Genetics & Molecular Biology explores how genetic information is inherited, expressed, and regulated at the molecular level. This category integrates classical genetics with modern molecular biology to explain the mechanisms governing heredity, variation, and gene expression , making it suitable for Class 11–12 students , NEET aspirants , and undergraduate learners .
In this section, you will study:
Basic concepts of genetics and heredity
Mendelian and non-Mendelian inheritance patterns
Molecular structure of DNA and RNA
DNA replication, transcription, and translation
Gene regulation and expression
Mutations and genetic disorders
Recombinant DNA technology and molecular tools
NCERT-based explanations, diagrams, MCQs, and exam-oriented questions
The content is structured to build strong conceptual foundations , improve problem-solving and analytical skills , and help students perform confidently in school examinations, NEET, and undergraduate assessments .
Develop a clear and integrated understanding of genetics and molecular biology to master one of the most important and scoring areas of modern Biology.
Q. What is a frameshift mutation?
A.
A mutation that changes one amino acid
B.
A mutation that adds or removes nucleotides, altering the reading frame
C.
A mutation that occurs in non-coding regions
D.
A mutation that duplicates a segment of DNA
Show solution
Solution
A frameshift mutation occurs when nucleotides are added or deleted from the DNA sequence, shifting the reading frame and potentially altering all downstream amino acids.
Correct Answer:
B
— A mutation that adds or removes nucleotides, altering the reading frame
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Q. What is a key difference between DNA and RNA?
A.
DNA is single-stranded, RNA is double-stranded
B.
RNA contains uracil instead of thymine
C.
DNA is found in the cytoplasm, RNA is found in the nucleus
D.
RNA is more stable than DNA
Show solution
Solution
RNA contains uracil (U) in place of thymine (T), which is found in DNA, making this a key difference between the two nucleic acids.
Correct Answer:
B
— RNA contains uracil instead of thymine
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A.
A change in the DNA sequence
B.
A process of DNA replication
C.
The synthesis of RNA from DNA
D.
The formation of ribosomes
Show solution
Solution
A mutation is a change in the DNA sequence that can affect gene function and protein production.
Correct Answer:
A
— A change in the DNA sequence
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Q. What is recombinant DNA technology primarily used for?
A.
To create genetically identical organisms
B.
To produce proteins, such as insulin
C.
To sequence entire genomes
D.
To analyze gene expression
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Solution
Recombinant DNA technology is used to combine DNA from different sources, often to produce proteins like insulin.
Correct Answer:
B
— To produce proteins, such as insulin
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Q. What is recombinant DNA?
A.
DNA that is naturally occurring
B.
DNA that has been artificially created by combining DNA from different sources
C.
DNA that is only found in viruses
D.
DNA that is only found in bacteria
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Solution
Recombinant DNA is formed by combining DNA from different organisms, allowing for the study and manipulation of genes.
Correct Answer:
B
— DNA that has been artificially created by combining DNA from different sources
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Q. What is the basic structural unit of DNA?
A.
Nucleotide
B.
Amino acid
C.
Monosaccharide
D.
Fatty acid
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Solution
DNA is composed of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.
Correct Answer:
A
— Nucleotide
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Q. What is the basic unit of heredity in living organisms?
A.
Chromosome
B.
Gene
C.
DNA
D.
RNA
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Solution
A gene is the basic unit of heredity, responsible for the transmission of traits from parents to offspring.
Correct Answer:
B
— Gene
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Q. What is the basic unit of heredity in Mendelian genetics?
A.
Chromosome
B.
Gene
C.
DNA
D.
RNA
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Solution
A gene is the basic unit of heredity, responsible for the transmission of traits from parents to offspring.
Correct Answer:
B
— Gene
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Q. What is the expected genotype ratio from a cross between two heterozygous individuals (Aa x Aa)?
A.
1:1
B.
3:1
C.
1:2:1
D.
