Q41. A mutation resulting in the conversion of a regular codon into a stop codon is termed:
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 41–50 of 179 questions
Q42. The structural change in a chromosome where a segment breaks off and reattaches in the reverse direction is called:
Explanation
An inversion is a chromosomal rearrangement in which a segment of a chromosome breaks off, flips 180 degrees, and reattaches in the reverse orientation. While the total amount of genetic material may remain the same, the change in the order of genes can interfere with proper pairing during meiosis or affect gene regulation. This structural change is a significant source of chromosomal variation.
Q43. Identify the incorrect statement regarding mutations.
Explanation
Most random mutations are either neutral, having no effect, or deleterious, causing harm to the organisms fitness or function. Beneficial mutations that provide an adaptive advantage are relatively rare in nature. Other statements are accurate: mutations are indeed the ultimate source of all genetic variation, can occur spontaneously, and somatic mutations generally affect only the individual rather than being passed to offspring.
Q44. The exchange of chromosomal segments between non-homologous chromosomes is referred to as:
Explanation
Translocation is a type of chromosomal abnormality where a segment from one chromosome breaks off and attaches to a non-homologous chromosome. This is distinct from crossing over, which involves the exchange of segments between homologous chromosomes. Translocations can be reciprocal, where two chromosomes swap segments, or non-reciprocal. Such rearrangements can lead to serious health issues or reduced fertility by disrupting gene function.
Q45. What is the effect of a missense mutation?
Explanation
A missense mutation is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid than the original. This substitution can alter the proteins shape, stability, or enzymatic activity, potentially leading to disease. For instance, the mutation causing sickle cell anemia is a missense mutation where glutamic acid is replaced by valine.
Q46. Down syndrome is a genetic disorder caused by the presence of an extra copy of which chromosome?
Explanation
Down syndrome, also known as Trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. This extra genetic material alters the course of development and causes the characteristic physical and intellectual features associated with the condition. It is typically the result of nondisjunction during the process of meiosis in one of the parents.
Q47. Match List-I with List-II regarding genetic disorders:
| Genetic Disorder | Cause/Characteristic |
|---|---|
| A. Sickle cell anaemia | i. X-linked recessive disorder preventing blood clotting |
| B. Haemophilia | ii. Point mutation in the beta-globin chain |
| C. Down syndrome | iii. Absence of one X chromosome in females (45, X0) |
| D. Turners syndrome | iv. Trisomy 21 |
Explanation
Overview of Human Genetic Disorders P. Sickle cell anemia is caused by a specific point mutation in the beta-globin chain. Q. Haemophilia is an X-linked recessive disorder that inhibits proper blood clotting. R. Down syndrome arises from the trisomy of chromosome twenty-one. S. Turners syndrome involves the absence of one X chromosome in females, resulting in forty-five total chromosomes.
Q48. Sickle cell anaemia is characterized by the substitution of glutamic acid by which amino acid in the beta-globin chain of haemoglobin?
Explanation
In sickle cell anemia, a specific point mutation occurs in the HBB gene encoding the beta-globin chain of hemoglobin. At the sixth position of the polypeptide chain, the amino acid glutamic acid is replaced by valine.
Q49. Which of the following represents the correct sequence of events leading to sickle cell anaemia?
Explanation
The development of sickle cell anemia begins with a point mutation in the DNA, which is then transcribed into an altered mRNA codon. This results in the substitution of valine for glutamic acid in the hemoglobin protein. In low oxygen environments, these mutant hemoglobin molecules aggregate and polymerize. This internal structural change forces the red blood cell to transform from a disc to a sickle shape.
Q50. Haemophilia is often referred to as the Royal Disease. It is genetically transmitted as an:
Explanation
Haemophilia is a genetic disorder that impairs the bodys ability to make blood clots, a process needed to stop bleeding. It is inherited as an X-linked recessive trait. This means the gene is located on the X chromosome. Because males have only one X chromosome, they are more frequently affected, while females are usually asymptomatic carriers unless they inherit two copies of the defective gene.Answer key for these questions
| Q | Correct answer |
|---|---|
| 41 | (c) Nonsense mutation |
| 42 | (b) Inversion |
| 43 | (a) Most random mutations are beneficial to the organism. |
| 44 | (c) Translocation |
| 45 | (a) Single amino acid substitution within the protein sequence |
| 46 | (d) Chromosome 21 |
| 47 | (a) A-ii, B-i, C-iv, D-iii |
| 48 | (c) Valine |
| 49 | (a) Point mutation in DNA - Altered mRNA - Altered amino acid sequence - Polymerization of haemoglobin under low oxygen - RBC shape changes |
| 50 | (a) X-linked recessive trait |
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.