inheritance and population

Question 1

genotype

Answer 1

genetic constitution of organism

Question 2

phenotype

Answer 2

expression of genetic constitution and interaction with the environment

Question 3

allele and how does it arise

Answer 3

variation of particular gene
arise by mutation

Question 4

homozygous

Answer 4

alleles at specific locus on each HC are the same

Question 5

Monohybrid cross

Answer 5

inheritance of one phenotypic characteristic coded for by a single gene

Question 6

dihybrid

Answer 6

inheritance of two phenotypic characterises
coded for by 2 Dif genes

Question 7

how does autosomal linkage affect allele inheritance

Answer 7

● Two genes located on same autosome (non-sex chromosome)
● So alleles on same chromosome inherited together
○ Stay together during independent segregation of homologous chromosomes during meiosis
● But crossing over between homologous chromosomes can create new combinations of alleles
○ If the genes are closer together on an autosome, they are less likely to be split by crossing over

Question 8

Suggest why in genetic crosses, the observed phenotypic ratios obtained in
the offspring are often not the same as the expected ratios

Answer 8

fertilisation of gametes is random
● Autosomal linkage epistasis sex-linkage
● Small sample size → not representative of whole population
● Some genotypes may be lethal

Question 9

population

Answer 9

group of organisms of same species in one are and one time that can interbreed

Question 10

gene pool

Answer 10

all alleles of genes in a population at any one time

Question 11

What does the Hardy-Weinberg principle state and what are the conditions
under which the principle applies?

Answer 11

Allele frequencies will not change from generation to generation, given:
○ Population is large
○ No immigration / emigration
○ No mutations (to create new alleles)
○ No selection for / against particular alleles
○ Mating is random

Question 12

What is the Hardy-Weinberg equation?

Answer 12

● p = frequency of one (usually dominant) allele of the gene
● q = frequency of the other (usually recessive) allele of the gene
● p2 = frequency of homozygous (usually dominant) genotype
● 2pq = frequency of heterozygous genotype
● q2 = frequency of homozygous (usually recessive) genotype
p+q=1
p^2 + 2pq +q^2 = 1