inheritance

Question 1

a recessive allele which has harmful effects is able to reach a higher frequency in a poulation than a harmful dominant allele- explain how

Answer 1

if it causes a lethal disease, then the person is less likely to survive to pass on the dominant allele. A harmful recessive allele in the heterozygous genotype will not be lethal so it can still be passed on, more likely the dominant one will be expressed and recessive will be carriers.

recessive alleles can be carried by individuals without showing any effects
carriers are more likely to reproduce
therefore recessive alleles are more likely to be passed on to a higher extent compared to dominant alleles.

Question 2

instead of saying they only have 1 x chromsome

Answer 2

thats unqualified

say they only posess 1 allele and the y chromosome does not carry an allele

Question 3

in genetic crosses suggest 2 reasons why the observed phenotypic ratios in offpsring are not the same as the expected ratios

Answer 3

as fertilisation is random

sample size is too small

Question 4

what if it says that a person had a disease caused by a recessive t and a recessive m, what is their genotype

Answer 4

ttmm

Question 5

9:3:3:1

Answer 5

9= double dominant
1= double recessive
3 and 3= mixxy uppy ones

Question 6

suggest how single stranded cDNAA could prevent the transcrip of a gene

Answer 6

it could bind to the mrna of that gene meaning that ribosomes cant bind

Question 7

what does the hardy weinberg principle predict

Answer 7

the proportion of alleles of a gene
and how it will stay constant from one gen to the next gen no genetic change
providing theres no mutations or selection or migration etc