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NUMERICAL PROBLEMS ON ICSE GENETICS 1. What type of children will appear in F1 generation if a colour blind man marries with a normal woman? Gene for colour blindness is Xc and gene for normal vision is Xc+. 2. Gene A is dominant over gene a. What will be the phenotypic ratio in the offspring obtained from the following mating?(a) Aa X aa. (b) Aa X AA. (c) Aa X Aa. 3. In humans pointed eyebrows is dominant over smooth eyebrows. Rahul s father has pointed eyebrows but he and his mother has smooth eyebrows. Predict the following:(a) Give the genotype of Rahul. (b) What will be the genotype of his father and mother? (c) If Rahul marries a woman who is heterozygous, what will be the possible genotype of the offspring in the next generation? State the % probability of having homozygous dominant, homozygous recessive and heterozygous dominant. 4. A haemophilic man marries a normal homozygous woman. What is the probability that their daughter will be haemophilic? 5. In a certain mammal curly hair is dominant over straight hair. In a cross between the two in the F 2 generation, three had curly hair and one had straight hair. (a) What would be the genotype of parents? (b) Work out the genetic cross. 6. A cross is made between Tall plant with Yellow seeds (TtYy) and a tall plant with green seeds (Ttyy). What proportion of phenotype would be expected in the offspring to be (a) Tall and green (b) Dwarf and green. 7. A man with AB blood group marries a woman of O blood group. Work out the possible genotype and phenotype of the progeny. 8. A heterozygous Smooth seeded and Red flowered pea plant is crossed with homozygous recessive rough seeded white flowered plant. Determine the progeny. 9. Ravi s parents have normal colour vision but his maternal grandfather is colourblind. Gene for colour vision is located on the X chromosome. (a) Work out a cross, showing the percentage of chances of Ravi and his siblings being colour blind. (b) What is the genotype of mother. (c) State the type of inheritance being shown in the above cross. 10. A haemophilic man marries a carrier woman. Obtain phenotypes of offspring using Punnett square.What is Y- linked inheritance? 11. A normal visioned woman marries a normal visioned man. They have a colour blind child.How can it be explained? Use Punnett square to substantiate your answer. 12. Some dogs bark while trailing while others are silent. The barking trait is due to dominant gene. Erect ears are dominant over drooping ears. What kind of puppies would be expected from the heterozygous erect eared barker mated to a droop silent trailer? 13. A man with blood group A marries a woman with B blood group. Find out the genotypes and the blood groups of their children, when (a) Both parents are heterozygous. (b) Both parents are homozygous. (c) Man is heterozygous and female is homozygous. (d) Man is homozygous and female is heterozygous. 14. Zicco s parents have normal colour vision but his maternal grandfather is colour-blind. Gene for colour vision is located on the X chromosome. (a) Work out a cross showing showing the percent chances of Zicco and his siblings being colour blind, normal or carrier. (b) What is the genotype of his maternal grandfather? 15. A haemophilic man marries a carrier woman. Find out the genotypes of the offspring. 16. Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
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