1. Red-green colour blindness is caused by an X-linked recessive /6my7ol u y;ytallele. In the pedigree chart below which individuals must be carriers of tlm/tyy; u6 y7ohe red-green colour blindness allele?

  2. If the parents in the pedigree chart above had a fourth child who was fema7 m edu*sl4 u egk0n3*4 sdqb-lg45wvrle, what w*5l u 4sr dn w3lk4v*ge0su7mg bqe4-dould be the probability that she was colour blind?

  3. In Labrador dogs, black coat isw9*eu9owfz1zr (hdo 5 dominant over chocolate coat. The genotype of a black male labrador is unknown. How can the genotype of this black Labradou * owf 5w9zeor1zd9(hr be determined?

  4. Which of the following 1g5 l-c:a e.vh 8ltj 1tcafzy/wka63ubest defines the term, “gene”?

  5. Phenylketonuria (PKU) is c ,hexr,vt r(acz9eucn+(-c 4an inherited human disease caused by a recessive autosomal allele in a gene which codes for an enzyme needed to convert phenylalanine to tyrosine. The PKU allele produces uarcezc(x(e4 , cvnr+t c-h9,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 tyi+f0* s :0u/izlievhhe alleles, yellow or green, is dominant.

ii. Deduce the genotype of the okdbr y2 0nz-wx ,g,:p,n: fhjfffspring.

Iii. Construct a Punnet grid to show tv9 eoq .vxvdb-d kalb,09s96xhe cross between two offspring plants of the F1 gene. ldd-vb99x6 9xosaq kv0vb,eration.

Iv. Deduce the phenotypic *ws9jyctie+ww s4 ./xvf g7i-ratio for the offspring of the F1 cross.

7. Amand has a daughter with Padmavathi. Amand is blood group A, Pa9k1,i*lv2wk wyuk-o p dmavathi is blood group B, and their daughter is blood group O. They1uy iok,9pkk *w-vl2w are having a second child, a son.
Deduce the probability that their unborn son will be blood group O. Explain your working.

8. Explain how inherita f,b+kkxga0p fc87;dhxqcq+ .nce and environmental factors can interact in a phenotype to cause the appeara+8x . ;7 agbck0hfqpdk+fx, qcnce of human skin colour.

a. Deduce genotypes for the three coat co*ai* 2)qd, *st:kuqtn;kddfzlour 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 cow in theu s9+qfk etz:4b4k ozpl n*4+w 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 white coat, ld2ke t5bd4d v rt ;*c-l*5lwphorned b -tpell; *v t54wkd dldb2c5*rull.
Construct a Punnett square showing all possible phenotypes of the offspring.

10. The pedigree chart shows ABO blood group alleles and tmfr1geud8v60ab ; 4q8og8juk heir genotype for nail-patelvjgau e brm4g60 d18ofq;8u8kla syndrome, an inherited condition. The 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.