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

Directions: Choose the correct answer for the following question on the basis of the given passage:

The primary purpose a the passage is to show that extensive experimentation has ________________________________________.

RC Passage 6:
Few areas of neuron behavioral research seemed more promising is the early sixties than that investigating the relationship between protein synthesis and learning. The conceptual framework for the research was derived directly from molecular biology, which had shown that genetic information is stored in nucleic acids and expressed in proteins why not acquired information as well.
The first step towards establishing a connection between protein synthesis and learning seemed to be to block memory (cause adhesion) by interrupting the production of proteins. We were fortunate in finding a non lethal dosage of puromycin that could, it first appealed, thoroughly inhibit brain protein synthesis as well as reliability produce amnesia. Before the actual connection between protein synthesis and learning could be established however we began to have douche about whether inhibition of protein synthesis was in fact the method by which puromycin produced amnesia. First, ocher drugs, glutavimides themselves potent protein synthesis inhibitors either failed to cause amnesia in some situations where it could easily be induced by puromycin or produced an amnesia with a different time course from that of puromycin. Second, puromycin was found to inhabit protein  synthesis by breaking certain amino acid chain, and the resulting fragments were suspected of being the actual cause of amnesia is some eases. Third, puromycin was reported to cause abnormalities in the train, including seizures. Thus, not only were decreased protein synthesis and amnesia dissociated, but alternative mechanism for the amnestic action of puromycin were readily suggested.

So, puromycin turned out to be a disappointment. It came to be regarded as a poor agent for amnesia studies, although, of course, it was poor only in the context of our original paradigm of protein synthesis inhibition. In our frustration, our initial response was simply to change dregs rather than our conceptual orientation. After many such disappointments, however, it now appears unlikely, that we will make a firm connection between protein synthesis and learning merely by pursuing the approaches of the past our experience with drugs has shown that all the amnestic agents, often interfere with memory in ways that seem unrelated to their inhibition of protein synthesis. More importantly, the notion that the interruption or intensification of protein production in the train can be related in cause and affect fashion to learning now seems simplistic and unproductive. Remove the battery from a car and the car will not go Drive the car a long distance at high speed and the battery will become more highly charged. Neither of these facts proves that the battery power the car, only knowledge of the overall automotive system will reveal its mechanism of locomotion and the role of the battery with in the system.

  1. not supported the hypothesis that learning is directly dependent on protein synthesis

  2. cast doubt on the value of puromycin in the newer behavioral study of learning

  3. revealed the importance of amnesia in the neuron behavioral study of learning

  4. demonstrated the importance of amino acid fragmentation in the induction of amnesia

  5. not yet demonstrated the applicability of molecular biology to behavioral research
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 The prinary urpose was to show that past research has not supported the link between learning and protein synthesis, however, the conclusion of the passage says otherwise.

Multiple choice

Assertion: Transposition starts by forming a strand transfer complex in which the transposon is connected to the target site through one strand at each end. Reason: Replicative Transposition Proceeds through a Cointegrate.

  1. A and R both are correct and R is correct explanation of A.

  2. A and R both are correct and R is not correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A and R both are correct and R is not correct explanation of A. Transposition starts by forming a strand transfer complex in which the transposon is connected to the target site through one strand at each end. Replicative Transposition Proceeds through a Cointegrate. Replication of a strand transfer complex generates a cointegrate, which is a fusion of the donor and target replicons. The cointegrate has two copies of the transposon, which lie between the original replicons. Recombination between the transposon copies regenerates the original replicons, but the recipient has gained a copy of the transposon.

Multiple choice

Which of the following statements are not true?

  1. Transposition occurs by only nonreplicative mechanism.
  2. Homologous recombination between multiple copies of a retrotransposon causes rearrangement of host DNA.
  3. Homologous recombination between the repeats of retrotransposon may lead to imprecise excision.
  4. Imprecise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome.

  1. Only 1 and 2

  2. Only 1 and 3

  3. Only 1 and 4

  4. Only 2 and 3

  5. Only 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Transposition occurs by both Replicative and Nonreplicative Mechanisms. All transposons use a common mechanism in which staggered nicks are made in target DNA, the transposon is joined to the protruding ends, and the gaps are filled. The order of events and exact nature of the connections between transposon and target DNA determine whether transposition is replicative or nonreplicative. Precise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome. Imprecise excision occurs when the transposon removes itself from the original insertion site, but leaves behind some of its sequence.

Multiple choice

RFLP (Restriction Fragment Length Polymorphism) is a

  1. growth promoter

  2. molecular marker

  3. growth retardent

  4. herbicide

  5. germicide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RFLP (Restriction Fragment Length Polymorphism) is a molecular marker technique used in genetics and DNA fingerprinting. It analyzes variations in DNA sequences after restriction enzyme digestion, helping identify genetic differences between individuals or species. The other options (growth promoter, retardent, herbicide, germicide) are agricultural/chemical substances, not genetic analysis tools.

Multiple choice

Eukaryotic DNA replication is a conserved mechanism. Which among the following statements regarding the DNA replication is false?

  1. Duplex DNA is always antiparallel.

  2. Two replicative polymerases synthesise DNA in opposite orientations.

  3. Okazaki fragments are formed on the lagging strand.

  4. The lagging strand usually contains longer stretches of single-stranded DNA.

  5. Each Okazaki fragment is preceded by an RNA dimer.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Each Okazaki fragment is preceded by an RNA primer, which is displaced by the procession of the next Okazaki fragment during synthesis.

Multiple choice

Which of the following is the inducer of the lac operon?

  1. Isopropyl-β-D-thio-galactoside

  2. Phenyl-β-D-galactose (phenyl-Gal)

  3. ONPG

  4. Allolactose

  5. Phosphoenolpyruvic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Allolactose is an isomer of lactose and is the inducer of the lac operon. Lactose is galactose-(β1->4)-glucose, whereas allolactose is galactose-(β1->6)-glucose. Lactose is converted to allolactose by β-galactosidase in an alternative reaction to the hydrolytic one.

Multiple choice

The activator proteins frequently binds with the pertinent DNA segment in ______________________.

  1. positive inducible operons

  2. positive repressible operons

  3. negative inducible operons

  4. negative repressible operons

  5. neutral repressible operons
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In positive repressible operons, the activator proteins are normally bound to the pertinent DNA segment. However, when an inhibitor is bound by the activator, it is prevented from binding the DNA. This stops activation and transcription of the system.