Q631. The basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around histone protein cores, is known as a:
Science and Technology: RAS Prelims MCQs
1113 RAS Prelims practice MCQs on science and technology are on this page, in 6 chapters. They cover the basics of everyday science, computers and information technology, defence and space technology in India, genetics, biotechnology and nanotechnology, science and technology policies and government programmes, and recent advances with Indian contributors and indigenisation. Each question has an answer and an explanation.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 631–640 of 1113 questions
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Q632. A mutation that involves the substitution of a single base pair in the DNA sequence is known as a:
Explanation
A point mutation is a type of genetic alteration where a single nucleotide base is changed, inserted, or deleted from a DNA or RNA sequence. When one base is substituted for another, it can result in various outcomes, such as changing a single amino acid in a protein or having no effect at all. These mutations are the smallest scale of genetic variation that can occur.
Q633. Given below are two statements, one labeled as
Assertion (A) and the other as Reason (R):
Assertion (A): Frameshift mutations generally have a more severe effect on protein function than point mutations.
Reason (R): Frameshift mutations alter the entire reading frame of the mRNA downstream of the mutation site.
Select the correct answer from the codes given below:
Assertion (A) and the other as Reason (R):
Assertion (A): Frameshift mutations generally have a more severe effect on protein function than point mutations.
Reason (R): Frameshift mutations alter the entire reading frame of the mRNA downstream of the mutation site.
Select the correct answer from the codes given below:
Explanation
Frameshift mutations occur when nucleotides are inserted or deleted in numbers not divisible by three. Because the genetic code is read in triplets, this shifts the entire reading frame for all subsequent codons. This usually results in a completely different and often non-functional protein. In contrast, a point mutation typically affects only one codon, making its impact generally less severe than a frameshift.
Q634. Which of the following is an example of a physical mutagen?
Explanation
Mutagens are agents that increase the frequency of mutations in an organisms DNA. Physical mutagens include various forms of high-energy radiation. Ultraviolet radiation is a well-known physical mutagen that causes the formation of pyrimidine dimers, particularly thymine dimers, which distort the DNA structure. This contrasts with chemical mutagens like nitrous acid or mustard gas, which interact chemically with the nitrogenous bases.
Q635. Consider the following statements regarding mutations:
I. Germline mutations can be inherited by the offspring.
II. Somatic mutations are passed down to future generations.
III. Silent mutations do not change the amino acid sequence of the protein.
Which of the above statement(s) is/are correct?
I. Germline mutations can be inherited by the offspring.
II. Somatic mutations are passed down to future generations.
III. Silent mutations do not change the amino acid sequence of the protein.
Which of the above statement(s) is/are correct?
Explanation
Germline mutations occur in the reproductive cells and are passed on to offspring, making them heritable. Silent mutations are changes in the DNA sequence that do not alter the resulting amino acid sequence due to the redundancy of the genetic code. Somatic mutations, however, occur in non-reproductive body cells and are not inherited by future generations, affecting only the individual in whom they occur.
Q636. A mutation resulting in the conversion of a regular codon into a stop codon is termed:
Explanation
A nonsense mutation is a specific type of point mutation where a single base substitution changes a codon that codes for an amino acid into a premature stop codon. This leads to the early termination of protein synthesis during translation, resulting in a truncated and usually non-functional polypeptide. Such mutations often have significant biological consequences depending on their location within the gene sequence.
Q637. 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.
Q638. 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.
Q639. 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.
Q640. 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.Answer key for these questions
| Q | Correct answer |
|---|---|
| 631 | (d) Nucleosome |
| 632 | (c) Point mutation |
| 633 | (a) Both A and R are true and R is the correct explanation of A. |
| 634 | (a) Ultraviolet (UV) radiation |
| 635 | (c) I and III only |
| 636 | (c) Nonsense mutation |
| 637 | (b) Inversion |
| 638 | (a) Most random mutations are beneficial to the organism. |
| 639 | (c) Translocation |
| 640 | (a) Single amino acid substitution within the protein sequence |
Key facts from Science and Technology
- The RPSC paper is General Knowledge and General Science, so science questions come with a strong dose of applied and recent topics.
- Everyday science questions test the laws and terms of physics, chemistry and biology through examples.
- Defence and space questions pair a missile, satellite or mission with its year and organisation.
- Policy questions ask for the year, the body and the aim of schemes like STIP, the National Quantum Mission and BioE3.
- Health, environment and agriculture are on a separate page, with their own chapters.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Science and Technology?
This page has 1113 practice MCQs on Science and Technology. Each has the correct answer, and most have an explanation.
Which chapters does the science and technology set cover?
Six chapters: basics of everyday science; computers, information and communication technology; defence and space technology in India; genetics, biotechnology and nanotechnology; science and technology policies and government programmes; and recent advances, Indian contributors and indigenisation.
Is science and technology part of the RAS Prelims syllabus?
Yes. The RPSC paper is called General Knowledge and General Science, and its syllabus lists science and technology topics along with environment, health, agriculture and government programmes, so questions can come from any of these areas.
How should I prepare science for RAS Prelims?
Revise the concepts by examples, then learn the missions, schemes and scientists with their year and organisation. Attempt each chapter, read the explanations and keep a list of the facts you missed.