Class 12/Question Bank/Competency Based
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
BioNotesBioNotesCreated by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Online
Competency Based Questions on Principles of Inheritance
1. Analyze the Pedigree: A male has a rare genetic disorder. He marries a healthy female. All their daughters are affected, but none of their sons are affected. What is the most likely mode of inheritance? a) Autosomal Dominant b) X-linked Dominant c) X-linked Recessive d) Y-linked
2. Predict the Outcome: In a cross between AABB and aabb, the F1 progeny is AaBb. If the genes are completely linked (0% recombination), what will be the phenotypic ratio of the F2 generation? a) 9:3:3:1 b) 1:1:1:1 c) 3:1 d) 1:2:1
3. Assertion (A): Sickle-cell anaemia is an example of a point mutation. Reason (R): It involves the substitution of Glutamic acid by Valine at the 6th position of the beta-globin chain. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true.
4. Evaluate: A couple, both carriers for Thalassemia (minor), want to know the risk of having a child with Thalassemia major. What is the probability? a) 100% b) 50% c) 25% d) 0%
5. Calculate: In a population of 100 individuals, 16 are homozygous recessive (aa). According to Hardy-Weinberg equilibrium, what is the frequency of the heterozygous (Aa) individuals? a) 0.48 b) 0.36 c) 0.16 d) 0.60
6. Analyze the blood group: A child has blood group 'O'. The father has blood group 'A' and the mother has blood group 'B'. What are the genotypes of the parents? a) , b) , c) , d) ,
7. Identify the Phenomenon: In Mirabilis jalapa, crossing a red-flowered plant with a white-flowered plant yields pink-flowered offspring. This is due to: a) Codominance b) Incomplete Dominance c) Epistasis d) Pleiotropy
8. Assertion (A): Frequency of crossing over between two genes is directly proportional to the physical distance between them. Reason (R): Genes located farther apart on a chromosome are more likely to undergo recombination. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true.
9. Clinical correlation: A sterile female with a webbed neck, short stature, and karyotype 45,XO is diagnosed with: a) Down's Syndrome b) Klinefelter's Syndrome c) Turner's Syndrome d) Edwards Syndrome
10. Analyze: Why does color blindness occur more frequently in males than in females? a) The gene is on the Y chromosome. b) Males have only one X chromosome, so a single recessive allele is expressed. c) Females have a stronger immune system against the defect. d) Males have higher testosterone levels affecting vision.
11. Differentiate: Which of the following differentiates Polygenic Inheritance from Pleiotropy? a) Polygenic: One gene -> Many traits; Pleiotropy: Many genes -> One trait. b) Polygenic: Many genes -> One trait; Pleiotropy: One gene -> Many traits. c) Polygenic involves blending; Pleiotropy involves dominance. d) Polygenic is qualitative; Pleiotropy is quantitative.
12. Assertion (A): In Honeybees, females are diploid (32 chromosomes) and males are haploid (16 chromosomes). Reason (R): Males develop parthenogenetically from unfertilized eggs. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true.
13. Map the genes: If recombination between A-B is 20%, B-C is 15%, and A-C is 35%, what is the order? a) A-C-B b) A-B-C c) B-A-C d) C-A-B
14. Identify the chromosomal disorder: A karyotype shows 47, XX, +21. The individual has a broad palm with a simian crease and mental retardation. a) Patau Syndrome b) Down's Syndrome c) Turner's Syndrome d) Cri-du-chat Syndrome
15. Reasoning: In T.H. Morgan's experiment on Drosophila, why did the 'white eye' and 'yellow body' genes show very low recombination (1.3%)? a) The genes were tightly linked. b) The genes were on different chromosomes. c) Mutation rates were high. d) Environment.
Haemophilia is a sex-linked recessive disorder where blood fails to clot.
16. Analyze: If a carrier female marries a normal male, what is the probability of their sons being haemophilic? a) 0% b) 25% c) 50% d) 100%
17. Explain: Why is it rare to find a female with haemophilia?
18. Contrast: Difference between Haemophilia and Thalassemia?
A gardener crosses pure red and pure white snapdragons. All F1 are pink.
19. Identify: The phenotypic ratio in F2?
20. Interpret: Does this disprove Mendel's Law of Segregation?
Morgan crossed yellow-bodied, white-eyed females with wild-type males.
21. Deduce: Why did the ratio deviate from 9:3:3:1?
22. Define: Physical association of genes on a chromosome is called Linkage.
23. Designing a Cross: Determine if a tall plant is TT or Tt.
24. Formulating a Hypothesis: Industrial Melanism.
25. Creating a Pedigree: Autosomal Dominant disorder.
26. Visualizing Development: Sickle Cell hemoglobin.
27. Analyzing Complexity: Skin color is polygenic.
28. Debating Ethics: Embryo selection (PGD).
29. Solving a Genetic Puzzle: Group A man + Group B woman = Group O daughter.
30. Concept Map: