Populations and evolution

Question 1

What is the definition of genotype

Answer 1

-genotype is the genetic constitution of an organism

genotypes are the gene

Question 2

what is the phenotype

Answer 2

phenotype is the expression of this genetic constitution and its interaction with the environment.

phenotype is what we see ( how the genes express)

Question 3

what are alleles

Answer 3

different versions of the same gene

Question 4

what is meant by the term dominant

Answer 4

the dominant allele masks the effect of the other

Question 5

what is meant by the term codominant

Answer 5

both alleles are expressed so the phenotype is a combination of both alleles e.g. red and white alleles making pink phenotype

Question 6

what is meant by the term recessive

Answer 6

the recessive allele is masked by a dominant one

Question 7

what is meant by homozygous

Answer 7

both alleles at a specific gene locus are the same. could be homozygous recessive or dominant

Question 8

what is meant by the term heterozygous

Answer 8

the alleles at a specific gene locus are different

Question 9

what does monohybrid inheritance mean

Answer 9

the inheritance of a single gene e.g. plant height

Question 10

what does dihybrid inheritance mean

Answer 10

the inheritance of two separate genes

Question 11

what is meant by sex linkage

Answer 11

sex linkage is when an allele that codes for a characteristic is found on the sex chromosome. It is therefore inherited with the sex
e.g gene for colour vision, haemophilia

Question 12

what is meant by autosomal linkage

Answer 12

autosomal linkage is when two genes are found on the same chromosome they are therefore very likely to be inherited together

the closer two genes are, the more likely they are to be inherited together

Question 13

what is meant by multiple alleles

Answer 13

when there are more than two alleles

e.g. blood group A B O

Question 14

what is the formula for chi squared

Answer 14

(Observed-Expected)² /Expected

Question 15

what is meant by epistasis

Answer 15

the interaction of one gene upon another gene

Question 16

what is a population

Answer 16

group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed

Question 17

what is a gene pool

Answer 17

number of alleles within in a population

Question 18

what is the definition of allele frequency

Answer 18

the likelyhood of one allele being at a specific gene locus

Question 19

what is a species

Answer 19

a group of organisms that breed to make fertile offspring

Question 20

what is the hardy-weinberg equation

Answer 20

p² + 2pq + q²=1
p+q=1

p= the allele frequency of the dominant allele
q= the allele frequency of the recessive allele
p²= frequency of the homozygous dominant genotype 
q²= frequency of the homozygous recessive genotype
2pq= the frequency of heterozygous genotype

Question 21

what assumptions/ conditions does the population have to fulfil to be a Hardy weinberg population

Answer 21

no selection based on trait. e.g eye colour
no mutation
large population

Question 22

What is sympatric speciation

e.g. disruptive natural selection

Answer 22

• reproductive isolation within the same habitat
• mutation can cause genetic differences this is called DISRUPTIVE natural selection
• thus changes allele frequency and different alleles passed on
• this results in 2 separate species
• these different species can no longer interbreed

Question 23

What is Allopatric speciation

Answer 23

• where 2 populations become geographically isolated
• this prevents interbreeding
• environmental conditions in either side may change
• this causes natural selection and adaptions to new environment take place
• populations become different from one another to the point where they can no longer interbreed and become new species