MCQs On Nitrogen Cycle

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MCQs On Nitrogen Cycle - Quiz


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Questions and Answers
  • 1. 

    Nitrogen is absorbed by the plants in the form of

    • A.

      Ammonium

    • B.

      Nitrites

    • C.

      Nitrates

    • D.

      All

    Correct Answer
    D. All
    Explanation
    Plants absorb nitrogen in various forms, including ammonium, nitrites, and nitrates. Ammonium is a positively charged ion, while nitrites and nitrates are negatively charged ions. These different forms of nitrogen are taken up by plants through their roots and used for various biological processes, such as protein synthesis and growth. Therefore, the correct answer is that plants can absorb nitrogen in the form of all these compounds.

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  • 2. 

    Which of the following statements is correct?

    • A.

      Atmosphere is the major reservoir for plants

    • B.

      Nitrogen is the most abundant nutrient for plants

    • C.

      Nitrogen cycle is a sedimentary cycle

    • D.

      All

    Correct Answer
    A. Atmosphere is the major reservoir for plants
    Explanation
    The correct answer is "Atmosphere is the major reservoir for plants." This statement is correct because plants obtain the majority of their nutrients, including carbon dioxide, from the atmosphere. Through the process of photosynthesis, plants convert carbon dioxide into carbohydrates and release oxygen back into the atmosphere. Therefore, the atmosphere serves as a major source of nutrients for plants.

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  • 3. 

    Nitrogen fixation is the conversion of

    • A.

      Nitrogenase and hydrogenase

    • B.

      Nitrogenase and hexokinase

    • C.

      Nitrogenase and peptidase

    • D.

      Nitrogenase and hydrolyase

    Correct Answer
    A. Nitrogenase and hydrogenase
    Explanation
    Nitrogen fixation is the process of converting atmospheric nitrogen into a form that can be used by plants and other organisms. Nitrogenase is an enzyme that catalyzes this conversion by breaking the strong triple bond between nitrogen molecules and allowing them to react with other elements. Hydrogenase, on the other hand, is an enzyme that helps in the production of hydrogen gas during nitrogen fixation. Therefore, the correct answer is Nitrogenase and hydrogenase.

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  • 4. 

    Symbiotic nitrogen-fixing cyanobacteria are not present in

    • A.

      Azolla

    • B.

      Gnetum

    • C.

      Anthoceros

    • D.

      Cycas

    Correct Answer
    B. Gnetum
    Explanation
    Gnetum is the correct answer because it is a genus of gymnosperms, which are non-flowering plants. Symbiotic nitrogen-fixing cyanobacteria are commonly found in plants such as Azolla, Anthoceros, and Cycas, but not in Gnetum.

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  • 5. 

    How many molecules of ATP are required to fix one molecule of nitrogen?

    • A.

      12

    • B.

      20

    • C.

      6

    • D.

      16

    Correct Answer
    D. 16
    Explanation
    Nitrogen fixation is a process in which atmospheric nitrogen is converted into a usable form by certain microorganisms. This process requires energy in the form of ATP. Each molecule of nitrogen requires 16 molecules of ATP to be fixed. Therefore, the correct answer is 16.

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  • 6. 

    Ammonification is the formation of

    • A.

      Ammonia from nitrates by decomposers

    • B.

      Ammonia from nitrogen

    • C.

      Ammonia from amino acids

    • D.

      Ammonia from nitrates by nitrogen fixers

    Correct Answer
    C. Ammonia from amino acids
    Explanation
    Ammonification is the process by which decomposers break down organic matter, such as dead plants and animals, and convert the nitrogen present in the organic compounds into ammonia. Amino acids, which are the building blocks of proteins, contain nitrogen. When organic matter is decomposed, the proteins are broken down into amino acids, and the nitrogen in these amino acids is released as ammonia through the process of ammonification. Therefore, the correct answer is "Ammonia from amino acids."

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  • 7. 

    Conversion of nitrates to nitrogen is called

    • A.

