Principles of Inheritance and Variation MCQ. Test your understanding of Class 12 Inheritance & Variation with MCQs on Mendel’s work, gene linkage, sex linkage, mutation & genetic diseases.
Principles of Inheritance and Variation MCQ – Mock Online Test
Question 1: What is the term for the process by which characters are passed on from parent to progeny?
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Correct Answer: B. Inheritance. It is the basis of heredity.
Question 2: Which of the following is NOT a contrasting trait in pea plants that Mendel studied?
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Correct Answer: C. Smooth/wrinkled seeds. While Mendel did study seed shape, he focused on round/wrinkled, not smooth/wrinkled.
Question 3: What type of plants did Mendel use in his hybridization experiments?
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Correct Answer: B. Pea plants. They were ideal due to their distinct traits and ease of controlled pollination.
Question 4: What is the term for the degree to which progeny differ from their parents?
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Correct Answer: B. Variation. It contributes to the diversity within a species.
Question 5: Why did Mendel select pea plants for his experiments?
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Correct Answer: D. All of the above. These characteristics made pea plants suitable for genetic studies.
Question 6: What is a true-breeding line?
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Correct Answer: A. A line that shows stable trait inheritance for several generations. This is achieved through continuous self-pollination.
Question 7: Which of the following did Mendel NOT introduce to the field of biology?
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Correct Answer: C. Microscopic observation of chromosomes. Chromosome studies came after Mendel’s work.
Question 8: What is the difference between inheritance and variation?
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Correct Answer: A. Inheritance is the passing of traits, while variation is the differences in those traits.
Question 9: Why are contrasting traits important in genetic studies?
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Correct Answer: A. They make it easier to observe patterns of inheritance.
Question 10: How did Mendel ensure that his pea plants were true-breeding?
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Correct Answer: C. He allowed them to self-pollinate for several generations.
Question 11: What is the significance of Mendel’s work?
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Correct Answer: A. He discovered the basic principles of inheritance.
Question 12: What is the expected phenotypic ratio in the F2 generation of a monohybrid cross?
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Correct Answer: C. 3:1 This ratio represents the dominant to recessive phenotype.
Question 13: What is the purpose of a test cross?
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Correct Answer: A. To determine the genotype of an individual with a dominant phenotype.
Question 14: Which of the following is an example of a recessive trait in humans?
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Correct Answer: D. Cystic fibrosis. This genetic disorder is only expressed when an individual inherits two recessive alleles.
Question 15: What is the law of segregation?
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Correct Answer: A. Alleles of a gene separate from each other during gamete formation.
Question 16: What is a monohybrid cross?
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Correct Answer: A. A cross between two individuals that differ in one character.
Question 17: What is the F1 generation?
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Correct Answer: A. The first generation of offspring from a cross.
Question 18: What is the F2 generation?
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Correct Answer: B. The second generation of offspring from a cross.
Question 19: What is a dominant trait?
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Correct Answer: A. The trait that is expressed in the F1 generation.
Question 20: What is a recessive trait?
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Correct Answer: B. The trait that is not expressed in the F1 generation but may reappear in the F2 generation.
Question 21: What are genes?
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Correct Answer: B. The units of inheritance, containing information to express a particular trait.
Question 22: What are alleles?
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Correct Answer: C. Different forms of the same gene, responsible for contrasting traits.
Question 23: What is a genotype?
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Correct Answer: A. The genetic makeup of an organism.
Question 24: What is a phenotype?
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Correct Answer: B. The observable characteristics of an organism.
Question 25: What does it mean for an organism to be homozygous?
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Correct Answer: A. Having two identical alleles for a gene.
Question 26: What does it mean for an organism to be heterozygous?
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Correct Answer: B. Having two different alleles for a gene.
Question 27: What is the purpose of a Punnett square?
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Correct Answer: A. To visualize the possible genotypes and phenotypes of offspring from a cross.
Question 28: What is a test cross used for?
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Correct Answer: A. To determine the genotype of an individual with a dominant phenotype.
Question 29: What is the law of dominance?
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Correct Answer: A. One allele always dominates the other.
Question 30: In a monohybrid cross between a homozygous dominant (TT) and a homozygous recessive (tt) individual, what is the expected genotype of the F1 offspring?
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Correct Answer: A. All Tt. The offspring inherit one ‘T’ allele from the dominant parent and one ‘t’ allele from the recessive parent.
Question 31: In a monohybrid cross, if the F1 generation exhibits only the dominant trait, what does this indicate about the parents?
