1. Red-green colour blindnew9bsf.v mb:,q(3hudgfgj 5,k ss is caused by an X-linked recessive allele. In the pedigree chart below which individuals must be carriers of the red-ggdmgfu5, h9wvj, s3 :( .bqkfbreen colour blindness allele?

  2. If the parents in the pedi6 nxj*o hnbk -laq:v/y,.veq /gree chart above had a fourth child who was female, what would be the pr*lov:-akq .eqy/nj,xn bh6/v obability that she was colour blind?

  3. In Labrador dogs, black coat is dominant over chocolate coat. The gei.6/sj tjwwe 0notype of a black male labrador is unknown. How can the genotype of ts6wtej. jwi/ 0his black Labrador be determined?

  4. Which of the followigs2, vz +*msvrng best defines the term, “gene”?

  5. Phenylketonuria (PKU) is an inherited human dm9)0od0qdd lrisease caused by a recessive autosomal allele in a gene which codes for an enzyme needed to convert phenylalanine to tyrosine. The PKU allele prdq m 9do0)0lrdoduces a non-functional enzyme.
Which of the following statements are correct?
I. Two parents heterozygous for the condition could have a child with PKU.
II. If the mother of the child is homozygous and not affected by PKU, her children will not be affected.
III. The polypeptide sequence of the enzyme of an affected person is identical to a person without the condition.
IV. Two parents who are not affected with PKU cannot have a child with the disorder.

I. Identify which of the alleles, yellow or green,,p nj)jdg 1t8s is dominant.

ii. Deduce the genotype -o2 l +e)wpsraof the offspring.

Iii. Construct a Punnet grid to sr u565giqg2 oi* dob)qhow the cross between two offspring plants of the F1 generatiod2o q556 )ogigq*ruibn.

Iv. Deduce the phenotypicc nj f2, i*redmk4gj9(wh0o,a;ph28 eq,w x gm ratio for the offspring of the F1 cross.

7. Amand has a daughter with Pad) qsxu)i8p pd;7 vv+inmavathi. Amand is blood group A, Padmavathi is blood group B, and their daughter is blood group O. They arn)i8pp7iuvq ) d x;vs+e having a second child, a son.
Deduce the probability that their unborn son will be blood group O. Explain your working.

8. Explain how inheritance and environmental factors can interact in a phenos )8b6t; kj yi(awayn*type to cause the appearances;6w yb )*nj8aiyta k( of human skin colour.

a. Deduce genotypes for the three coasbf ow)y*bo *-(zy;r(ey .mcgt colour phenotypes in these cattle.
Use the symbols $C^W$ for the white coat allele, and $C^R$for red coat allele.

b. Deduce the parental genotypes of the cownk 5p)kphjk )lj5:hf) in the image.
Use P for the allele for polled and p for the allele for horns.

c. The roan colour, polled cow in the image is mated with a wcx/,5kyebn+fyze3g: d:;l i ghite coat, horned bulb; +cl:ngde y y:k5e3g,zx/ifl.
Construct a Punnett square showing all possible phenotypes of the offspring.

10. The pedigree chart shob 1 ;85sdxn27 )l.egb lzrxxpows ABO blood group alleles and their genotype for nail-patella syndrome, an inherited condition. Tp b ;r2xd 1 .l58s7xeblxno)zghe individuals 1, 3, and 4 in row III are recombinants. Image by D.B. Pylypiv.

Use the pedigree chart to explain the meaning of gene linkage.