molecular basic q
Studied by 0 people
Learn
Practice Test
Spaced Repetition
Match
Flashcards1/193
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
194 Terms
Assertion (A): DNA is the genetic material in most organisms, while RNA primarily functions as a messenger in cellular processes.Reasoning (R): RNA can also act as a genetic material in certain viruses, which shows its versatility in the biological system.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Assertion is correct: DNA is indeed the primary genetic material in most living organisms.
Reasoning is also correct: In some viruses (like retroviruses), RNA acts as the genetic material. This reflects RNA’s versatility.
✅ However, the Reasoning does not fully explain why RNA is primarily a messenger in most organisms.
So, the Reasoning is true but does not directly explain the Assertion.
👉 Correct Answer: B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.
Assertion (A): The sequence of nucleotides in DNA determines the amino acid sequence in proteins.Reasoning (R): The genetic code is degenerate, meaning multiple codons can specify the same amino acid, ensuring that mutations may not always lead to changes in protein structure.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Both statements are correct.
The Reasoning supports the Assertion indirectly: it explains how the nucleotide sequence maps to amino acids.
But it's not directly explaining why the DNA sequence determines the amino acid sequence — it's more about mutation tolerance.
👉 Correct Answer: B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.
Assertion (A): DNA replication occurs in a semi-conservative manner.Reasoning (R): During replication, one strand of the DNA serves as a template, and the newly synthesized strand is complementary to the template strand.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Both are correct.
And the Reasoning does directly explain the concept of semi-conservative replication.
👉 Correct Answer: A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): RNA plays a crucial role in protein synthesis, as it serves as an adapter molecule between DNA and proteins.Reasoning (R): RNA's role in translation is limited to serving as a template for amino acid sequence synthesis, without any structural or catalytic function.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Assertion is correct — RNA (like tRNA, mRNA, rRNA) is crucial in protein synthesis.
Reasoning is incorrect — RNA does have structural and catalytic roles (e.g., rRNA in ribosomes is catalytic).
👉 Correct Answer: C) Assertion is correct, but the Reasoning is incorrect.
Assertion (A): The determination of the human genome sequence in the last decade has had significant implications for understanding genetic diseases and evolution.Reasoning (R): The sequencing of the human genome has provided insights into the exact sequence of nucleotides that constitute human DNA, enabling targeted therapies for genetic disorders.
Options
:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion
.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.
C) Assertion is correct, but the Reasoning is incorrect.
D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Both are correct.
And Reasoning clearly supports and explains the Assertion.
👉 Correct Answer: A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): DNA is more abundant than RNA in most cells.Reasoning
(R): DNA is typically the genetic material and is present in the nucleus of eukaryotic cells, while RNA is a transient molecule involved in protein synthesis.
Options:
A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.
C) Assertion is correct, but the Reasoning is incorrect.
D) Assertion is incorrect, but the Reasoning is correct.
✅ Solution:
Both statements are correct.
The Reasoning explains exactly why DNA is more stable and abundant — it's stored long-term, while RNA is short-lived.
👉 Correct Answer: A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): DNA is a polymer of deoxyribonucleotides, with the length of DNA often measured in terms of base pairs.Reasoning (R): The length of DNA determines the characteristics of an organism, with different organisms having varying numbers of base pairs in their genomes.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
Solution:
Assertion (A): This is correct. DNA is indeed a polymer made up of deoxyribonucleotides, and its length is commonly measured in terms of base pairs.
Reasoning (R): This is also correct. The length of DNA in an organism is a crucial characteristic that contributes to the organism’s traits, and different species have different numbers of base pairs.
Answer:
A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): The size of the DNA in different organisms is similar, with the number of base pairs being nearly the same across species.Reasoning (R): DNA size is a characteristic that defines the organism, but the number of base pairs varies greatly between species, such as between bacteriophages and humans.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is incorrect, but the Reasoning is correct.D) Assertion is correct, but the Reasoning is incorrect.
Solution:
Assertion (A): This is incorrect. The size of DNA in different organisms varies widely, from small genomes in bacteriophages to large genomes in humans.
Reasoning (R): This is correct. The number of base pairs differs significantly across species, with simpler organisms having fewer base pairs and more complex ones having larger genomes.
Answer:
C) Assertion is incorrect, but the Reasoning is correct.
Assertion (A): The length of DNA is defined by the number of nucleotides or base pairs in it.Reasoning (R): The base pairs in a DNA molecule contribute to its structure and determine the genetic information encoded in an organism.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
Solution:
Assertion (A): This is correct. The length of DNA is indeed defined by the number of nucleotides or base pairs.