9:3:3:1
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Solution
The expected genotype ratio from a cross between two heterozygous individuals (Aa x Aa) is 1:2:1, representing the possible combinations of alleles.
Correct Answer:
C
— 1:2:1
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Q. What is the expected genotypic ratio from a dihybrid cross?
A.
1:2:1
B.
3:1
C.
9:3:3:1
D.
1:1:1:1
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Solution
The expected genotypic ratio from a dihybrid cross is 9:3:3:1, representing the combinations of two traits.
Correct Answer:
C
— 9:3:3:1
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Q. What is the expected genotypic ratio from a monohybrid cross between two heterozygous parents (Aa x Aa)?
A.
1:2:1
B.
3:1
C.
9:3:3:1
D.
1:1
Show solution
Solution
The expected genotypic ratio from a monohybrid cross of Aa x Aa is 1:2:1.
Correct Answer:
A
— 1:2:1
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Q. What is the expected genotypic ratio from a monohybrid cross?
A.
1:1
B.
3:1
C.
1:2:1
D.
9:3:3:1
Show solution
Solution
The expected genotypic ratio from a monohybrid cross is 1:2:1, representing the combinations of alleles.
Correct Answer:
C
— 1:2:1
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Q. What is the expected genotypic ratio in the F2 generation of a monohybrid cross?
A.
1:2:1
B.
3:1
C.
9:3:3:1
D.
1:1
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Solution
The expected genotypic ratio in the F2 generation of a monohybrid cross is 1:2:1, representing the homozygous dominant, heterozygous, and homozygous recessive genotypes.
Correct Answer:
A
— 1:2:1
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Q. What is the expected genotypic ratio of a monohybrid cross?
A.
1:1
B.
3:1
C.
1:2:1
D.
9:3:3:1
Show solution
Solution
The expected genotypic ratio of a monohybrid cross is 1:2:1, representing the combinations of alleles.
Correct Answer:
C
— 1:2:1
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Q. What is the expected phenotypic ratio in a monohybrid cross?
A.
3:1
B.
1:2:1
C.
9:3:3:1
D.
1:1
Show solution
Solution
The expected phenotypic ratio in a monohybrid cross is 3:1 for dominant to recessive traits.
Correct Answer:
A
— 3:1
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Q. What is the expected phenotypic ratio in the F2 generation of a monohybrid cross?
A.
3:1
B.
1:2:1
C.
9:3:3:1
D.
1:1
Show solution
Solution
In a monohybrid cross, the expected phenotypic ratio in the F2 generation is 3:1, where three offspring display the dominant trait and one displays the recessive trait.
Correct Answer:
A
— 3:1
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Q. What is the expected phenotypic ratio in the offspring of a monohybrid cross?
A.
1:1
B.
3:1
C.
9:3:3:1
D.
1:2:1
Show solution
Solution
In a monohybrid cross, the expected phenotypic ratio is 3:1, where three offspring display the dominant trait and one displays the recessive trait.
Correct Answer:
B
— 3:1
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Q. What is the expected phenotypic ratio of a dihybrid cross between two heterozygous individuals (AaBb x AaBb)?
A.
3:1
B.
9:3:3:1
C.
1:2:1
D.
1:1
Show solution
Solution
The expected phenotypic ratio for a dihybrid cross is 9:3:3:1, representing the combinations of two traits.
Correct Answer:
B
— 9:3:3:1
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Q. What is the expected phenotypic ratio of a test cross involving a heterozygous individual?
A.
1:1
B.
3:1
C.
9:3:3:1
D.
1:2:1
Show solution
Solution
The expected phenotypic ratio of a test cross involving a heterozygous individual is 1:1, as it is crossed with a homozygous recessive individual.
Correct Answer:
A
— 1:1
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Q. What is the function of a promoter in gene expression?
A.
To enhance transcription
B.
To initiate transcription
C.
To terminate transcription
D.
