# CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT

## CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT

CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT. Population and Environment is a peer-reviewed academic journal covering research on the two-way linkages between population, natural resources, and the natural environment. CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT.

### CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT

CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT. The editor-in-chief is Dr. Elizabeth Fuss ell, associate professor of population and environmental and society studies at Brown University. The magazine’s former editors-in-chief include prominent racists such as Virginia Abernathy and Kevin B. MacDonald; Racists appear to have lost control of the magazine since MacDonald’s term as editor ended in 2004.CLASS 9th SCIENCE NOTES CHAPTER 4 POPULATION AND ENVIRONMENT.

## UNIT: 4

Q.1: Define demography.

Ans: Demography is the statistical study of human population. It can analyze any living population. Demography includes the study of the size, structure and distribution of the population and changes in them in response to birth, death, aging and migration.

Q.2: Differentiate between birth rate and mortality rate.

Ans: Birth rate is the live births per 1000 people per year. It is calculated by dividing the number of births by the total population and multiplies by 1000. Birth rate= No of births/total population x 1000

Death rate is the number of deaths per 1000 people per year. It is calculated by dividing the number of deaths by the total population and multiplies by 1000. Death rate= No of deaths /total population x 1000

Q.3: What do you mean by infant mortality rate?

Ans: Infant immortality rate is the number of deaths per 1000 live births of children under one year of age. The rate for a given region is the number of children dying under one year of age divided by number of live births during the year multiplied by 1000.

= No of deaths/live births x 1000

Q.4: Define the term migration. Differentiate between immigration and emigration.

Ans: Migration is the movement of people from one place to another.

Immigration and emigration are two different forms of migration. Migration into an area is called immigration. Migration out of an area is called emigration

Q.6: What do you mean by population growth? Give a comparative account of population growth of Pakistan and its neighbors.

Ans: Population growth is the increase in number of humans in a population. Global human population growth is around 83 million annually, or 1.1% per year.

Population growth of Pakistan and its neighbors:

Pakistan’s population is more than Bangladesh and Afghanistan. It is less than India and China.

Pakistan’s birth rate is higher than China, Bangladesh and India. It is less than Afghanistan only.

Death rate of Pakistan is less than Bangladesh, India and Afghanistan. It is more than China only.

Pakistan’s population growth rate is higher than China, Bangladesh and India. It is less than Afghanistan only.

Q.7: How do over population has its impact on the agriculture and forests? Or What are the Disadvantages of overpopulation?

Ans: Agriculture and over population:

Over population has greatly increased the quantity of food.

More population means more struggles for more resources.

More use of land results in loss of lands fertility.

Natural habitats are destroyed to bring more land under cultivation.

Overuse of fertilizers and pesticides pollute water, land and air.

Urbanization and overpopulation:

Migration of people from rural areas to big cities for a better lifestyle is called urbanization. More and more people migrate to rural areas due to increase in population. It has put pressure on some basic facilities such as water, electricity, gas and public transport. Traffic has increased and health facilities has fall short. It has disturbed the sewage system. Domestic waste has made its way to the irrigation canal.

Overgrazing and overpopulation:

Cattle are fed mainly on plants. Grasslands can support a specific number of cattle. As a result of growing population more and more cattle graze on grasslands which damage its fertility. It is called overgrazing. Due to overgrazing plants lose its ability to recover again and ultimately die. Overgrazing results in barren and exposed soil which is easily eroded and results in desertification.

Deforestation and overpopulation:

The unwise and unplanned destruction or removal of trees is called deforestation. Forests are cut to build more houses and roads for the over growing population. More land is required for cultivation to feed the growing population. Wood is used as timber or fuel wood. Cattle need pastures for grazing. All these things lead to the removal of trees. This leads to deforestation that causes soil erosion, loss of habitats and species, floods climate change and desertification.

Q.8: Sustainable development is key to survival in this modern day world. Evaluate the statement.

Ans: Sustainable development means to meet the present day needs without disturbing the needs of the future generation. It needs proper planning and management. We should consume the available resources wisely. We have to search for new ways of resources. Sustainable development is facing serious threats from over population. There are so many issues to be addressed for sustainable development for example; a balanced diet or food, health facilities, proper education, search and use of natural resources. Things that greatly affect sustainable development are; unwise and unjust use of resources, over population, unemployment, corruption and natural disasters. It needs wisdom, devotion, sacrifice and sense of responsibility. It is to think not only of yourself but also about the people coming after you. It is to leave this world a fair and better place to live in for the coming generations. It is our individual as well as mutual responsibility.

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