General Science & Environmental Science

General Science & Environmental Science

Which of the following is the primary reason for the tremendous energy generated from the Sun and the other stars?

Sun's core fuses hydrogen nuclei into helium via proton-proton cycle at 15 million Kelvin, converting mass deficit into enormous energy per Einstein's E=mc2. This thermonuclear fusion sustains stellar luminosity and nucleosynthesis across main-sequence lifetimes.

Ref: Carroll and Ostlie An Introduction to Modern Astrophysics 2nd Edition Chapter 10 Nuclear Fusion in sun and stars explains proton-proton chain generating solar energy via mass-energy conversion published by Pearson Addison Wesley.

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General Science & Environmental Science

Alfred Nobel, the founder of Nobel prizes was once called the ‘merchant of death’ for which of the following inventions?

Alfred Nobel invented dynamite in 1867 by stabilizing nitroglycerin with kieselguhr, revolutionizing construction and warfare. A mistaken French obituary titled him merchant of death for profiting from explosives causing mass destruction, motivating him to create Nobel Prizes.

Ref: Fant Alfred Nobel A Biography and Nobel Foundation history documents describe dynamite invention leading to merchant of death epithet and establishment of Nobel Prizes published by Arcade Publishing and Nobel Foundation Stockholm.

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General Science & Environmental Science

Which of the following provided the major clue that led to the recognition of the double helical structure of DNA?

Rosalind Franklin's X-ray diffraction Photo 51 revealed helical diffraction pattern with characteristic cross and 3.4 Å base spacing. Watson and Crick interpreted this image plus Chargaff data to build antiparallel double helix model explaining complementarity and replication.

Ref: Watson James D The Double Helix A Personal Account and Alberts Molecular Biology of the Cell 6th Edition Chapter 4 DNA Structure chapter describes role of X-ray crystallography in elucidating double helical structure published by Garland Science WW Norton.

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General Science & Environmental Science

A mixture of oxygen with this gas reduces oxygen density and can be used in hospitals?

Heliox, mixture of helium and oxygen, has lower density than air reducing airflow resistance and work of breathing. It helps patients with severe airway obstruction, croup and asthma, improves oxygen delivery without increasing pressure and eases breathing effort.

Ref: West John B Respiratory Physiology The Essentials 10th Edition Chapter on Airway Resistance describes helium oxygen mixtures reducing gas density and used therapeutically for obstructive airway conditions published by Wolters Kluwer Lippincott.

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General Science & Environmental Science

Which part of the earth is suitable to witness the natural phenomena of dynamic light displays called ‘aurora’?

Auroras occur when solar wind charged particles interact with Earth's magnetosphere, funneling toward magnetic poles. Near Arctic and Antarctic, particles excite atmospheric oxygen and nitrogen, producing dynamic green, pink and violet light displays called aurora borealis and australis.

Ref: Kivelson and Russell Introduction to Space Physics Chapter 9 Magnetosphere and Auroras explains auroral oval near polar regions and solar particle precipitation mechanism published by Cambridge University Press.

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General Science & Environmental Science

Which among the following radiofrequencies is most commonly used in global air navigational systems?

VHF band 30-300 MHz, specifically 108-137 MHz, is globally standardized for air traffic control voice communication, VOR and ILS localizer navigation. It provides line-of-sight propagation with minimal atmospheric distortion and equipment compatibility for aviation safety.

Ref: Bhatta and others Aeronautical Communications Principles Systems Chapter on VHF Air-Ground Communication describes VHF frequencies used globally for navigation and air traffic management published by CRC Press.

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General Science & Environmental Science

The full form of RT-PCR is:

RT-PCR involves reverse transcriptase enzyme synthesizing complementary DNA from RNA template first, followed by conventional PCR amplification. This enables detection and quantification of RNA viruses, gene expression studies, and diagnostic applications requiring RNA conversion.

Ref: Sambrook and Russell Molecular Cloning A Laboratory Manual 4th Edition Chapter 8 Reverse Transcription describes RT-PCR as reverse transcriptase polymerase chain reaction for RNA analysis published by Cold Spring Harbor Laboratory Press.

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General Science & Environmental Science

Which of the following is an egg laying mammal?

Duck-billed platypus is monotreme mammal endemic to Australia that oviparously lays eggs while possessing mammary glands producing milk without nipples. It represents primitive mammalian lineage retaining reptilian reproductive traits alongside mammalian fur and endothermy.

Ref: Campbell et al Biology 11th Edition Chapter 34 Mammalian Diversity section on Monotremes describes platypus as egg-laying mammal with reptilian and mammalian characters published by Pearson Education Inc.

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General Science & Environmental Science

The Nobel Prize in Medicine is actually named as Nobel Prize in:

Alfred Nobel's will instituted prize for Physiology or Medicine, awarded annually by Karolinska Institute. The official name reflects contributions to both mechanistic understanding of life functions and clinical medical advances, honoring combined impact on healthcare.

Ref: Official Nobel Prize Organization literature and Lindsten Nobel Foundation documents describe prize established by Alfred Nobel as Nobel Prize in Physiology or Medicine awarded by Karolinska Institutet Stockholm Sweden published by Nobel Foundation.

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General Science & Environmental Science

A key tool used for determining the age of prehistoric samples is:

Radiocarbon dating measures decay of carbon-14 isotope with half-life 5730 years incorporated in living organisms. After death, 14C decreases predictably, allowing calculation of time elapsed, effective up to 50,000 years for archaeological and paleontological specimens.

Ref: Renfrew and Bahn Archaeology Theories Methods and Practice 7th Edition Chapter 4 Dating Methods details radiocarbon dating principles for determining age of prehistoric organic materials published by Thames and Hudson.

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General Science & Environmental Science

The pH of gastric acid (HCl) in the human stomach lumen can be as low as 1.5. Still, normally, it does not corrode the g

Gastric mucosa secretes bicarbonate-rich mucus forming protective gel layer over epithelium. This barrier neutralizes acid locally, prevents back-diffusion of H+ ions and contains prostaglandins maintaining blood flow, thus protecting stomach lining from autodigestion despite pH 1.5.

Ref: Guyton and Hall Textbook of Medical Physiology 14th Edition Chapter 65 Gastric Secretions explains mucus bicarbonate barrier protecting mucosa from highly acidic gastric juice published by Elsevier Saunders.

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General Science & Environmental Science

Humans have the ability to detect and discriminate at least 10,000 different odorants because we have one of the most ev

Olfactory epithelium contains millions of olfactory receptor neurons expressing around 400 functional odorant receptor types. Combinatorial activation allows discrimination of over 10,000 odorants. Humans possess highly evolved olfactory system for smell perception and memory.

Ref: Purves et al Neuroscience 6th Edition Chapter 15 Chemical Senses Olfaction discusses human olfactory receptor diversity and ability to discriminate thousands of odorants published by Sinauer Associates Oxford.

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