Chapter 13 National Environmental Issues

NIOS Class 12 Environmental Science Chapter 13

INTEXT QUESTIONS 13.1

1. What does the statement, “some Indian flora and fauna are endemic”, mean?

Ans: Endemic are those plant and animal species that are local, i.e. not found anywhere else.

2. Which part of India holds the ‘granaries’ and which part is mineral–rich?

Ans: The northern plains (granaries) and the peninsular plateau (mineral-rich).

3. List five major forest types of India.

Ans: Tropical rain forest, tropical deciduous forest, temperate broad leaf forests, temperate needle leaf or coniferous forest, alpine and tundra vegetation.

4. Name any three materials that forests provide to us.

Ans: Wood, gums, dyes, tannins, fibres, medicines, food (any three)

INTEXT QUESTIONS 13.2

1. Define population.

Ans: Population is defined as a group of individuals living in the same given area and capable of interbreeding and sharing genetic material.

2. List four major periods of human population growth

Ans: Through history, four major periods of human population growth worldwide can be traced:

(1) An early period of hunters and gatherers: At that time, the total population was less than a few million.
(2) The period of rise of agriculture: This period led to greater density of people and caused the first major rise in the human population.
(3) The industrial revolution: This resulted in better food supply, improved healthcare, which, in turn, led to a rapid rise in the population, and
(4) The present: When the population is slowing down in the wealthy and industrialized nations, but is still growing rapidly in poorer and developing and underdeveloped nations.

3. List the major parameters for the study of demography

Ans: Size, growth, age-structure, fertility, birth rate, death rate, standard of living, Migration, etc.

4. Define exponential growth.

Ans: Growth at a constant rate of increase per unit time is termed as exponential growth.

5. Why does internal migration within a country not affect its total population size? What kind of migration affects the population size of a country?

Ans: Because the internal migration within the country is usually from rural areas to the urban sector. Because it is still within a country. The types of migration that affect the population of the country are emigration and immigration.

INTEXT QUESTIONS 13.3

1. Name at least three countries which have a higher population density than India.

Ans: Japan, Bangladesh, the Netherlands, Malta.

2. Prepare a dispersion map of your locality.

Ans: Do it yourself.

3. Why is the age structure data of a population so important?

Ans: Age structure data of a population so important due to Study of age structure is important because it provides.

Current and future status of age profile;
Possible effects on the environment;
Insights into population history;
Available and future workforce (15-59 years)/manpower;
Status of elderly people needing social support, now and in the future;
Projection for current and future educational needs;
Projection for job needs
Projection for medical/social/housing/healthcare needs;
Economic status of the society.

4. What does a poor sex ratio of a state/country suggest?

Ans: The sex-ratio hints that there is discrimination against female children, there is social pressure to raise male children, and about female foeticide, etc.

INTEXT QUESTIONS 13.4

1. Enumerate at least three human activities that cause lasting impact on the environment.

Ans: Some human activities that have modified or degraded the environment are:

(1) Food shortage or famine: It could be because of less agricultural production; transfer of agricultural land for utilization; improper and inadequate storage, transport facilities; economic poverty to purchase food, etc.
(2) Inadequate shelter: Every individual is not provided with a safe shelter and is exposed to extremes of high and cold temperatures of the atmosphere, and falls prey to tigers, lions, wolves, leopards, rats, snakes, etc.
(3) Diseases: Malnutrition, inadequate sanitation, lack of medical facilities, increased susceptibility to disease, especially among young and old, as well as invasion and mutation of the pathogens, lead to epidemic/fatal attacks of bubonic plague, malaria, yellow fever, typhoid, tuberculosis, HIV-AIDS, dengue, influenza, etc.
(4) Calamities: Natural calamities such as floods, cyclones, earthquakes, volcanoes, tsunamis, avalanches, etc., uproot human settlements and damage property.
(5) Miscellaneous: Various mostly human-made accidents involving explosions, fire, pollution, ship wrecks, air and road accidents wipe out lives.

2. List three parameters that characterize the standard of living of a population.

Ans: A population is characterized by these parameters:

Life expectancy (should be high)
Infant mortality rate (should be low)
Income per head (should be high)
Literacy (the maximum number of individuals who are literate)
Consumption of food, natural resources (should be balanced)
Kind of energy used (eco-friendly)
Eco-friendly activity.

