Principles of Inheritance Quiz - CBSE Class 12 Biology

Free practice quiz: Principles of Inheritance (CBSE Class 12 Biology). 20 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This CBSE Class 12 Biology practice quiz has 20 multiple-choice questions on Principles of Inheritance, and 20 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. What is the phenotypic ratio of a monohybrid cross between two heterozygous individuals?

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

   Answer: B. 3:1

   A monohybrid cross between two heterozygotes (e.g., Aa x Aa) results in a 3:1 phenotypic ratio of dominant to recessive traits.

2. What is codominance?

   1. When one allele masks another.
   2. When both alleles are expressed equally in the heterozygote.
   3. When the heterozygote shows an intermediate phenotype.
   4. When there are multiple alleles for a single gene.
   Show answer

   Answer: B. When both alleles are expressed equally in the heterozygote.

   Codominance is a type of inheritance where both alleles are fully expressed in the heterozygote, unlike incomplete dominance where the heterozygote displays an intermediate phenotype.

3. In a dihybrid cross between two heterozygotes (AaBb x AaBb), what is the probability of obtaining an offspring with the genotype AABB?

   1. 1/2
   2. 1/4
   3. 1/8
   4. 1/16
   Show answer

   Answer: D. 1/16

   The probability of inheriting AA from both parents is 1/4 (1/2 x 1/2), and the probability of inheriting BB from both parents is also 1/4 (1/2 x 1/2). Therefore, the probability of obtaining AABB is (1/4) x (1/4) = 1/16.

4. In a cross involving two genes, what is the expected phenotypic ratio in the F2 generation if the two genes show complete linkage?

   1. 9:3:3:1
   2. 1:1:1:1
   3. 3:1
   4. The ratio will depend on the parental genotypes.
   Show answer

   Answer: C. 3:1

   Complete linkage means the genes are located very close together on the same chromosome and do not recombine during meiosis. Therefore, the phenotypic ratio will resemble that of a monohybrid cross.

5. How does the environment interact with genotype to influence phenotype?

   1. The environment has no influence on phenotype.
   2. The environment completely determines the phenotype, ignoring the genotype.
   3. The environment can modify or mask the expression of a genotype.
   4. The genotype and environment are completely independent.
   Show answer

   Answer: C. The environment can modify or mask the expression of a genotype.

   The environment can interact with the genotype to influence the phenotype. Environmental factors can affect gene expression, resulting in variations in phenotypic expression, even among individuals with the same genotype.

More questions in this quiz

Answers and explanations are in the full quiz.

1. If a homozygous tall plant (TT) is crossed with a homozygous dwarf plant (tt), what is the genotype of the F1 generation?
2. Explain the concept of incomplete dominance.
3. What is the term for the physical expression of a gene?
4. Describe the concept of multiple alleles.
5. A plant with genotype AaBb produces gametes. How many different types of gametes are possible, and what are they?
6. Explain the law of independent assortment.
7. What is pleiotropy?
8. Two parents with blood types A and B have a child with blood type O. Explain how this is possible, including the genotypes of the parents and child.
9. Explain the concept of epistasis.
10. A test cross is performed to determine the genotype of an individual expressing the dominant phenotype. What is the genotype of the individual used in the test cross?
11. Describe how sex-linked inheritance differs from autosomal inheritance.
12. Explain the concept of genetic mapping using recombination frequencies.
13. Discuss the implications of polygenic inheritance and its role in continuous variation.
14. A complex trait is influenced by multiple genes and environmental factors. How can we study the heritability of this trait, considering both genetic and environmental contributions?
15. Explain how genomic imprinting affects gene expression and inheritance patterns, and provide an example of a human disorder influenced by genomic imprinting.

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