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Correct Answer: C. One parent was homozygous dominant, and the other was homozygous recessive.
Question 32: In a monohybrid cross, if the F2 generation exhibits a 3:1 ratio of dominant to recessive phenotypes, what does this indicate about the F1 generation?
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Correct Answer: C. The F1 generation was heterozygous.
Question 33: What is the expected phenotypic ratio in the F2 generation of a monohybrid cross where incomplete dominance is observed?
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Correct Answer: B. 1:2:1. This ratio reflects the blending of traits seen in incomplete dominance.
Question 34: What is an example of a trait that exhibits incomplete dominance?
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Correct Answer: A. Flower color in snapdragons. A cross between red and white snapdragons produces pink offspring.
Question 35: What is co-dominance?
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Correct Answer: A. When both alleles in a heterozygote are fully expressed.
Question 36: What is an example of a trait that exhibits co-dominance?
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Correct Answer: C. Human blood type. The AB blood type is a result of both A and B alleles being expressed.
Question 37: What is the difference between incomplete dominance and co-dominance?
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Correct Answer: A. In incomplete dominance, the heterozygote has a blended phenotype; in co-dominance, both alleles are distinctly expressed.
Question 38: What is the purpose of a test cross?
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Correct Answer: A. To determine the genotype of an individual with a dominant phenotype.
Question 39: In a test cross, an individual with a dominant phenotype is crossed with which of the following?
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Correct Answer: C. A homozygous recessive individual.
Question 40: If the offspring of a test cross all exhibit the dominant phenotype, what does this indicate about the genotype of the unknown parent?
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Correct Answer: A. It is homozygous dominant.
Question 41: If the offspring of a test cross exhibit a 1:1 ratio of dominant to recessive phenotypes, what does this indicate about the genotype of the unknown parent?
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Correct Answer: B. It is heterozygous.
Question 42: What is the role of meiosis in the law of segregation?
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Correct Answer: A. Meiosis separates homologous chromosomes, which carry the alleles, into different gametes.
Question 43: How does the law of segregation contribute to genetic variation?
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Correct Answer: A. It ensures that each gamete receives a random combination of alleles.
Question 44: What is the relationship between genes and alleles?
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Correct Answer: B. Alleles are different forms of genes.
Question 45: How do dominant and recessive alleles interact in a heterozygous individual?
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Correct Answer: A. The dominant allele is expressed, while the recessive allele is masked.
Question 46: How can a recessive trait be expressed?
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Correct Answer: A. Only in a homozygous recessive individual.
Question 47: What is a dihybrid cross?
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Correct Answer: B. A cross between two individuals that differ in two characters.
Question 48: What is the law of independent assortment?
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Correct Answer: C. The segregation of one pair of characters is independent of the other pair.
Question 49: What is the expected phenotypic ratio in the F2 generation of a dihybrid cross?
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Correct Answer: C. 9:3:3:1. This ratio reflects the independent assortment of two different traits.
Question 50: In a dihybrid cross, what does the law of independent assortment imply about the inheritance of two different traits?
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Correct Answer: B. The inheritance of one trait does not influence the inheritance of the other trait.
Question 51: What is the chromosomal theory of inheritance?
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Correct Answer: A. Genes are located on chromosomes.
Question 52: How does the behavior of chromosomes during meiosis support Mendel’s laws?
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Correct Answer: A. Chromosomes segregate independently during meiosis, just like alleles.
Question 53: What is linkage?
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Correct Answer: A. The physical association of genes on a chromosome.
Question 54: What is recombination?
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Correct Answer: A. The generation of non-parental gene combinations.
Question 55: How does linkage affect the inheritance of genes?
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Correct Answer: C. Linked genes are more likely to be inherited together.
Question 56: How does recombination affect the inheritance of genes?
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Correct Answer: B. Recombination increases the number of non-parental gene combinations.
Question 57: What is a linkage map?
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Correct Answer: A. A map showing the physical location of genes on a chromosome.
Question 58: How are linkage maps constructed?
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Correct Answer: A. By analyzing the frequency of recombination between genes.
Question 59: What is the significance of linkage maps?
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Correct Answer: D. All of the above.
Question 60: What is the relationship between linkage and recombination?
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Correct Answer: B. Linkage decreases the frequency of recombination.
Question 61: What are polygenic traits?
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Correct Answer: C. Traits controlled by three or Mmore genes.
Question 62: What is the additive effect in polygenic inheritance?
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Correct Answer: A. Each allele contributes equally to the phenotype.
