Explanation : 

Bisphenol A (BPA) in Polycarbonate Plastics and Epoxy Resins

Bisphenol A (BPA) is a chemical compound that is primarily used in the production of polycarbonate plastics and epoxy resins. Polycarbonate is a type of plastic known for its strength, durability, and transparency, which makes it suitable for a wide range of applications, including the manufacture of water bottles, sports equipment, medical devices, and the lining of metal food cans.

The reason BPA is a key component in the manufacture of polycarbonate plastics is due to its chemical structure. BPA has two phenol functional groups, which are reactive and can be used to form the backbone of the polycarbonate polymer chain through a process known as polymerization. When BPA molecules react with phosgene (COCl₂) or with a carbonyl chloride-based compound in a condensation reaction, they form long chains of polycarbonate polymer.

Alternative Plastics and BPA Usage

The other plastics listed do not typically use BPA in their manufacturing processes:

1. Low-density polyethylene (LDPE) is made from the polymerization of ethylene and does not require BPA for its production.
2. Polyethylene terephthalate (PET) is made from the polymerization of ethylene glycol and terephthalic acid and does not include BPA in its structure.
3. Polyvinyl chloride (PVC) is made from the polymerization of vinyl chloride monomers and also does not contain BPA.

Health Concerns and BPA

BPA has become a cause for concern because it can leach out of plastics and into food and drinks, particularly when the plastic is heated or damaged. Studies have shown that BPA can mimic estrogen and other hormones in the body, potentially leading to health effects such as reproductive disorders, developmental problems, and other illnesses. As a result, many manufacturers and governments have taken steps to reduce the use of BPA in consumer products, especially those intended for food and drink storage.

Explanation : 

ACE2 in Viral Disease Spread

ACE2 stands for Angiotensin-Converting Enzyme 2. It is an enzyme that is attached to the outer surface (cell membranes) of cells in various organs such as the lungs, heart, kidney, and intestines. ACE2 has gained significant attention in the context of the spread of viral diseases, particularly due to its role as a receptor for the coronavirus responsible for COVID-19, known as SARS-CoV-2.

Receptor for SARS-CoV-2 : The spike protein of SARS-CoV-2 binds to the ACE2 receptor on the surface of human cells. This binding is the first step in the viral infection process, as it allows the virus to gain entry into the cell. Once inside, the virus can replicate and spread to other cells, leading to the development of COVID-19.

Viral Entry Point: Because ACE2 is expressed in various organs, it provides multiple potential entry points for the virus, which can lead to multi-organ infection and a range of symptoms associated with COVID-19.

Therapeutic Target: Understanding the interaction between ACE2 and the coronavirus spike protein has been crucial for developing therapeutic strategies, such as monoclonal antibodies that can block this interaction and prevent the virus from entering cells.

Genetic Research: Research into the variations in the ACE2 gene among different populations may provide insights into why some individuals are more susceptible to severe COVID-19 than others.

Explanation : 

Street Lighting: Sodium vs. LED Lamps

The comparison between sodium lamps and LED lamps for street lighting involves several factors, including the direction of light emission, lifespan, and color spectrum. Here’s a detailed explanation:

Direction of Light Emission

Sodium lamps are known for their 360-degree light emission, which requires the use of reflectors in streetlights. In contrast, LED lamps emit light directionally, enhancing their efficiency in street lighting applications.

Lifespan Comparison

LED lamps boast a longer lifespan than sodium lamps. While sodium lamps can last up to 24,000 hours, LEDs can last up to 100,000 hours, offering greater durability and cost-effectiveness over time.

Color Spectrum and Visibility

Sodium lamps produce a nearly monochromatic yellow light with poor color rendering, making it difficult to distinguish colors. LED lamps, however, provide a broad spectrum of visible light with excellent color rendering, which significantly improves night-time visibility and color distinction.

Explanation : 

Pressure Cooker Cooking Temperatures

The correct answer is “1 and 3 only,” which means that the temperature at which the food is cooked in a pressure cooker depends mainly upon the area of the hole in the lid and the weight of the lid.

Area of the Hole in the Lid

The area of the hole, or vent, in the lid of a pressure cooker is critical because it determines the pressure that can be maintained inside the cooker. A pressure cooker works by trapping steam inside, which increases the pressure and consequently raises the boiling point of water. The size of the hole is usually designed to allow just enough steam to escape to maintain a specific pressure, which correlates with a specific temperature. If the hole were larger, the pressure would be lower, and the temperature would be reduced.

Temperature of the Flame

While the temperature of the flame does affect how quickly the pressure cooker reaches the desired pressure, it does not directly determine the cooking temperature once the cooker has reached pressure. The cooking temperature is primarily set by the pressure inside the cooker, which is controlled by the design of the pressure valve (related to the area of the hole) and the weight on the lid.

Weight of the Lid

The weight of the lid, or more specifically, the weight of the pressure regulator that sits on the vent pipe, plays a direct role in controlling the pressure inside the cooker. The heavier the weight, the higher the pressure that can be maintained before steam is allowed to escape. This higher pressure results in a higher cooking temperature. In many pressure cookers, different weights can be used to achieve different pressures, which correspond to different cooking temperatures.

Official Answer by UPSC is c

Explanation : 

Rivers Originating from the Eastern Ghats

Brahmani River: is formed by the confluence of two rivers, the Sankh and the Koel, which rise from the Chota Nagpur Plateau and flow through the Eastern Ghats before merging.

