NIOS Class 12 Environmental Science Chapter 7 Human Modified Ecosystems

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NIOS Class 12 Environmental Science Chapter 7 Human Modified Ecosystems

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Human Modified Ecosystems

Chapter: 7

Module 2: Ecological Concepts and Issues

Textual Question Answer

INTEXT QUESTIONS 7.1

1. Name two human modified ecosystems.

Ans: Agro ecosystem and plantation forest.

2. Give two characteristics of human modified ecosystems.

Ans: (i) Low species diversity, unsustainable and need inputs of human beings in the form of energy.

(ii) They are highly susceptible to rapid spread diseases.

INTEXT QUESTIONS 7.2

1. Name any gas that contributes global warming.

Ans: CO₂ , Methane.

2. Write the full form of MIC and AIDS.

Ans: Methyl Isocyanate (MIC),

Acquired Immuno Deficiency Syndrome (AIDS).

3. What causes soil erosion? 

Ans: Overgrazing, poor irrigation, over cultivation, deforestation

INTEXT QUESTIONS 7.3

1. Name five types of plantations.

Ans: Acassia, Lucaenas (Subabus) Prosopis, Sesbannia, Caruarin Jatropa, Monnga and neem.

2. Which type of trees are preferred for plantation forests?

Ans: Fast growing tree species of economic value are preferred.

3. List any two common features of agro ecosystem and plantation forests.

Ans: Features of agro-ecosystems are:

(i) Species diversity is lowest.

(ii) Highly unstable and not self sustaining.

Features of plantation forests are:

(i) Plantation forests have trees of approximately same age.

(ii) Requires constant human care and management.

4. Which plant you would recommend to raise a plantation for obtaining bio diesel?

Ans: Jatropha curcas.

INTEXT QUESTIONS 7.4

1. List any two advantages of rural ecosystems.

Ans: Clean and natural environment is available, people have simple life style.

2. Why do people tend to migrate from villages to cities? 

Ans: For better employment,health and education opportunities and for better living amenities.

3. List any two disadvantages of urban ecosystem.

Ans: (i) The level of air pollution, water pollution, and soil pollution are high as compared to a rural ecosystem.

(ii) People are getting dependent on technologies and running away from nature.

4. Why do you like to go to a hill station during vacations? 

Ans: People like to go to a hill station during vacation as there is less pollution in hill stations. Hill stations are generally surrounded by mountains on all their sides. In the hill station, there is less air pollution and the quality of air is good over there. In hill stations, the rate of pollution is less. Less crowd is present in the hill station. Hill station is less congested than the city.

INTEXT QUESTIONS 7.5

1. What is the difference between fisheries and aquaculture? 

Ans: Aquaculture is the artificial cultivation of aquatic plants and animals whereas fisheries refers to capturing of fish and other aquatic organisms from seas and other fresh water bodies.

2. Name any two fresh water fishes that are being grown in pond culture.

Ans: Eel and Rohu.

3. Name the fish that is commonly known as aquatic chicken.

Ans: Tilapia.

4. In what way aquacultures affect the mangrove forests?

Ans: Aquaculture affects mangrove forests by destroying them to make space for aquaculture ponds, which leads to loss of biodiversity and degradation of coastal ecosystems.

INTEXT QUESTIONS 7.6

1. List any two advantages of dams.

Ans: (i) They store water.

(ii) They generate hydro electric power increase provide water for crop irrigation and other domestic uses.

2. Name the harmful gas that is released during burning of plastics.

Ans: Poly chlorinated biphenyls (PCB).

3. How does the introduction of an alieu species affects the indigenous species? 

Ans: Reduced population of nature species.

4. What effect does overgrazing by livestock have on grassland? 

Ans: It results in soil erosion and future loss of productivity. 

TERMINAL EXERCISE

1. Define human modified ecosystems.

Ans: Human modified ecosystems are man made ecosystem, such as agro ecosystem, aquaculture ponds, cities etc. for his own benefits. They require inputs of fossil fuel for their survival.

