Q611. Which of the following best describes an operon in bacterial gene expression?
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 611–620 of 1113 questions
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Q612. Identify the correct pair:
Explanation
Homozygous refers to a genetic condition where an individual inherits two identical versions of a particular gene from both parents. This contrasts with the heterozygous state, where the two alleles at a specific locus are different. Genotype represents the internal genetic makeup, while phenotype describes the observable physical traits. Accurate terminology is essential for predicting inheritance patterns in classical Mendelian genetics.
Q613. Which cellular organelle is directly involved in the translation phase of gene expression?
Explanation
Ribosomes are the cellular organelles responsible for the translation phase of gene expression. They serve as the site where messenger RNA is read and converted into a specific sequence of amino acids to form a protein. These structures can be found floating freely in the cytoplasm or attached to the rough endoplasmic reticulum, facilitating the synthesis of essential biological molecules for the cell.
Q614. Mendels Law of Segregation states that:
Explanation
Mendels Law of Segregation states that during the formation of gametes, the two alleles for a heritable character separate from each other. Consequently, each gamete carries only one allele for every gene. The original paired condition is restored during fertilization when two gametes unite. This fundamental principle ensures that offspring receive one genetic contribution from each parent for every trait.
Q615. What is the phenotypic ratio in the F2 generation of a standard Mendelian monohybrid cross?
Explanation
In a standard Mendelian monohybrid cross, the F2 generation typically displays a phenotypic ratio of 3:1. This occurs when two heterozygous F1 individuals are crossed. Three-quarters of the offspring will exhibit the dominant trait, while one-quarter will show the recessive trait. This ratio reflects the underlying genotypic distribution of one homozygous dominant, two heterozygous, and one homozygous recessive individual.
Q616. Consider the following statements about Mendels laws:
I. The law of independent assortment applies to genes located on the same chromosome that are tightly linked.
II. A dihybrid cross involves studying two traits simultaneously.
III. The law of segregation is universally applicable with no exceptions in diploid organisms.
IV. Mendels experiments used Pisum sativum.
Which of the above statement(s) is/are correct?
I. The law of independent assortment applies to genes located on the same chromosome that are tightly linked.
II. A dihybrid cross involves studying two traits simultaneously.
III. The law of segregation is universally applicable with no exceptions in diploid organisms.
IV. Mendels experiments used Pisum sativum.
Which of the above statement(s) is/are correct?
Explanation
Mendels dihybrid crosses involved the simultaneous study of two distinct traits, providing the basis for his laws. The law of segregation is a universal principle in diploid organisms during gamete formation. Mendel used the garden pea, Pisum sativum, for his research. However, the law of independent assortment does not apply to genes located very close together on the same chromosome.
Q617. A test cross is performed to determine:
Explanation
A test cross is a genetic tool used to determine whether an organism expressing a dominant trait is homozygous or heterozygous. This is achieved by breeding the individual with a homozygous recessive organism. If any offspring display the recessive phenotype, the parent must be heterozygous. This method is fundamental for verifying the genetic composition of organisms in classical breeding experiments.
Q618. Which of the following is the cause of the 9:3:3:1 ratio in a dihybrid cross?
Explanation
The 9:3:3:1 phenotypic ratio in a dihybrid cross is a direct consequence of the Law of Independent Assortment. This principle states that the alleles of two or more different genes get sorted into gametes independently of one another. As a result, the inheritance of one trait does not influence the inheritance of another, leading to diverse combinations in the offspring.
Q619. Mendels laws may not apply strictly in which of the following situations?
Explanation
Linked genes are those located close together on the same chromosome. Because they are physically near each other, they tend to be inherited together during meiosis rather than assorting independently. This proximity interferes with the expected Mendelian ratios, such as the 9:3:3:1 dihybrid ratio. Genetic linkage represents a major exception to Mendels original observations regarding the independent assortment of traits.
Q620. Identify the incorrect statement regarding Mendelian genetics.
Explanation
When two true-breeding parents with contrasting traits are crossed, the F1 generation typically exhibits a uniform phenotype. In cases of complete dominance, all offspring will display the dominant trait rather than a mix or intermediate phenotype. Recessive traits only reappear in the F2 generation. Other Mendelian principles hold that gametes carry one allele and segregation occurs during the process of meiosis.Answer key for these questions
| Q | Correct answer |
|---|---|
| 611 | (b) Group of genes transcribed together from a single promoter |
| 612 | (c) Homozygous - Two identical alleles at a locus |
| 613 | (d) Ribosome |
| 614 | (c) Alleles separate into gametes and unite at fertilization |
| 615 | (c) 3:1 |
| 616 | (b) II, III and IV only |
| 617 | (a) Genotype of an individual showing a dominant phenotype |
| 618 | (c) Law of Independent Assortment |
| 619 | (a) Linked genes on the same chromosome |
| 620 | (d) F1 progeny of true-breeding parents show mixed phenotypes |
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.