🧬 Genetics MCQs – Part 1 (Q1–Q25)

Q1. Genetics is best defined as the study of:

A) Cells and their structure
B) Inheritance and variation of traits
C) Evolutionary changes in organisms
D) Functions of enzymes

✅ Answer: B) Inheritance and variation of traits
Explanation: Genetics deals with heredity (inheritance of characters) and variation among organisms.

Q2. Who is regarded as the Father of Genetics?

A) Charles Darwin
B) Gregor Mendel
C) Hugo de Vries
D) Francis Crick

✅ Answer: B) Gregor Mendel
Explanation: Mendel discovered laws of inheritance using pea plants (Pisum sativum).

Q3. The basic unit of heredity is:

A) Chromosome
B) Gene
C) Protein
D) DNA

✅ Answer: B) Gene
Explanation: A gene is a DNA segment that codes for a functional product (RNA/protein).

Q4. In Mendel’s dihybrid cross, the phenotypic ratio is:

A) 3:1
B) 1:2:1
C) 9:3:3:1
D) 1:1

✅ Answer: C) 9:3:3:1
Explanation: In a dihybrid cross (AaBb × AaBb), Mendel observed independent assortment → 9:3:3:1 ratio.

Q5. The phenomenon where one gene masks the effect of another is called:

A) Incomplete dominance
B) Codominance
C) Epistasis
D) Pleiotropy

✅ Answer: C) Epistasis
Explanation: Epistasis occurs when one gene’s expression suppresses/modifies another’s (e.g., coat color in mice).

Q6. Incomplete dominance is observed in:

A) Human blood groups
B) Snapdragons (Antirrhinum)
C) Pea plants (Mendel)
D) Bacteria

✅ Answer: B) Snapdragons (Antirrhinum)
Explanation: Red × White → Pink flowers (blended phenotype).

Q7. Codominance is seen in:

A) Pea flower color
B) Human ABO blood groups
C) Fruit fly eye color
D) Mice coat color

✅ Answer: B) Human ABO blood groups
Explanation: In AB blood group, both IA and IB alleles are expressed equally (codominance).

Q8. A condition where one gene influences multiple traits is called:

A) Epistasis
B) Pleiotropy
C) Polygenic inheritance
D) Incomplete dominance

✅ Answer: B) Pleiotropy
Explanation: One gene → multiple phenotypic effects (e.g., sickle-cell anemia).

Q9. A polygenic trait shows:

A) Discontinuous variation
B) Continuous variation
C) No variation
D) Mendelian 3:1 ratio

✅ Answer: B) Continuous variation
Explanation: Traits like height, skin color are polygenic → continuous distribution.

Q10. The sex of a human child is determined by:

A) X chromosome of mother
B) Y chromosome of father
C) Mitochondrial DNA
D) Both parents equally

✅ Answer: B) Y chromosome of father
Explanation: Sperm contributes X or Y, determining child’s sex.

Q11. Hemophilia is inherited as a:

A) Autosomal dominant trait
B) Autosomal recessive trait
C) X-linked recessive trait
D) Y-linked trait

✅ Answer: C) X-linked recessive trait
Explanation: More common in males; females act as carriers.

Q12. Which chromosome abnormality causes Down syndrome?

A) Trisomy 13
B) Trisomy 18
C) Trisomy 21
D) Monosomy X

✅ Answer: C) Trisomy 21
Explanation: Down syndrome → extra chromosome 21.

Q13. Turner’s syndrome is caused by:

A) XXY
B) XO
C) XYY
D) XXX

✅ Answer: B) XO
Explanation: Females with single X (45, XO) → short stature, infertility.

Q14. Klinefelter’s syndrome has the karyotype:

A) 45, XO
B) 47, XXY
C) 47, XXX
D) 46, XY

✅ Answer: B) 47, XXY
Explanation: Males with an extra X → infertility, tall stature, gynecomastia.

Q15. The scientist who coined the term “gene” was:

A) Johannsen
B) Morgan
C) Watson
D) Mendel

✅ Answer: A) Johannsen
Explanation: Wilhelm Johannsen (1909) introduced the term gene.

Q16. Crossing over occurs during:

A) Mitosis – Prophase
B) Meiosis I – Prophase I
C) Meiosis II – Metaphase
D) Cytokinesis

✅ Answer: B) Meiosis I – Prophase I
Explanation: Homologous chromosomes exchange segments during pachytene stage.