      Ammonification

    • B.

      Nitrification

    • C.

      Nitrogen fixation

    • D.

      Denitrification

    Correct Answer
    D. Denitrification
    Explanation
    Denitrification is the correct answer because it refers to the process of converting nitrates (NO3-) to nitrogen gas (N2) or nitrous oxide (N2O) by certain bacteria. This process occurs in anaerobic conditions, such as waterlogged soils or stagnant water bodies, where oxygen is limited. Denitrification plays a crucial role in the nitrogen cycle by returning nitrogen to the atmosphere, balancing the excess nitrogen in ecosystems, and preventing the accumulation of nitrates, which can be harmful to the environment.

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  • 8. 

    Conversion of nitrites to nitrates is called

    • A.

      Nitrosococcus

    • B.

      Clostridium

    • C.

      Nitrobacter

    • D.

      Nitrosomonas

    Correct Answer
    C. Nitrobacter
    Explanation
    The correct answer is Nitrobacter. Nitrobacter is a type of bacteria that converts nitrites to nitrates through a process known as nitrification. This conversion is an important step in the nitrogen cycle, as it helps to convert toxic nitrites into less harmful nitrates, which can then be used by plants for growth. Nitrobacter is commonly found in soil and water environments and plays a crucial role in maintaining the balance of nitrogen in ecosystems.

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  • 9. 

    Conversion of ammonia to nitrite and then to nitrates is called

    • A.

      Ammonification

    • B.

      Denitrification

    • C.

      Assimilation

    • D.

      Nitrification

    Correct Answer
    D. Nitrification
    Explanation
    Nitrification is the correct answer because it refers to the process of converting ammonia (NH3) into nitrite (NO2-) and then into nitrates (NO3-). This process is carried out by specific groups of bacteria called nitrifying bacteria. Ammonification is the process of converting organic nitrogen into ammonia, denitrification is the process of converting nitrates back into nitrogen gas, and assimilation refers to the incorporation of nitrogen into organic compounds by plants and other organisms. Therefore, nitrification is the most appropriate term for the given conversion process.

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  • 10. 

    Baval trees should be planted and used to prevent and control

    • A.

      Water pollution

    • B.

      Air pollution

    • C.

      Soil pollution

    • D.

      Noise Pollution

    Correct Answer
    B. Air pollution
    Explanation
    Baval trees should be planted and used to prevent and control air pollution. Baval trees are known for their ability to absorb pollutants from the air, such as carbon dioxide, sulfur dioxide, and nitrogen dioxide. They release oxygen and help in reducing air pollution. By planting and utilizing Baval trees, we can effectively combat air pollution and improve the quality of the air we breathe.

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  • 11. 

    Depletion of ozone layer causes, Which of the following? 1. Cataract in eyes leading to blindness 2.  Reduced productivity of forests 3. Lung infection

    • A.

      Only 1

    • B.

      Only 1 and 2

    • C.

      Only 2 and 3

    • D.

      1,2 and 3

    Correct Answer
    B. Only 1 and 2
    Explanation
    Depletion of the ozone layer causes cataract in eyes leading to blindness because the ozone layer protects the Earth from harmful ultraviolet (UV) radiation. When the ozone layer is depleted, more UV radiation reaches the Earth's surface, which can damage the eyes and lead to the development of cataracts. Additionally, reduced productivity of forests is also caused by the depletion of the ozone layer. This is because UV radiation can inhibit the growth and development of plants, leading to decreased productivity in forests.

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  • 12. 

    The protocol which decided to completely phase out CFC is

    • A.

      Cartagena protocol

    • B.

      Stockholm Convention

    • C.

      Montreal protocol

    • D.

      Kyoto protocol

    Correct Answer
    C. Montreal protocol
    Explanation
    The Montreal Protocol is the correct answer because it is an international treaty designed to protect the ozone layer by phasing out the production and use of substances that deplete it, including chlorofluorocarbons (CFCs). The protocol was adopted in 1987 and has been successful in reducing the production and consumption of CFCs worldwide. It is considered a landmark environmental agreement and has played a crucial role in the recovery of the ozone layer.