Reasoning (R): This is correct. Base pairs in DNA not only contribute to its physical structure but also encode the genetic information that determines the traits of an organism.
Answer:
A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): The genome size of Escherichia coli is approximately 4.6 × 10^6 base pairs.Reasoning (R): The genome size of E. coli is relatively small compared to that of a human, which has 3.3 × 10^9 base pairs.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
Solution:
Assertion (A): This is correct. The genome size of E. coli is approximately 4.6 × 10^6 base pairs.
Reasoning (R): This is also correct. The genome of E. coli is indeed much smaller compared to that of humans, whose genome contains around 3.3 × 10^9 base pairs.
Answer:
A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.
Assertion (A): A bacteriophage known as φ ×174 has a genome length of 5386 nucleotides.Reasoning (R): Bacteriophages like φ ×174 have small genomes compared to organisms like E. coli or humans due to their simple structure and function.
Options:A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion.B) Both Assertion and Reasoning are correct, but the Reasoning does not explain the Assertion.C) Assertion is correct, but the Reasoning is incorrect.D) Assertion is incorrect, but the Reasoning is correct.
Assertion (A): This is correct. The φ ×174 bacteriophage has a genome length of 5386 nucleotides.
Reasoning (R): This is also correct. Bacteriophages have smaller genomes because they are simpler and do not require as much genetic material as more complex organisms like E. coli or humans.
Answer:
A) Both Assertion and Reasoning are correct, and the Reasoning correctly explains the Assertion
Assertion (A): DNA is the genetic material in most organisms, while RNA mainly acts as a messenger.Reason (R): RNA is found only in the cytoplasm of eukaryotic cells and serves no catalytic function.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: C
👉 RNA is indeed a messenger, but it is also found in the nucleus (e.g., hnRNA) and can have catalytic roles (e.g., ribozymes).
Assertion (A): RNA can act as genetic material in some viruses.Reason (R): RNA is more stable than DNA and hence preferred in viruses.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: C
👉 RNA can be genetic material (e.g., retroviruses), but it is less stable than DNA — which is why DNA is genetic material in most organisms.
Assertion (A): The sequence of nucleotides in DNA determines the sequence of amino acids in a protein.Reason (R): The genetic code is non-overlapping, unambiguous, and universal in all living organisms.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: B
👉 Both are true, but R is describing properties of the genetic code — not directly explaining how nucleotide sequences determine proteins.
Assertion (A): DNA is a long polymer of ribonucleotides.Reason (R): The presence of ribose sugar and uracil in DNA makes it more stable than RNA.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is false, but R is trueD) Both A and R are false
✅ Correct Answer: D
👉 DNA is made of deoxyribonucleotides, not ribonucleotides. Also, DNA contains deoxyribose and thymine, not ribose and uracil.
Assertion (A): The discovery that DNA is the genetic material was established much after Mendel’s time.Reason (R): Mendel had postulated "factors" without knowing the molecular nature of genes.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Mendel worked in the 1860s, and DNA was established as the genetic material in the 1940s–50s (Avery, Hershey-Chase). He didn’t know about DNA but called them "factors."
Assertion (A): In DNA, Adenine always pairs with Thymine, and Guanine always pairs with Cytosine.Reason (R): The base pairing rules are based on the fact that Adenine and Thymine form two hydrogen bonds, while Guanine and Cytosine form three hydrogen bonds.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both statements are correct, and the Reasoning explains the Assertion because the specific hydrogen bonds between the bases help form stable pairs.
Assertion (A): DNA is a right-handed double helix with two strands running in anti-parallel direction.Reason (R): Anti-parallel strands refer to the fact that one strand has a 5' → 3' polarity and the other strand has 3' → 5' polarity.
Options:A) Both A and R are true, and R explains AB) Both A and R are true,
but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both the Assertion and Reasoning are correct, and the Reasoning directly explains why the DNA strands run anti-parallel.
Assertion (A): The backbone of a polynucleotide chain is composed of sugar-phosphate linkages.Reason (R): The nitrogenous bases in the polynucleotide chain are linked to each other via hydrogen bonds.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both statements are correct. The sugar-phosphate backbone holds the chain together, while the bases form hydrogen bonds between the two strands of DNA.
