Biology

DNA and Genetics

1,095 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice

Okazaki fragments are

  1. short DNA fragments on the lagging strand

  2. short DNA fragments on the leading strand

  3. RNA primers required for initiation of DNA synthesis

  4. DNA fragments produced due to radiation action
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Okazaki fragments are short DNA fragments on the lagging strand. Synthesis of the lagging strand requires working in relatively small, discontinuous stretches. These discontinuous stretches are synthesised just as the leading strand, by the addition of new nucleotides one at a time to the 3′ end of the new strand, but the synthesis of this new strand moves in the direction opposite to that in which the replication fork is moving. These stretches of new DNA for the lagging strand are called Okazaki fragments.

Multiple choice

The Avery-Macleod-McCarty experiment demonstrated that

  1. RNA is involved in transduction in bacteria

  2. DNA is involved in transduction in bacteria

  3. DNA causes transformation in bacteria

  4. RNA causes transformation in bacteria
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 The Avery-Macleod-McCarty experiment was carried out by three scientists to show that transformation in bacteria is caused by taking up free DNA by bacteria either naturally or artificially in lab.

Multiple choice

Identify the respect in which these two items are similar. The relation between an enzyme and its substrate is like the relationship between a lock and a key. Just as each key acts only upon a specific lock, so each enzyme acts only upon a specific substrate. Thus, no enzyme is an all-purpose tool.

  1. An enzyme acts only upon a specific substrate and it is not an all-purpose tool.

  2. A key acts only upon a specific lock and it is not an all-purpose tool.

  3. An enzyme acts only upon a specific substrate and it is a key.

  4. A key acts only upon a specific lock and it is an all-purpose tool.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Choice (2) is the fundamental example. Choice (1) is correct but the phrase “an enzyme is not an all-purpose tool” is a conclusion of the argument based on the similarity (or specificity of action) between an enzyme and a lock.

Multiple choice

Which of the following statements does not characterise the organisms containing recombinant DNA?

  1. Western hybridisation methods can be used to detect RNA and/or protein products.

  2. The organisms containing recombinant DNA have apparently normal phenotypes.

  3. Additional phenotypes that are encountered include toxicity to the host organism.

  4. Recombinant DNA can have beneficial effects even if it is not expressed.

  5. Inappropriate activation of previously unexpressed host cell genes can insert rDNA into chromosomal DNA.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In some cases, recombinant DNA can have deleterious effects even if it is not expressed. 

Multiple choice

Which of the following sequencing methods is a non-enzymatic method of DNA sequencing?

  1. Microscopy-based techniques

  2. Sequencing by hybridization

  3. Tunneling currents DNA sequencing

  4. RNAP sequencing

  5. Microfluidic Sanger sequencing
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sequencing by hybridization is a non-enzymatic method that uses a DNA microarray. A single pool of DNA whose sequence is to be determined, is fluorescently labeled and hybridized to an array containing known sequences. Strong hybridization signals from a given spot on the array identify its sequence in the DNA being sequenced.

Multiple choice

Below are some ways through which DNA molecule can be analyzed. In which of these methods, the agarose gel electrophoresis is associated?

  1. DNA transformation

  2. Microarrays

  3. Restriction Enzyme Digestion and Analysis

  4. Polymerase chain reaction

  5. DNA sequencing
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Restriction enzymes are made up of proteins. The main purpose of restriction enzymes is to make new copies of DNA and analyze it. Agarose gel electrophoresis is the main technique which makes use of the restriction enzymes. When the solution containing DNA molecules and restriction enzymes is placed in the gel, an electric current is passed through it which cuts the DNA into fine small fragments.  

Multiple choice

Which of the following statements regarding DNA footprinting procedure is incorrect?

  1. DNA fragment thought to contain protein binding sequence is extracted, amplified and labelled at both the ends of DNA.

  2. Protein has protected the DNA binding site from cleavage agent.

  3. DNA fragments are separated by polyacrylamide gel electrophoresis.

  4. The missing band indicates the protein binding specific DNA sequence.

  5. The labelled DNA fragments are mixed with cleavage agents without DNA binding protein.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This statement is incorrect, hence the right answer. DNA fragment thought to contain protein binding sequence is extracted, amplified and labelled at one end of the double helix using polymerase chain reaction technique.

Multiple choice

The pseudogenes can interfere with the PCR and in situ hybridisation experiments. Which of the following statements regarding the pseudogenes is FALSE?

  1. Exact mapping of the pseudogenes onto chromosomes is extremely difficult.

  2. The absolute rate of mutation is lower in nucleus than the one occurring in mitochondria.

  3. They form a molecular record of the evolutionary history and statistics of the parental genome.

  4. They are also useful to find the rate of nucleotide substitutions, DNA loss, etc.

  5. Multiple pseudogenes of the same sequence are found in human genes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

They form a molecular record of the evolutionary history and dynamics of the parental genome.

Multiple choice

A vast range of specific protein-DNA interactions occur due to the unique and major motifs. Which of the following listed motifs includes lactose repressors and cyclic AMP catabolite activator protein?

  1. Leucine Zipper Motif

  2. Zinc Finger Motif

  3. Helix-Turn-Helix Motif

  4. Helix-Loop-Helix Motif

  5. BLAST
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Helix motif proteins include lactose repressors and cyclic AMP catabolite activator protein or CAP of E.coli,  and several developmentally important transcription factors in mammals, collectively referred to as homeodomain proteins. Homeodomain proteins play a major role in development of mammals.

Multiple choice

There are certain mechanisms involved in the origin of new genes. Which of the following mechanisms occurs between the genomes of the cell organelles like mitochondria, chloroplasts and nuclear genomes?

  1. Gene duplication

  2. De Novo Gene Origination

  3. Gene Fusion and Fison

  4. Transposable Element(TE) protein domestication

  5. Lateral Gene Transfer
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

It is referred to the situation in which a gene does not have a vertical origin (that is direct inheritance from parent to offspring), but comes from an unrelated genome. It is recognised that this type of transfer occurs between bacteria and has taken place between the genomes of the cell organelles like mitochondria, chloroplasts and nuclear genomes.