Q61. The primary goal of inserting a gene into a host organism during genetic engineering is to:
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 61–70 of 179 questions
Q62. Identify the incorrect statement regarding the tools of genetic engineering.
Explanation
The enzyme used to synthesize complementary DNA from a messenger RNA template is reverse transcriptase, not RNA polymerase. RNA polymerase is actually responsible for synthesizing RNA from a DNA template during transcription. Other tools mentioned are correct: restriction enzymes act as molecular scissors, DNA ligase functions as molecular glue, and plasmids serve as essential vectors for carrying foreign genetic material into host cells.
Q63. What role does calcium chloride play in the transformation process of bacteria in genetic engineering?
Explanation
During the transformation process, bacteria are treated with a high concentration of calcium chloride to increase their competence, or their ability to take up foreign DNA. The divalent calcium ions are thought to neutralize the negative charges on both the DNA and the bacterial cell membrane, making it easier for the recombinant DNA to pass through the cell wall during a subsequent heat shock.
Q64. Restriction endonucleases are enzymes that:
Explanation
Restriction endonucleases are specialized enzymes that recognize specific, usually palindromic, sequences of nucleotides within a DNA molecule. Upon finding these recognition sites, the enzymes cleave the sugar-phosphate backbone at precise internal locations. This ability to cut DNA at predictable and specific sites is the cornerstone of recombinant DNA technology, enabling the isolation and manipulation of particular genes or DNA fragments.
Q65. Match List-I with List-II regarding enzyme functions in biotechnology:
| Enzyme | Function |
|---|---|
| A. Restriction Endonuclease | i. Forms phosphodiester bonds to join DNA fragments |
| B. DNA Ligase | ii. Cleaves DNA at specific palindromic sequences |
| C. DNA Polymerase | iii. Synthesizes complementary DNA from an RNA template |
| D. Reverse Transcriptase | iv. Synthesizes new DNA strands by adding nucleotides |
Explanation
Different enzymes perform specific tasks in biotechnology. Restriction endonucleases cut DNA at palindromic sequences. DNA ligase joins DNA fragments by forming phosphodiester bonds. DNA polymerase is used to synthesize new DNA strands by adding nucleotides to a primer. Reverse transcriptase is essential for creating complementary DNA from an RNA template, which is a key step in cloning eukaryotic genes from messenger RNA.
Q66. EcoRI is a widely used restriction enzyme. In its naming convention, what does the co stand for?
Explanation
The nomenclature of restriction enzymes follows a specific system based on the source organism. In the case of EcoRI, the E stands for the genus Escherichia, and the co stands for the species coli. The R represents the specific strain, and the Roman numeral I indicates that it was the first enzyme isolated from that particular strain. This systematic naming allows scientists to identify origins.
Q67. The specific sequences recognized by restriction endonucleases are typically:
Explanation
Restriction endonucleases typically recognize palindromic sequences in the DNA. A molecular palindrome is a sequence of base pairs that reads the same on both strands when the orientation is kept the same. These symmetrical sequences allow the enzyme, which often functions as a dimer, to bind and cut both strands of the double helix at specific, mirrored locations, enabling precise genetic engineering applications.
Q68. DNA ligase joins two DNA fragments by catalyzing the formation of which type of bond?
Explanation
DNA ligase is the enzyme responsible for permanently joining two DNA fragments by catalyzing the formation of a covalent phosphodiester bond. This bond occurs between the 3-hydroxyl group of one nucleotide and the 5-phosphate group of another. This reaction effectively seals the nicks in the sugar-phosphate backbone of the double helix, resulting in a continuous and stable recombinant DNA molecule for further applications.
Q69. Which of the following is an exception to the rule that restriction endonucleases produce sticky ends?
Explanation
Most commonly used restriction enzymes, such as EcoRI, BamHI, and HindIII, cut the DNA strands at staggered positions within the recognition site, creating short, single-stranded overhanging sticky ends. However, some enzymes like SmaI cut both strands of the DNA at the same central position. This results in blunt ends which do not have overhanging sequences. Blunt-ended fragments are generally more difficult to ligate efficiently.
Q70. Overhanging, single-stranded ends of DNA created by certain restriction enzymes are called:
Explanation
Sticky ends are short, single-stranded overhanging sequences of DNA produced when certain restriction endonucleases cut the double helix in a staggered fashion. These ends are called sticky because they can easily form complementary hydrogen bonds with other DNA fragments cut by the same enzyme. This temporary base-pairing significantly facilitates the subsequent action of DNA ligase, making the cloning process much more efficient and reliable.Answer key for these questions
| Q | Correct answer |
|---|---|
| 61 | (a) Production of gene copies or the encoded protein product |
| 62 | (c) RNA polymerase is the primary enzyme used to synthesize cDNA from mRNA. |
| 63 | (a) Facilitation of DNA entry by enhancing cell competence |
| 64 | (d) Cleavage of DNA at specific internal recognition sites |
| 65 | (a) A-ii, B-i, C-iv, D-iii |
| 66 | (b) Coli |
| 67 | (c) Palindromic sequences |
| 68 | (d) Phosphodiester bond |
| 69 | (c) SmaI |
| 70 | (b) Sticky ends |
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.