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  • 13. 

    Which of the following is/are not Green House Gases? 1. Nitrous oxide 2. Ozone 3. Sulphur dioxide

    • A.

      Only 3

    • B.

      Only 1 and 2

    • C.

      Only 2 and 3

    • D.

      1,2 and 3

    Correct Answer
    A. Only 3
    Explanation
    Nitrous oxide and ozone are both considered greenhouse gases, as they have the ability to trap heat in the atmosphere. However, sulphur dioxide is not a greenhouse gas. Instead, it is a pollutant that contributes to air pollution and can have negative effects on human health and the environment.

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  • 14. 

    With reference to effect of green house gases, Which of the following is/are true? 1. Changes to plant growth and nutrition levels 2. Ozone depletion 3. Smog pollution Select the correct answer from the following codes

    • A.

      Only 1

    • B.

      Only 1 and 2

    • C.

      Only 2 and 3

    • D.

      1,2 and 3

    Correct Answer
    D. 1,2 and 3
    Explanation
    Greenhouse gases have a significant impact on the environment. They contribute to changes in plant growth and nutrition levels by affecting the availability of carbon dioxide, a vital component for photosynthesis. Ozone depletion is also caused by greenhouse gases, particularly chlorofluorocarbons (CFCs), which break down the ozone layer. Smog pollution is another consequence of greenhouse gases, as they contribute to the formation of ground-level ozone and particulate matter, leading to poor air quality. Therefore, all three statements are true, and the correct answer is 1, 2, and 3.

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  • 15. 

    With reference to sources of water pollution, which of the following is/are true? 1. Natural Sources 2. Domestic Sources 3. Agricultural Sources 4. Industrial Sources

    • A.

      Only 4

    • B.

      Only 2, 3 and 4

    • C.

      Only 3 and 4

    • D.

      1,2, 3 and 4

    Correct Answer
    D. 1,2, 3 and 4
    Explanation
    The given answer states that all options 1, 2, 3, and 4 are true regarding the sources of water pollution. This means that natural sources, domestic sources, agricultural sources, and industrial sources can all contribute to water pollution.

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  • 16. 

    Which of the following chemicals cause water pollution? 1. Arsenic 2. Copper 3. Zinc Select the correct answer from the following codes

    • A.

      Only 1

    • B.

      Only 1 and 2

    • C.

      Only 2 and 3

    • D.

      1,2 and 3

    Correct Answer
    D. 1,2 and 3
    Explanation
    Arsenic, copper, and zinc are all chemicals that can cause water pollution. Arsenic is a toxic substance that can contaminate water sources, causing serious health risks. Copper is commonly found in industrial waste and can be harmful to aquatic life. Zinc is also a common pollutant in water, often originating from industrial and agricultural activities. Therefore, the correct answer is 1, 2, and 3, as all three chemicals can contribute to water pollution.

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  • 17. 

    Which of the following pairs are correctly matched?     Pollutant                Disease 1. Arsenic                 Skin Cancer      2. Lead                     Itai – Itai 3. Cadmium              displexia

    • A.

      Only 1

    • B.

      Only 1 and 2

    • C.

      Only 2 and

    • D.

      1,2 and 3

    Correct Answer
    D. 1,2 and 3
  • 18. 

    Consider the following statements 1. The Biological Demand for oxygen is directly proportional to the quantity of discharge of waste in water bodies. 2. Increase in water temperature decreases dissolved oxygen in water which adversely affects aquatic life. Select the correct answer from the following codes

    • A.

      Only 1

    • B.

      Only 2

    • C.

      Both 1 and 2

    • D.

