Science and Technology Quiz: Revision |7 Mar, 2021

Aerosols are minute particles suspended in the atmosphere. When these particles are sufficiently large, we notice their presence as they scatter and absorb sunlight.

· Their scattering of sunlight can reduce visibility (haze) and redden sunrises and sunsets. Aerosols interact both directly and indirectly with the Earth’s radiation budget and climate.

· As a direct effect, the aerosols scatter sunlight directly back into space.

· As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the Earth’s energy budget

· Aerosols come from both natural and human sources—and sometimes both at once. Dust, for example, is scoured from deserts, the dried-out edges of rivers, dry lakebeds, and more.

· Its concentrations in the atmosphere rise and fall with climate; in cold, dry, periods in the planet‘s history like the last ice age, more dust filled the atmosphere than during warmer stretches of Earth‘s history.

Source: NCERT and The Hindu

A nucleotide is an organic molecule that is the building block of DNA and RNA.

· They also have functions related to cell signaling, metabolism, and enzyme reactions.

· A nucleotide is made up of three parts: a phosphate group, a 5-carbon sugar, and a nitrogenous base.

· The four nitrogenous bases in DNA are adenine, cytosine, guanine, and thymine.

· RNA contains uracil, instead of thymine.

· A nucleotide within a chain makes up the genetic material of all known living things.

· They also serve a number of functions outside of genetic information storage, as messengers and energy moving molecules.

Source: NCERT and The Hindu

In recent years, fundamental research has focused increasingly on the short- and long-term effects of CO2 injection into reservoirs to assess the feasibility of CO2 storage on a commercial scale.

· Sequestration processes involve different trapping mechanisms according to the hydrodynamic, physical and chemical conditions in the formation.

· It is common to divide these mechanisms into four different categories: hydrodynamic trapping, residual trapping, solubility trapping, and mineral trapping.

Source: Indian Express

A composite material is a combination of two materials with different physical and chemical properties.

· When they are combined, they create a material which is specialised to do a certain job, for instance to become stronger, lighter or resistant to electricity.

· They can also improve strength and stiffness.

· The reason for their use over traditional materials is because they improve the properties of their base materials and are applicable in many situations.

· Use of composite materials in indigenously developed aircraft (Tejas), missiles (Agni) and in defense and civilian sectors is poised for big growth, where Indian companies are set to get into manufacturing mode.

Source: NCERT and The Hindu

Proton, neutron, and electron are tiny particles that make up atoms.

· The neutrino is also a tiny elementary particle, but it is not part of the atom. Such particles are also found to exist in nature.

· Neutrino has a very tiny mass and no charge. It interacts very weakly with other matter particles.

· So weakly that every second trillion of neutrinos fall on us and pass through our bodies unnoticed.

· Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated.

· They can also be produced in the lab.

Source: The Hindu

Genetic drift can have major effects when a population is sharply reduced in size by a natural disaster (bottleneck effect) or when a small group splits off from the main population to found a colony (founder effect).

· The founder effect is another extreme example of drift, one that occurs when a small group of individuals breaks off from a larger population to establish a colony.

· The new colony is isolated from the original population, and the founding individuals may not represent the full genetic diversity of the original population.

· That is, alleles in the founding population may be present at different frequencies than in the original population, and some alleles may be missing altogether.

· The founder effect is similar in concept to the bottleneck effect, but it occurs via a different mechanism (colonization rather than catastrophe).

· Genetic studies done on the people of the Lakshadweep archipelago by a team, led by K. Thangaraj at CSIR-Centre for Cellular and Molecular Biology (CCMB), for the first time have shown that a majority of human ancestry in Lakshadweep is largely derived from South Asia with minor influences from East and West Eurasia.

· And, there was no evidence of early human migration through the Lakshadweep islands.

· “We found a strong founder effect for both paternal and maternal lineages — a sign that the island population had limited genetic mixing”, said by scientists.

Source: The Hindu & NCERT

The United Nations announced 2019 as the International Year of the Periodic Table of the Chemical Elements to highlight its first publication in 1869.

· The periodic table as we know it today was first designed by the Russian scientist Dmitri Ivanovich Mendeleev.

· This year marks the 150th anniversary of the first publication of the periodic table by Mendeleev.

· Since its creation, the periodic table has been at the centre of a lot of vivid debates and is now considered as “one of the most important and influential achievements in modern science reflecting the essence not only of chemistry, but also of physics, biology and other disciplines.”

· Mendeleev’s genius lies in the acknowledgement that at the time, not all the elements were known yet, so he left gaps in the table for undiscovered elements.

· At that time, only 63 elements had been identified. Still the properties of five other elements (the gaps brilliantly added to complete the table) could already been determined using the table.

Source: NCERT

Bats serves as natural hosts for numerous viruses including Ebola virus, Nipah virus, corona viruses such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) and the 2019 novel corona virus that has infected nearly 10,000 people and killed over 200 others.

· Even as these viruses cause harm in humans, they rarely if at all cause any harmful effects in bats. This is the case even when the viral load is extremely high in bats.

· The reason why bats can harbour these viruses without getting affected is simply because bats can avoid excessive virus-induced inflammation, which often causes severe diseases in animals and people infected with viruses.

· The researchers found that significantly reduced inflammation in bats was because activation of an important protein — NLRP3 — that recognizes both cellular stress and viral/bacterial infections was significantly dampened in bat immune cells.

· Studying further, the researchers found that reduced activation of the NLRP3 protein was in turn due to impaired production of mRNA (transcript).

· Since mRNA production is impaired the NLRP3 protein production gets compromised leading to less amount of the protein being produced.

· But this was not the case with mice and humans — there was no impairment to mRNA production so the NLRP3 protein was unaffected.

Source: The Hindu

The traces pesticides leave in treated products or those left by veterinary drugs in animals are called “residues”.

· The traces pesticides leave in treated products or those left by veterinary drugs in animals are called “residues”.

· A study of fruits and vegetables grown in the Nilgiris has found that some of the produce might be harbouring high levels of pesticide, beyond what is considered advisable. This was mainly true of potato and carrot.

· While the Food Safety and Standards Authority of India (FSSAI) prescribes a maximum residual level (MRL) for some of the organophosphate pesticides used, it does not prescribe it for some other pesticides used in the cultivation of fruit and vegetables.

Source: NCERT

Rani Rashmoni is a fast patrol vessel, indigenously built by Hindustan Shipyard.

· It is built under the Fast Patrol Vessel (FPV) project of Indian Coast Guard.

· Under the first phase of the project, 5 FPV ‘s has been built.

· The first four such ships are ICGS Rani Abbakka, ICGS Rani Avanti Bai, ICGS Rani Durgavati and ICGS Rani Gaidinliu.

Source: The Hindu