Q17. A test cross is used to determine:

A) Homozygosity or heterozygosity
B) Mutation rate
C) Gene mapping
D) Sex linkage

✅ Answer: A) Homozygosity or heterozygosity
Explanation: Cross with homozygous recessive → reveals genotype of dominant phenotype.

Q18. The physical location of a gene on a chromosome is called:

A) Allele
B) Locus
C) Centromere
D) Chromatid

✅ Answer: B) Locus
Explanation: Each gene has a fixed locus (position) on a chromosome.

Q19. In humans, mitochondrial DNA is inherited from:

A) Both parents
B) Only mother
C) Only father
D) Randomly

✅ Answer: B) Only mother
Explanation: Maternal inheritance because sperm mitochondria are lost after fertilization.

Q20. Which scientist discovered sex-linked inheritance in fruit flies?

A) Mendel
B) Thomas Hunt Morgan
C) Hugo de Vries
D) Watson & Crick

✅ Answer: B) Thomas Hunt Morgan
Explanation: Morgan showed eye color inheritance in Drosophila is sex-linked.

Q21. The total set of chromosomes in an organism is called:

A) Allele
B) Genome
C) Proteome
D) Exome

✅ Answer: B) Genome
Explanation: Genome = complete set of DNA/chromosomes in an organism.

Q22. DNA is replicated by which enzyme?

A) DNA polymerase
B) RNA polymerase
C) Helicase
D) Ligase

✅ Answer: A) DNA polymerase
Explanation: Synthesizes new strand complementary to template.

Q23. Okazaki fragments are formed during:

A) Leading strand synthesis
B) Lagging strand synthesis
C) mRNA transcription
D) DNA repair

✅ Answer: B) Lagging strand synthesis
Explanation: DNA synthesized discontinuously in Okazaki fragments.

Q24. The central dogma of molecular biology was proposed by:

A) Mendel
B) Watson
C) Crick
D) Morgan

✅ Answer: C) Francis Crick
Explanation: DNA → RNA → Protein (flow of genetic information).

Q25. In eukaryotes, transcription occurs in:

A) Cytoplasm
B) Nucleus
C) Mitochondria only
D) Ribosome

✅ Answer: B) Nucleus
Explanation: In eukaryotes, transcription occurs in the nucleus, translation in the cytoplasm.

🧬 Genetics MCQs – Part 2 (Q26–Q50)

Q26. Which base pairing is correct in DNA according to Chargaff’s rule?

A) A–C and G–T
B) A–T and G–C
C) A–G and T–C
D) A–U and G–C

✅ Answer: B) A–T and G–C
Explanation: In DNA: A pairs with T (2 H-bonds) and G pairs with C (3 H-bonds).

Q27. The three-letter code in mRNA that specifies an amino acid is called:

A) Anticodon
B) Codon
C) Triplet repeat
D) Exon

✅ Answer: B) Codon
Explanation: A codon is a triplet of nucleotides on mRNA that codes for an amino acid.

Q28. How many codons in the genetic code specify amino acids?

A) 61
B) 64
C) 20
D) 3

✅ Answer: A) 61
Explanation: Of 64 codons, 61 code for amino acids and 3 are stop codons.

Q29. Which of the following is a stop codon?

A) AUG
B) UAA
C) GGG
D) UAC

✅ Answer: B) UAA
Explanation: Stop codons: UAA, UAG, UGA. AUG is start codon (methionine).

Q30. The enzyme that synthesizes RNA from DNA is:

A) DNA polymerase
B) RNA polymerase
C) Reverse transcriptase
D) Ligase

✅ Answer: B) RNA polymerase
Explanation: RNA polymerase catalyzes transcription of RNA from DNA template.

Q31. The first amino acid in protein synthesis (translation) in eukaryotes is:

A) Glycine
B) Alanine
C) Methionine
D) Valine

✅ Answer: C) Methionine
Explanation: Initiation codon AUG codes for methionine (Met).

Q32. In prokaryotes, translation and transcription occur:

A) In nucleus
B) In cytoplasm simultaneously
C) On ribosomes after transcription
D) Independently in different compartments

✅ Answer: B) In cytoplasm simultaneously
Explanation: Prokaryotes lack nucleus → transcription & translation coupled.

Q33. The non-coding sequences of eukaryotic DNA are called:

A) Exons
B) Introns
C) Codons
D) Operons

✅ Answer: B) Introns
Explanation: Introns are non-coding; exons are coding sequences expressed.

