Review Concepts

Quick review of important concepts asked in the UPSC exams.

Climate of India

India has monsoon type of climate. The word 'monsoon' refers to the seasonal reversal of the wind direction in a year. Due to this, India has four prominent seasons - cold weather season, hot weather season, advancing southwest monsoon season and post or retreating monsoon season.

Bio Diversity in India

The diversity of plants and animal provide us food, fuel, medicine, shelter and other essentials without which we cannot live. Bio-diversity is a short form of biological diversity. In simple terms, bio-diversity is the total number of genes, species and ecosystems of a region. It includes (i) genetic diversity (ii) species diversity and (iii) eco-system diversity.

Governance at Union Level

The Constitution of India has made alternate provision for the structure and functioning of all the three branches of the government - executive, legislature and judiciary, The President, the Council of Ministers with Prime Minister constitute the executive branch of the Government, the Parliament with its two houses - House of the People or Lok Sabha and Council of States or Rajya Sabha is the legislative branch and the Supreme Court heads the judicial branch.

Quadratic Equations

Quadratic polynomial is a polynomial of degree 2. Quadratic equation is an equation having degree 2. General form of a quadratic equation is ax² + bx + c = 0, a ≠ 0 where a, b, c are real numbers and x is a variable.

Food and Nutrition

Food is an essential requirement for obtaining energy needed for performing vital activities. Food also helps in growth, maintenance, repair and protection from various diseases.

Control and Coordination

Nervous system (NS) and endocrine system together ensure that all the parts of the body work in a controlled and coordinated manner. NS includes brain, spinal cord, sense organs and nerves.

Optics: Light Energy

Light is the form of energy which makes the objects visible to us. When light reaches from object to our eyes, it becomes visible to us. Reflection, refraction and dispersion are the important properties of light.

Physiography of India

India is the seventh largest country of the world. It extends from the state of Jammu and Kashmir in the North to the state of Tamil Nadu in the South; from the state of Arunachal Pradesh in the east to the state of Gujarat in the west.

Carbon and its Compounds

Diamond has a three-dimensional network of covalently bonded carbon atom. It is hard and colourless. It has high melting and boiling point and is a good conductor of heat but poor conductor of electricity.

Motion

A continuous change in the position of the object with respect to time is called motion.

Natural Environment

In an ecosystem, living organisms interact among themselves and also with the surroundings. Ecosystem is divided into two basic categories - terrestrial and aquatic. Humans can also make ecosystems. For example, aquarium, gardens and agricultural fields are examples of man-made ecosystem.

Percentage and its Applications

Percent means per every hundred and denoted by the symbol %. A fraction with denominator 100 is called a Percent.

Matter

Anything that has mass and occupies space is matter. There are three different physical states of matter - solid, liquid and gas. A particular state of matter can be changed into other states by changing the temperature or pressure.

Agriculture in India

India is said to be the land of farmers and these farmers are mostly living in the rural India. Various types of agricultural activities are found in different parts of the country. Agriculture is categorised into different types on the basis of purpose of farming.

Metals and Non-metals

Elements are broadly classified as metals non-metals. Metals can be distinguished from non-metal on the basis of their physical properties like malleability ductility, lusture. Metals have tendency to lose electrons whereas non-metal have tendency to gain electrons. Thus, metals show electropositive character whereas non-metals show electronegative character.

Water

Water is essential for survival of all living beings. Although sea water is the largest natural source of water, it is unfit for domestic use and drinking. Decantation, filtration, chlorination and boiling are some of the steps that convert non potable water into potable water.

Air

Air is a mixture of different gases. It contains oxygen, Nitrogen, Argon, Carbon dioxide and traces of some inert gases. It also contains water vapour.

Heredity

Features passed down from one generation to the other is Heredity or Inheritance. Genes control heredity. Differences in features of individuals of the same species is variation.

