50 questions · self-marked practice — reveal the answer and mark yourself.
Wind causes weathering of rocks through:
Explanation:
Winds transport the rocks. During the transport abrasion occurs i.e. the rocks are scraped off as a result of friction between the rocks and sediment particles.
Wind breaks are:
Explanation:
Wind breaks are rows of trees and shrubs on land to prevent erosion of soil by high speed wind.
Why water is necessary for living organisms? Explain.
Living organisms need water because it plays a vital role in the reactions taking place within organism’s cells and body. Water acts as a universal solvent, providing a medium for the chemical reactions to occur. Substances are also transported from one part of body to the other in the dissolved state. Therefore, it is necessary for the organisms to maintain a distinct level of water within their bodies in order to stay alive. Terrestrial life forms require fresh water because their bodies cannot tolerate or get rid of the high amounts of the dissolved salts in saline water. So, water sources need to be easily accessible to animals and plants to survive on land. Thus, availability of water decides not only the number of individuals of each species that are able to survive in a particular area, but it also decides the diversity of life there.
Who is popularly known as ‘water man’?
Explanation:
Rajendra Singh is popularly known as water man of India. He is a water conservationist from Alwar, Rajasthan.
Which one is inexhaustible resource?
Explanation:
Solar energy is a renewable form of energy that cannot be exhausted ever. Radiations from sun are solar radiation so they are too inexhaustible and sustainable form of energy. Fossil fuels, minerals and soil are non-renewable sources. Once lost, they cannot be replenished.
Which of the following soil is transported by air?
Explanation:
Aeolian soil are wind deposited sand and silt sized particles. They have no coarse fragments.
Which of the following is a secondary pollutant:
Explanation:
Peroxyacytyl nitrate is a part of smog that causes air pollution. It is a secondary pollutant because they are formed in the atmosphere after the emission of primary pollutants. PAN is formed when oxidized volatile organi compounds combine with nitrogen oxide.
Which of the following contribute to green house effect?
Explanation:
Methane, carbon dioxide and chlorofluorocarbons, all of them are greenhouse gases that trap the infrared rays and thus trap the heat, not allowing it to escape the earth’s surface, hence contributing to greenhouse effect.
Which are sensitive to SO2 pollution?
Explanation:
Sulphur dioxide is a gas that dissolves in water and produces acidic ions that are highly reactive. When lichen absorb this gas, it disrupts photosynthesis, inhibits reproduction and other activities.
What is weathering? Elucidate in the various types of weathering.
Break down of bigger rocks into smaller mineral particles is called weathering.
It is of three types:
Physical weathering: Various climatic factors such as temperature, wind, rain water, ice, snow, glaciers and running water contribute to physical weathering. Water and high temperature cause corrosive humidity and bring about unequal expansion and contraction of rocks, facilitating their break down.
Chemical weathering: It involves a variety of chemical processes, such as hydrolysis, hydration, oxidation and reduction. The breakdown of complex compounds by the carbonic acids present in water and acidic substances derived from the decomposition of organic matter in soil, are examples of chemical weathering.
Biological weathering: Is done by living organisms such as lichens and bryophytes. They create small crevices which deepen to form cracks in the rocks. Cracks gradually widen and cause slow fragmentation and eventually pulverisation of rocks.
What is soil? How does it form?
Soil is a mixture of small particles of rocks and humus (i.e., organic matter obtained from decaying of living organisms or their wastes). Temperature variations due to radiations of the sun, rain water, winds and living organisms influence the formation of soil from the rocks involving two processes: weathering and paedogenesis. Breakdown of bigger rocks into small, fine soil particles is called weathering. It may occur due to physical, chemical or biological means. Under the influence of solar radiations, rocks heat up and expand. At night, these rocks cool down and contract. Since all the parts of rocks do not expand and contract at the same rate, cracks appear in the rocks and ultimately the large rocks breakdown into smaller pieces. Flow of water through or over the rocks makes the cracks bigger. Flowing/ falling water also has an erasing effect on the rocks. On freezing the water expands in rock crevices and breaks the rocks. Similarly, strong winds continue to rub against hard rocks and erode them. Growth of lichens, mosses and other plants also influence the formation of soil by eroding the rocks over which they are growing.
Paedogenesis: This process concludes the decomposition by bacteria and fungi, during which organic materials are broken down, leading to humification and mineralization. Detritivores such as nematods, earthworms, etc., consume organic matter and add excretory nitrogen to it. Thus, addition of organic matter (humus) from dead and decomposed plants and animals, is the final stage in soil formation.
What is nitrogen fixation? Describe this phenomenon in context with N2cycle.
The conversion of atmospheric nitrogen into ammonia NH3 is known as nitrogen fixation. Bacteria that perform nitrogen fixation are either free living or they may form symbiotic associations with other organisms.