      Neither 1 nor 2

    Correct Answer
    C. Both 1 and 2
    Explanation
    Both statements 1 and 2 are correct. Statement 1 states that the biological demand for oxygen is directly proportional to the quantity of discharge of waste in water bodies, which means that as the amount of waste in water bodies increases, the demand for oxygen by organisms also increases. Statement 2 states that an increase in water temperature decreases dissolved oxygen in water, which negatively impacts aquatic life. This is because warmer water holds less dissolved oxygen, making it harder for organisms to obtain the oxygen they need to survive. Therefore, both statements are true and support each other.

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  • 19. 

    With reference to Eutrophication, Which of the following is/are true? 1. It is phenomenon of nutrient enrichment of a water body 2.  It depletes the water of dissolved oxygen (DO). 3. Human activities are mainly responsible for the eutrophication Select the correct answer from the following codes

    • A.

      Only 1

    • B.

      Only 1 and 2

    • C.

      Only 2 and 3

    • D.

      1,2 and 3

    Correct Answer
    D. 1,2 and 3
    Explanation
    Eutrophication is the phenomenon of nutrient enrichment of a water body, which leads to excessive growth of algae and other aquatic plants. This excessive growth depletes the water of dissolved oxygen (DO) as the plants decay and consume oxygen during decomposition. Human activities, such as agriculture runoff, sewage discharge, and industrial pollution, are mainly responsible for introducing excessive nutrients into water bodies and causing eutrophication. Therefore, all three statements are true.

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  • 20. 

    The natural residence of every organism is known as:

    • A.

      Biome

    • B.

      Niche

    • C.

      Habit

    • D.

      Habitat

    Correct Answer
    D. Habitat
    Explanation
    Habitat refers to the natural residence or environment where an organism lives and thrives. It includes the physical factors such as climate, soil, water, and other biotic factors like plants and other animals that make up the specific area. A habitat provides the necessary resources and conditions for an organism to survive, reproduce, and carry out its daily activities. It is the specific location or area where an organism is naturally found and adapted to.

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  • 21. 

    What is the name of the feature that allows organisms to survive in the conditions of its habitat?

    • A.

      Adjustment

    • B.

      Adaptation

    • C.

      Acclimatisation

    • D.

      Adaptative Variation

    Correct Answer
    B. Adaptation
    Explanation
    Adaptation is the correct answer because it refers to the ability of organisms to adjust to their habitat and survive in its conditions. Through adaptation, organisms develop traits and behaviors that enhance their chances of survival and reproduction in their specific environment. This process occurs over generations through natural selection, where individuals with advantageous traits are more likely to pass them on to their offspring.

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  • 22. 

    Shelford’s law of tolerance is named after:

    • A.

      James Shelford

    • B.

      Jacob Shelford

    • C.

      Ernest Shelford

    • D.

      None of these

    Correct Answer
    A. James Shelford
    Explanation
    Shelford's law of tolerance is named after James Shelford. This law states that an organism's success is determined by its ability to tolerate a range of environmental conditions. It suggests that organisms have a minimum and maximum tolerance limit for various environmental factors, and their survival and growth are optimal within a certain range. James Shelford was an American ecologist who formulated this concept in the early 20th century.

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  • 23. 

    Shelford’s law of tolerance suggests that organisms with a wide tolerance limit for environmental factors show:

    • A.

      Narrow distribution with low population

    • B.

      Wide distribution with high  population

    • C.

      Wide distribution with high population

    • D.

      Narrow distribution with high population

    Correct Answer
    B. Wide distribution with high  population
    Explanation
    Shelford's law of tolerance states that organisms with a wide tolerance limit for environmental factors are able to survive and thrive in a wide range of conditions. This means that they can be found in various habitats and locations, leading to a wide distribution. Additionally, these organisms are able to adapt and reproduce successfully in different environments, resulting in a high population. Therefore, the correct answer is "Wide distribution with high population."

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  • 24. 

    Wide variety of living organisms is called:

    • A.

      Biodiversity

    • B.

      Population

    • C.

      Habitat

    • D.