Assertion (A): The DNA structure proposed by Watson and Crick is based on the observation that the ratio of Adenine to Thymine and Guanine to Cytosine is always 1:1 in double-stranded DNA.Reason (R): This observation was made by Erwin Chargaff, and it helped confirm the base-pairing rules in DNA.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both statements are correct, and the Reasoning directly explains why the Chargaff ratio is important for the base-pairing rules in DNA.
Assertion (A): DNA replication is semi-conservative, meaning each new DNA molecule consists of one old strand and one newly synthesized strand.Reason (R): This is because the DNA strands act as templates for the synthesis of complementary strands during replication.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both statements are correct, and the Reasoning explains how the semi-conservative model works by using the template-strand mechanism during DNA replication..
Assertion (A): The double-helix structure of DNA has a uniform distance between the two strands, which is maintained due to the complementary base-pairing.Reason (R): The base-pairing rules, where Adenine pairs with Thymine (2 hydrogen bonds) and Guanine pairs with Cytosine (3 hydrogen bonds), result in a consistent width between the two strands.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A👉 Both the Assertion and Reasoning are correct, and the Reasoning explains how the chain’s directionality is maintained through 3'-5' phosphodiester bonds.
Assertion (A): The 5' end of a polynucleotide chain has a free phosphate group, and the 3' end has a free hydroxyl group.Reason (R): The 3'-5' phosphodiester linkage connects the nucleotides in the polynucleotide chain.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Correct Answer: A
👉 Both the Assertion and Reasoning are correct, and the Reasoning explains how the chain’s directionality is maintained through 3'-5' phosphodiester bonds.
Assertion (A): DNA replication is semi-conservative in nature.Reason (R): Each new DNA molecule contains two newly synthesized strands.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅
✅ Answer: C
🔍 Reason is incorrect because only one strand in each daughter DNA is newly synthesized. The other strand is from the parent.
Assertion (A): DNA polymerase can initiate DNA synthesis on its own.Reason (R): DNA polymerase can only extend a pre-existing nucleotide chain using a template.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: D
🔍 DNA polymerase cannot start synthesis on its own; it requires a primer. So, the assertion is false, but the reason is true.
Assertion (A): Okazaki fragments are formed on the leading strand during DNA replication.Reason (R): DNA replication on the leading strand is discontinuous.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: D🔍 Okazaki fragments are formed on the lagging strand, not the leading. So Assertion is false, but Reason is correct (for the lagging strand).
Assertion (A): DNA ligase is essential for joining the fragments formed on the lagging strand.Reason (R): DNA ligase synthesizes RNA primers for initiating DNA synthesis.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 DNA ligase’s job is to seal the nicks between Okazaki fragments, not synthesize primers (that's the job of primase).
Assertion (A): Helicase unwinds the DNA double helix at the replication fork.Reason (R): Helicase creates phosphodiester bonds between the nucleotides.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Helicase does unwind DNA, but it does not make phosphodiester bonds. That’s done by DNA polymerase.
Assertion (A): The distance between the two strands in a DNA double helix remains nearly constant.Reason (R): A purine always pairs with another purine, and a pyrimidine with another pyrimidine.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅
Answer: C🔍 Purines pair with pyrimidines (A with T, G with C), not with each other. This maintains a uniform diameter of ~2 nm.
Assertion (A): Hydrogen bonds alone are responsible for the stability of the DNA double helix.Reason (R): The base pairs in DNA stack over one another which adds additional stability.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: D🔍 Base stacking interactions (hydrophobic forces and Van der Waals) also contribute to DNA's stability, not just hydrogen bonds.
Assertion (A): The central dogma of molecular biology explains the flow of genetic information from DNA → RNA → Protein.Reason (R): Reverse transcription is the process of converting DNA to RNA.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Reverse transcription is RNA → DNA, not DNA → RNA. So the reason is false.
Assertion (A): Histones are positively charged proteins that help in DNA packaging in eukaryotes.Reason (R): Histones are rich in lysine and arginine, which have negatively charged side chains.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Lysine and arginine have positively charged side chains, not negative. That’s why histones can bind negatively charged DNA.
Assertion (A): A nucleosome contains around 200 base pairs of DNA.
Reason (R): DNA is negatively charged and wraps around the positively charged histone octamer.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: A🔍 This is the exact mechanism — electrostatic interaction allows DNA to coil around histone octamers forming nucleosomes.
Assertion (A): Euchromatin is transcriptionally active chromatin.Reason (R): Euchromatin is loosely packed and stains dark under a microscope.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Euchromatin is transcriptionally active, but it stains light, not dark. Dark stain = heterochromatin.