2. Give differences between natural and human modified ecosystems.

Ans: 

Aspect	Natural Ecosystems	Human-Modified Ecosystems
Source of Energy	The energy required is mainly from sunlight.	The energy required is fulfilled by fossil fuels and electricity.
Modification	Natural ecosystems are less modified by human activities.	Human-modified ecosystems are highly altered by human activities.
Complexity	Natural ecosystems tend to be complex and self-sustaining.	Human-modified ecosystems are often simpler and controlled.
Examples	Ponds, lakes, forests, and deserts.	Agroecosystem, aquaculture, and urban areas.

3. Why the following conditions lead to stress in a population:

(a) Over crowding.

Ans: Due to an increase in population, overcrowding occurs which results in competition among individuals. An increase in population also exerts tremendous pressure on natural resources. Human beings are uncontrollably using natural resources. If this continues resources will deplete soon. Natural resources should be used in a sustainable manner such as that it meets the requirement of the present generation as well as the future generation.

(b) Over harvesting. 

Ans: Over-harvesting is excess use of resources. Overharvesting of any resources could lead to its depletion. Nowadays consumer and consumerism are increasing day by day, human beings are using natural resources in an uncontrollable manner which can leads to the deprivation of resources in the future. Resources should be used wisely so that it can meet the present requirement as well as the future too.

(c) Human intervention.

Ans: Human beings are interfering in nature, which could eventually destroy natural resources. Half of the earth has been turned into cropland and urban areas, Man and biosphere program has been framed to restrict the intervention of human being n nature.

4. Give characteristics of human modified ecosystems.

Ans: Characteristics of human modified ecosystems are:

(i) Highly simplified.

(ii) Species diversity is very low.

(iii) Food chains are simple and small.

(iv) Depend on human (anthropogenic) support for survival; need for fossil fuel energy, fertilizers, irrigation etc.

(v) Attract large number of weeds.

(vi) More susceptible to epidemic diseases.

(vii) Suffer from soil erosion.

(viii) Highly unstable.

5. Write short notes on the following:

(i) Human population explosion.

Ans: The main result of the human population is poverty. An increase in the human population has led to an increase in demand for natural resources and it’s putting tremendous pressure on natural resources. Pollution is also increasing day by day due to this. The level of global warming is increasing day by day.

(ii) Industrial pollution.

Ans: Industrial effluents result in various kinds of pollution in the environment. Industrial pollution is increasing day by day due to this. Pollution has direct and indirect effects on natural resources. Air pollution and water pollution occurs due to industrial effluents. Water pollution occurs due to industrial effluents released in water bodies. Polluted water leads to various kinds of waterborne diseases such as typhoid and cholera.

(iii) Human health and disease.

Ans: Increased human population has led to increased chances of epidemic disease. Various types of the disease occur due to an increase in population. There is more chance of an increase in epidemic diseases such as AIDS, Hepatitis. These diseases are caused by an increase in population.

6. What are the advantages of tree plantation?

Ans: Tree station is a type of plantation forest and known as a man-made ecosystem. It is generally monoculture. Tree plantation is mainly done for raising fruits, oils, rubber and coffee. Tree plantation serves as windbreaks or shelterbelts. It controls soil erosion and increases soil fertility. Tree plantation helps in providing job opportunities. Tree plantation serves as the source of income.

7. List some impacts those are leading to environmental degradation?

Ans: The condition of the environment is degraded day by day due to an increase in air pollution, water pollution, and noise pollution. Pollution is severely affected. Overharvesting, overgrazing, habitat destruction, the introduction of alien species, Many problems have been created by agroecosystems such as soil erosion, depletion of groundwater. By the use of fertilizers and pesticides, environmental pollution has increased. Pesticides and fertilizers get washed away in rainwater and mix in water bodies leading to water pollution, eutrophication, Fishes die in polluted water as they do not get enough oxygen.