The countries that are densely populated in the world has more than 200 persons on every sq km. These are the North -Eastern part of U.S.A., North-Western part of Europe, South, South-East and East Asia. The marginal lands in many parts of South and East Asia have been brought under cultivation, and many former pastoral ranges in Southwest and Central Asia are now irrigated, the broad ecological factors touched upon above have continued to give rise to geographic variations in population and economic activity.

Climate has a great impact on human beings. Human beings prefer to live in a place with normal temperature and rainfall. Excessive coldness or hotness in the climate affects the population of the area. Thus, Greenland being a place with excessive coldness is the least densely populated country in the world. 

Enclosures in England were seen as necessary to make long term investments on land and plan crop rotations to improve the soil. Enclosures also allowed the richer landowners to expand the land under their control and produce more for the market. 

India is the first country in the world to have adopted an official policy favouring family planning. Before it did so in 1951, a number of social reformers, thinkers and voluntary organisations had desired the government to adopt a policy of population control as a measure to protect the health of the mother.

Even with the absence of market and exchange economy, only the introduction of agriculture enabled the steady growth of population. In this period, the development of agriculture and livestock ranching encouraged spread of population from Mediterranean and South-West Asia to  Central Asia, China, India and even in far east Asia.

Many of the world's population live in developing countries already strained by food insecurity, inadequate sanitation, water supplies and housing, and an inability to meet the basic needs of the current population. A large proportion of these populations are supported through subsistence agriculture. As populations grow, competition for fertile land and the use of limited resources increase. So, people of developing countries puts strain on the local environment.

 A developed country  is a term used  to describe an industrialized country with a highly developed economy. Developed countries consume far more natural resources than people in developing or underdeveloped countries.

With the increase in population, also the demands increases. People have the basic requirement for food and shelter. So, the demands for resources like land and water also increases which in turn creates pressure on the availability of natural resources.

Only 2.5% of water is freshwater and less than 0.3% of all freshwater is in river, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater(0.003) is contained within biological bodies and manufactured products.

 In the last few decades, there has been a tremendous increase in the demand for fresh water.  Approximately 20% of the world population lacks safe drinking water and nearly half the world population lacks adequate sanitation, this problem is acute in many developing countries ,which discharge an estimated 95% of their untreated urban sewage directly into surface water.  The surface water bodies rivers, streams, ponds and lake, which are the most important sources of water for human activities are unfortunately under sever environmental stress.

Developed countries consumption patterns and resource use are more which puts strain on global resources.The relationship between population growth and environmental degradation may appear to be rather straightforward. More people demand more resources and generate more waste. Clearly one of the challenges of a growing population is the mere presence of so many people sharing a limited number of resources strains the environment.

Population explosion in urban centers around the world is expected to rise demand for food.  In order to meet an increased demand in growing cities, the system by which food is produced, processed and delivered needs to be changed and there should be an increase in the food supply.

By 2025, 2 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions. Water scarcity is both a natural and a man-made phenomenon. There is enough freshwater on the planet for seven billion people but it is distributed unevenly and too much of it is wasted, polluted and unsustainably managed. 

With the increase in population, the increasing need for space is also turning out to be an area of concern. With desperate need for land for agricultural, industrial and most importantly urban needs to contain cities and their growing population, a direct action that we have come to recognize as “Deforestation” occurs. Deforestation in simple term means the felling and clearing of forest cover or tree plantations in order to accommodate agricultural, industrial or urban use. It involves permanent end of forest cover to make that land available for residential, commercial or industrial purpose.

Overexploitation of resources is disturbing environment in many ways. Wasting water has far-reaching consequences, which include the destruction of aquatic environments, lack of agricultural productivity and scarcity of safe drinking water.  Wastage of water leads to water scarcity. Unplanned exploitation of environmental resources has caused a lot of havoc to man and his environment on one hand. Air pollution, pollution of water, dumping of waste etc are some of the results of an unplanned exploitation of environmental resources. Desertification at the global level is the reduction in biodiversity, as it contributes to the destruction of the habitats of animal and vegetal species and micro-organisms.

Most of our energy is derived from non-renewable sources. 80% of the world's commercial energy comes from fossil fuels i.e oil, coal and natural gas. As non-renewable resources, their use is clearly unsustainable. While these resources will still exist in the ground for many years, both the financial and energy costs of bringing them to market will become increasingly prohibitive as their supplies dwindle.

Forests naturally absorb water from rainfall and slowly release the water into the rivers. After deforestation, rainfall flows too quickly to the rivers, stripping the topsoil and causing erosion and flooding to occur. When these floods break the river's banks, further problems arise as the path of the river changes and further soil erosion occurs along the river's new path. Deforestation also makes an area more arid, contributing to droughts.