3. When we modify the environment, what problems are we generally failing to address?

Ans:

Ability to produce food through agriculture.
Transfer excess food to regions of food shortage.
Store excess food in warehouses, cold storage and canneries, thereby preventing food deterioration.
Impressive and innovative efficiency of energy utilization has caused a shift from wood energy to fossil energy to electric energy to atomic energy.
Ability to provide shelter for self (housing), the elderly and the young, protection against unfavourable weather or enemies.
Ability to destroy animal enemies, e.g. lions, tigers, wolves, snakes, rats, mice, household insects, etc.
Ability to reduce competition from other animals by fencing crops and livestock.
Reducing the mortality rate by controlling a number of life-threatening diseases through proper sanitation, medication, immunization, etc.

INTEXT QUESTIONS 13.5

1. How does one classify water as fresh, brackish or marine?

Ans:

Fresh water: It is inland water, and its salt content is less than 5 ppt or 0.5%.
b) Marine water: It occurs in seas, oceans, and its salt content is more than 35 ppt or 3.5%.
c) Brackish water: Its salt content is more than 5 ppt but less than 35ppt. It is present in estuaries, salt marshes and salt lakes. A lot of underground water in Rajasthan, Gujarat, Haryana and Punjab is brackish.

2. List four major causes that result in scarcity of fresh water in urban areas.

Ans: The scarcity of urban water is due to:

(i) Careless attitude: Release of untreated sewage and other waters into rivers and lakes;
(ii) Lowering of the water table: Due to excessive pumping of groundwater.
(iii) Waste in agriculture: Water is lost due to seepage or evaporation during irrigation and poor water management practices;
(iv) Increase in water demand: Due to increased urbanization and increased population, and an increase in per capita water consumption.
(v) Water pollution: Pollution of groundwater by nitrates, fertilizers, toxic chemicals, sewage, industrial effluents, domestic wastes, etc.

3. How does the improper sewage system in the cities affect the quality of water?

Ans:

Domestic wastes (effluents) contain pathogens that cause various viral, bacterial and other parasitic diseases. Cholera, dysentery, typhoid, jaundice, and worm-related diseases affect the health of the population.
Household effluents are also rich in nitrates and phosphates (from laundry detergents). These deteriorate the water quality and promote the growth of aquatic organisms, making the water unfit for human consumption.

4. Define flood. How does it affect human lives?

Ans: A Flood is a body of water that covers normally dry land. Its consequences are,

Destroy homes and valuable property.
Carry top fertile soil, leaving the land barren.
Destroy both food and cash crops.
Causes huge losses to human lives and cattle.
Cause landslides in the hilly areas.
Cause the dam burst.

5. List three preventive methods to overcome the miseries caused by floods.

Ans: Floods can be controlled by building dams to store water; planting trees on eroded land, and by building dykes, flood walls, and hurricane barriers along the coastline. Floods, however, can be controlled by proper planning involving

(a) Storage of water when there is plenty
(b) Migrating people from the affected areas
(c) Storing plentiful stocks of food and fodder during good times
(d) Cloud seeding
(e) Proper and effective water-shed/catchment area management.
(f) Afforestation, etc.

6. Name three major kinds of energy-generating plants in our country. What are their relative contributions towards our electric energy needs?

Ans: Hydroelectric (21%), Thermal (75%), Nuclear (3%)

7. List some of the measures that you would adopt to prevent the wasteful expenditure of electrical energy in your household.

Ans:

Turn off lights and appliances when not in use.
Using power-efficient electricals and appliances.
Using alternative methods for daily power usage.

8. How does urbanization lead to pollution?

Ans: With urbanization population gets unevenly dispersed, causing imbalanced demand for resources and even the release of harmful matter into the surroundings. Such harmful and often hazardous material comes from industrial, domestic, transport, and vehicle etc. When released, they severely affect the soil, water and air.

TERMINAL EXERCISE

1. “Environment has no geographical boundaries.” Explain.

Ans: Whatever damage is done to the environment at a place, it affects nearby or even distant places. This is why the environment has no geographical boundaries. These effects show up immediately or slowly.

2. How does an increase in population lead to depletion and degeneration of natural resources?

Ans: The explosive growth of the human population has been accompanied by rising expectations and an increase in the standard of living. More food, more houses, more transport, more energy and more of everything are required. This growing human need has resulted in depletion of natural resources; deforestation, loss of biodiversity, water and energy scarcity, increasing exploitation of mineral resources, etc., have led to the degradation of the environment.

3. List major environmental issues that confront us.

Ans: Major environmental issues that confront us include climate change, global warming, air, water and soil pollution, ozone depletion, etc.

4. Enumerate the various climate factors that determine the vegetation of a region.

Ans: Flood, drought, deforestation, desertification, soil degradation, and biodiversity loss.

