Genetics questions | form six Biology

Albinism is an autosomal recessive genetic defect. The pedegree below shows the inheritance of the defect in a certain family.

1. i) State the number of all individuals who are definitely heterozygous for the gene controlling the defect 

          ii)What is the probabilty that individual 6 is heterozygous?

2. i) How is inheritance of Albinism similar and yet different from that of haemophilia?

          ii) Why are men more likely to be haemophiliacs than women?

Distinguish between sex determination and sex linkage

Define the following terms

1. Chromosomal mutation
2. Co-dominance
3. Polygenic inheritance

Albinism in human beings is caused by a recessive gene which is transmitted in Mendelian fashion.A couple which is phenotypically normal for skin pigmentation has four children. The first three have normal skin and the fourth is an albino.

1. What is the genotype of the parents?
2. What is the probability that the fifth child will be an albino?
3. One of the first three children marries a normal skinned woman. What predictions can you make regarding the skin of their first child ?
4. The albino child marries a normal skinned widow who had an albino child in her first marriage. What is the probabilty of this couple to produce a normal skinned child?

In man, the ability to roll the tongue into almost a complete cycle is determined by a dominant gene, while its recessive allele fails to produce this ability. A man and his wife and can both roll their tongues. They are suprised to find that their daughter cannot. Explain this by showing the genotypes of all three persons.

Discuss the role of isolating mechanisms in the formation of new species.

1. Mrs Lutu has two haemophiliac sons and two normal sons. What is her genotype and that of her husband with respect to this gene? Explain your answer.
2. Giving reasons explain whether Mrs Lutu could have a haemophiliac daughter.

1. Mrs Lutu has two haemophiliac sons and two normal sons. What is her genotype and that of her husband with respect to this gene? Explain your answer.
2. Giving reasons explain whether Mrs Lutu could have a haemophiliac daughter.

1. Explain how the formation of messenger ribonucleic acid takes place during protein synthesis.
2. (i) Identify three types of ribonucleic acids.
   (ii) Describe the structure and location of the types of ribonucleic acids identified in 6(b)(i). (Diagrams are not required).

Describe the disorders given below and show clearly their modes of inheritance

1. Haemophilia
2. Albinism