To bind ribosomes
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Solution
A promoter is a DNA sequence that initiates transcription by providing a binding site for RNA polymerase.
Correct Answer:
B
— To initiate transcription
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Q. What is the function of messenger RNA (mRNA)?
A.
To carry amino acids
B.
To store genetic information
C.
To transfer genetic information from DNA to ribosomes
D.
To catalyze biochemical reactions
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Solution
Messenger RNA (mRNA) serves as the template that carries genetic information from DNA to ribosomes for protein synthesis.
Correct Answer:
C
— To transfer genetic information from DNA to ribosomes
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Q. What is the function of ribosomal RNA (rRNA)?
A.
Carries genetic information
B.
Forms the core of ribosome structure
C.
Transports amino acids
D.
Catalyzes peptide bond formation
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Solution
Ribosomal RNA (rRNA) forms the structural and functional core of ribosomes, which are essential for protein synthesis.
Correct Answer:
B
— Forms the core of ribosome structure
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Q. What is the function of ribosomes in protein synthesis?
A.
To transcribe DNA
B.
To translate mRNA into proteins
C.
To replicate DNA
D.
To splice RNA
Show solution
Solution
Ribosomes are the cellular machinery that translate mRNA into proteins by facilitating the assembly of amino acids.
Correct Answer:
B
— To translate mRNA into proteins
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Q. What is the function of ribosomes in the process of translation?
A.
To synthesize DNA
B.
To provide a site for protein synthesis
C.
To transport RNA
D.
To degrade proteins
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Solution
Ribosomes serve as the site of protein synthesis, where mRNA is translated into a polypeptide chain.
Correct Answer:
B
— To provide a site for protein synthesis
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Q. What is the function of RNA polymerase during transcription?
A.
To replicate DNA
B.
To synthesize RNA from a DNA template
C.
To splice RNA
D.
To translate mRNA into protein
Show solution
Solution
RNA polymerase synthesizes RNA by transcribing the genetic information from a DNA template.
Correct Answer:
B
— To synthesize RNA from a DNA template
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Q. What is the function of the ribosome during translation?
A.
To synthesize RNA
B.
To provide a site for protein synthesis
C.
To splice mRNA
D.
To replicate DNA
Show solution
Solution
Ribosomes serve as the cellular machinery that facilitates the assembly of amino acids into proteins during the translation process.
Correct Answer:
B
— To provide a site for protein synthesis
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Q. What is the function of transfer RNA (tRNA) during protein synthesis?
A.
To carry genetic information
B.
To form ribosomes
C.
To bring amino acids to the ribosome
D.
To replicate DNA
Show solution
Solution
tRNA brings amino acids to the ribosome during protein synthesis, matching them to the mRNA codons.
Correct Answer:
C
— To bring amino acids to the ribosome
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Q. What is the function of tRNA during translation?
A.
To carry amino acids to the ribosome
B.
To synthesize mRNA
C.
To form the ribosome structure
D.
To splice introns from mRNA
Show solution
Solution
tRNA carries specific amino acids to the ribosome, where they are added to the growing polypeptide chain.
Correct Answer:
A
— To carry amino acids to the ribosome
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Q. What is the function of tRNA in protein synthesis?
A.
To carry genetic information
B.
To synthesize RNA
C.
To bring amino acids to the ribosome
D.
To form the ribosome structure
Show solution
Solution
Transfer RNA (tRNA) functions to bring specific amino acids to the ribosome during translation, matching them to the corresponding codons on the mRNA.
Correct Answer:
C
— To bring amino acids to the ribosome
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Q. What is the function of tRNA in the cell?
A.
To carry genetic information
B.
To transport amino acids to the ribosome
C.
To synthesize RNA from DNA
D.
To splice introns from mRNA
Show solution
Solution
tRNA transports amino acids to the ribosome for incorporation into proteins.
Correct Answer:
B
— To transport amino acids to the ribosome
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