Case Study Questions Class 9 Science Chapter 14 Natural Resources
CBSE Class 9 Case Study Questions Science Natural Resources. Important Case Study Questions for Class 9 Exam. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Natural Resources.
At Case Study Questions there will given a Paragraph. In where some Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks or 4 marks.
CBSE Case Study Questions Class 9 Science – Natural Resources
CASE 1
Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules essential to life like proteins, nucleic acids (DNA and RNA) and some vitamins. Nitrogen is found in other biologically important compounds such as alkaloids and urea too. Nitrogen is thus an essential nutrient for all life-forms and life would be simple if all these life-forms could use the atmospheric nitrogen directly. Most commonly, the nitrogen-fixing bacteria are found in the roots of legumes (generally the plants which give us pulses) in special structures called root nodules. Other than these bacteria, the only other manner in which the nitrogen molecule is converted to nitrates and nitrites is by a physical process. During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain. These are then utilised by various life forms.
Plants generally take up nitrates and nitrites and convert them into amino acids which are used to make proteins. These proteins and other complex compounds are subsequently consumed by animals. Once the animal or the plant dies, other bacteria in the soil convert the various compounds of nitrogen back into nitrates and nitrites. Thus, there is a nitrogen-cycle in nature in which nitrogen passes from its elemental form in the atmosphere into simple molecules in the soil and water, which get converted to more complex molecules in living beings and back again to the simple nitrogen molecule in the atmosphere.
(1) How much Nitrogen is present in our atmosphere?
(a) 76 %
(b) 77 %
(c) 78 %
(d) 79 %
(2) Identify the correct statement
Statement 1 – Nitrogen is an essential nutrient for all life-forms and life.
Statement 2 – all life-forms use the atmospheric nitrogen directly.
Statement 3 – Nitrogen is a part of DNA & RNA
Statement 4 – Our atmosphere have 79 % nitrogen.
(a) Both 1 & 2
(b) Both 1 & 3
(c) Both 3 & 4
(d) All of the above
(3) Plants use nitrates and nitrites and convert them into
(a) Vitamins
(b) Enzymes
(c) Amino acids
(d) Nitrogen
(4) What is the main function of root nodules in legume plants?
(5) Explain the physical process by which nitrogen molecule is converted to nitrates and nitrites?
Answer key
(1) c
(2) b
(3) c
(4) Nitrogen fixation is the main function of root nodules which is one of the most important features of legumes.
(5) During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain.
CASE 2
Oxygen is a very abundant element on our Earth. It is found in the elemental form in the atmosphere to the extent of 21%. It also occurs extensively in the combined form in the Earth’s crust as well as also in the air in the form of carbon dioxide. In the crust, it is found as the oxides of most metals and silicon, and also as carbonate, sulphate, nitrate and other minerals. It is also an essential component of most biological molecules like carbohydrates, proteins, nucleic acids and fats (or lipids).
When we talk of the oxygen-cycle, we are mainly referring to the cycle that maintains the levels of oxygen in the atmosphere. Oxygen from the atmosphere is used up in three processes, namely combustion, respiration and in the formation of oxides of nitrogen. Oxygen is returned to the atmosphere in only one major process, that is, photosynthesis. And this forms the broad outline of the oxygen-cycle in nature.
Though we usually think of oxygen as being necessary to life in the process of respiration, it might be of interest to you to learn that some forms of life, especially bacteria, are poisoned by elemental oxygen. In fact, even the process of nitrogen-fixing by bacteria does not take place in the presence of oxygen.
(1) How much oxygen is present in our atmosphere?
(a) 20 %
(b) 21 %
(c) 22 %
(d) 23 %
(2) Identify the correct statement
Statement 1 – Oxygen is also an essential component of most biological molecules.
Statement 2 – Oxygen is returned to the atmosphere through process called photosynthesis
Statement 3 – Oxygen -cycle maintains the levels of oxygen in the atmosphere.
Statement 4 – Our atmosphere have 21 % oxygen.
(a) Only 1
(b) Both 2 & 3
(c) Both 1 & 4
(d) All of the above
(3) Oxygen from the atmosphere is used up in three main processes,
(a) Combustion
(b) Respiration
(c) Formation of oxides of nitrogen
(d) All of the above
(4) By which process Oxygen is returned to the atmosphere
(a) Respiration
(b) Photosynthesis
(c) Photolysis
(d) None of the above
(5) Write the molecular formula of oxygen?
Answer key
(1)b
(2) d
(3) d
(4) b or c
(5) Molecular formula of oxygen is: O2
CASE 3
Carbon is found in various forms on the Earth. It occurs in the elemental form as diamonds and graphite. In the combined state, it is found as carbon dioxide in the atmosphere, as carbonate and hydrogen carbonate salts in various minerals, while all life-forms are based on carbon-containing molecules like proteins, carbohydrates, fatsnucleic acids and vitamins. The endoskeletons and exoskeletons of various animals are also formed from carbonate salts. Carbon is incorporated into life-forms through the basic process of photosynthesis which is performed in the presence of Sunlight by all life-forms that contain chlorophyll. This process converts carbon dioxide from the atmosphere or dissolved in water into glucose molecules. The utilisation of glucose to provide energy to living things involves the process of respiration in which oxygen may or may not be used to convert glucose back into carbon dioxide. This carbon dioxide then goes back into the atmosphere. Another process thatadds to the carbon dioxide in the atmosphere is the process of combustion where fuels are burnt to provide energy for various needs like heating, cooking, transportation and industrial processes. In fact, the percentage of carbon dioxide in the atmosphere is said to have doubled since the industrial revolution when human beings started burning fossil fuels on a very large scale. Carbon, like water, is thus cycled repeatedly through different forms by the various physical and biological activities.