NITROGEN CYCLE: It is a process by which nitrogen is converted into various chemical forms and is made available to living organisms. There are various steps in a nitrogen cycle. Nitrogen fixation takes place by the action of microbes, inert nitrogen breaks down in the air and combines with oxygen to form nitrous oxide. Nitrifying bacterias in the soil take up this atmospheric nitrogen and make it available for plants. Plants get this nitrogen. Later when they decay, the nitrogen is returned back into the environment. In the soil there are some denitrifying bacterias too, they break down nitrate and release nitrogen into the atmosphere thus they end the nitrogen cycle.
Toxic chemical released by paper industry is:
Explanation:
Paper industry uses fuels and during of fuels like coal releases mercury that is a toxic chemical.
To which height is ozonosphere present over the equator:
Explanation:
Ozone layer or ozonosphere occurs in the stratosphere. It is generally lowest at the equator and highest in polar regions. It is present to a height of 23-25kms over the equator.
The ultimate source of energy in an ecosystem is:
Explanation:
Green plants are producers in an ecosystem i.e. they produce food. The food obtained from plants is utilized by all the other components of an ecosystem. Hence, Green plants are ultimate source of energy.
The ozone layer of the atmosphere blocks:
Explanation:
Ozone layer blocks the UV radiations coming from sun and thus preventing organisms on earth from various diseases like cataract and preventing the immune system from weakening.
The conversion of NO3 to N2 is called:
Explanation:
Denitrification is the removal of nitrogen or nitrogen compounds. The conversion of NO3 into N2 is denitrification.
Sun causes weathering of rocks through:
Explanation:
Sun’s energy heats up rocks to a high temperature which causes them to expand. When temperature falls, these rock contract. This continuous expansion and contraction causes the rock layer to wear off. And hence results in weathering of rocks.
SPM includes:
Explanation:
Suspended Particulate Matter (SPM)are finely divided matter particles that cause aur pollution. They may be dispersed into air by combustion or industrial processes. Dust, soot and smoke, flash are all Suspended Particulate Matter.
Solar radiation heat-up:
Explanation:
Land absorbs more heat because they are darker, hence heat up faster than water bodies by absorbing solar radiations. Water bodies on the other hand reflect most of the solar radiation that fall on it thus not getting heated faster.
Soil that is best suited for plant growth is:
Explanation:
Loamy soil contains a small amount of organic material hence it is best suited for plant growth.
Soil is the component of:
Explanation:
Lithosphere is the upper part of the earth consisting f crust and solid part of mantle. It contains rocks, minerals and soil.
Soil erosion is caused due to:
Explanation:
Winds erode away lose soil, heavy rains also wash away soil that is loosely bound. If the fields are left fallow for long , since there will be no plants to hold the soil the soil easily gets eroded away by wind and water.
Soil erosion can be prevented by:
Explanation:
Terrace farming and intensive cropping, both are helpful in preventing soil erosion. Terrace reduces the speed of water moving across the soil surface which reduces soil erosion. Also, Terrace farming allows more intensive cropping which thus binds the soil and prevents soil erosion.
Signs of eutrophication of water bodies include:
Explanation:
Eutrophication is a phenomenon that occurs in water bodies. Excess of nutrients result in algal blooms which stops the penetration of light into the water body and the aquatic plants are thus unable to perfrom photosynthesis.
Set up an experiment to measure gain and loss of heat by water, sand arld air.
Set up an experiment to demonstrate the effect of low pressure and particulate nuclei over water vapours.
This simple experiment replicates, on a very small scale, the happenings when air with a very high content of water vapour goes from a region of high pressure to a region of low pressure. When bottle containing water is kept in the sun, the water evaporates and air inside the bottle gets saturated with water vapour. When the bottle is pressed between your hands, the pressure inside becomes high and air inside the bottle moves in a region of low pressure. It expands and cools. The smoke particles act as 'nuclei' on which water vapours condense in the form of tiny droplets. When you release the pressure, the air inside the bottle becomes foggy. When bottle is again pressed, the fog will disappear. It is so because due to high pressure condensed water vapours will fall down and collect as water at the bottom of the bottle. When the experiment is repeated without smoke inside the bottle, one will not observe foggy air inside the bottle as smoke particles are absent and nothing is available in air to act as ‘nucleus’ for water vapours to condense as tiny droplets.
Run-off from fertilizer-rich crop-fields causes:
Explanation:
Fertilizers run of from crop fields lead to accumulation of the chemicals in water bodies which results in algal blooms. These alagal blooms thus block the sunlight from penetrating into the aquatic bodies. The aquatic plants thus do not get sunlight to synthesize food and oxygen, thus causing Eutrophication.
Rajasthan and Gujarat fall under:
Explanation:
Arid zone is characterized by areas of low rainfall and desert. Rajasthan and Gujarat fall in this zone.
Prepare a flow chart of various natural resources.
Natural resources are living and non-living components of nature which are used by humans to meet their requirements. Since natural resources are available only from the Earth, they are called Earth resources.
Based on their abundance, natural resources are of two main types, inexhaustible and exhaustible.
Inexhaustible natural resources: They are natural resources which occur in such abundance that they are not likely to get exhausted despite continuous use, e.g., air, water, solar energy.