Assertion (A): Thomas Hunt Morgan’s experiments with Drosophila confirmed that genes are located on chromosomes
.Reason (R): Morgan's experiments showed that genes are inherited together as they are physically linked on the chromosome.
Options:
A) Both A and R are true, and R explains A
B) Both A and R are true,
but R does not explain A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A🔍 Morgan’s work confirmed that genes are located on chromosomes, and his discovery of linked genes showed how genes inherit together due to their physical proximity on chromosomes.
Assertion (A): Sutton and Boveri’s chromosome theory of inheritance proposed that chromosomes carry genetic material.Reason (R): The chromosome theory was crucial in narrowing down the search for genetic material.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: A🔍 Sutton and Boveri’s work helped focus attention on chromosomes as the likely carriers of genetic material, which was crucial for further research.
Assertion (A): Meischer was the first to isolate DNA from the nucleus.
Reason (R): Meischer’s work led to the identification of the molecule that carries genetic information.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Meischer isolated nuclein (DNA) but did not know it was the genetic material. The conclusion came much later after more research.
Assertion (A): Thomas Hunt Morgan’s experiments with Drosophila confirmed that genes are located on chromosomes.
Reason (R): Morgan's experiments showed that genes are inherited together as they are physically linked on the chromosome.
Options:
A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
🔍 Morgan’s work confirmed that genes are located on chromosomes, and his discovery of linked genes showed how genes inherit together due to their physical proximity on chromosomes.
Assertion (A): Griffith's experiment demonstrated the phenomenon of bacterial transformation
.Reason (R): Griffith’s experiment proved that proteins were the genetic material responsible for inheritance in bacteria.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: C🔍 Griffith's experiment showed transformation occurred via a "transforming principle," which was later identified as DNA, not protein.
Q5.
Assertion (A): Avery, MacLeod, and McCarty’s experiment conclusively showed that DNA is the transforming principle.
Reason (R): Their work was pivotal in proving that DNA, not protein, is the carrier of genetic information.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: A🔍 Avery, MacLeod, and McCarty demonstrated that DNA was the transforming principle, showing that DNA carries genetic information.
Q6.
Assertion (A): Hershey and Chase’s experiment with bacteriophages proved that DNA is the genetic material.Reason (R): Hershey and Chase used radioactive phosphorus to label the DNA of the phage and tracked it during infection.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: A🔍 Hershey and Chase demonstrated that DNA, not protein, was injected into bacterial cells during viral infection, thus proving it’s the genetic material.
Assertion (A): Heat-killed S strain of Streptococcus pneumoniae caused pneumonia in mice.Reason (R): The heat-killed S strain possesses a polysaccharide coat which is responsible for virulence.
Options:A) Both A and R are true, and R explains AB) Both A and R are true, but R does not explain AC) A is true, but R is falseD) A is false, but R is true
✅ Answer: D🔍 Heat-killed S strain alone cannot cause pneumonia. It’s non-virulent after heating, even though the polysaccharide coat remains.
Q2. Conceptual
What was the main conclusion drawn by Griffith from his experiment?
A) Protein is the genetic materialB) R strain naturally mutates into S strainC) A chemical from heat-killed S strain transformed R strainD) DNA is the genetic material
✅ Answer: C🔍 Griffith didn’t identify DNA but discovered that a "transforming principle" could transfer virulence.
Q3. True or False
Griffith's experiment proved that DNA is the genetic material.
✅ Answer: False🔍 Griffith's experiment only showed that a transforming principle exists. Later experiments proved that the transforming principle is DNA.
Q4. Fill in the Blank
Griffith’s experiment involved the transformation of ___ strain into ___ strain by a transforming principle.
✅ Answer: R strain into S strain
1. Assertion-Reason Question (Hard)
Assertion (A): Griffith’s experiment with Streptococcus pneumoniae demonstrated that a transforming principle could change a non-virulent strain into a virulent strain.Reason (R): The experiment provided evidence that the transforming principle was a protein, as proteins are known to play a role in genetic inheritance.
Options:A) Both A and R are true, and R explains A.B) Both A and R are true, but R does not explain A.C) A is true, but R is false.D) A is false, but R is true.
Answer:✅ C) A is true, but R is false.🔍 Griffith's experiment showed transformation, but the nature of the transforming principle was not identified as protein. It was later shown to be DNA (not protein).