(1) Which process converts carbon dioxide from the atmosphere or dissolved in water into glucose molecules
(a) Photolysis
(b) Photosynthesis
(c) Respiration
(d) Nitrogen cycle
(2)Identify the correct statement
Statement 1 – Carbon is incorporated into life-forms through the basic process of Photosynthesis
Statement 2 – Photosynthesis is performed by all life-forms that contain Chlorophyll
Statement 3 -Carbon occurs in the elemental form as diamonds and graphite.
Statement 4 -Proteins and carbohydrates are carbon containing molecules.
(a) Both 1 & 4
(b) Both 2 & 4
(c) Only 3
(d) All of the above
(3) The endoskeletons and exoskeletons of various animals are made up of
(a) Carbon Dioxide
(b) Diamond
(c) Graphite
(d) Carbonate salts
(4) What is the respiration?
(5) Enlist the elemental form of carbon.
Answer key
(1)b
(2) d
(3) d
(4) It is process in which glucose are used to provide energy to living things. This process is termed as respiration.
(5) Elemental form of carbon are
- Diamond
•Graphite
CASE 4
Elemental oxygen is normally found in the form of a diatomic molecule. However, in the upper reaches of the atmosphere, a molecule containing three atoms of oxygen is found. This would mean a formula of O3 and this is called ozone. Unlike the normal diatomic molecule of oxygen, ozone is poisonous and we are lucky that it is not stable nearer to the Earth’s surface. But it performs an essential function where it is found. It absorbs harmful radiations from the Sun. This prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life. Recently it was discovered that this ozone layer was getting depleted. Various man-made compounds like CFCs (carbon compounds having both fluorine and chlorine which are very stable and not degraded by any biological process) were found to persist in the atmosphere. Once they reached the ozone layer, they would react with the ozone molecules. This resulted in a reduction of the ozone layer and recently they have discovered a hole in the ozone layer above the Antarctica. It is difficult to imagine the consequences for life on Earth if the ozone layer dwindles further, but many people think that it would be better not to take chances. These people advocate working towards stopping all further damage to the ozone layer.
(1) Identify the correct statement
Statement 1 – Ozone is poisonous.
Statement 2 – Absorbs harmful radiations from the Sun
Statement 3 – Ozone prevents those harmful radiations from reaching the surface of the Earth.
Statement 4 – Molecule containing three atoms of oxygen is termed as ozone.
(a) Both 1 & 4
(b) Both 2 & 4
(c) Only 3
(d) All of the above
(2) The molecule containing three atoms of oxygen is termed as
(a) Oxygen
(b) Ozone
(c) Diatomic oxygen
(d) None of above
(3) What is the molecular formula of ozone?
(a) O
(b )O2
(c) O3
(d) O4
(4)Why ozone layer is important?
(5) What is CFC?
Answer key
(1) d
(2) b
(3) c
(4) Ozone performs an essential function where it is found. It absorbs harmful radiations from the Sun. It also prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life.
(5) CFCs are carbon compounds having both fluorine and chlorine which are very stable and not degraded by any biological process. CFCs are the main reasons for ozone layer depletion.
CASE 5
The fossil fuels like coal and petroleum contain small amounts of nitrogen and sulphur. When these fuels are burnt, nitrogen and sulphur too are burnt and this produces different oxides of nitrogen and sulphur. Not only is the inhalation of these gases dangerous, they also dissolve in rain to give rise to acid rain. The combustion of fossil fuels also increases the amount of suspended particles in air. These suspended particles could be unburnt carbon particles or substances called hydrocarbons. Presence of high levels of all these pollutants cause visibility to be lowered, especially in cold weather when water also condenses out of air. This is known as smog and is a visible indication of air pollution. Studies have shown that regularly breathing air that contains any of these substances increases the incidence of allergies, cancer and heart diseases. An increase in the content of these harmful substances in air is called air pollution.
(1) Identify the correct statement
Statement 1 – The unburnt carbon particles which suspended in air called hydrocarbons.
Statement 2 – Fossil fuels like coal and petroleum contain small amounts of nitrogen and sulphur.
Statement 3 – In cold weather when water condenses out of air. This is known as smog.
Statement 4 – Smog is the indication of air pollution
(a) Both 1 & 4
(b) Both 2 & 4
(c) Only 3
(d) All of the above
(2) The unburnt carbon particles or substances which suspended in air are termed as ____
(a) Smog
(b) Fog
(c) Hydrocarbons
(d) Ozone
(3) An increase in the content of harmful substances in air is called as _________
(a) Pollution
(b) Air pollution
(c) Smog
(d) All of the above
(4)What is hydrocarbons?
(5) Enlist the adverse effect of air pollution on health.
Answer key
(1) d
(2) a
(3) b
(4) The unburnt carbon particles or substances which suspended in air called hydrocarbons.
(5) Adverse effect of air pollution on health
•Regularly breathing air that contains air pollutants increases the incidence of allergies, cancer and heart diseases.