      Diversity

    Correct Answer
    A. Biodiversity
    Explanation
    Biodiversity refers to the wide variety of living organisms in a particular area or on the entire planet. It encompasses the different species, genetic variations within species, and the ecosystems they inhabit. Biodiversity is important for maintaining the balance of ecosystems, providing resources for humans, and contributing to the overall health of the planet. Therefore, the correct answer is Biodiversity.

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  • 25. 

    Animal adopt a similar state like sleep to reduce their metabolic rate, it is called:

    • A.

      Migration

    • B.

      Transpiration

    • C.

      Hibernating

    • D.

      None of These

    Correct Answer
    C. Hibernating
    Explanation
    Animals adopt a state similar to sleep called hibernating to reduce their metabolic rate. During hibernation, animals enter a prolonged period of dormancy where their body temperature drops, heart rate slows down, and they conserve energy by minimizing their activity levels. This adaptation helps them survive in harsh conditions when food is scarce or temperatures are extremely cold. Migration refers to the seasonal movement of animals from one region to another, while transpiration is the process of water movement through plants.

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  • 26. 

    Hyenas and Vultures are ________________.

    • A.

      Omnivorous

    • B.

      Scavengers

    • C.

      Carnivorous

    • D.

      Herbivorous

    Correct Answer
    B. Scavengers
    Explanation
    Hyenas and Vultures are scavengers because they feed on dead animals. They do not hunt and kill their own prey, but instead rely on finding and eating carrion. Scavengers play an important role in the ecosystem by helping to clean up and recycle nutrients from dead animals, preventing the spread of diseases and maintaining the balance of the food chain.

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  • 27. 

    A mutual relationship between two organisms, where both of them are benefitting from watch other is called:

    • A.

      Mutualism

    • B.

      Symbiosis

    • C.

      Parasitism

    • D.

      Food Chain

    Correct Answer
    A. Mutualism
    Explanation
    Mutualism refers to a type of relationship between two organisms where both individuals benefit from each other. In this symbiotic interaction, both organisms rely on each other for survival, reproduction, or obtaining resources. This relationship is characterized by cooperation and mutual support, resulting in a mutual advantage for both parties involved.

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  • 28. 

    Which is not a feature of heliophyte among the following?

    • A.

      Stem with long internodes

    • B.

      Numerous rootlets

    • C.

      Long lateral roots

    • D.

      Vigorous fruiting and flowering

    Correct Answer
    A. Stem with long internodes
    Explanation
    A heliophyte is a plant that thrives in direct sunlight. The feature that is not characteristic of a heliophyte is a stem with long internodes. Heliophytes typically have short internodes to maximize exposure to sunlight. Numerous rootlets, long lateral roots, and vigorous fruiting and flowering are all common features of heliophytes as they enable the plant to absorb more nutrients and produce more energy through photosynthesis.

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  • 29. 

    Which of the following is not a feature of ‘r’ selected species

    • A.

      Reproduce quickly

    • B.

      The low survival rate of progenies

    • C.

      Reproduce a large number of progenies

    • D.

      Paternal care

    Correct Answer
    D. Paternal care
    Explanation
    The correct answer is "Paternal care" because r-selected species are characterized by their ability to reproduce quickly and produce a large number of progenies, but they do not provide parental care to their offspring. They have a low survival rate of progenies as they invest less energy in individual offspring and focus on producing as many offspring as possible to increase their chances of survival.

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  • 30. 

    Nitrogen fixation is the conversion of

    • A.

      Nto N

    • B.

      Nto NH3

    • C.

      Nto NO3

    • D.

      Nto urea

    Correct Answer
    B. Nto NH3
    Explanation
    Nitrogen fixation is the process by which atmospheric nitrogen (N2) is converted into ammonia (NH3). This process is carried out by certain bacteria, either free-living or symbiotic with plants, that possess the enzyme nitrogenase. Nitrogen fixation is essential for the Earth's nitrogen cycle as it provides a usable form of nitrogen for plants and other organisms. Ammonia can be further converted into other nitrogen compounds, such as nitrate (NO3-), which can be taken up by plants for growth and development.

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