Principles of Inheritance & Variation – Mendel, Multiple Alleles, Polygenic, Chromosomal Theory Quiz - ICSE Class 12 Biology

Free practice quiz: Principles of Inheritance & Variation – Mendel, Multiple Alleles, Polygenic, Chromosomal Theory (ICSE Class 12 Biology). 116 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 12 Biology practice quiz has 116 multiple-choice questions on Principles of Inheritance & Variation – Mendel, Multiple Alleles, Polygenic, Chromosomal Theory, and 116 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. In a dihybrid cross between two heterozygous parents for two independently assorting genes, what is the phenotypic ratio of the offspring if incomplete dominance is observed at both loci?

   1. 9:3:3:1
   2. 1:2:1:2:4:2:1:2:1
   3. 3:1
   4. 1:1:1:1
   Show answer

   Answer: B. 1:2:1:2:4:2:1:2:1

   When incomplete dominance occurs at two loci for independently assorting genes, the phenotypic ratio for each gene is 1:2:1. To find the combined phenotypic ratio for both genes, we multiply the individual ratios. (1:2:1) x (1:2:1) = 1(AABB) : 2(AABb) : 1(AAbb) : 2(AaBB) : 4(AaBb) : 2(Aabb) : 1(aaBB) : 2(aaBb) : 1(aabb). This expands to the genotypic classes which, with incomplete dominance, directly correspond to distinct phenotypes.

2. If a chromosome undergoes a deletion, the result is:

   1. A loss of genetic material.
   2. A change in the position of a chromosome segment.
   3. A repetition of genetic material.
   4. A reversal of a chromosome segment.
   Show answer

   Answer: A. A loss of genetic material.

   A deletion is a type of chromosomal mutation where a segment of a chromosome is lost or removed. This results in a net loss of genetic material. Translocation involves the movement of a segment to a non-homologous chromosome. Inversion involves reattachment in reverse order. Duplication involves repetition of a segment.

3. A chromosomal mutation where a segment of a chromosome is lost is called:

   1. Inversion
   2. Duplication
   3. Translocation
   4. Deletion
   Show answer

   Answer: D. Deletion

   A deletion is a chromosomal mutation that results in the loss of a segment of a chromosome and, therefore, the loss of genetic material. Inversion involves a reversal of a segment within the same chromosome. Duplication is the repetition of a chromosome segment. Translocation involves the movement of a chromosome segment to a non-homologous chromosome.

4. Which of the following is a characteristic of quantitative traits?

   1. They are determined by a single gene with two alleles.
   2. They show discrete, distinct phenotypic categories.
   3. They are influenced by multiple genes and environmental factors.
   4. They always exhibit complete dominance.
   Show answer

   Answer: C. They are influenced by multiple genes and environmental factors.

   Quantitative traits, such as height, weight, or skin color, are influenced by the additive effects of multiple genes (polygenes) and often by environmental factors. This results in a continuous variation of phenotypes, rather than discrete categories. Traits determined by a single gene are typically Mendelian and show distinct categories.

5. In a population in Hardy-Weinberg equilibrium, if the frequency of the allele 'A' is 0.4, what is the frequency of the homozygous recessive genotype 'aa'?

   1. 0.16
   2. 0.36
   3. 0.48
   4. 0.64
   Show answer

   Answer: B. 0.36

   In Hardy-Weinberg equilibrium, if the frequency of the dominant allele 'A' (p) is 0.4, then the frequency of the recessive allele 'a' (q) is p + q = 1. So, q = 1 - p = 1 - 0.4 = 0.6. The frequency of the homozygous recessive genotype 'aa' is represented by q^2. Therefore, the frequency of 'aa' is (0.6)^2 = 0.36.

More questions in this quiz

Answers and explanations are in the full quiz.