Griffith observed that when live R strain and heat-killed S strain were mixed, the mice died. Which of the following is the most likely reason for this outcome?A) The R strain became virulent due to mutations in the bacteria.B) The heat-killed S strain bacteria were reactivated and became virulent.C) The R strain was transformed by a genetic material from the heat-killed S strain.D) The R strain produced toxins when exposed to heat-killed S strain.
Answer:✅ C) The R strain was transformed by a genetic material from the heat-killed S strain.🔍 The R strain was not virulent on its own but took up genetic material (likely DNA) from the heat-killed S strain, resulting in the formation of virulent S strain bacteria.
Which of the following statements about Griffith's experiment is incorrect?A) Heat-killed S strain caused pneumonia when mixed with live R strain.B) Griffith concluded that the transforming principle was a protein.C) The heat-killed S strain alone did not cause pneumonia in mice.D) The heat-killed S strain could pass on its virulence trait to R strain bacteria.
Answer:✅ B) Griffith concluded that the transforming principle was a protein.🔍 Griffith only concluded that some "transforming principle" existed, but he didn’t identify it as protein. It was later proven to be DNA by other scientists.
Which of the following experimental results would have most likely disproven Griffith's hypothesis that transformation of R strain into S strain was due to a "transforming principle"?A) If no bacteria were found in the blood of the mice that were injected with the mixture of live R and heat-killed S strain.B) If live R strain was injected alone into the mice and the mice survived.C) If live S strain was injected into mice and they survived.D) If protein-digesting enzymes completely eliminated the transforming ability of the heat-killed S strain bacteria.
Answer:✅ D) If protein-digesting enzymes completely eliminated the transforming ability of the heat-killed S strain bacteria.🔍 If protein-digesting enzymes destroyed the ability of heat-killed S strain to transform the R strain, it would have supported the idea that protein was the transforming material. However, the transforming material was later proven to be DNA.
Answer:
✅
A = 1) Transformation
B = 2) Heat-killed S strain
C = 3) Avery, MacLeod, and McCarty
D = 4) Mice dying from mixed injection of live R and heat-killed S strain
5. Matching (Advanced)
Match the statements with the correct description based on Griffith's experiment.
A) The phenomenon observed by Griffith.
B) The hypothesis made by Griffith.
C) The subsequent experiment that identified the transforming principle.
D) The key result of Griffith’s experiment.
Statements | Descriptions |
|---|---|
1) Transformation | i) Protein is the genetic material. |
2) Heat-killed S strain | ii) R strain is converted to S strain. |
3) Avery, MacLeod, and McCarty | iii) DNA is the genetic material. |
4) Mice dying from mixed injection of live R and heat-killed S strain | iv) Mice survive without the heat-killed S strain. |
Answer:
✅ B) The transformation would still occur, and the mice would still develop pneumonia because the genetic material from the heat-killed S strain would still be transferred.
🔍 Transformation is the process where genetic material is transferred, not dependent on the formation of a polysaccharide coat. The R strain would still acquire the genetic information to form a virulent S strain
.If a similar experiment to Griffith's had been conducted with a strain of bacteria that lacked a cell wall (i.e., no polysaccharide coat), which of the following would be most likely true about the outcome?
A) The transformation would still occur, but the mice might not show pneumonia symptoms because there is no cell wall to protect the bacteria.
B) The transformation would still occur, and the mice would still develop pneumonia because the genetic material from the heat-killed S strain would still be transferred.
C) The transformation would not occur because no polysaccharide coat is formed by the R strain.
D) The transformation would not occur because bacteria without a cell wall cannot be transformed.
Q1: What was the key finding from the work of Oswald Avery, Colin MacLeod, and Maclyn McCarty (1933-44) regarding the transforming principle in Griffith's experiment?
A) Proteins were the transforming principle.
B) RNA was the transforming principle.
C) DNA was the transforming principle.
D) Carbohydrates were the transforming principle.
Answer:
C) DNA was the transforming principle.In their experiments, Avery, MacLeod, and McCarty demonstrated that DNA is the substance responsible for transferring genetic information and is the true transforming principle, as opposed to proteins or RNA.
Q2: What did Avery, MacLeod, and McCarty discover when they digested the heat-killed S bacteria with proteases and RNases?
A) Transformation still occurred, suggesting the transforming principle was DNA.
B) Transformation was blocked, suggesting the transforming principle was RNA.
C) Transformation was blocked, suggesting the transforming principle was protein.
