Science and Technology: UPSC Previous Year Questions (Prelims)

Explanation

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules. This technology has gained immense popularity because of its potential in gene silencing, therapeutic applications, and agricultural improvements.

Statement 1 is correct: RNAi technology is primarily used to silence specific genes by targeting the messenger RNA (mRNA) produced by a gene. When RNAi molecules (small interfering RNA or siRNA) are introduced into cells, they bind to complementary mRNA, causing its degradation and preventing protein translation. This has vast potential in treating genetic diseases caused by overactive or malfunctioning genes. Gene therapies targeting diseases like amyotrophic lateral sclerosis (ALS) and Huntington’s disease use RNAi to silence mutant genes causing the disease.

Statement 2 is correct: Numerous studies have demonstrated that RNAi can provide a more specific approach to inhibit tumor growth by targeting cancer-related genes (i.e., oncogene). Researchers are investigating RNAi-based therapeutics to target these oncogenes selectively.

Statement 3 is incorrect: Hormone Replacement Therapy (HRT) is a medical treatment that involves replacing hormones in the body to alleviate symptoms related to hormonal imbalances or deficiencies. Though RNAi has been investigated as a potential tool for regulating hormone-related genes, it is not a primary mechanism of action for HRT.

Statement 4 is correct: RNAi is increasingly applied in agriculture to create genetically modified crops that are resistant to viral infections. By silencing the genes of the virus or the plant’s genes that are required for viral replication, RNAi-based technologies offer a potential solution to combat viral pathogens that affect crops. Crops like papaya and potatoes have been genetically engineered using RNAi technology to confer resistance to viruses such as the papaya ringspot virus and potato virus Y.

Explanation

Antimicrobial Resistance (AMR) is the ability of microorganisms like bacteria, viruses, fungi, and parasites to resist the effects of antimicrobial drugs, making infections harder to treat. When microorganisms such as bacteria develop resistance to multiple drugs, it is specifically termed Multidrug Resistance (MDR), posing a serious challenge to effective treatment.

Statement 1 is incorrect: Multi-drug resistance is primarily a result of microbial adaptation, excessive antibiotic use, and misuse rather than human genetic predisposition. Genetic predisposition is a genetic trait that, in response to environmental factors, may influence the potential phenotypic development of an individual organism within a species or community. Antibiotic resistance is not related to the genetic tendency of a small minority of persons in a society.

Statement 2 is correct: Misuse of antibiotics, such as incorrect dosing, premature discontinuation of prescribed antibiotics, or self-medication, allows bacteria to survive and develop resistance. WHO mentions inappropriate use of antibiotics as a major driver of antimicrobial resistance.

Statement 3 is correct: The extensive use of antibiotics in animals, especially for growth promotion and disease prevention, contributes to the development of resistant bacteria. These resistant strains can transfer to humans through the food chain or direct contact.

Statement 4 is incorrect: While having multiple chronic diseases (like diabetes, hypertension, or cancer) may lead to prolonged or frequent use of antibiotics due to recurrent infections, it is not a direct cause of multi-drug resistance (MDR) in microbial pathogens.

Explanation

The Cas9 protein, often referred to as "molecular scissors," is an enzyme utilized in targeted gene editing. It originates from the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) system, which serves as an adaptive immune mechanism in bacteria. Guided by a specific RNA sequence, Cas9 binds to a complementary DNA sequence and introduces a double-stranded break. This break facilitates targeted modifications, such as gene insertion, deletion, or correction. Cas9 has revolutionized genetic research and therapy by enabling precise edits in the genomes of various organisms, including plants, animals, and humans. This technology holds potential for treating genetic disorders, developing disease-resistant crops, and advancing gene therapy.

Explanation

Hepatitis is an inflammation of the liver, often caused by viral infections (hepatitis A, B, C, D, E). Its symptoms include fatigue, jaundice, and abdominal pain. Statement (a) is correct: Both Hepatitis B virus (HBV) and HIV are transmitted through contact with infected blood, semen, or other body fluids. Statement (b) is incorrect: A vaccine is available for Hepatitis B, which is effective in preventing HBV infection. However there is currently no vaccine for Hepatitis C. Statement (c) is correct: The global prevalence of HBV and HCV infections is significantly higher than that of HIV. Statement (d) is correct: Both HBV and HCV can lead to chronic infections where individuals remain asymptomatic for years, often until significant liver damage has occurred.

Explanation

Statement 1 is incorrect: LTE is a 4G (Fourth Generation) wireless communication standard, not 3G. It offers higher data transfer speeds compared to 3G technologies. VoLTE is a service that allows voice calls to be transmitted over the LTE network thereby providing high-quality voice services. Both LTE and VoLTE are associated with 4G technology, not 3G.

Statement 2 is incorrect: LTE is not a data-only technology as it supports both data and voice services. However without VoLTE, voice calls on LTE networks typically fall back to 3G or 2G networks (a process called Circuit-Switched Fallback, or CSFB). VoLTE is not voice-only as it enhances voice call quality and efficiency while still supporting data services.