Exhaustible natural resources: They are natural resources which are available in limited quantity. They may to get depleted by continuous and indiscriminate human consumption. Exhaustible resources are of two kinds, renewable and non-renewable.
Renewable resources: They are exhaustible resources which get replenished regularly. These are both living and non-living resources which can replenish themselves by quick recycling, e.g., forests, wildlife, soil and underground water. Renewable resources can last for ever if they are used responsibly.
Non-renewable resources: They are exhaustible resources which once used cannot be replenished. Thus, these resources are non-living and cannot replenish themselves by recycling and replacement. If not used carefully they will ultimately get exhausted. Their increased consumption results in quicker exhaustion, e.g., minerals, fossil fuels such as coal and petroleum.
Pollution of water is caused by:
Explanation:
Waste from industries into water bodies pollutes the water bodies as majority of the waste is non-biodegradable. Sewage waste which is mostly from houses is also directed into water bodies. Runoff water from farms carries along with it chemicals of fertilizers and pesticides thus again polluting the water bodies.
Pollution is not caused by:
Explanation:
Water flowing through through dams spin the turbine plates to generate electricity. There is no air or water pollution caused by hydroelectric power plant.
Photochemical smog is formed by:
Explanation:
Photochemical smog is formed in atmosphere when ozidized volatile organic compounds react with nitrogen oxide.
Percolation tanks and wells are used for:
Explanation:
Percolation tanks and wells are made to percolate the surface water so that it reacharges ground water level which supples drinking water.
Percentage of total water found as fresh water is:
Explanation:
Only 2.5 percent of total water is found as fresh water which occurs in lakes and rivers.
Ozone hole was discovered in:
Explanation:
Ozone hole was discovered in 1985 over Antarctic by Joe Farman, Brian Gardiner and Jonathan Shanklin.
Ozone hole over Antarctica appears during:
Explanation:
Very low winter temperatures in the Antarctic stratosphere leads to appearance of ozone hole over Antarctica due to formation of polar stratospheric clouds.
Organisms such as lichens are very sensitive to the level of ___________ in the atmosphere.
Explanation:
Lichens are sensitive to Sulphur dioxide because they have efficient absorption systems due to which they rapidly accumulate Sulphur from high levels of Sulphur dioxide in air.
Nitromonas bacteria convert:
Explanation:
Nitrosomonas are rod shaped bacteria that oxidize ammonia into nitrite. Nitrosomonas are useful in bioremediation.
Nif genes occur in:
Explanation:
Rhizobium is a gram -ve bacteria that fixes nitrogen. Nif gene occurs in Rhizobium.
Name the gas which plays major role in global warming:
Explanation:
Carbon dioxide traps the infrared rays and prevent heat from escaping the earth’s atmosphere. This causes the temperature of earth to rise which is known as global warming.
Name the gas which plays a major role in global warming:
Explanation:
Carbon dioxide traps infrared rays and prevent them from escaping the earth’s surface thereby increasing the temperature of earth and resulting in global warming.
Minamata human disease is caused by pollution of water by:
Explanation:
Mercury contaminated water in Japan lead to the outspread of Minamata disease when people consumed this water polluted with high levels of mercury.
Major source of formation of soil is:
Explanation:
Soil is a thin layer of sediments and fine particles covering the earth’s surface. It is mainly formed from weathering of rocks by various processes.
Major source of air pollution is:
Explanation:
Burning of fossil fuels like coal, natural gas and oil for fulfilling various needs is a major source of air pollution. The gases that are released on the burning of these compounds results in air pollution.
Major component of the atmosphere on Venus and Mars planet is:
Explanation:
The atmosphere on Venus is primarily composed of 97% carbon dioxide which is denser and hotter than that at earth. Mars too, is composed of 95% carbon dioxide.
In nitrogen cycle, which bacteria are responsible for nitrification:
Explanation:
Nitrosomonas and Nitrobacter are bacteria that carry out nitrification.
Nitrosomonas oxidize ammonia into nitrite. Nitrobacter break down nitrite into nitrate.
In a natural ecosystem, decomposers include:
Explanation:
Bacteria and fungi are microorganisms that decompose the dead and decaying matter.
How does soil formation takes place in nature? Explain.
Soil formation in nature takes place by weathering of rocks by mechanical, chemical and biological methods.
Physical/ Mechanical: Breakdown of rocks into smaller pieces. The rocks get heated up during the day and it cools down during night. This expansion and contraction due to heating and cooling of rocks lead to splitting of rocks. Water might enter the rocks in the cracks made by expansion and contraction. When this water freezes, the rocks widen and thus rocks break.
Chemical: It occurs when rocks are worn away by chemical changes like the chemicals released by lichens. These chemicals cause the rock surface to powder own which forms layers of soil.
Biological: Disintegration of rocks by activities of living organisms like plant grow in the cracks of rocks thus breaking the rocks.
Green plants in an ecosystem are called:
Explanation:
Green plants are the producers as they produce their own food by photosynthesis.