D) There was no effect on transformation, suggesting the transforming principle was lipids.
Answer:
A) Transformation still occurred, suggesting the transforming principle was DNA.
Q3: What was the effect of DNase digestion in Avery's experiment?
A) It had no effect, suggesting DNA was not the transforming principle.
B) It blocked transformation, suggesting DNA was the transforming principle.
C) It enhanced transformation, suggesting DNA was the transforming principle.
D) It completely killed the R strain bacteria.
Answer:
B) It blocked transformation, suggesting DNA was the transforming principle.
Q4: What is the main difference between DNAs and DNase?
A) DNAs are enzymes that break down DNA, while DNase is the genetic material.
B) DNAs is the genetic material in organisms, while DNase is an enzyme that degrades DNA.
C) DNAs are proteins, while DNase is a carbohydrate.
D) DNAs is a lipoprotein, while DNase is a glycoprotein.
Answer:
B) DNAs is the genetic material in organisms, while DNase is an enzyme that degrades DNA.
Q1: In Avery’s experiment, transformation was not inhibited by protease or RNase but was inhibited by DNase. What does this imply about the nature of the transforming principle?
A) The transformation was RNA-mediated but protein-dependent
B) The transforming principle was likely a lipid protected by proteins
C) The genetic material responsible for transformation is DNA
D) RNA and protein together are responsible for transformation
Answer:
C) The genetic material responsible for transformation is DNA
Q2: If DNase was accidentally inactivated in Avery’s experiment, what misleading conclusion might the scientists have drawn?
A) DNA is not necessary for transformation
B) Protein is the genetic material
C) Transformation does not occur at all
D) RNA is more important than DNA in heredity
Answer:
A) DNA is not necessary for transformation
Q3: Why did the scientific community initially hesitate to accept DNA as the genetic material despite Avery’s findings?
A) DNA was already known to be a structural protein
B) Proteins were more chemically complex and thought to carry genetic information
C) DNA was too stable to store dynamic information
D) DNA could not be isolated from bacterial cells
Answer:
B) Proteins were more chemically complex and thought to carry genetic information
Q4: Which of the following experimental conditions would most likely disprove Avery’s conclusion if transformation still occurred?
A) Treating the extract with RNase
B) Treating the extract with lipase
C) Treating the extract with DNase
D) Boiling the DNA extract before adding it to R strain
Answer:
C) Treating the extract with DNase
Q5: Avery's conclusion about DNA being the genetic material was strengthened primarily because:
A) DNA resisted all enzymatic digestion
B) DNA from S strain alone was sufficient to transform R strain
C) RNA from R strain could transform the S strain
D) Protein alone was enough to cause transformation
Answer:
B) DNA from S strain alone was sufficient to transform R strain
Assertion (A): Avery, MacLeod and McCarty used DNase to destroy the transforming principle.
Reason (R): DNA was the only biomolecule that stopped transformation when digested.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
Q2.
Assertion (A): Protease and RNase treatment did not prevent transformation in Avery’s experiment.
Reason (R): Proteins and RNA are not involved in genetic information transfer.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: B
(Reason is partially true — while RNA is involved in gene expression, it is not the genetic material in most organisms.)
Q3.
Assertion (A): Avery’s experiment conclusively proved that DNA is the genetic material in all living organisms.
Reason (R): DNA is the only biomolecule capable of transforming R strain into virulent S strain.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: D
(Avery’s experiment strongly suggested DNA is the genetic material, but it wasn’t accepted as universal proof until the Hershey-Chase experiment.)
Q5.
Assertion (A): The transforming principle is heat-sensitive.
Reason (R): Heat-killed S strain bacteria could not cause pneumonia in mice on their own.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: C
(The transforming principle — DNA — is heat-stable. Proteins denature with heat, but DNA can survive mild heating, so A is incorrect.)
Q1.
Assertion (A): In the double-helix model, the two strands of DNA are anti-parallel.
Reason (R): One strand runs in 5’ to 3’ direction while the other runs in 3’ to 5’.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
Q2.
Assertion (A): Purines always pair with purines and pyrimidines with pyrimidines.
Reason (R): This pairing maintains the uniform diameter of the DNA helix.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: C
(Purines pair with pyrimidines — not with purines — to maintain a uniform width of 20 Å.)
Q3.
Assertion (A): Base stacking contributes to DNA helix stability.
Reason (R): The bases are hydrophilic and form hydrogen bonds with the aqueous environment.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is truex
✅ Answer: C
(Purines pair with pyrimidines — not with purines — to maintain a uniform width of 20 Å.)
