HOTS Questions: Natural Resources - HTET MCQ

Answer:
Definition of a Pollutant:
A pollutant is any substance, chemical, or other factor that changes the natural balance of our environment by causing harm or discomfort to living organisms or damaging the environment.
Effects of Pollutants:
Pollutants can have various negative effects on our environment, including:
1. Disruption of the Balance of our Environment: Pollutants can alter the delicate balance of ecosystems, affecting the interactions between different organisms and their habitats.
2. Deterioration of Air Quality: Air pollutants, such as carbon monoxide, sulfur dioxide, and particulate matter, can lead to poor air quality, which can have detrimental effects on human health and the environment.
3. Contamination of Water Bodies: Water pollutants, such as heavy metals, pesticides, and industrial waste, can contaminate rivers, lakes, and oceans, leading to water pollution and impacting aquatic life and ecosystems.
4. Destruction of Natural Habitats: Pollutants can destroy or degrade natural habitats, making them unsuitable for the survival of certain plant and animal species.
5. Adverse Effects on Wildlife: Pollutants can directly harm wildlife, leading to reduced populations or even extinction of certain species. They can also indirectly impact wildlife by contaminating their food sources or habitats.
6. Health Risks for Humans: Many pollutants have harmful effects on human health, causing respiratory problems, allergies, cancers, and other diseases.
7. Global Environmental Issues: Certain pollutants, such as greenhouse gases, contribute to global environmental issues like climate change and ozone depletion.
Conclusion:
Pollutants have wide-ranging negative effects on our environment, disrupting the natural balance and causing harm to living organisms. It is crucial to minimize pollutant emissions and take necessary measures to protect our environment and the well-being of both humans and wildlife.

Among the pollutants motor vehicles produce are various sulfur oxides, nitrogen oxides, unburned hydrocarbons, carbon dioxide, carbon monoxide and particulates.

Reasons why lichens do not like to grow in cities:
There are several factors that contribute to the reluctance of lichens to grow in cities. These include:
1. SO₂ pollution: Lichens are highly sensitive to air pollution, particularly sulfur dioxide (SO₂) emissions. Cities tend to have high levels of air pollution due to industrial activities, vehicle emissions, and other human activities. The presence of SO₂ in the air can be toxic to lichens and inhibit their growth.
2. Missing natural habitat: Lichens typically thrive in natural environments such as forests, grasslands, and wetlands. Cities, on the other hand, are characterized by concrete structures, asphalt roads, and limited green spaces. This lack of natural habitat and suitable substrate for lichen growth makes cities unfavorable for their establishment and development.
3. Absence of right type of algae and fungi: Lichens are symbiotic organisms composed of a fungus and an alga or cyanobacterium. The availability of the right combination of algae or fungi is crucial for lichen growth. Urban environments often lack the specific species of algae and fungi that are compatible with each other to form lichens.
4. Lack of moisture: Lichens require a certain level of moisture to survive and grow. In cities, the presence of impervious surfaces like concrete and asphalt limits the absorption of water into the ground, resulting in reduced moisture availability for lichens. Additionally, urban heat island effects can lead to increased evaporation, further exacerbating the lack of moisture.
In conclusion, lichens do not like to grow in cities primarily due to SO₂ pollution, the absence of natural habitat, the lack of the right type of algae and fungi, and the limited availability of moisture. These factors make urban environments inhospitable for lichens, which prefer more pristine and natural habitats.

The amount of carbon dioxide in atmospheric air is relatively small, but it plays a significant role in the Earth's climate system. To determine the correct answer to this question, we need to understand the percentage of carbon dioxide present in the atmosphere.
1. Introduction:
- Carbon dioxide (CO2) is a greenhouse gas that is essential for life on Earth.
- It is released through natural processes such as respiration and volcanic eruptions, as well as human activities like burning fossil fuels.
2. Percentage of carbon dioxide in atmospheric air:
- The correct answer is Option C: 0.03%.
- Carbon dioxide accounts for approximately 0.03% of the Earth's atmosphere.
- This means that for every 10,000 molecules of air, about 3 molecules are carbon dioxide.
3. Importance of carbon dioxide:
- Although the percentage is relatively small, carbon dioxide plays a crucial role in regulating the Earth's temperature.
- It acts as a greenhouse gas by trapping heat and preventing it from escaping into space.
- Without carbon dioxide and other greenhouse gases, the Earth would be much colder and uninhabitable.
4. Human activities and carbon dioxide levels:
- Human activities, particularly the burning of fossil fuels, have significantly increased the concentration of carbon dioxide in the atmosphere.
- This increase in carbon dioxide levels is a major contributor to climate change and global warming.
In conclusion, the correct answer is Option C: 0.03%. While the percentage of carbon dioxide in the atmosphere may seem small, it plays a crucial role in regulating the Earth's climate. Human activities have increased carbon dioxide levels, leading to climate change and global warming.

