CLASS – XII
Biology Worksheet
Principles of inheritance
1. Turner’s syndrome is a sterile female generally with normal intelligence and known viable
monosony in humans. Is the combination ‘44+YO’ is also viable. Justify?
2. The genetic disorders can be grouped under two broad categories- Mendelian disorders and chromosomal disorders which one of two can be traced in a family by pedigree chart? Name two such disorders.
3. . What are three allelic forms of gene”I” responsible for blood groups in human and the different phenotypes
4. . A relevant portion of b-chain of haemoglobin of a normal human is given below:
The codon for the sixth amino acid is GAG. This codon mutates to GAA as a result of mutation ‘A’ and into GUG as a result of mutation ‘B’. Haemoglobin structure did not change as a result of mutation A ahereas it changed in mutation B leading to sickle shaped RBCs. Explain giving reason how could mutation B change the structure and not mutation A.
5. .In a pedigree chart, show the inheritance of colour blindness in three generation
6. Describe linkage of genes with the help of dihybrid cross
7. .Predict genotypic and phenotypic ratio in dihybrid test cross of kittens with black hair and eyes
8. Why are females blamed for birth of male child? Do you support it ? Give reasons for your answer
9. If two genes are located far apart from each other on a chromosome, how will the frequency of recombination will affected?
a) Increase b) Decrease c) Remain unaffected d) None of the above
10. How many kinds of phenotypes would you expect in F2 generation in a monohybrid cross exhibiting incomplete -dominance?
11. What are the 2 major similarities between behavior of chromosomes and genes
12. A colourblind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.
13. A) Draw a pedigree chart of a family consisting of the following members, age given Within brackets: - father [80] is normal, mother [75] is a carrier, one son [42] is Normal, second son [27] is affected (sufferer). One daughter (33) is normal (non - Carrier), second daughter (30) is carrier. Draw a pedigree chart .What conclusion can be drawn from analysis of above mentioned pedigree chart?
b)If no daughter in the above family could be born as affected for this trait , work out in a punnet square to find out if this trait could be albinism and conclude by saying yes or no .Give reasons for your answer [You can use the letters ‘A’ and ‘a’ for the dominant and recessive allele of this gene respectively )
14. Which Mendel’s law of inheritance is universally acceptable and without any exception? State the law.