Reproduction

Giving rise to offspring of one’s own kind is called Reproduction. Reproduction is a means for continuance of species. It is a characteristic of all living beings.

Respiration

Respiration provides O₂ to cells for energy production and removes CO₂ from cells.

Excretion

Excretion is the removal of harmful wastes like urea by kidneys, sweat from skin and CO₂ by lungs.

Transportation (Blood Circulation)

Blood transports food and oxygen to all the cells of the body. It is made of fluid plasma and cells. Plasma which transports glucose, enzymes and hormones to cells, carries waste material from liver to kidneys for removal.

Life Processes

Life Processes such as Nutrition, Respiration, Circulation and Excretion are necessary for the survival of living beings. Energy is needed for running life processes.

Cells and Tissues

Cell is the structural and functional unit of life. A typical cell includes a cell membrane, cytoplasm and genetic material either within the nucleus or in the cytoplasm. The cytoplasm contains cell organelles such as mitochondria, endoplasmic reticulum lysosomes, vacuoles, ribosomes, golgi bodies.

History of Life on Earth

The Earth is the only planet in the solar system which sustains life. But earth was not the same as it is today. It was a ball of gases when it was first formed about 4.5 billion years ago.

Classification of Living Organisms

The earth came into existence 4 to 5 billion years ago and life originated around 3.4 billion years ago. In these many years, approximately 15 million different kinds of organisms have evolved. The wide variety of organisms is termed biodiversity.

Sound

Sound is the form of energy which gives the sensation of hearing. It travels in the form of waves. The wave which can travel without medium is called non mechanical or electromagnetic wave. The wave which requires medium for its propagation is called mechanical wave.

Magnetic Effect of Electric Current

Magnet is a naturally occurring or artificially designed material which has a peculiar property of attracting some materials like iron, nickel and cobalt, called magnetic materials.

Electricity: Electrical Energy

There are two types of charges: positive charge and negative charge. Like charges repel each other while opposite charges attract each other.

Heat: Thermal Energy

Thermal energy, also called heat, is a form of energy which gives sensation of hotness. Like other forms of energy, its SI unit is Joule (J).

Work and Energy

The product of displacement and force in the direction of displacement of a body is called work.

Gravitation

Gravity: The gravitational force due to earth is called gravity.

Force and Motion

Inertia: The property of a body which tends to keep the body in its state of rest or of uniform motion is called inertia. Inertia is measure of mass.

Acids, Bases and Salts

Acids are the substances which taste sour, change blue litmus red, are corrosive to metals and furnish H⁺ ions in their aqueous solutions. Bases are the substances which taste bitter, change red litmus blue, feel slippery and furnish OH^– ions in their aqueous solutions.

Chemical Bonding

The basic cause of chemical bonding is to attain noble gas configuration either by transfer of electron from a metal to non-metal or by sharing of electrons between two non-metal atoms. All the atoms have a tendency to acquire stable state or noble gas configuration and is called Octet Rule.

Periodic Classification of Elements

The first classification of elements was as metals and non-metals. After the discovery of atomic mass, it was thought to be the fundamental property of elements and attempts were made to correlate it to their other properties.

Atomic Structure

According to Dalton’s atomic theory, the atom is considered to be the smallest indivisible constituent of all matter. This theory could explain the law of conservation of mass, law of constant composition and law of multiple proportions.

Chemical Reactions and Equations

A chemical equation is a shorthand description of a reaction. It symbolically represents the reactants, products and their physical states. In a balanced chemical equation, number of atoms of each type involved in the chemical reaction is equal on the reactants and products sides of the equation.

Atoms and Molecules

According to law of constant proportions, a sample of a pure substance always consists of the same elements combined in the same proportion by mass.

Measurement in Science and Technology

Measurement is a process of comparing a physical quantity with a standard quantity. The standard quantity used to compare a physical quantity for its measurement is called unit. The internationally accepted modern system of units used in science is known as SI units.