Q34. Alternative splicing in eukaryotes results in:

A) Mutation
B) More than one protein from same gene
C) Gene silencing
D) DNA replication errors

✅ Answer: B) More than one protein from same gene
Explanation: Different arrangements of exons → multiple proteins.

Q35. The operon model was proposed by:

A) Watson and Crick
B) Jacob and Monod
C) Mendel
D) Morgan

✅ Answer: B) Jacob and Monod
Explanation: They proposed the lac operon model in E. coli (gene regulation).

Q36. In lac operon, the structural genes are expressed when:

A) Lactose absent, glucose present
B) Lactose present, glucose absent
C) Lactose absent, glucose absent
D) Lactose and glucose both present

✅ Answer: B) Lactose present, glucose absent
Explanation: Lactose induces operon; glucose represses via catabolite repression.

Q37. Which type of mutation changes a codon into a stop codon?

A) Missense mutation
B) Silent mutation
C) Nonsense mutation
D) Frameshift mutation

✅ Answer: C) Nonsense mutation
Explanation: Creates premature stop codon, truncating protein.

Q38. A mutation with no change in amino acid sequence is:

A) Frameshift
B) Missense
C) Silent
D) Nonsense

✅ Answer: C) Silent
Explanation: Base substitution → no change due to degeneracy of genetic code.

Q39. Which enzyme repairs UV-induced thymine dimers?

A) DNA ligase
B) Photolyase
C) DNA helicase
D) RNA polymerase

✅ Answer: B) Photolyase
Explanation: Uses visible light energy to repair thymine dimers (photoreactivation).

Q40. Mutations in BRCA1 and BRCA2 genes increase risk of:

A) Diabetes
B) Breast and ovarian cancer
C) Sickle cell anemia
D) Alzheimer’s disease

✅ Answer: B) Breast and ovarian cancer
Explanation: Tumor suppressor genes; mutations increase cancer susceptibility.

Q41. Which technique is used to amplify DNA fragments?

A) ELISA
B) PCR
C) Gel electrophoresis
D) Blotting

✅ Answer: B) PCR
Explanation: Polymerase Chain Reaction amplifies DNA exponentially.

Q42. Which blotting technique detects DNA sequences?

A) Northern blot
B) Southern blot
C) Western blot
D) Eastern blot

✅ Answer: B) Southern blot
Explanation:

Southern → DNA
Northern → RNA
Western → Protein

Q43. Which technique separates DNA fragments based on size?

A) Centrifugation
B) Chromatography
C) Gel electrophoresis
D) Spectrophotometry

✅ Answer: C) Gel electrophoresis
Explanation: Smaller fragments migrate faster in agarose gel.

Q44. Which scientist discovered transposable elements (“jumping genes”)?

A) Watson
B) Barbara McClintock
C) Mendel
D) Morgan

✅ Answer: B) Barbara McClintock
Explanation: Discovered transposons in maize.

Q45. Which genetic disorder is caused by a single point mutation in the β-globin gene?

A) Hemophilia
B) Sickle cell anemia
C) Cystic fibrosis
D) Thalassemia

✅ Answer: B) Sickle cell anemia
Explanation: Point mutation (Glu → Val) in β-globin → abnormal HbS.

Q46. Which genetic disease is caused by a defect in CFTR gene?

A) Hemophilia
B) Cystic fibrosis
C) Phenylketonuria
D) Huntington’s disease

✅ Answer: B) Cystic fibrosis
Explanation: Mutation in CFTR chloride channel → thick mucus in lungs, pancreas.

Q47. Huntington’s disease is caused by:

A) Trinucleotide repeat expansion (CAG)
B) Point mutation
C) Chromosomal deletion
D) Chromosomal translocation

✅ Answer: A) Trinucleotide repeat expansion (CAG)
Explanation: CAG repeats in HTT gene cause neurodegeneration.

Q48. Which disorder is due to defective phenylalanine metabolism?

A) PKU (Phenylketonuria)
B) Albinism
C) Tay-Sachs disease
D) Galactosemia

✅ Answer: A) PKU (Phenylketonuria)
Explanation: Deficiency of phenylalanine hydroxylase → phenylalanine buildup.

Q49. The Human Genome Project was completed in:

A) 1990
B) 1995
C) 2003
D) 2010

✅ Answer: C) 2003
Explanation: HGP sequenced entire human genome by 2003.