Q5.
Assertion (A): Euchromatin is more transcriptionally active than heterochromatin.
Reason (R): Euchromatin is loosely packed and accessible to RNA polymerase.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
🦠 HERSHEY-CHASE EXPERIMENT
Q6.
Assertion (A): Hershey and Chase used radioactive phosphorus to label viral proteins.
Reason (R): Proteins contain phosphorus but not sulfur.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: C
(Proteins lack phosphorus; DNA contains it. Proteins were labeled with S-35, not P-32.)
Q7.
Assertion (A): DNA entered the bacterial cells in the Hershey-Chase experiment, but not the protein coat.
Reason (R): DNA carries the genetic material needed for viral replication.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
1.
Assertion (A): Thymine is replaced by uracil in RNA because uracil is more stable than thymine.
Reason (R): Uracil has an additional methyl group which makes it more reactive.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(Uracil is less stable than thymine. Thymine has the extra methyl group, not uracil!)
Assertion (A): Hydrogen bonding between base pairs is the only reason for the stability of DNA helix.
Reason (R): Base stacking interactions and hydrophobic interactions also play a significant role in DNA stability.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: C
(Base stacking interactions significantly contribute to helix stability.)
Assertion (A): Avery, MacLeod and McCarty used enzymes to destroy proteins, RNA and DNA to confirm the transforming principle.
Reason (R): Transformation was not affected by DNase treatment but stopped with RNase.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also falsee.)
✅ Answer: C
(Transformation was unaffected by RNase, but stopped by DNase. So R is fals
Assertion (A): DNA replication follows semi-conservative mode.
Reason (R): In each new DNA molecule, one strand is old and the other is newly synthesized.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: A
Assertion (A): Eukaryotic DNA is wrapped around histones forming nucleosomes, which are acidic in nature.
Reason (R): Histone proteins contain large numbers of acidic amino acids like aspartic acid.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(Histones are basic, not acidic. They contain lysine and arginine, not aspartic acid.)
Assertion (A): In Watson and Crick’s DNA model, the helix turns right-handedly with 10 base pairs per turn.
Reason (R): The pitch of the helix is 3.4 nm, and the distance between base pairs is 0.34 nm.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
v
✅ Answer: A
Assertion (A): The genetic material in all organisms is always DNA.
Reason (R): RNA is never found as the genetic material in any organism.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(Some viruses like retroviruses use RNA as genetic material.)
Assertion (A): DNA was confirmed as the genetic material by tracking radioactive sulfur in bacteriophages.
Reason (R): Sulfur is present in DNA, not in proteins.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(DNA does not contain sulfur; proteins do. They used sulfur to label protein, not DNA.)
Assertion (A): DNA is the only molecule from bacteriophage that enters the bacterial host.
Reason (R): DNA carries the complete information required for synthesis of new viral particles.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: A
In the Hershey-Chase experiment, it was shown that only DNA from the bacteriophage enters the bacterial cell, not the protein coat.
DNA contains the genetic instructions to produce new viral particles.
Both A and R are true, and R correctly explains A.
Correct answer: A) Both A and R are true, and R is the correct explanation of A
Assertion (A): In Hershey and Chase’s experiment, protein coat entered the host cell and caused infection.
Reason (R): The protein of the virus carries instructions for making new viral particles.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(Protein coat does not enter the host, and does not carry genetic instructions. DNA does!)
Assertion (A): The blender step in Hershey and Chase's experiment was used to separate the phage coats from bacterial cells.
Reason (R): Viral genetic material is loosely attached to the outer surface of the host and can be removed by agitation.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: C
(A is true – the blender separated coats, but R is false – the genetic material enters the cell and cannot be removed by shaking.)
Assertion (A): DNA is preferred over RNA as genetic material in most organisms.
Reason (R): DNA is chemically less reactive and structurally more stable than RNA.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: A
(Stability of DNA due to deoxyribose sugar and double-stranded structure makes it ideal for long-term storage.)
Assertion (A): RNA is more stable than DNA because it is single stranded and contains uracil.
Reason (R): Uracil pairing with adenine makes RNA less susceptible to hydrolysis.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(RNA is actually less stable than DNA due to 2'-OH group in ribose and uracil instead of thymine.)
Assertion (A): DNA has thymine instead of uracil, which contributes to its greater stability.