The Greenhouse Effect is a phenomenon that is primarily related to global warming. Here is a detailed explanation:
What is the Greenhouse Effect?
The Greenhouse Effect refers to the process by which certain gases in the Earth's atmosphere trap heat from the sun and prevent it from escaping back into space. These gases, known as greenhouse gases, include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and others.
How does the Greenhouse Effect work?
1. Sunlight enters the Earth's atmosphere and reaches the surface.
2. Some of the sunlight is reflected back into space, while the rest is absorbed by the Earth's surface.
3. The absorbed sunlight warms the Earth's surface, which then emits infrared radiation.
4. Greenhouse gases in the atmosphere trap some of this infrared radiation, preventing it from escaping into space.
5. This trapped heat leads to an increase in the Earth's temperature, causing global warming.
Why is it related to global warming?
1. Human activities, such as burning fossil fuels, deforestation, and industrial processes, have significantly increased the concentration of greenhouse gases in the atmosphere.
2. The increased levels of greenhouse gases enhance the greenhouse effect, leading to a rise in the Earth's average temperature.
3. This rise in temperature contributes to global warming, which has numerous negative impacts on the environment, including melting ice caps, rising sea levels, extreme weather events, and disruptions to ecosystems.
Other options:
Although the other options mentioned (green trees on a house, grasslands, greenery in a country) may contribute to the overall environmental health, they are not directly related to the greenhouse effect. The greenhouse effect primarily focuses on the role of greenhouse gases in trapping heat and causing global warming.

The greenhouse effect is due to:
A: Impermeability of long wavelength radiations through CO2 of the atmosphere
- The greenhouse effect is primarily caused by the presence of certain gases in the Earth's atmosphere, including carbon dioxide (CO2).
- These greenhouse gases have the ability to absorb and emit infrared radiation, which is a form of long wavelength radiation.
- CO2, in particular, is known for its ability to trap and retain heat in the atmosphere.
- When sunlight reaches the Earth's surface, it warms the planet, and some of the heat is radiated back into the atmosphere as infrared radiation.
- However, the presence of greenhouse gases like CO2 prevents a significant amount of this radiation from escaping into space.
- This trapped heat leads to an increase in the overall temperature of the Earth, resulting in the greenhouse effect.
B: Penetrability of low wavelength radiations through O3 layer
- The ozone (O3) layer in the Earth's atmosphere plays a crucial role in protecting the planet from harmful ultraviolet (UV) radiation from the sun.
- The ozone layer absorbs and filters out most of the high-energy UV radiation, preventing it from reaching the Earth's surface.
- Low wavelength radiations, such as UV radiation, are not directly related to the greenhouse effect.
- The greenhouse effect primarily involves the absorption and re-emission of long wavelength radiation, such as infrared radiation.
C: Penetrability of low wavelength radiations through CO2
- Low wavelength radiations, such as UV radiation, are not directly related to the greenhouse effect.
- The greenhouse effect mainly occurs due to the impermeability of long wavelength radiations, such as infrared radiation, through CO2 and other greenhouse gases in the atmosphere.
- CO2 has the ability to absorb and re-emit infrared radiation, thus trapping heat in the atmosphere and contributing to the greenhouse effect.
D: Impermeability of long wavelength radiations through O3 layer
- The ozone (O3) layer primarily filters out high-energy UV radiation from the sun, preventing it from reaching the Earth's surface.
- Long wavelength radiations, such as infrared radiation, are not directly affected by the O3 layer in terms of permeability.
- The greenhouse effect is primarily caused by the impermeability of long wavelength radiations through greenhouse gases like CO2, rather than the O3 layer.
Therefore, the correct answer is option A: Impermeability of long wavelength radiations through CO2 of the atmosphere.

Greenhouse effect can be defined as the trapping of the radiations of the sun by the atmospheric gases and the subsequents reflection on the earth’s surface causing global warming. There are many greenhouse gases like water vapour, methane, CFCs, etc. but carbon dioxide is the major concern because it has contributed to most of the Global Warming 1750 to 2011 as per IPCC data and it tends to accumulate in the atmosphere. It is released in greater amounts from the vehicular emissions, deforestation, industrial emissions etc. so it constitutes around 81% of the greenhouse gases.
Hence, the correct answer is “CO2”.
 

Greenhouse gases that occur both naturally and from human activities include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3). Other greenhouse gases have essentially no natural sources, but are side products of industrial processes or manufactured for human purposes such as cleaning agents, refrigerants, and electrical insulators. These include the fluorinated gases: chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HCFCs), bromofluorocarbons (halons), perfluorcarbons, PFCs, nitrogen trifluoride, NF3, and sulfur hexafluoride, SF6. 

