UGC NTA NET/JRF Exam, Environmental Sciences, June-2021

A Hunting and Gathering Society is a human living in a society in which most or all food is obtained by foraging (collecting wild plants and pursuing wild animals).

Hunting and Gathering Societies stand in contrast to agricultural societies, which rely mainly on domesticated species. Hunting and Gathering Society was humanity's first and most successful adaptation, occupying at least 90 per cent of human history.

Following the invention of agriculture, hunter - gatherers who did not change have been displaced or conquered by farming or pastoralist groups in most parts of the world.

Wangari Maathai (1940-2011) was the founder of the Green Belt Movement and the 2004 Nobel Peace Prize Laureate. She authored four books:
• The Green Belt Movement;
• Unbowed: A Memoir;
• The Challenge for Africa; and
• Replenishing the Earth.

As well as having been featured in a number of books, she and the Green Belt Movement were the subject of a documentary film, Taking Root: The Vision of Wangari Maathai (Marlboro Productions, 2008).

Wangari Muta Maathai was born in Nyeri, a rural area of Kenya (Africa), in 1940. The first woman in East and Central Africa to earn a doctorate degree, Professor Maathai became chair of the Department of Veterinary Anatomy and an associate professor in 1976 and 1977 respectively. In both cases, she was the first woman to attain those positions in the region.

Entropy can also refer to the amount of energy available to humans. As a piece of wood is burned, for example, its available energy - also called 'exergy' - decreases as the wood is transformed into high entropy matter - carbon dioxide and other substances useless from an energy point of view, its original exergy dissipated as useless heat.

Available energy corresponds to the useful part of energy, which can be transformed into work. The so-called Entropy Law (the Second Law of Thermodynamics) uses this definition of entropy to express the everyday experience that transformations of energy and matter are unidirectional.

It states that the entropy of an isolated thermodynamic system never decreases, but strictly increases in irreversible transformations and remains constant in reversible transformations. This places significant constraints on natural as well as technical processes.

For example, the temperature of a cup of hot coffee left in a cold room will always decrease, never increase, to eventually reach equilibrium with room temperature. In this process, the entropy of the room has increased.

No option is correct or the question is wrong.

Gibbs free energy (G) is a state function defined with regard to system quantities only and may be used to predict the spontaneity of a process.

A negative value for △G indicates a spontaneous process; a positive △G indicates a nonspontaneous process; and a △G of zero indicates that the system is at equilibrium. A number of approaches to the computation of free energy changes are possible.

Man-made compounds such as chlorofluorocarbons (CFCs), hydro fluorocarbons (HCFCs) and halons destroy ozone in the upper atmosphere (stratosphere), though they all vary in their Ozone Depletion Potential;

Detrital sedimentary rocks form from detritus, the rock and mineral fragments that are transported by gravity, water, ice, or wind. Detrital sediments are classified by grain size.

Detritus is classified by its grain size. Grains larger than 2 millimeters are called gravel. Grains between 1/16 mm and 2 mm are called sand. Grains smaller than 1/16 mm are in the silt and clay size ranges, often referred to as mud.

Chalk is a non-clastic carbonate sedimentary rock that is form of limestone composed of the mineral calcite. It is soft, fine-grained and easily pulverized. Colour is white-to-grayish variety of limestone rock.

It is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 per cent calcium carbonate in the form of the mineral calcite.