Nagavali River: The Nagavali River originates from the Eastern Ghats in Odisha and flows through Odisha and Andhra Pradesh.

Subarnarekha River: The Subarnarekha River originates from the Chota Nagpur Plateau in Jharkhand and does not rise from the Eastern Ghats.

Vamsadhara River: The Vamsadhara River also originates from the Eastern Ghats in Odisha and flows through Odisha and Andhra Pradesh.

Based on the above information, the rivers that rise from the Eastern Ghats are the Nagavali and the Vamsadhara. Therefore, the correct answer is:

Explanation : 

Official Answer – Sutlej

Explanation : 

Representation of the People Act (RPA), 1951

The Representation of the People Act (RPA), 1951, is the legal framework that governs elections in India. To address the statements provided, we need to refer to specific sections of the RPA and the amendments made to it over the years.

Candidate Restrictions in Lok Sabha Elections

As per the current law, the statement regarding the restriction on candidates from contesting in one Lok Sabha election from three constituencies is incorrect. The RPA 1951 was amended in 1996 to include Section 33(7), which limits the number of constituencies from which a candidate can contest in general elections. According to this amendment, a person cannot contest a general election from more than two parliamentary constituencies. Therefore, the law restricts a candidate from contesting in one Lok Sabha election from three constituencies.

The statement regarding Shri Devi Lal contesting from three Lok Sabha constituencies in the 1991 elections is correct. Before the 1996 amendment to the RPA, there was no restriction on the number of constituencies from which a candidate could contest. Therefore, Shri Devi Lal was able to contest from three Lok Sabha constituencies in the 1991 elections.

Rules on By-election Costs

The statement about the existing rules requiring a candidate’s party to bear the cost of bye-elections if a candidate contests and wins from multiple constituencies is incorrect. The existing rules, as per the RPA, do not explicitly require the candidate’s party to bear the cost of bye-elections. The cost of conducting elections is generally borne by the government. However, there have been discussions and suggestions to amend the law to include such a provision, but as of the knowledge cutoff date in 2023, no such amendment has been made to the RPA.

Given the above explanations, the correct answer to the question is “2 only,” which corresponds to the statement that Shri Devi Lal contested from three Lok Sabha constituencies in the 1991 election.

Explanation : 

Right to Privacy in India

The ‘Right to Privacy’ in India is protected under Article 21 of the Constitution of India. Article 21 states:

“No person shall be deprived of his life or personal liberty except according to the procedure established by law.”

While the text of Article 21 does not explicitly mention the ‘Right to Privacy,’ the Supreme Court of India has interpreted the right to life and personal liberty to include the right to privacy. This interpretation has evolved over time through various landmark judgments.

Landmark Judgment: Justice K.S. Puttaswamy (Retd.) vs Union of India

The most significant judgment regarding the ‘Right to Privacy’ came in the case of Justice K.S. Puttaswamy (Retd.) vs Union of India (2017). In this landmark decision, a nine-judge bench of the Supreme Court unanimously recognized that the right to privacy is protected as an intrinsic part of the right to life and personal liberty under Article 21 and as a part of the freedoms guaranteed by Part III of the Constitution.

Therefore, the ‘Right to Privacy’ is not enumerated as a separate right in the Constitution but is derived from Article 21 through judicial interpretation. It is now considered a fundamental right that protects individuals’ privacy from intrusion by the state, subject to reasonable restrictions.

Explanation : 

Administrative Reforms in India

The recommendation for a minister and a secretary to be designated solely for administrative reforms did not originate from the N. Gopalaswami Ayyangar Committee. Instead, it was the Appleby Report in 1953, penned by American public administration expert Paul H. Appleby, which suggested the creation of an organization within the Government of India focused on administrative improvement. This proposal led to the establishment of the Organization and Methods Division in the Cabinet Secretariat.

Formation of the Department of Personnel

In line with the recommendations of the first Administrative Reforms Commission (ARC), set up in 1966, the Department of Personnel was established in 1970. The ARC was tasked with examining the system of public administration and proposing reforms. The Department of Personnel was placed under the charge of the Prime Minister, highlighting the importance attached to the process of administrative reforms.

Explanation : 

Parliamentary Democracies: India vs. United Kingdom

The parliamentary systems of India and the United Kingdom are fundamentally different in several ways. One of the most significant differences lies in the legislative powers and the concept of sovereignty.

Legislative Powers and Sovereignty

In the UK, the British Parliament is recognized as supreme or sovereign, adhering to the doctrine of parliamentary sovereignty. This means that the Parliament has the ultimate authority to create or repeal any law without legal restraint. In contrast, the Indian Parliament operates within the constraints of a written constitution, which limits its legislative capabilities and ensures that laws do not contravene constitutional provisions. Additionally, India’s federal structure divides legislative authority between the Union and state governments.

Constitutionality and Judicial Review

Another key difference is the role of the judiciary in reviewing the constitutionality of legislation. The Indian Supreme Court has the power of judicial review and can convene a Constitution Bench to address substantial questions of constitutional law. On the other hand, the UK Supreme Court does not have the authority to declare an Act of Parliament unconstitutional due to the absence of a codified constitution and the principle of parliamentary sovereignty.