Question 63: How does the environment influence polygenic traits?
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Correct Answer: B. The environment can affect the expression of polygenic traits.
Question 64: What is an example of a polygenic trait in humans?
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Correct Answer: C. Skin color. Human skin color is influenced by multiple genes and the environment.
Question 65: What is the difference between polygenic inheritance and Mendelian inheritance?
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Correct Answer: D. Both A and C.
Question 66: What is pleiotropy?
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Correct Answer: A. When one gene affects multiple traits.
Question 67: What is a pleiotropic gene?
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Correct Answer: C. A gene that affects multiple traits.
Question 68: How does a pleiotropic gene affect multiple traits?
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Correct Answer: A. By coding for a protein that is involved in multiple metabolic pathways.
Question 69: What is an example of a pleiotropic gene in humans?
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Correct Answer: C. The gene that causes phenylketonuria. This gene affects mental development, hair color, and skin pigmentation.
Question 70: What is the significance of pleiotropy?
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Correct Answer: D. All of the above.
Question 71: What are sex chromosomes?
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Correct Answer: A. Chromosomes that determine the sex of an organism.
Question 72: What are autosomes?
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Correct Answer: B. Chromosomes that are the same in both sexes.
Question 73: What is the XO type of sex determination?
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Correct Answer: A. Females have two X chromosomes, males have one.
Question 74: What is the XY type of sex determination?
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Correct Answer: B. Females have two X chromosomes, males have one X and one Y.
Question 75: What is the ZW type of sex determination?
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Correct Answer: C. Females have one Z and one W chromosome, males have two Z chromosomes.
Question 76: What type of sex determination is found in humans?
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Correct Answer: B. XY type.
Question 77: What type of sex determination is found in honey bees?
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Correct Answer: D. Haplodiploid system.
Question 78: In humans, which parent determines the sex of the offspring?
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Correct Answer: B. The father. The sex of the offspring depends on whether the sperm carries an X or a Y chromosome.
Question 79: In honey bees, how are males produced?
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Correct Answer: B. From unfertilized eggs.
Question 80: What is the difference between male heterogamety and female heterogamety?
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Correct Answer: D. Both A and B.
Question 81: What is a mutation?
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Correct Answer: C. The alteration of DNA sequences.
Question 82: What are chromosomal aberrations?
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Correct Answer: D. All of the above.
Question 83: What is a point mutation?
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Correct Answer: C. A change in a single base pair of DNA.
Question 84: What is a mutagen?
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Correct Answer: A. An agent that induces mutations.
Question 85: What is an example of a mutagen?
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Correct Answer: D. All of the above.
Question 86: What is the significance of mutations?
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Correct Answer: D. All of the above.
Question 87: What is the difference between a mutation and a chromosomal aberration?
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Correct Answer: A. A mutation is a change in a single base pair of DNA; a chromosomal aberration is a change in the number or structure of chromosomes.
Question 88: What is pedigree analysis?
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Correct Answer: A. Analyzing the inheritance patterns of traits in a family over generations.
Question 89: What are Mendelian disorders?
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Correct Answer: C. Disorders caused by alteration or mutation in a single gene.
Question 90: What are examples of Mendelian disorders?
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Correct Answer: D. All of the above.
Question 91: What are chromosomal disorders?
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Correct Answer: B. Disorders caused by absence, excess, or abnormal arrangement of one or more chromosomes.
Question 92: What are examples of chromosomal disorders?
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Correct Answer: D. All of the above.
Question 93: What is the difference between Mendelian disorders and chromosomal disorders?
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Correct Answer: A. Mendelian disorders are caused by mutations in a single gene; chromosomal disorders are caused by abnormalities in the number or structure of chromosomes.
Question 94: What is haemophilia?
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Correct Answer: A. A genetic disorder that affects blood clotting.
Question 95: What is cystic fibrosis?
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Correct Answer: B. A genetic disorder that affects the lungs.
Question 96: What is sickle-cell anaemia?
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Correct Answer: C. A genetic disorder that affects the shape of red blood cells.
Question 97: What is Down’s syndrome?
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Correct Answer: A. A chromosomal disorder caused by an extra copy of chromosome 21.
Question 98: What is Turner’s syndrome?
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Correct Answer: B. A chromosomal disorder caused by a missing X chromosome.
Question 99: What is Klinefelter’s syndrome?
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Correct Answer: C. A chromosomal disorder caused by an extra X chromosome.
Question 100: What is the significance of genetic disorders?
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Correct Answer: D. All of the above.