UPSC 2011 Science and Technology Questions with Answers

Explanation

DNA Sequencing means determining the order of the four chemical building blocks - called "bases" - that make up the DNA molecule. This sequence informs scientists the kind of genetic information that is carried in a particular DNA segment.

Statement 1 is correct: Pedigree analysis is the examination of a particular trait that is inherited from generation to generation. It helps in understanding the inheritance pattern of that trait and determining whether it is dominant or recessive. A thorough pedigree analysis using pedigree files received via DNA sequencing from the relevant breed organisations will certainly help in interpreting the pattern of inheritance of a livestock.

Statement 2 is correct: Mapping genes allows researchers to identify genetic variations associated with diseases. This understanding facilitates the development of targeted therapies and personalized medicine approaches.

Statement 3 is incorrect: Knowledge of gene positions enables the identification of genes responsible for disease resistance. This information can be utilized to breed or genetically engineer animals that are more resilient to specific diseases. However UPSC has not recognised it as completely true as if this application of DNA sequencing is still under development.

Explanation

Any substance that can inhibit the formation of unstable molecules known as free radicals, which harm DNA, cell membranes, and other components of cells, is referred to as an "antioxidant." Free radicals grab electrons from other molecules in order to complete their electron complement, which causes those molecules to suffer damage. Regular consumption of fresh fruits and vegetables is recommended because they are rich sources of antioxidants. Antioxidants play a crucial role in maintaining health and promoting longevity by neutralizing free radicals produced during metabolism. Free radicals are unstable molecules that can damage cells, proteins, and DNA, contributing to ageing and various diseases. By donating electrons, antioxidants stabilize free radicals, thereby preventing cellular damage and supporting overall health.

Explanation

Option (a) is correct: Bluetooth operates in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. Wi-Fi, depending on the standard, operates in the 2.4 GHz and/or 5 GHz bands.

Option (b) is incorrect: Bluetooth is typically used for short-range communication, forming Personal Area Networks (PANs), such as connecting peripherals like headphones or keyboards to a computer. Wi-Fi is used for Wireless Local Area Networks (WLANs), providing network connectivity within a local area like a home or office. Neither Bluetooth nor Wi-Fi is typically used for Wireless Wide Area Networks (WWANs), which cover broader areas and are usually associated with cellular networks.

Option (c) is incorrect: Bluetooth does not require a direct line of sight between devices as it can transmit data through obstacles like walls or furniture, though the presence of obstacles can affect the range and quality of the connection. Wi-Fi also does not require line of sight and can cover greater distances than Bluetooth, with its signals capable of passing through walls and other obstructions, though signal strength may degrade with obstacles.

Option (d) is incorrect: Since statement (b) is incorrect the fourth statement ("The statements (a) and (b) given above are correct in this context") is also incorrect.

Explanation

A VPN is a technology that creates a secure, encrypted connection(computer network) over a public internet network (such as the internet) to allow remote users to access their organization’s private network securely. It ensures that data transmitted between the user and the organization’s network is protected from interception or unauthorized access. A VPN encrypts the data transmitted between the user’s device and the VPN server. This ensures that even if the data is intercepted it cannot be read by unauthorized parties. They allow users to bypass geo-restrictions and access content that may be blocked in their region (e.g., streaming services, websites, or social media platforms).

Explanation

Artificial satellites are launched into orbit for a variety of purposes, including communications, navigation, Earth imaging, weather observation, and scientific study. In satellites, humans typically experience a sense of weightlessness because the net force acting on our body is practically zero. This is due to the satellite’s centrifugal force, which cancels out the size of the earth’s gravitational pull. On the other hand, the earth’s gravitational pull is required for the satellite to continuously change its direction, giving acceleration for the satellite’s direction-changing process.

Explanation

Statement 1 is correct: Asteroids are primarily composed of rock and metal and are remnants from the early solar system. In contrast, Comets are made of ice, dust, and rocky material and originate from the Kuiper Belt or Oort Cloud.

Statement 2 is incorrect: Asteroids are predominantly located in the asteroid belt between Mars and Jupiter. Comets originate from distant regions of the solar system: short-period comets come from the Kuiper Belt beyond Neptune, and long-period comets originate from the distant Oort Cloud. They are not typically found between Venus and Mercury.

Statement 3 is correct: As comets approach the Sun, the heat causes their icy components to sublimate, forming a glowing coma and often a visible tail that points away from the Sun due to solar wind. Asteroids, being rocky and lacking volatile materials, do not exhibit such features.

Explanation

Statement 1 is correct: Geostationary Orbit is a type of geosynchronous orbit. The earth rotates in the same direction that satellites do. It lasts for roughly 24 hours and holds its place in relation to the earth.

Statement 2 is correct: The orbit must be nearly circular, ensuring that the satellite’s distance from Earth remains constant throughout its revolution. An elliptical orbit would cause the satellite to move closer and farther from Earth, disrupting its stationary position.

Statement 3 is correct: A Geostationary Orbit (GEO) is a special case of a Geosynchronous Orbit (GSO) where the satellite orbits exactly in the Earth’s equatorial plane (0° inclination). This ensures that the satellite appears fixed over a specific point on Earth.

Statement 4 is incorrect: Geostationary orbit is at an altitude of around 35,786 km.

Explanation

In severe winter, a lake’s surface freezes while the bottom remains liquid due to the anomalous density behavior of water. Unlike most substances, water reaches its maximum density at 4°C, meaning that as it cools, denser water sinks while colder, lighter water (below 4°C) stays at the surface. When temperatures drop below 0°C, the surface water freezes first, forming an insulating ice layer that prevents further heat loss from the deeper water, keeping it in a liquid state. This phenomenon protects aquatic life, as it prevents the entire lake from freezing solid

Explanation

Microbial fuel cells (MFCs) are a bioelectrochemical technique, proposed to generate power using electrons from biological reactions in microorganisms.

Statement 1 is correct: These devices primarily use bacteria as catalysts to break down organic and inorganic substances, generating electrical current.

Statement 2 is incorrect: Microorganisms oxidise organic compounds, not inorganic substrates in the anode chamber, producing electrons and protons (reaction of anodes).

Statement 3 is correct: An MFC typically consists of two electrodes: the anode and the cathode. At the anode, bacteria decompose organic matter in wastewater, producing electrons and protons. The electrons travel through an external circuit to the cathode, generating electricity, while the protons move from the anode to the cathode. At the cathode, the electrons and protons combine with an electron acceptor, such as oxygen, to form water. As a result, MFCs can be implemented in wastewater treatment facilities to purify water and generate electricity.

Explanation

Moderator is used in a nuclear reactor for slowing down the neutrons produced during the fission reaction so that the chain reaction can be sustained. Due to its high moderating ratio and low neutron absorption cross section, heavy water makes a good moderator. Deuterium oxide, popularly known as heavy water (D₂O), is a hydrogen isotope with a mass double that of regular hydrogen and oxygen. However, In nuclear power reactors, heavy water can also be utilized as a coolant.