Explanation

Statement 1 is incorrect: AR overlays digital elements onto the real world, enhancing the user’s perception without replacing the physical environment. Examples include Pokémon Go and AR navigation apps.

Statement 2 is incorrect: VR creates an immersive digital environment that replaces the real world entirely, isolating the user through devices like VR headsets. Examples include virtual classrooms and gaming environments.

Statement 3 is correct: Augmented Reality enhances the user’s experience by integrating digital elements with their physical environment in real-time. AR applications utilize cameras on smartphones, tablets, or PCs to superimpose virtual features, such as graphics or text, over the real-world view displayed on the device’s screen.

Statement 4 is correct: Virtual Reality isolates the user from their physical surroundings by immersing them in a fully simulated digital environment. VR systems achieve this through specialized devices, such as VR headsets, which block out external visual and auditory input. This technology is commonly used for gaming, training simulations, and immersive experiences, offering users a sense of presence within the virtual world.

Explanation

A digital signature is a type of electronic signature that can be used to verify the identity of the person sending a message or signing a document and to guarantee that the message’s or document’s original content hasn’t changed. Digital signatures are portable and impossible for anyone to forge.

Statement 1 is incorrect: A digital signature is a cryptographic technique used to validate the authenticity and integrity of digital messages or documents. It is not primarily used to identify the certifying authority. A digital certificate serves that purpose by linking a public key with the identity of the certificate authority that issued it.

Statement 2 is incorrect: While digital signatures can authenticate the origin of a message or document, their primary function is to ensure that the content has not been altered and to verify the sender’s identity in the context of that specific document. They are not typically used as general proof of identity for accessing information or servers; other mechanisms, such as passwords or digital certificates, serve that purpose

Statement 3 is correct: Digital signatures use cryptographic methods to provide authentication of original and unmodified documentation, ensuring that the content has not been altered since it was signed

Explanation

Electronic devices can be comfortably worn on the body are known as wearables. Real-time information tracking is done with these wearable gadgets. They have motion sensors that capture an image of user’s daily activity and sync it with laptops or mobile devices.

Statement 1 is correct: Wearable devices like smartwatches and fitness trackers equipped with GPS can track a person’s real-time location which makes them useful for navigation, fitness activities, and safety purposes, especially for outdoor enthusiasts and travelers.

Statement 2 is correct: Wearables can monitor sleep by analyzing heart rate, movement, and breathing patterns. Devices like the Oura Ring provide detailed insights into sleep quality, helping users identify issues and improve their overall sleep health.

Statement 3 is correct: Certain wearables such as modern hearing aids and Apple’s AirPods Pro assists people with hearing impairments by amplifying sounds and reducing background noise, offering an affordable and efficient solution for mild-to-moderate hearing loss.

Explanation

For assessing chlorophyll content from remote sensing data utilising a multispectral imaging system, the Normalized Area Vegetation Index (NAVI) has been developed. The most widely used instruments are radiometers and photometers, which can collect radiation that is emitted and reflected at a variety of frequencies. Additionally, they can be used to identify the emission spectra of different substances, providing information on atmospheric chemical concentrations.

Statement 1 is correct: Satellite remote sensing such as hyperspectral imaging can estimate chlorophyll levels in vegetation by analyzing specific spectral wavelengths. This technique is widely used to evaluate plant health and productivity over large regions without requiring direct sampling.

Statement 2 is correct: Advanced remote sensing tools, including drones with multispectral sensors, help monitor methane emissions from rice paddies. By integrating environmental data with computational models, these methods provide a non-invasive way to assess emissions across agricultural landscapes.

Statement 3 is correct: Remote sensing satellites measure land surface temperatures by detecting thermal infrared radiation emitted from the Earth’s surface. This data is critical for applications like climate research, urban heat management, and agricultural monitoring, offering accurate temperature readings across various regions.

Explanation

Option (b) is correct: The LIGO detectors detected the first gravitational waves produced by two giant merging blackholes in 2016. Gravitational waves are ripples in spacetime’s fabric brought on by cosmic catastrophes like neutron stars or black hole collisions. These disturbances are incredibly powerful, yet their signals are feeble and difficult to detect when they travel through distant regions of space and time. In other words, it took that long for the signals to reach Earth. As a result, the observatory provides a chance to go back in time and solve puzzles about the origins of the universe. Options (a), (c) and (d) are incorrect:

A wormhole is a hypothetical structure that connects dispersed places in spacetime. It is based on a unique solution to the Einstein field equations. It is also known as an Einstein-Rosen bridge or wormhole. Although wormholes are consistent with the general theory of relativity, it is yet unknown whether they truly exist. The Higgs field, one of the fields in particle physics theory, undergoes quantum excitation to form the Higgs boson, an elementary particle in the Standard Model of particle physics. The Higgs particle is a large scalar boson with no electric charge, colour, or spin in the Standard Model. A gravitational singularity, or spacetime singularity, is a point where the values used to describe the gravitational field become infinitely large, regardless of the coordinate system used. At this point, the distinction between physical laws breaks down, and space and time lose their independent identities, merging into an indistinguishable and undefined state.