80% of the world's natural forests is destroyed by human development activities. Forests destruction by human activity is mainly for the purpose of harvesting natural resources for industry production and urbanization. Human activity is to blame for deforestation, though natural disasters do play a role. Clearing forests for agriculture is the principal cause for habitat destruction.

Sputnik 1 was the first artificial satellite launched by the Soviet Union. The Soviet Union launched it into an elliptical low Earth orbit on 4 october 1957. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennae to broadcast radio pulses. It was visible all around the Earth and its radio pulses were detectable.

Remote sensing refers to the use of satellite-or aircraft-based sensor technologies to detect and classify objects on Earth, including on the surface and in the atmosphere and oceans, based on propogated signals. Some of the remote sensing satellites (sensors) are LANDSAT, SPOT, IRS, AVHRR, CARTOSAT etc.

Density methods are used to describe populations. Density describes how many individuals are in that given space. We might say that there are 100 people per square mile, or 20 plants per square inch. This gives us an idea of how tightly or loosely packed the organisms are in a given space.

The number of people living in a particular area is known as population of that area. The latest census of 2011 declared that population of India is second largest in the world. The most populous country is China having 1.34 billion people, whereas India has the population of 1.21 billion people, and it accounts for 16.7% of the world's population.

The population of India as per the 2011 census was 1,210,854,977. India added 181.5 million to its population since 2001, slightly lower than the population of Brazil. India, with 2.4% of the world's surface area, accounts for 17.5% of its population.

According to the State Census 2011, the most populated state in India is Uttar Pradesh with a population of 19.96 crores. The least populated state in the country is Sikkim with a population of 60, 7688.

China has the world's largest population (1.4 billion), followed by India (1.3 billion). The next most-populous nations are – the United States, Indonesia, Brazil and Pakistan.

Number of people that lives in square kilometer of land is classified as population density. It is frequently applied to living organism, and most of the time to humans.

Asia is the most populous continent on earth. It leads the ranking of the global population by continent in mid 2013. The continenet of Africa has the second highest population.

 A census is an official enumeration of the population done periodically. The Indian census is the most comprehensive source of demographic, social and economic data.

The term 'sparse' means scattered, thus, sparsely populated means a small number of people living over an area. If the population density of a particular area remains less than 50 persons per sq. km than that area is said to be sparsely populated. 

The density of the population is expressed as the number of persons per unit area. It helps in getting a better understanding of the spatial distribution of the population concerning land. The density of population can be divided into:

The density of the population is expressed as the number of persons per unit area. It helps in getting a better understanding of the spatial distribution of the population concerning land. To calculate the population density, you will divide the population by the size of the area. Thus, Population Density = Number of People/Land Area. The unit of land area should be square miles or square kilometers.

 A high population density implies that the population is high relative to the size of the country. Some countries have large populations living in a small area. In Bangladesh, people are packed more closely together. Countries like this have a high population density or a dense population. The area of a high density of population are:

A moderate population density is somewhere in the middle. If the population density of a particular area remains between 5--100 persons per sq. km then that area is said to be moderately populated. France has 107.8 people per square kilometer, so it has a moderate population density.

The density of the population is expressed as the number of persons per unit area. It helps in getting a better understanding of the spatial distribution of the population concerning land. The density of the population in India (2011) is 382 persons per sq km. 

Mongoloids,

The correct statement is that the tertiary sector contributes the maximum to the GDP, because is contributes $55.7$% in $2011-12$.

The people are important to develop the economy and society. The people make and use resources and are themselves resources  with varying quality of any country. India's has 18% of the Earth's  population. India ranks 2nd in the list of countries by population. 

The Indian Remote Sensing Satellite-1A (IRS-1A) was launched on March 17, 1988. IRS-1A is the first of a series of semi-operational/ operational remote sensing satellites developed by Indian space. It was launched at Baikonur Cosmodrome, Tyuratam, Russia.

ISR1A was the first  Indian remote sensing mission undertaken by the Indian Space Research Organization(ISRO). It was launched from Baikanour.

Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957. It was a 58 cm diameter polished metal sphere, with four external radio antennae to broadcast radio pulses.

A group of organisms of a species that interbreed and live in the same place at a same time is known as population. They are capable of interbreeding or reproduction. Population is the entire pool from which a statistical sample is drawn. The information obtained from the sample allows statisticians to develop hypotheses about the larger population.

Following are the impacts of underpopulation:

Underpopulation: when there are not enough people to make full use of the resources and technology of the place they live in. Canada is said to be underpopulated because it could increase its population but still have a high standard of living.

Underpopulation: when there are not enough people to make full use of the resources and technology of the place they live in.