1. A human ABO blood group locus has alleles I^A, I^B, and i. If a woman with blood group AB and a man with blood group O have children, what is the probability that their child will have blood group B?
2. Which of the following statements about chromosomal abnormalities is INCORRECT?
3. In a population exhibiting a quantitative trait influenced by three independently assorting genes, each with two additive alleles (e.g., A/a, B/b, C/c), what is the maximum number of distinct phenotypic classes that can be observed if the contribution of each additive allele is equal?
4. Consider a scenario where eye color in a certain insect is determined by a single gene with three alleles: C1 (red), C2 (pink), and C3 (white). C1 exhibits complete dominance over C2 and C3, and C2 exhibits incomplete dominance over C3. What would be the phenotypic ratio if a cross is made between a heterozygote C1C2 and a heterozygote C2C3?
5. Which of the following is characteristic of a quantitative trait controlled by multiple genes (polygenic inheritance)?
6. In humans, the gene for albinism is inherited as an autosomal recessive trait (aa). The ABO blood group system is determined by multiple alleles (I^A, I^B, i). If a man who is heterozygous for albinism and has blood group AB marries a woman who is homozygous dominant for normal pigmentation and has blood group O, what is the probability that their child will be an albino with blood group A?
7. A specific mutation causes a delay in the completion of meiosis I in a certain organism. If this mutation affects approximately 5% of the sperm produced by an affected male, what is the likely consequence for the resulting offspring, assuming normal meiosis II?
8. In a population of butterflies, wing color is determined by three genes (A/a, B/b, C/c) that interact epistatically. Gene A controls the production of pigment precursor, Gene B controls its conversion to pigment, and Gene C controls its deposition. If the epistatic interaction is such that the absence of pigment precursor (genotype aa) masks the effect of genes B and C, and the absence of pigment conversion (genotype bb) masks the deposition of pigment, what is the expected phenotypic ratio for a cross between two triply heterozygous butterflies (AaBbCc x AaBbCc)? Assume a dominant epistatic interaction where A_ is required for pigment, and B_ is required for color development, and C_ for specific color.
9. Which of the following statements best describes the role of the chromosomal theory of inheritance?
10. A plant species exhibits quantitative inheritance for height, controlled by two independently assorting genes (H1/h1 and H2/h2), where each dominant allele (H1, H2) contributes additively to height. The shortest plant has genotype h1h1h2h2 and the tallest plant has genotype H1H1H2H2. If the shortest plant is 10 cm tall and the tallest plant is 30 cm tall, what would be the expected height of a plant with genotype H1h1H2h2?
11. In a population with multiple alleles for a gene, if the allele frequencies are p, q, and r for alleles A1, A2, and A3 respectively, under Hardy-Weinberg equilibrium, what would be the genotype frequencies?
12. A specific type of chromosomal mutation involves the breakage of a chromosome segment, followed by its reattachment in the reverse order. This type of mutation is known as:
13. In a population that is in Hardy-Weinberg equilibrium, the frequency of the recessive allele 'a' for a certain trait is 0.3. What is the frequency of individuals who are heterozygous carriers of this trait?
14. Which of the following scenarios is most likely to lead to aneuploidy in offspring?
15. If a trait is controlled by two genes (A/a and B/b) where gene A exhibits complete dominance over a and gene B exhibits incomplete dominance over b, and the genes assort independently, what would be the phenotypic ratio in a cross of AaBb x AaBb if the phenotypes are: A_B1B1 (Red), A_B1B2 (Pink), A_B2B2 (White), and aa_ (any genotype) is always Black?
16. Somatic mosaicism refers to:
17. Consider a gene with three alleles: I^A, I^B, and i. If in a population, the frequency of I^A is 0.3, I^B is 0.4, and i is 0.3, and the population is in Hardy-Weinberg equilibrium, what is the expected frequency of individuals with blood group AB?
18. Which of the following is a consequence of nondisjunction of homologous chromosomes during meiosis I in males?
19. In a dihybrid cross involving two independently assorting genes, where complete dominance is observed for both genes, what is the phenotypic ratio of offspring exhibiting at least one dominant trait?
20. Which of the following chromosomal abnormalities is most commonly associated with the development of certain cancers, particularly leukemia?
21. If a gene exhibits multiple alleles, and an individual is heterozygous for two of these alleles, what is the maximum number of different types of gametes that can be produced by this individual with respect to this gene locus?