5. Look at Figure 13.2 and answer the following questions:

a. What kind of forest type dominates Western India?

b. Which region of our country has alpine/tundra vegetation?

c. Which kind of forest type is maximally distributed in India?

d. In which part of the country is the tropical rainforest found?

Ans:

a. Tropical deciduous forests
b. Himalayan region
c. Tropical deciduous
d. Andaman Nicobar islands, Western Ghats and Northeast states

6. Define: Death rate, birth rate, natality, mortality, growth rate, migration.

Ans:

Death rate: The Rate at which deaths occur in the population
Birth rate: The Rate at which births occur in a population
Natality: Natality is an expression of the addition of new individuals in a population.
Mortality: Mortality refers to the death of individuals.
Growth rate: The growth rate (g) is the result of the number of births minus the number of deaths per unit time divided by the total number of individuals in the population.
Migration: Migration means the movement of individuals of a population.

7. When would a region be called overpopulated?

Ans: If the resources get overused and it is not possible to produce the same amount of goods or services for every individual in the region, the region is termed overpopulated.

8. Draw the population curve and explain the different phases of the curve.

Ans:

The population growth of human beings is a J-shaped curve. It took thousands of years to reach a billion human population. It took, further, 130 years to reach 2 billion, only 30 years to reach 3 billion, and only 11 years to add another billion. When the population approaches the full carrying capacity (the capacity sustain itself at equilibrium), the growth rate decreases, and the growth changes froma J-shaped curve to an S-shaped curve. (Sigmoid curve).

9. Define census. How does this help a country?

Ans: The complete count of the individuals in an area is called a census. It helps the country assess its population size as well as understand the number of its citizens living outside the country.

10. Why should the sex ratio of a population remain more or less constant/balanced?

Ans: The sex ratio of a population should remain more or less constant/balanced to avoid female discrimination and to maintain a male-to-female ratio compatible.

11. Discuss urbanization and socio-economic factors.

Ans: With economic development comes urbanization, and with urbanization comes destruction

of the environment. Urbanization causes environmental and social upheaval.

Urbanization and socio-economic factors

Population is redistributed.
Peasant society changes to a factory/business-dependent community;
Automobiles/industries pollute the air;
Civic amenities are unable to cope with increased sewage disposal.
Poor sanitation leads to water and soil pollution
Poor sanitation breeds pathogens/vectors resulting in the rise of communicable diseases;
Overcrowding, unemployment lead to an unbalanced urban life, which causes, in turn, a number of social evils.

12. Visit the various households in your locality (a) and interact with people, interview them and prepare a status of energy/water requirement/need and availability. (b)What measures would you propose at the local level so that wasteful expenditure of energy and water is avoided?

Ans: Write in your own words.

13. (a) List as many as possible the harmful and hazardous materials from different sources that occur/accumulate in your locality, and (b)suggestt measures to minimize this kind of pollution in your locality.

Ans:

Hazardous Products

Cleaning products
Pest repellents
Air purifiers
Exhaust from vehicles
Fertilizers

Measures to minimize pollution

Using eco-friendly products for cleaning
Using organic manure and fertilizers
Biopesticides instead of chemical ones
Using natural essential oils for air purification
Using lean energy to reduceemissionsn of harmful compounds

14. Differentiate between floods and drought.

Ans: Floods and drought are events connected with water that affect our lives.

A flood is a body of water that covers normally dry land. Floods occur when there is too much rain. Heavy rains cause flash floods. Sudden melting of ice also results in a flood. In deserts, the floods are caused by thunderstorms. Certain human activities, such as deforestation and over-intensive farming, are also the causes floods.

Drought is the condition that results when the average rainfall for an area drops below the normal amount for a long time. The consequences of drought arDried-upup water bodies

Reduced water supply for essential services
Dry topsoil
Death of livestock
Increased susceptibility to diseases such as diarrhea.

15. List four diseases caused by contaminated home-discharged water.

Ans: Such domestic wastes (effluents) contain pathogens that cause various viral, bacterial, and other parasitic diseases. Cholera, dysentery, typhoid, jaundice, and worm-related diseases affect the health of the population.

16. How is the regular supply of water maintained on Earth?

Ans: Regular supply of water on Earth is maintained through its circulation in the atmosphere. Precipitation of water vapour, in the form of rain, snow, dew, hail, etc,. is the main source of water in the environment. Water vapours present in the atmosphere, in turn, come from the water bodies such as lakes, streams, oceans, ponds, moist earth, as well as from living organisms.