NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment

NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment Solutions to each chapter is provided in the list so that you can easily browse throughout different chapters NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment Notes and select need one. NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment Question Answers Download PDF. NIOS Study Material of Class 12 Environmental Science Paper Code 333.

NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment

Also, you can read the NIOS book online in these sections Solutions by Expert Teachers as per National Institute of Open Schooling (NIOS) Book guidelines. These solutions are part of NIOS All Subject Solutions. Here we have given NIOS Class 12 Environmental Science Chapter 3 Degradation of Natural Environment Solutions, NIOS Senior Secondary Course Environmental Science Solutions for All Chapter, You can practice these here.

Degradation of Natural Environment

Chapter: 3

Module 1: Environment Through Ages

Textual Question Answer

INTEXT QUESTIONS 3.1

1. State any two types of environmental degradation caused by humans. 

Ans: Deforestation/depletion of fossil fuels/depletion of minerals/air, water or soil pollution etc.

2. Give one reason for increase in human population.

Ans: Longevity due to better medical facilities/ availability of food.

3. Why rapid growth of world population is a cause for alarm?

Ans: Because natural resources are limited/degradation of environment is a threat to survival.

INTEXT QUESTIONS 3.2

1. What is deforestation?

Ans: Cutting down trees to clear forests.

2. Give two reasons why trees are cut down by humans.

Ans: For cultivation/timber/fuel wood/building houses etc.

3. State any two consequences of deforestation.

Ans: Biodiversity loss/soil erosion/floods/loss of CO2 sink etc.

4. Why do wild animals become endangered due to deforestation?

Ans: Forest is natural habitat of wild animals.

5. Why does deforestation cause soil erosion?

Ans: Roots hold soil in place.

INTEXT QUESTIONS 3.3

1. Why are chemical pesticides considered harmful even though they kill insects’ pests that damage crops?

Ans: They also kill useful insects.

2. How do chemical fertilizers used in fields reach water bodies?

Ans: The unused fertilizers from fields flow into water bodies during rains.

3. List any three degradational effects of modern agriculture on environment.

Ans: (i) water pollution, (ii) soil degradation, (iii) air pollution from burning stubble.

INTEXT QUESTIONS 3.4

1. Why there is water scarcity in cities? 

Ans: Consumers than available water.

2. Where do minerals and metals occur naturally? 

Ans: Under the soil and inside it.

3. Give one consequence of mining.

Ans: Depletion of useful metals/loss associated flora and fauna/land subsidence/landslides.

4. Name one natural resource that is getting depleted due to industrialization.

Ans: Fossil fuels/water/metal ores.

INTEXT QUESTIONS 3.5

1. Name the chemical responsible for Minamata disease.

Ans: Hg/Mercury.

2. Why do herbivores increase in number in the forest where lions have been killed by poachers? 

Ans: No lions to feed on them and reduce their number.

3. State one reason for excessive floods due to human activities.

Ans: Excessive deforestation, poor drainage, and encroachment of riverbeds cause floods.

4. What is the pH of pure rain water? 

Ans: 5 – 6.

5. What combines with seawater to form oil slick? 

Ans: Less volatile components of oil.

6. Expand CFC.

Ans: Chlorofluorocarbons.

TERMINAL EXERCISE

1. How is the utilization of fossils fuels related to a harmful impact on the environment?

Ans: The utilization of fossil fuels is related to a harmful impact on the environment because the burning of fossil fuels releases a large number of pollutants which is harmful to the environment. For example, when petroleum is burned carbon dioxide is released, which causes global warming.

2. List three reasons for human population explosion.

Ans: The three reasons for the human population explosion are illiteracy, reduced mortality, increased birth rate, and an increase in life expectancy.

3. In what way has increase in human population has degraded the environment?

Ans: The human population has degraded the environment in many ways such as industrialization, exploitation of soils, overgrazing, deforestation, etc.

4. State three reasons for deforestation.

Ans: The three major reasons for deforestation are:

(i) Agricultural expansion – Clearing forests for cultivation, shifting cultivation, and grazing.

(ii) Urbanization and industrialization – Forests are cut down for roads, buildings, factories, and infrastructure.

(iii) Logging and wood harvesting – Trees are felled for timber, fuelwood, paper, and furniture.

5. Write an essay on “impact of deforestation”.

Ans: Deforestation has several serious impacts on the environment. It increases the level of carbon dioxide in the atmosphere and contributes about 10% to global warming and climate change. It also leads to loss of biodiversity as many plants and animals lose their natural habitats.

Deforestation further causes soil erosion, irregular rainfall, and water scarcity, which reduce agricultural productivity. It also affects tribal and rural communities who depend on forests for their livelihood.

6. Why modern agriculture is held responsible for polluting air and water?

Ans: Modern agriculture usages excess use of inorganic fertilizers, insecticides, pesticides, fungicides. The excessive chemical fertilizers, insecticides, pesticides, and fungicides flow to the water bodies via rainwater which causes water pollution. The burning of leftover dried grasses results in air pollution. Flowing of chemical fertilizers causes water pollution, burning of organic materials causes air pollution that is how modern agriculture is held responsible for polluting air and water.

7. Why the modern influx of humans from villages to cities causing is serious concern to urban planners?

Ans: People are migrating from rural regions to urban areas because of poverty and in search of jobs.

(i) As a consequence of the migration of large populations to urban cities, cultivated land has been used up for building roads, homes, and industries.

(ii) To supply the portable to a growing population, water availability has been greatly affected.

(iii) The industries which provide necessary goods generate industrial waste, which is not disposed of properly.

(iv) Slums have developed which are unhygienic and hub of crime and social distortion.

8. Why “green house gases” are considered dangerous?

Ans: Greenhouses are considered dangerous because greenhouse gases cause rapid climate changes by trapping heat. Moreover, greenhouse gases also cause several types of respiratory disorders. Gases like carbon dioxide, methane can be poisonous on breathing.

9. Why do environmentalists think that “marine fisheries” may collapse, if we are not careful?

Ans: Environmentalists thinks that “marine fisheries” may collapse if we are not careful because overfishing may result in the endangerment of species or it may also lead to the extinction of species.

10. Write notes on:

(i) Mining and environmental degradation.

Ans: Mining of a certain ore or mineral may cause exhaustion of that particular element.

Environmental degradation takes place when environmental factors are degraded.

Mining may also lead to environmental degradation as in mining the elements like coal and other metals or ores are used to extract out.

(ii) Acid rain.

Ans: Acid rain occurs when compounds like sulfur dioxíde and nitrogen oxide are released into the air. When these compounds rise high in the atmosphere they mix up into the rainwater and rain as acid rain.

(iii) Global warming and green house effect.

Ans: Global warming is caused due to the trapping of greenhouse gases in the atmosphere.

Greenhouse gases like carbon dioxide, methane causes a rise in temperature which then further leads to global warming.

(iv) Biodiversity loss.

Ans: Biodiversity loss is the loss of flora and fauna. The major reason for the loss of biodiversity is industrialization, urbanization, deforestation, etc.