Q50. CRISPR-Cas9 is a tool for:

A) Protein folding
B) Gene editing
C) DNA replication
D) RNA splicing

✅ Answer: B) Gene editing
Explanation: CRISPR-Cas9 allows targeted modification of DNA sequences.

🧬 Genetics MCQs – Part 3 (Q51–Q75)

Q51. Who discovered the structure of DNA?

A) Rosalind Franklin and Maurice Wilkins
B) Watson and Crick
C) Hershey and Chase
D) Griffith

✅ Answer: B) Watson and Crick
Explanation: In 1953, Watson & Crick proposed the double helix model, based on Franklin’s X-ray data.

Q52. In DNA, the two strands are held together by:

A) Ionic bonds
B) Hydrogen bonds
C) Phosphodiester bonds
D) Peptide bonds

✅ Answer: B) Hydrogen bonds
Explanation: A–T (2 bonds), G–C (3 bonds) stabilize the double helix.

Q53. Hershey and Chase’s experiment with bacteriophages proved that:

A) Proteins are the genetic material
B) DNA is the genetic material
C) RNA is the only genetic material
D) Carbohydrates carry heredity

✅ Answer: B) DNA is the genetic material
Explanation: Radioactive labeling showed DNA enters bacteria, not protein.

Q54. Griffith’s transformation experiment showed that:

A) DNA is a double helix
B) Dead virulent bacteria can transfer traits to live non-virulent bacteria
C) RNA acts as enzyme
D) Chromosomes carry genes

✅ Answer: B) Dead virulent bacteria can transfer traits
Explanation: This demonstrated the concept of transformation.

Q55. Meselson and Stahl proved the mode of DNA replication is:

A) Conservative
B) Semi-conservative
C) Dispersive
D) Random

✅ Answer: B) Semi-conservative
Explanation: Each new DNA has one old and one new strand.

Q56. In eukaryotes, DNA replication occurs in:

A) G1 phase
B) S phase
C) G2 phase
D) M phase

✅ Answer: B) S phase
Explanation: DNA synthesis occurs in the S (synthesis) phase of the cell cycle.

Q57. Telomeres are important because they:

A) Prevent chromosome fusion and degradation
B) Help protein folding
C) Carry ribosomal RNA genes
D) Are centromeric regions

✅ Answer: A) Prevent chromosome fusion and degradation
Explanation: Telomeres maintain chromosome stability.

Q58. The enzyme that adds telomere sequences is:

A) DNA ligase
B) Telomerase
C) DNA helicase
D) Topoisomerase

✅ Answer: B) Telomerase
Explanation: Telomerase adds repetitive sequences to chromosome ends.

Q59. Which type of RNA carries amino acids to ribosomes?

A) mRNA
B) tRNA
C) rRNA
D) snRNA

✅ Answer: B) tRNA
Explanation: tRNA carries amino acids and has an anticodon to match mRNA codon.

Q60. Which type of RNA makes up ribosomes?

A) mRNA
B) rRNA
C) tRNA
D) siRNA

✅ Answer: B) rRNA
Explanation: Ribosomes are mainly ribosomal RNA + proteins.

Q61. Which mutation changes one amino acid to another?

A) Silent mutation
B) Missense mutation
C) Nonsense mutation
D) Frameshift mutation

✅ Answer: B) Missense mutation
Explanation: Substitution alters one amino acid (e.g., sickle-cell anemia).

Q62. Frameshift mutations occur due to:

A) Substitution of a base
B) Insertion or deletion of bases (not multiple of 3)
C) Duplication of DNA segment
D) Inversion of chromosome

✅ Answer: B) Insertion or deletion of bases
Explanation: Shifts reading frame, altering all codons downstream.

Q63. A mutagen that causes breaks in chromosomes is called:

A) Clastogen
B) Carcinogen
C) Teratogen
D) Allergen

✅ Answer: A) Clastogen
Explanation: Clastogens → structural chromosomal aberrations.

Q64. Which law of inheritance states that alleles of different genes assort independently?

A) Law of dominance
B) Law of segregation
C) Law of independent assortment
D) Law of probability

✅ Answer: C) Law of independent assortment
Explanation: Mendel’s 2nd law → genes for different traits assort independently.

Q65. A linkage group corresponds to:

A) Number of alleles
B) Number of chromosomes
C) Number of proteins
D) Number of codons

✅ Answer: B) Number of chromosomes
Explanation: A linkage group = genes present on a single chromosome.

Q66. Crossing over increases:

A) Mutations
B) Chromosome number
C) Genetic variation
D) DNA replication

✅ Answer: C) Genetic variation
Explanation: Recombination creates new allele combinations.

