Why are human females rarely haemophilic? Explain.  How do haemophilic patients suffer?

3

(a)

Recently a girl baby has been reported to suffer from haemophilia.  How is it possible? Explain with the help of a cross.

3

(a)

Name the phenomemon that leads to situations lie 'XO' abnormality in humans.  How do humans with 'XO' abnormality suffer? Explain.

3

(a)

Name a disorder, give the karyotupe and write the symptoms a human suffers from, as a result of monosomy of sex-chromosomes.

3

(a)

Name the genetic disorder caused by an extra 'X' chromosome in a human male.  State the diagnostic features of the individual suffering from it.

3

(a)

During his studies on genes in Drosophila that were sex-linked, T.H. Morgan found F₂ population phenotypid ratios deviated from the expected 9 : 3 : 3 : 1.  Explain the conclusion, he arrived at.

3

(a)

In a test cross, AaBb \(\times\) aabb, 90 percent of the progeny are like parents.  Determine.

(i) the progeny type for the rest of the population?

(ii) Are the genes linked?

(iii) Is there any crossing over of the genes?

3

(a)

In garden pea, smooth seed coat is dominant over wrinkled seed coat.  What will be the expected ratio of phenotypes of the offspring in a cross between:

(i) Heterozygous smooth \(\times\) Heterozygous smooth

(ii) Heterozygous smooth \(\times\) Homozygous wrinkled

(iii) Heterozygous smooth \(\times\) Homozygous smooth.

3

(a)

Work out a cross between red-eyed male Drosophila melanogaster fly and a white-eyed female.  Give the genotype and phenotype of the progeny.  What do you call this pattern of inheritance?

3

(a)

Explain the mechanism of sex-determination in honeybees.

3

(a)

What is the cause of phenylketonuria? Explain the disorder.

3

(a)

Differentiate between monosamy and trisomy.  Give an example of each from human genetics.

3

(a)

How are dominance, codominance and incomplete dominance patterns of inheritance different from each other?

3

(a)

In pea plants let symbol Y represent dominant yellow; symbol y, the recessive green; symbol R, the round seed shape and symbol r, the wrinkle seed shape. A typical Mendelian dihybrid cross was carried out in pea plants. Write the genotypes of :
(a) Homozygous dominant and recessive parents.
(b) Gametes produced by both the parents
(c) F₁ offspring
(d) Gametes produced by F}offspring

3

(a)

(a)Name the genetic disorder in a human female having 44 + XO karyotype. Mention the diagnostic features of the disorder
(b)Explain the cause of such chromosomal disorder.

3

(a)