the expression of the genetic constitution

Question 3

what is the defintion for recessive allele

Answer 3

an allele only expressed if no dominant allele is expressed

Question 4

what is the definition for dominant allele

Answer 4

an allele that will always be expressed in the phenotype

Question 5

what is the definition for codominant

Answer 5

both alleles are equally dominant and expressed in the phenotype

Question 6

what is the definition for multiple alleles

Answer 6

more than two alleles for a single gene

Question 7

what is the definition for sex linkage

Answer 7

a gene whose locus is on the X chromosome

Question 8

what is the definition for autosomal linkage

Answer 8

different genes that are located on the same chromosome

Question 9

epistasis definition

Answer 9

when one gene modifies or masks the expression of a different gene on a different locus

Question 10

monohybrid definition

Answer 10

genetic inheritance cross of a characteristic determined by one gene

Question 11

dihybrid definition

Answer 11

genetic inheritance cross for a characteristic determined by two genes

Question 12

what can also alter a persons phenotype

Answer 12

the enviroment

Question 13

what phenotypic ratio will you always get in a dihybrid cross with heterozygous parents for both genes

Answer 13

9:3:3:1

Question 14

when does this ratio change

Answer 14

• crossing over in meiosis
  -autosomal linkage
  -epistasis

Question 15

what does autosomal linkage mean

Answer 15

both genes will be inherited together

Question 16

what is the new ratio in a dihybrid cross with autosomal linkage for heterozygous parents

Answer 16

3:1

Question 17

what is the null hypothesis for chi squared

Answer 17

there is no significant difference between the expected and observed frequency of X phenotype

Question 18

how do you conclude for chi squared

Answer 18

• if our calculated value is less than the criritcal value at 0.05 then
• more than 5% probability that the results are due to chance
  -accept the null hypothesis
• there is no significant difference between the expected vs observed

if our calculated value is more than the value at 0.05 critical value
- there is a less than 5% probability the difference between observed vs expected due to chance and we can reject the null hypothesis and there is a significant difference between the expected vs observed

Question 19

what is the other format you can get for chi squared exam questions

Answer 19

-sometimes you are given a table which is just a p value and the change
- for this if the p value is <0.05 this means there is less than 5% probability the change is due to chance and we reject the null hypothesis

Question 20

what is meant by the term phenotype

Answer 20

phenotype is the characteristic from the genetic constitution of alleles and the characteristic due to enviroment

Question 21

what is the hardy weinberg pricniple

Answer 21

The proportion/frequency of alleles

2. Will stay constant from 1 generation to the next
3. Providing there’s : NO mutation / NO selection / the population’s large / pop. genetically isolated / mating is random

Question 22

what are the two equations used for the hardy weinberg principle

Answer 22

p + q = 1
- where p is the frequency of the dominant allele
- where q is the frequency of the recessive allele

P2 + 2PQ + Q2 = 1
- where P2 is the frequency of the homozygous dominant genotype
- where Q2 is the frequency of the homozygous recessive genotype
- where 2PQ is the frequency of the heterozygous genotype

Question 23

what must you remember and look out for in hardy Weinberg principle questions

Answer 23

• what the question is looking for , is it looking for the frequency of the allele or the frequency of the genotype
• never divide 2PQ by 2 it stays as 2 ( think of a genetic cross diagram - 2x probability of heterozygous )

Question 24

what are the assumptions of the hardy Weinberg principle

Answer 24

• no selection occurs
• no mutations so no new alleles formed
• no migration / immigration
• large population
• random mating
• questions may ask if the hardy Weinberg principle stands for these points , eg if there is a small population size then the principle will not stand

Question 25

what is a selection pressure

Answer 25

a selection pressure determines which traits are successful

Question 26

what is disruptive selection

Answer 26

selection pressure towards the extremes , creating two modal values

this selection forms speciation as you evolve 2 seperate populations

Question 27

what is stabilising selection

Answer 27

selection pressure towards the centre increases the number of individuals at the modal value - extremes are selected against

Question 28

what is directional selection

Answer 28

selection pressure toward one extreme moves the mode in this direction

• causes evolution

Question 29

what is intraspecific competition

Answer 29

intraspecific competition is competition within a species for the same resources

Question 30

what is interspecific competition

Answer 30

interspecific competition is when organisms of different species compete with eachother for the same resources

Question 31

what are the downsides of interspecific competition

Answer 31

population sizes of both can decrease as there might be less energy for growth and reproduction . it can mean the resources available for both species decreases but sometimes one species will out compete another