Reason (R): Thymine is methylated form of uracil and resists spontaneous mutation.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
(Presence of thymine makes mutation repair easier; methyl group adds to stability.)
Assertion (A): DNA can act as both genetic material and catalyst.
Reason (R): DNA has 2'-OH group that allows it to function as a ribozyme.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(RNA—not DNA—acts as ribozyme due to 2’-OH group. DNA lacks catalytic activity.)
Assertion (A): RNA is considered the first genetic material during evolution.
Reason (R): RNA can store genetic information as well as catalyse chemical reactions.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is true, but R is false
✅ Answer: A
(This is the basis of RNA World Hypothesis — RNA is ancient and multifunctional.)
Assertion (A): RNA was the first genetic material during early evolution.
Reason (R): RNA can act as both genetic material and catalyst in biochemical reactions.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
✅ Answer: A
(RNA world hypothesis is based on the fact that RNA could store information AND catalyse reactions.)
Q2.
Assertion (A): DNA evolved later from RNA to become a more stable genetic material.
Reason (R): DNA contains ribose sugar, which makes it more chemically stable than RNA.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(DNA evolved for stability, but it has deoxyribose, not ribose. Hence R is false.)
Assertion (A): RNA is still present in all living organisms because it carries out essential catalytic roles.
Reason (R): All enzymes in cells are made up of RNA.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(RNA plays catalytic roles in some reactions like splicing (e.g., ribozymes), but not ALL enzymes are RNA-based.)
Assertion (A): The presence of repair mechanisms in DNA is an adaptation to prevent loss of genetic information.
Reason (R): DNA is double-stranded and has complementary base pairing which allows error correction.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: A
(The double-stranded nature with base complementarity enables repair — important for stability and storage.)
Q5.
Assertion (A): RNA evolved into DNA because RNA was too stable to perform genetic functions efficiently.
Reason (R): DNA is more reactive due to the presence of uracil, which enhances mutation rate.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is false, but R is true
D) A is false, and R is also false
✅ Answer: D
(Completely incorrect: RNA was too unstable, not too stable. DNA has thymine, not uracil. Hence both false.)
Assertion (A): DNA replication is called semiconservative.
Reason (R): In each daughter DNA molecule, one strand is newly synthesized and the other is parental.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: A
(This is the exact definition of semiconservative replication.)
Assertion (A): Watson and Crick were awarded the Nobel Prize in Physiology or Medicine for discovering the semiconservative nature of DNA replication.
Reason (R): They performed experiments that confirmed the replication model.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(Watson and Crick proposed the model. Meselson and Stahl confirmed it experimentally. Watson and Crick were awarded for the structure of DNA.
Assertion (A): Each strand of DNA serves as a template during replication.
Reason (R): DNA polymerase can initiate synthesis of a new strand without a primer.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(DNA strands do act as templates, but DNA polymerase requires a primer to initiate synthesis.)
Assertion (A): Complementary base pairing plays a crucial role in DNA replication.
Reason (R): Each nitrogenous base can pair with any other base in the newly forming strand.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(Complementary base pairing is crucial, but the base pairing is specific — A with T, G with C.)
Assertion (A): The process of DNA replication is called semiconservative.
Reason (R): Both daughter DNA molecules are made entirely from new nucleotides.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: C
(Semiconservative means one old + one new strand. So R is incorrect.)
Assertion (A): After one round of replication in 14N medium, E. coli DNA showed intermediate density.
Reason (R): One strand was made of 15N-DNA and the other was made of 14N-DNA.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: A
(Hybrid DNA forms because one parental (heavy) strand pairs with one newly synthesized (light) strand.)
Assertion (A): In Meselson and Stahl’s experiment, DNA extracted after two generations showed two bands in CsCl gradient.
Reason (R): After two generations, half of the DNA molecules are hybrid and half are light.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: A
(With each generation, the proportion of hybrid decreases and light DNA increases.)
Assertion (A): DNA replication was proven to be conservative by Meselson and Stahl.
Reason (R): After one generation, both heavy and light bands were observed.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: D (They disproved the conservative model. Only one intermediate band was seen after one generation, not both heavy and light.)DNA replication is not conservative.
Q1.
Assertion (A): After one round of replication in 14N medium, E. coli DNA showed intermediate density.
Reason (R): One strand was made of 15N-DNA and the other was made of 14N-DNA.
A) Both A and R are true, and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, and R is also false
✅ Answer: A
(Hybrid DNA forms because one parental (heavy) strand pairs with one newly synthesized (light) strand.)