Q67. Genes located on the same chromosome and inherited together are called:

A) Codominant genes
B) Linked genes
C) Alleles
D) Epistatic genes

✅ Answer: B) Linked genes
Explanation: Genes close on same chromosome → inherited together.

Q68. If two genes are far apart on a chromosome, recombination frequency will be:

A) 0%
B) 50%
C) 100%
D) Very low

✅ Answer: B) 50%
Explanation: Far apart genes behave like unlinked genes (independent assortment).

Q69. Sex-linked traits in humans are mostly located on:

A) Y chromosome
B) X chromosome
C) Autosomes
D) Mitochondria

✅ Answer: B) X chromosome
Explanation: X-linked traits (hemophilia, color blindness) are more common.

Q70. Color blindness is inherited as:

A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) Y-linked

✅ Answer: C) X-linked recessive
Explanation: More frequent in males; females are carriers.

Q71. Lyon hypothesis refers to:

A) Gene mutation
B) X-chromosome inactivation in females
C) Crossing over
D) DNA replication

✅ Answer: B) X-chromosome inactivation
Explanation: One X is inactivated (Barr body) in female somatic cells.

Q72. Which process produces gametes with half the chromosome number?

A) Mitosis
B) Meiosis
C) Binary fission
D) Amitosis

✅ Answer: B) Meiosis
Explanation: Meiosis reduces diploid (2n) → haploid (n).

Q73. Which phase of meiosis is responsible for genetic recombination?

A) Metaphase I
B) Anaphase II
C) Prophase I (Pachytene)
D) Telophase I

✅ Answer: C) Prophase I (Pachytene)
Explanation: Crossing over occurs in pachytene stage.

Q74. Aneuploidy refers to:

A) Loss or gain of entire set of chromosomes
B) Loss or gain of one or more chromosomes
C) Duplication of gene segment
D) Inversion of chromosome segment

✅ Answer: B) Loss or gain of one or more chromosomes
Explanation: Examples: trisomy 21 (Down), monosomy X (Turner).

Q75. Polyploidy is common in:

A) Animals
B) Humans
C) Plants
D) Viruses

✅ Answer: C) Plants
Explanation: Polyploidy (3n, 4n, etc.) is frequent in plants, rare in animals.

🧬 Genetics MCQs – Part 4 (Q76–Q100)

Q76. Which type of inheritance shows blending of traits in heterozygotes?

A) Codominance
B) Incomplete dominance
C) Epistasis
D) Multiple alleles

✅ Answer: B) Incomplete dominance
Explanation: Heterozygotes show an intermediate phenotype (e.g., pink snapdragons).

Q77. Multiple alleles are exemplified by:

A) Sickle cell anemia
B) ABO blood groups
C) Hemophilia
D) Albinism

✅ Answer: B) ABO blood groups
Explanation: ABO system has three alleles (IA, IB, i).

Q78. The Human Genome contains approximately:

A) 1,000 genes
B) 10,000 genes
C) 20,000–25,000 genes
D) 100,000 genes

✅ Answer: C) 20,000–25,000 genes
Explanation: HGP revealed about ~21,000 protein-coding genes.

Q79. The process by which mRNA is synthesized from DNA is:

A) Replication
B) Translation
C) Transcription
D) Splicing

✅ Answer: C) Transcription
Explanation: RNA polymerase synthesizes mRNA from DNA template.

Q80. The conversion of mRNA into protein is called:

A) Replication
B) Translation
C) Transcription
D) Reverse transcription

✅ Answer: B) Translation
Explanation: Ribosomes decode mRNA → polypeptide chain.

Q81. In prokaryotes, the site of transcription is:

A) Nucleus
B) Cytoplasm
C) Mitochondria
D) Endoplasmic reticulum

✅ Answer: B) Cytoplasm
Explanation: Prokaryotes lack nucleus → transcription occurs in cytoplasm.

Q82. The universal start codon is:

A) UAA
B) AUG
C) UGA
D) UAG

✅ Answer: B) AUG
Explanation: AUG codes for methionine (Met), the universal initiation codon.

Q83. Which codons act as stop signals in protein synthesis?

A) AUG, GGG, UUU
B) UAA, UAG, UGA
C) UGG, CUA, AAA
D) GCU, CCG, UGC

✅ Answer: B) UAA, UAG, UGA
Explanation: These are termination codons → no amino acid.

