How is our atmosphere different from the atmosphere on Venus and Mars?
The difference in the atmosphere of Earth and that on Venus and mars is that the atmosphere of Earth is made of nitrogen 79% and oxygen 20%, small fraction of carbon dioxide and other gases whereas the atmosphere of Venus and Mars is composed mainly of carbon dioxide ranging from 95-97%.
How does the atmosphere act as a blanket?
Atmosphere acts as a blanket in the following ways-
What causes winds?
Unequal heating of landmass and water bodies by sun’s heat generate air movement and as a result wind is produced. When the air around landmass gets heated, it becomes lighter and rises up creating a region of low pressure. Air from high pressure region escapes to the low pressure region thus generating wind currents.
How are clouds formed?
List any three human activities that you think would lead to air pollution.
Human activities that lead to air pollution are
•Use of automobiles as they use fuels like petrol which release toxic compounds when burned in the engine of the vehicle thus making the air polluted.
•Use of Chloroflourocarbons in refrigerators and air conditioners releases chlorine atoms in the atmosphere which deplete the ozone layer.
•Industries release a lot of harmful gases like sulphur dioxide, oxides of nitrogen, heavy metals which pollute the atmosphere.
Why do organisms need water?
Organisms need water for the following reasons-
•Reactions taking place inside the cells occur between substances that are dissolved in water.
•Water also helps in transporting substances in dissolved form in the body.
Hence, organisms need water because it plays a major role in transporting substances and is a vital component in carrying out life processes
What is the major source of fresh water in the city/town/village where you live?
Major source of freshwater in the city is underground water reservoirs and Rivers.
Do you know of any activity which may be polluting this water source?
Industrial wastes, fertilizers and pesticides from farm runoff are polluting the underground water sources.
How is soil formed?
Five main interacting factors affect the formation of soil:
What is soil erosion?
Soil erosion is the wear of top fertile soil by wind or water is known as soil erosion.
Top soil is blown away by high speed wind. Deforestation also losens the soil as the roots that hold the soil together no longer exist. This loosened soil gets eroded away by wind and water easily.
What are the different methods of preventing or reducing soil erosion?
Some methods to prevent soil erosion are-
• Soil should have some vegetations like grass growing in it so that it does not get carried away by rainwater.
•Afforestation or planting of trees, so that roots hold the soil prevent soil erosion.
What are the different states in which water is found during the water cycle?
There are these different states in which water is found during the water cycle.
•Solid state- as ice/snow.
•Liquid state- as water that falls as rain.
•Gaseous state- as water vapour in the atmosphere by evaporation due to sun’s heat. It also exists in clouds in gaseous state.
Name two biologically important compounds that contain both oxygen and nitrogen.
Deoxyribonucleic acid and ribonucleic acid are two biologically important compounds that contain both oxygen and nitrogen (in their chemical formula).
List any three human activities which could lead to an increase in carbon dioxide content of air.
•Burning of fossil fuels like coal and petroleum releases carbon dioxide in the atmosphere.
•Deforestation also causes increase in carbon dioxide content as the plants that use carbon dioxide are cut down.
•Industries release various harmful gases into the atmosphere. Carbon dioxide is one such gas.
•Overpopulation will also lead to increase in carbon dioxide content as humans release carbon dioxide by respiration.
What is the greenhouse effect?
Greenhouse effect is a phenomenon that heats the earth’s surface. The greenhouse gases prevent infrared diations from escaping the earth which results in heating of the earth’s surface.
What are two forms of oxygen found in the atmosphere?
Two forms of oxygen found in the atmosphere are diatomic as Oxygen O2 and triatomic as Ozone O3.
Why is the atmosphere essential for life?
How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Living organisms depend on soil for food indirectly. Plants need soil for support as well as getting nutrients to prepare their own food.
Herbivore obtains food from plant. Carnivore is directly dependent on the herbivore, the herbivore is directly dependent on the plant and the plant is directly dependent on the soil for the minerals, Thus making them indirectly depending on the soil.
Organisms living in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food. These aquatic plants, in turn, require nutrients from the soil which carried to the water body by the river or by the wind.
Thus, we get to the conclusion that living organisms are dependent on soil.
Why is water essential for life?
Water is essential for life because of the following reasons:
(i) Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.
(ii) Transportation of biological substances needs water needs water as a medium.
(iii) Organisms need to maintain the level of water within their bodies in order to stay alive.
You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Weather is predicted by meterological department of the government. The characteristics of weather like temperature, rainfall, humidity are collected in the form of data by using various instruments. Temperature is measured by a thermometer. Rainfall is measured by an instrument known as rian gauge. Various instruments are used to measure humidity.
We know that many human activities lead to increase levels of pollution of air, water bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing Pollution?
Yes, isolating these activities to specifid and limited areas would help in reducing pollution. Like if industries are set up in only isolated areas it will reduce the pollution by gas emissions and chemicals.
Write a note on how forests influence the air, soil and water resources.
a) Air- Forest manages the content of CO2 and O2 in the atmosphere. Plants take up the CO2 to perform photosynthesis and release oxygen which is inhaled by humans and animals. Humans and animals exhale CO2 tat is used by plants in photosynthesis.
b) Soil- Roots of plants bind the soil together and prevent the soil from being eroded away by wind or water.
c) Water- Forest means large number of plants. Forest transpire huge amount of water as water vapour which condenses around the dust particles to form clouds. When the clouds get saturated, rainfall occurs and the water flows into water bodies.