Q81. Identify the incorrect statement regarding the annealing step in PCR.
Genetics, Biotechnology and Nanotechnology: RAS Prelims MCQs
179 RAS Prelims MCQs on genetics, biotechnology and nanotechnology cover DNA structure, chromosomes, recombinant DNA tools, plant tissue culture, biotech products and bioethics. Purines, base pairing, Chargaff’s rule, vectors, totipotency, Humulin, Feynman’s lecture, the Nagoya Protocol and biopiracy are asked as facts and sequences, with explanations that name the process behind each fact.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 81–90 of 179 questions
Q82. A thermocycler is an instrument used primarily for:
Explanation
A thermocycler, also known as a PCR machine, is a specialized laboratory instrument designed to automatically cycle through the precise temperature changes required for the denaturation, annealing, and extension steps of the Polymerase Chain Reaction. By accurately and rapidly heating and cooling the reaction tubes, the device allows for the efficient and repeated amplification of DNA sequences without the need for manual intervention.
Q83. Extra-chromosomal, self-replicating, circular, double-stranded DNA molecules found naturally in many bacteria are called:
Explanation
Plasmids are small, circular, double-stranded DNA molecules found in many bacteria, separate from the main chromosomal DNA. They are capable of self-replication and often carry genes that provide a survival advantage, such as antibiotic resistance. Because they are easy to isolate and manipulate, plasmids are the most commonly used vectors in genetic engineering for carrying and cloning foreign DNA segments in host cells.
Q84. Match List-I with List-II regarding cloning vector components:
| Vector Component | Function |
|---|---|
| A. Origin of replication (ori) | i. Region containing several restriction sites for gene insertion |
| B. Selectable marker | ii. Sequence where DNA replication begins |
| C. Multiple cloning site (MCS) | iii. Gene that helps identify transformed cells (e.g., antibiotic resistance) |
| D. Promoter | iv. Sequence needed to initiate transcription of the inserted gene |
Explanation
The origin of replication is where DNA replication begins, a selectable marker identifies transformed cells, the multiple cloning site has several restriction sites for inserting a gene and the promoter starts transcription of the inserted gene. This gives A-ii, B-iii, C-i, D-iv.
Q85. Consider the following statements about gene cloning vectors:
I. pBR322 is a widely used, artificially synthesized plasmid vector.
II. Plasmids can accommodate infinitely large fragments of foreign DNA.
III. Selectable markers allow the differentiation between recombinants and non-recombinants.
Which of the above statement(s) is/are correct?
I. pBR322 is a widely used, artificially synthesized plasmid vector.
II. Plasmids can accommodate infinitely large fragments of foreign DNA.
III. Selectable markers allow the differentiation between recombinants and non-recombinants.
Which of the above statement(s) is/are correct?
Explanation
pBR322 was indeed one of the first widely used artificial plasmid vectors. Selectable markers are essential for distinguishing between host cells that contain the recombinant plasmid and those that do not. However, plasmids have a limited capacity for the size of the foreign DNA they can carry; very large fragments require different vectors like BACs or YACs, making certain statements regarding their capacity incorrect.
Q86. The ampicillin resistance gene in plasmid pBR322 acts as a:
Explanation
In the plasmid pBR322, the ampicillin resistance gene functions as a selectable marker. When bacteria are grown on a medium containing the antibiotic ampicillin, only those cells that have successfully taken up the plasmid will be able to survive and form colonies. This allows researchers to easily identify and isolate the transformed bacteria from the vast majority of cells that did not receive the plasmid.
Q87. The phenomenon where the insertion of a foreign gene within the coding sequence of an enzyme gene leads to the loss of that enzymes activity is known as:
Explanation
Insertional inactivation is a technique used to identify recombinant clones. When a foreign DNA fragment is inserted into the coding sequence of a reporter gene, it disrupts the genes function. For example, if the lacZ gene is inactivated, the bacteria will no longer be able to produce the enzyme beta-galactosidase, resulting in white colonies instead of blue on specific media, signaling a successful insertion.
Q88. Which of the following vectors is most commonly used to transfer genes into dicot plants?
Explanation
The Ti plasmid of the soil bacterium Agrobacterium tumefaciens is the most widely used vector for genetic engineering in dicotyledonous plants. In nature, this bacterium transfers a segment of its Ti plasmid into the plant genome. Scientists have disarmed this plasmid by removing the disease-causing genes and replacing them with genes of interest, effectively turning the bacterium into a natural gene delivery system.
Q89. The process of introducing recombinant vectors into animal cells is often achieved through:
Explanation
Introducing recombinant DNA into animal cells requires different methods than bacterial transformation. Microinjection involves using a very fine glass needle to inject DNA directly into the nucleus of a cell or embryo. Electroporation uses brief pulses of high-voltage electricity to create temporary pores in the cell membrane, allowing the DNA to enter. Other methods include using viral vectors or lipid-based carriers.
Q90. Identify the incorrect statement regarding cloning vectors.
Explanation
Bacteriophages are viruses that infect bacteria, and they are extensively used as cloning vectors because they can naturally inject their DNA into host cells and accommodate larger DNA inserts than standard plasmids. Other statements are correct: high copy numbers increase yield; YACs and BACs are specialized for very large genomic fragments; and expression vectors are designed with regulatory sequences needed to produce proteins.Answer key for these questions
| Q | Correct answer |
|---|---|
| 81 | (c) It requires the presence of DNA ligase. |
| 82 | (a) Automating the temperature changes required for PCR |
| 83 | (d) Plasmids |
| 84 | (a) A-ii, B-iii, C-i, D-iv |
| 85 | (c) I and III only |
| 86 | (a) Selectable marker |
| 87 | (c) Insertional inactivation |
| 88 | (b) Ti plasmid of Agrobacterium tumefaciens |
| 89 | (d) Electroporation or microinjection |
| 90 | (a) Bacteriophages cannot be used as cloning vectors. |
Key facts from Genetics, Biotechnology and Nanotechnology
- Adenine is a purine and pairs with thymine through two hydrogen bonds; the distance between consecutive base pairs in B-DNA is 0.34 nm.
- Chargaff’s rule says that adenine equals thymine and guanine equals cytosine; the human karyotype has 22 pairs of autosomes.
- Telomeres maintain genomic stability during DNA replication; heterochromatin is the condensed, inactive region.
- Humulin was the first commercially produced genetically engineered human hormone.
- Totipotency is the capacity of a single plant cell to regenerate a whole plant; the meristem is used to get virus-free plants.
- Richard Feynman’s 1959 lecture began nanotechnology; the Nagoya Protocol governs benefit sharing; the US patent on turmeric was revoked after a biopiracy battle.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Genetics, Biotechnology and Nanotechnology?
This page has 179 practice MCQs on Genetics, Biotechnology and Nanotechnology (Science and Technology). Each has the correct answer, and most have an explanation.
How many hydrogen bonds pair adenine with thymine?
Two. Adenine pairs with thymine by two hydrogen bonds, and guanine pairs with cytosine by three, which is why DNA rich in G and C is more stable.
What is totipotency?
The capacity of a single plant cell to regenerate into an entire plant. It is the basis of plant tissue culture, in which cells grown on a nutrient medium form a callus and then shoots and roots.
Which protocol deals with sharing the benefits of genetic resources?
The Nagoya Protocol to the Convention on Biological Diversity. It ensures that the benefits from using genetic resources are shared fairly with the countries and communities that provide them.