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NCERT Based MCQ with Explanation:
1. What is the focus of the chapter "Principles of Inheritance and Variation"?
(A) Evolution theories
(B) Study of heredity and variations
(C) Molecular structure of genes
(D) Biochemical pathways
Explanation: The chapter explains how traits are passed from parents to offspring and the variations observed, which form the foundation of genetics.
2. Who is considered the father of genetics?
(A) Charles Darwin
(B) Gregor Mendel
(C) Watson and Crick
(D) Francis Galton
Explanation: Gregor Mendel conducted experiments on pea plants, proposing the fundamental laws of inheritance and laying the groundwork for modern genetics.
3. Which plant did Gregor Mendel use for his experiments?
(A) Tomato
(B) Pea
(C) Corn
(D) Wheat
Explanation: Mendel selected pea plants (Pisum sativum) because they had distinct traits, short life cycles, and allowed controlled cross-pollination.
4. What is the basic unit of inheritance?
(A) Chromosomes
(B) Genes
(C) Nucleotides
(D) Proteins
Explanation: Genes are the basic units of inheritance, carrying the information required to express a particular trait in an organism.
5. What are alleles?
(A) Different traits of a gene
(B) Chromosomes carrying genetic material
(C) Protein molecules in DNA
(D) Enzymes facilitating inheritance
Explanation: Alleles are variations of a gene that occupy the same position on homologous chromosomes and determine contrasting traits.
6. What did Mendel’s experiments use to study inheritance patterns?
(A) Statistical analysis and mathematics
(B) Biochemical pathways
(C) Microscopy
(D) Molecular biology
Explanation: Mendel applied statistical methods and mathematical logic to study patterns of inheritance systematically.
NCERT MCQ, CLASS-11, CHAPTER-197. What is the term for offspring showing variation from parents?
(A) Mutation
(B) Progeny
(C) Variation
(D) Hybridization
Explanation: Variation refers to the differences observed among offspring in their traits compared to their parents.
8. Which of these traits did Mendel study in pea plants?
(A) Leaf size
(B) Seed color
(C) Root length
(D) Pod weight
Explanation: Mendel studied traits like seed color, seed shape, and flower position, which exhibited clear contrasting variations.
9. What does the Law of Dominance state?
(A) Alleles blend to form new traits
(B) One factor in a pair masks the expression of the other
(C) Genes segregate randomly
(D) Traits are inherited as a group
Explanation: According to Mendel’s Law of Dominance, in a pair of contrasting traits, one (dominant) masks the expression of the other (recessive).
10. What is the phenotypic ratio in a typical monohybrid F2 cross?
(A) 1:2:1
(B) 2:1:1
(C) 3:1
(D) 9:3:3:1
Explanation: In a monohybrid cross, Mendel observed that the F2 generation exhibited a 3:1 phenotypic ratio of dominant to recessive traits.
11. What is a true-breeding line in Mendel's experiments?
(A) A line showing genetic mutations
(B) A line that self-pollinates with consistent traits
(C) A hybrid with multiple traits
(D) A plant variety that does not produce seeds
Explanation: Mendel used true-breeding lines that consistently expressed the same traits over generations due to self-pollination.
12. What proportion of the F2 generation in a monohybrid cross is homozygous recessive?
(A) 1/4
(B) 1/2
(C) 3/4
(D) None
Explanation: In the F2 generation of a monohybrid cross, 1/4 of the offspring are homozygous recessive, as shown in Mendel’s experiments.
13. What tool is used to predict genetic cross outcomes?
(A) Microscope
(B) DNA sequencer
(C) Punnett square
(D) Gel electrophoresis
Explanation: The Punnett square is a graphical representation used to calculate the probability of offspring genotypes in genetic crosses.
14. What are the contrasting traits for seed shape studied by Mendel?
(A) Round and wrinkled
(B) Yellow and green
(C) Inflated and constricted
(D) Tall and dwarf
Explanation: Mendel selected seed shape as one of the traits, contrasting round seeds with wrinkled seeds.
15. What is the genotypic ratio for a monohybrid F2 cross?
(A) 3:1
(B) 1:2:1
(C) 9:3:3:1
(D) 2:1:2
Explanation: The genotypic ratio of a monohybrid F2 cross is 1 homozygous dominant: 2 heterozygous: 1 homozygous recessive.
16. Which phenomenon supports Mendel's Law of Segregation?
(A) Gene linkage
(B) Chromosome pairing
(C) Meiosis
(D) Mutation
Explanation: During meiosis, alleles segregate randomly into gametes, supporting Mendel's observation of segregation.
17. What is the dominant allele for plant height in Mendel's pea plants?
(A) Short (t)
(B) Tall (T)
(C) Medium (M)
(D) None of these
Explanation: In Mendel's experiments, the tall trait (T) was dominant over the dwarf trait (t).
18. What does the Law of Independent Assortment state?
(A) Alleles of one gene pair do not affect others during gamete formation
(B) Traits always occur together
(C) Dominant traits suppress recessive traits
(D) Genes assort independently only in hybrids
Explanation: The Law of Independent Assortment states that gene pairs segregate independently if located on different chromosomes.
19. What is the phenotypic ratio in the F2 generation of a dihybrid cross?
(A) 1:2:1
(B) 3:1
(C) 9:3:3:1
(D) 6:2:2
Explanation: The F2 generation of a dihybrid cross exhibits a phenotypic ratio of 9 dominant-dominant: 3 dominant-recessive: 3 recessive-dominant: 1 recessive-recessive.
20. Which genotype represents a heterozygous individual?
(A) TT
(B) Tt
(C) tt
(D) TT and tt
Explanation: Heterozygous individuals have two different alleles (e.g., Tt) for a particular trait.
21. Which experiment demonstrated incomplete dominance?
(A) Yellow and green peas
(B) Red and white flowers in snapdragon
(C) Tall and dwarf plants
(D) Round and wrinkled seeds
NCERT Science MCQ, Class-1022. What is codominance?
(A) Both alleles are suppressed
(B) Both alleles are expressed simultaneously
(C) Only the recessive allele is expressed
(D) None of the above
23. What is the chromosomal theory of inheritance?
(A) Genes are located on chromosomes
(B) Alleles assort randomly
(C) Traits are inherited through proteins
(D) All traits are linked to chromosomes
24. Which scientist worked extensively on Drosophila melanogaster?
(A) Gregor Mendel
(B) Thomas Hunt Morgan
(C) Watson and Crick
(D) Alfred Sturtevant
25. What does linkage refer to in genetics?
(A) Genes located on the same chromosome that are inherited together
(B) Independent assortment of alleles
(C) Chromosomal mutations
(D) Protein binding in DNA
26. What term describes the random combination of alleles during gamete formation?
(A) Mutation
(B) Assortment
(C) Segregation
(D) Recombination
27. What are multiple alleles?
(A) More than two alleles governing the same gene
(B) Two contrasting alleles for a gene
(C) Linked alleles on the same chromosome
(D) Recessive alleles in different species
28. Which blood group shows codominance?
(A) A
(B) AB
(C) O
(D) B
29. What is polygenic inheritance?
(A) Traits controlled by a single gene
(B) Traits influenced by environmental factors
(C) Traits governed by multiple genes
(D) Traits passed exclusively through the maternal line
30. What does pleiotropy mean in genetics?
(A) One gene affects multiple traits
(B) Multiple genes affect one trait
(C) Genes are linked on the same chromosome
(D) Traits blend in heterozygous individuals
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