Q84. Which RNA has an anticodon?

A) mRNA
B) rRNA
C) tRNA
D) snRNA

✅ Answer: C) tRNA
Explanation: tRNA anticodon pairs with mRNA codon to bring correct amino acid.

Q85. The phenomenon where a single gene affects multiple traits is:

A) Epistasis
B) Pleiotropy
C) Polygenic inheritance
D) Codominance

✅ Answer: B) Pleiotropy
Explanation: Example: sickle cell gene affects RBC shape, anemia, malaria resistance.

Q86. The most common method of gene regulation in prokaryotes is:

A) RNA splicing
B) Operon system
C) Chromatin modification
D) RNA interference

✅ Answer: B) Operon system
Explanation: E. coli lac operon regulates genes in clusters.

Q87. Which enzyme joins Okazaki fragments in DNA replication?

A) DNA polymerase
B) DNA ligase
C) Helicase
D) Gyrase

✅ Answer: B) DNA ligase
Explanation: Ligase seals nicks between fragments on lagging strand.

Q88. Which enzyme unwinds DNA at replication fork?

A) Ligase
B) Helicase
C) Primase
D) Topoisomerase

✅ Answer: B) Helicase
Explanation: Helicase separates DNA strands for replication.

Q89. Which enzyme synthesizes RNA primers in replication?

A) Primase
B) DNA polymerase
C) Ligase
D) Helicase

✅ Answer: A) Primase
Explanation: Primase makes short RNA primers for DNA polymerase to start.

Q90. A genetic cross involving a single character is called:

A) Dihybrid cross
B) Monohybrid cross
C) Test cross
D) Back cross

✅ Answer: B) Monohybrid cross
Explanation: Cross between two heterozygotes (Aa × Aa).

Q91. Mendel’s Law of Segregation states that:

A) Alleles separate during gamete formation
B) Genes assort independently
C) Dominant alleles always mask recessive
D) Genes are linked

✅ Answer: A) Alleles separate during gamete formation
Explanation: Each gamete gets only one allele from a pair.

Q92. The process of making multiple identical copies of a gene is called:

A) Translation
B) Cloning
C) Splicing
D) Editing

✅ Answer: B) Cloning
Explanation: Gene cloning produces multiple identical copies.

Q93. Which blotting technique is used to detect RNA?

A) Southern blot
B) Northern blot
C) Western blot
D) Eastern blot

✅ Answer: B) Northern blot
Explanation: Detects RNA sequences.

Q94. Which blotting technique is used to detect proteins?

A) Northern blot
B) Southern blot
C) Western blot
D) Dot blot

✅ Answer: C) Western blot
Explanation: Detects specific proteins using antibodies.

Q95. DNA fingerprinting is based on:

A) rRNA sequences
B) Short tandem repeats (STRs)
C) Stop codons
D) Okazaki fragments

✅ Answer: B) Short tandem repeats (STRs)
Explanation: STRs vary among individuals → basis of DNA profiling.

Q96. The human karyotype normally contains:

A) 22 pairs autosomes + XY
B) 21 pairs autosomes + XY
C) 23 pairs autosomes + XY
D) 22 pairs autosomes + XX

✅ Answer: A) 22 pairs autosomes + XY
Explanation: Normal male karyotype = 46, XY (44 autosomes + 2 sex chromosomes).

Q97. Genomic imprinting means:

A) DNA replication
B) Genes expressed depending on parental origin
C) Mutation in somatic cells
D) RNA silencing

✅ Answer: B) Genes expressed depending on parental origin
Explanation: Some genes are active only when inherited from mother or father.

Q98. The Nobel Prize for discovery of CRISPR-Cas9 gene editing was awarded in:

A) 2000
B) 2010
C) 2020
D) 2022

✅ Answer: C) 2020
Explanation: Awarded to Emmanuelle Charpentier and Jennifer Doudna.

Q99. Which inheritance pattern shows traits controlled by many genes?

A) Pleiotropy
B) Polygenic inheritance
C) Codominance
D) Epistasis

✅ Answer: B) Polygenic inheritance
Explanation: Traits like height, skin color are controlled by multiple genes.

Q100. Which genome editing tool uses guide RNA to cut DNA at specific sites?

A) PCR
B) CRISPR-Cas9
C) Southern blot
D) DNA ligase

✅ Answer: B) CRISPR-Cas9
Explanation: Guide RNA directs Cas9 nuclease to target DNA for precise editing.

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