22. Which of the following best describes the outcome of a cross between two pea plants heterozygous for a single gene controlling seed color, where yellow (Y) is dominant over green (y)?
23. In a population of 1000 individuals, 100 are homozygous for the recessive allele 'a' (aa). Assuming Hardy-Weinberg equilibrium, what is the frequency of the dominant allele 'A' in this population?
24. Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?
25. If an individual has genotype I^A I^A for the ABO blood group system, what is their phenotype?
26. Which statement best describes the phenomenon of polyploidy?
27. In Mendelian inheritance, the principle of segregation states that:
28. What is the expected genotypic ratio of offspring from a cross between two individuals heterozygous for a single gene with incomplete dominance (e.g., Rr x Rr, where R1R1 is red, R1R2 is pink, R2R2 is white)?
29. A chromosomal rearrangement where a segment of one chromosome breaks off and attaches to another non-homologous chromosome is called:
30. Which of the following statements about polygenic traits is INCORRECT?
31. In humans, the ABO blood group system demonstrates multiple alleles. If a person has blood type O, what must be their genotype?
32. The failure of sister chromatids to separate during meiosis II would result in:
33. Mendel's principle of independent assortment applies to:
34. In a population with two alleles, 'A' and 'a', the frequency of the homozygous dominant genotype 'AA' is 0.16. Assuming Hardy-Weinberg equilibrium, what is the frequency of the heterozygous genotype 'Aa'?
35. Which of the following is a sex-linked recessive disorder commonly found in males?
36. In a population, if the frequency of the allele 'm' is 0.2, and the population is in Hardy-Weinberg equilibrium, what is the frequency of individuals who are homozygous for the dominant allele 'M'?
37. Which of the following is NOT a type of chromosomal mutation?
38. In a monohybrid cross with complete dominance, what is the genotypic ratio of the F2 generation when starting with homozygous parents (e.g., AA x aa)?
39. Consider a gene with three alleles: I^A, I^B, and i. If a person is heterozygous for I^A and i, what is their phenotype?
40. What is the typical outcome of nondisjunction in meiosis I regarding chromosome number in the resulting gametes?
41. In the context of polygenic inheritance, what is the term for genes that contribute additively to a trait?
42. Which of Mendel's principles states that alleles for different traits segregate independently during gamete formation?
43. If a population is in Hardy-Weinberg equilibrium for a gene with alleles A and a, and the frequency of 'a' is 0.4, what is the expected frequency of the homozygous recessive genotype 'aa'?
44. A person has the genotype I^A i for the ABO blood group. What is their phenotype?
45. In a quantitative trait influenced by multiple genes, an increase in the number of additive alleles generally leads to:
46. Which of the following is a violation of Mendel's principle of segregation?
47. If a population is in Hardy-Weinberg equilibrium, and the frequency of the recessive allele 'a' is 0.2, what is the frequency of the homozygous dominant genotype 'AA'?
48. In the ABO blood group system, a person with blood type B can have which of the following genotypes?
49. Which of the following is a consequence of a translocation that results in a gene being placed under the control of a different promoter region?
50. In a population exhibiting a trait influenced by three independently assorting genes, each with two additive alleles, what is the maximum number of phenotypic classes if gene expression is strictly additive?
51. Which of Mendel's principles describes the behavior of alleles for a single gene during gamete formation?
52. If a person's genotype for the ABO blood group is I^A I^B, what is their phenotype?
53. The chromosomal abnormality where a chromosome segment is repeated is called:
54. In quantitative inheritance, traits like height or skin color are influenced by:
55. Which of Mendel's principles explains why alleles for different traits (e.g., seed color and seed shape) tend to be inherited independently, as long as they are on different chromosomes?
56. In a population in Hardy-Weinberg equilibrium, if the frequency of the allele 'a' is 0.3, what is the frequency of the heterozygous genotype 'Aa'?
57. Which of the following is a consequence of nondisjunction of sister chromatids during meiosis II?
58. In a dihybrid cross involving independently assorting genes with complete dominance, if both parents are heterozygous for both traits (AaBb x AaBb), what proportion of offspring will exhibit the dominant phenotype for both traits?
59. The presence of a chromosome segment attached to a non-homologous chromosome is known as:
60. Which type of inheritance pattern is characterized by traits that show a continuous range of variation in the population, often influenced by multiple genes and environmental factors?

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