Social Science STD 7 Chapter 11: Components of the Environment and Interrelationships - Exercises

1. Answer the following questions in one sentence:

1. 1. State the components of environment.

   The environment is composed of four main components: lithosphere, hydrosphere, atmosphere, and biosphere.

2. 2. Which are the main sources of fresh water?

   The main sources of fresh water are glaciers, groundwater, freshwater lakes, and rivers.

3. 3. How much is the time period between two tides?

   The time interval between two tides is approximately 12 hours and 25 minutes.

4. 4. Which pollution induces irritability in the nature of man?

   Noise pollution, caused by excessive and unbearable sound, can lead to irritability in a person's nature and also adversely affects mental health.

5. 5. What is land pollution?

   Land pollution is a change in the quality of the soil or its nutrients due to the mixing of external impurities.

2. Answer the following questions:

1. 1. What is man-made environment?

   A man-made environment, also known as a cultural environment, is created by human intellect through interaction with the biotic (living) and abiotic (non-living) components of the natural environment. It includes things like agriculture, industries, transportation, and urban settlements, all of which are developed to fulfill human needs.

2. 2. Write the measures to prevent land pollution.

   To prevent land pollution, several measures can be taken:

   • Use organic and indigenous fertilizers instead of chemical fertilizers.
   • Use pesticides sparingly.
   • Sort and reuse solid waste.
   • Recycle and reuse plastic and other solid waste.
   • Utilize drip and sprinkler irrigation systems in agriculture to prevent over-irrigation.

3. 3. Which steps should be taken to prevent air pollution?

   To prevent air pollution, the following steps should be taken:

   • Governments should create and strictly enforce laws against pollution.
   • Equipment for filtering smoke and toxic gases from factories should be developed.
   • The use of fuels like coal, petrol, and diesel should be limited.
   • The use of pollution-free alternatives like CNG, PNG, and solar energy should be encouraged.
   • People should be made aware of the benefits of using public transport.
   • Strictly enforce PUC (Pollution Under Control) checks for vehicles.

4. 4. Mention the steps taken by you to prevent noise-pollution.

   To prevent noise pollution, one can take the following steps:

   • Keep the volume of radios, televisions, and mobile phones low.
   • Avoid making unnecessary noise during social occasions and festivals.
   • Regularly service machines and vehicles to reduce noise.
   • Plant more trees, especially around industries and airports, as they help absorb sound.
   • Avoid using fireworks in celebrations.

3. Give Reasons:

1. 1. Tides occur in the sea.

   Tides occur in the sea due to the gravitational forces of the sun and the moon. The moon has a greater effect on the Earth's tides because, despite its smaller mass, it is much closer to the Earth than the sun. The gravitational pull of these celestial bodies causes the water in the oceans to bulge, resulting in the periodic rise and fall of the sea level that we call tides and ebbs.

2. 2. High tides occur on the New moon day and Full moon day.

   High tides occur on the New moon day and Full moon day because on these days, the sun, the Earth, and the moon are aligned in a straight line. This alignment causes the gravitational pulls of the sun and the moon to combine, resulting in a stronger pull on the ocean water and creating exceptionally high tides.

4. Fill in the following blanks with appropriate words:

1. 1. The atmosphere absorbs ......... sun rays and protect living beings.

   ultraviolet

2. 2. Noise pollution is also called .........

   unnecessary sound or unbearable sound

3. 3. Rushing of sea water towards the shore, is called .........

   tide