UPSC 2016 Science and Technology Questions with Answers

Explanation

Viruses are obligate intracellular parasites, meaning they require a host cell to replicate. They can infect bacteria, fungi, plants, animals, and other viruses. Viruses that infect bacteria are called bacteriophages (or simply phages). These viruses play a crucial role in regulating bacterial populations. Phages attach to bacterial cells, inject their genetic material, and hijack the bacterial machinery to replicate themselves. This process often leads to the destruction (lysis) of the bacterial cell. Viruses that infect fungi are called mycoviruses (Mycophages). They do not have an extracellular phase (i.e., they lack the ability to move outside fungal cells). They are linked to plant diseases because they weaken fungi that help plant growth. Cryphonectria hypovirus 1 (CHV1) infects chestnut blight fungus (Cryphonectria parasitica). Plant viruses are well-known pathogens that cause significant economic losses in agriculture such as the Tobacco Mosaic Virus (TMV), Potato Virus Y (PVY), and Tomato Spotted Wilt Virus (TSWV). Plant viruses are typically transmitted by insects, nematodes, or through contaminated seeds and tools. They infect plant cells disrupting their normal cellular functions and cause symptoms such as leaf curling, stunting, and mosaic patterns.

Explanation

Option (b) is correct: A transcriptome is the full range of messenger RNA(mRNA) molecules expressed by an organism. The term "transcriptome" can also be used to describe the array of mRNA transcripts produced in a particular cell or tissue type. Transcriptome analysis (RNA sequencing or RNA-Seq) is a key tool in bioinformatics for studying gene expression, identifying biomarkers, and understanding cellular functions.

Option (a), (c) and (d) are incorrect:

Genome editing involves enzymes like CRISPR-Cas9, TALENs, etc which are used to modify DNA sequences. These enzymes are tools for targeted genetic modifications. Transcriptome doesn’t relate to enzymes used in editing Gene expression involves the processes of transcription (DNA to mRNA) and translation (mRNA to proteins). It includes regulatory mechanisms like transcription factors, epigenetic modifications, and post-transcriptional processing. Mutations are changes in the DNA sequence caused by errors during replication, environmental factors, or chemical agents.

Explanation

According to the Food Safety and Standards (Packaging and Labeling) Regulations, 2011, pre-packaged items in India must display key information, including:

Nutrition information List of ingredients (including additives) Vegetarian/Non-vegetarian label Date of manufacture and packing Best-before date Lot number, Code number, or Batch number The regulations mandate that foods containing allergens such as cereals containing gluten, nuts, soybeans, milk, and fish must declare the presence of these allergens on the label. However, the regulations do not require a specific medical recommendation regarding allergic reactions

Explanation

Viruses can infect bacteria and are commonly known as bacteriophages. They attach to bacterial cells and inject their genetic material, leading to the production of new viral particles within the bacterial host. Viruses that infect fungi are termed mycoviruses. These viruses can influence the physiology and pathogenicity of their fungal hosts. Notably, studies have shown that fungi can acquire viruses and viroids from plants, indicating cross-kingdom transmission. Numerous viruses infect plants, causing a variety of diseases that can significantly impact agricultural productivity. These plant viruses can be transmitted through various means, including insect vectors, mechanical damage, and seed transmission. Ex-Tobacco Mosaic Virus (TMV), infect plants, causing diseases that affect crop yields and quality.

Explanation

Statement 1 is correct: LiFi (Light Fidelity) uses visible light, ultraviolet, or infrared light to transmit data. This technology works through light-emitting diodes (LEDs), which modulate light signals at extremely high speeds to carry information. Unlike traditional radio frequency-based wireless systems, LiFi leverages the light spectrum for communication.

Statement 2 is correct: LiFi is a wireless communication technology that does not require cables for data transmission. In laboratory conditions, it has demonstrated speeds significantly faster than WiFi, reaching up to 224 Gbps. However, its performance depends on line-of-sight and is more suitable for indoor environments.

Explanation

AstroSat is the first dedicated Indian astronomy mission aimed to study celestial sources in X-ray, optical and UV spectral bands. The payloads cover the energy bands of Ultraviolet (Near and Far), limited optical and X-ray regime (0.3 keV to 100keV). The ability to simultaneously observe multiple celestial objects at multiple wavelengths with a single satellite is one of the special aspects of the AstroSat project.

Statement 1 is incorrect: India has joined the exclusive club of nations with its own space observatory with the successful launch of ASTROSAT, joining the US, Japan, Russia, and Europe. ASTROSAT, India’s first dedicated multi-wavelength space observatory, will aid in the knowledge of the cosmos.

Statement 2 is incorrect: AstroSat with a lift-off mass of 1515 kg was launched into a 650 km orbit inclined at an angle of 6 deg to the equator by PSLV-C30 from Satish Dhawan Space Centre, Sriharikota.

Explanation

Mangalyaan/Mars Orbiter Mission (MOM), the maiden interplanetary mission of ISRO, was launched on PSLV-C25. It entered into Martian orbit in its first attempt. MOM had completed 1000 Earth days in its orbit well beyond its designed mission life of six months.

Statement 1 and 3 are correct: The Mangalyaan launched by ISRO is also called the Mars Orbiter Mission. With this India became the first Asian nation to reach Mars orbit, and the first nation in the world to do so in its first attempt.

Statement 2 is incorrect: It is India’s first interplanetary mission and ISRO has become the fourth space agency to reach Mars, after the Soviet space Programme, NASA and the EuropeanSpace Agency.

Explanation

The International Thermonuclear Experimental Reactor (ITER) is a collaborative international project involving countries such as India, China, the European Union, Japan, Korea, Russia, and the United States. Its primary goal is to demonstrate the feasibility of nuclear fusion as a sustainable and large-scale energy source by replicating the fusion processes that power the sun. If ITER succeeds then the immediate advantage for India would be the capability to construct fusion reactors for power generation. Fusion energy offers a carbon-free and environmentally sustainable alternative, with the potential to provide a significant amount of power compared to fossil fuels.