The one gas out of these that is not a Greenhouse Gas is SO2.

Chief pollutants of the atmosphere that deplete the ozone layer:
- Nitrogen oxides (NOx): Nitrogen oxides, produced mainly from vehicle emissions and industrial processes, are a group of chemicals that include nitric oxide (NO) and nitrogen dioxide (NO2). These compounds can react with ozone, breaking it down and depleting the ozone layer.
- Chlorofluorocarbons (CFCs): CFCs are synthetic compounds used in various applications such as aerosol propellants, refrigerants, and solvents. They were widely used in the past but have been phased out due to their harmful effects on the ozone layer. CFCs can rise to the stratosphere, where they are broken down by ultraviolet radiation, releasing chlorine atoms. These chlorine atoms then catalytically destroy ozone molecules.
- Halons: Halons are similar to CFCs and were primarily used as fire extinguishing agents. They contain bromine, which has a similar effect to chlorine in depleting the ozone layer.
- Carbon tetrachloride (CCl4): Carbon tetrachloride was once used as a solvent and in fire extinguishers. It has a significant ozone depletion potential and is now regulated under international agreements.
- Methyl chloroform (CH3CCl3): Methyl chloroform is an industrial solvent that has been phased out due to its ozone-depleting properties.
- Hydrochlorofluorocarbons (HCFCs): HCFCs are transitional compounds used as replacements for CFCs. While they have lower ozone depletion potential than CFCs, they still contribute to ozone depletion and are being phased out under the Montreal Protocol.
It is important to note that carbon dioxide (CO2), carbon monoxide (CO), and sulfur dioxide (SO2) are greenhouse gases, but they do not directly deplete the ozone layer. The ozone layer depletion is primarily caused by the release of nitrogen oxides and chlorofluorocarbons into the atmosphere.

Formation of ozone hole is maximum over Antarctica:
- The ozone hole refers to the depletion of the ozone layer in the Earth's stratosphere.
- The formation of the ozone hole is primarily influenced by human-made chemicals called ozone-depleting substances (ODS), such as chlorofluorocarbons (CFCs) and halons.
- These chemicals are released into the atmosphere through human activities like industrial processes, aerosol propellants, and the use of certain types of fire extinguishers.
- Once released into the atmosphere, these ODS are transported by wind patterns to the polar regions, particularly Antarctica.
- The unique atmospheric and weather conditions in Antarctica contribute to the maximum formation of the ozone hole in this region.
- During the Antarctic winter, the polar vortex forms, creating a stable and isolated mass of cold air over the continent.
- This polar vortex prevents the exchange of air between the polar and mid-latitude regions, trapping the ODS within the vortex.
- The extreme cold temperatures in Antarctica, along with the presence of polar stratospheric clouds (PSCs), provide ideal conditions for chemical reactions that lead to the destruction of ozone.
- When sunlight returns to Antarctica in the spring, the combination of the accumulated ODS and the presence of sunlight triggers a series of chemical reactions that result in the depletion of ozone.
- This depletion leads to the formation of the ozone hole, which reaches its maximum extent in September-October.
- The formation of the ozone hole over Antarctica has significant implications for both human health and the environment, as it allows more harmful ultraviolet (UV) radiation from the sun to reach the Earth's surface.

Water pollution is caused by various factors, but the main factor is industrial wastes.
Explanation:
- Water pollution refers to the contamination of water bodies such as rivers, lakes, and oceans, which makes the water unfit for human use and harmful to the environment and aquatic life.
- Industrial wastes, which are generated by manufacturing and production processes, are a major source of water pollution.
- These wastes often contain harmful chemicals, heavy metals, and toxins that are released into water bodies, leading to pollution.
- Industrial activities such as mining, manufacturing, and power generation produce large volumes of waste materials, including toxic substances like lead, mercury, and arsenic.
- When these hazardous substances enter water bodies, they can have detrimental effects on the health of humans, animals, and plants.
- Industrial wastewater, which is discharged into water bodies without proper treatment, can also contain high levels of pollutants such as organic compounds, acids, and solvents.
- These pollutants can deplete oxygen levels in the water, leading to the death of aquatic organisms and disrupting ecosystems.
- Other factors such as pesticides, ammonia, and detergents can also contribute to water pollution, but industrial wastes are the main factor due to their large-scale production and release into water bodies.
In conclusion, while there are various factors contributing to water pollution, industrial wastes are the main factor due to their significant volume and the harmful substances they contain. It is crucial to implement proper waste management and treatment practices to reduce industrial pollution and protect our water resources.

Explanation:
The correct answer is B: Reduction of dissolved oxygen caused by microbial activity.
- Pathogens released by sewage: While sewage pollution can introduce pathogens into water bodies, these pathogens are not the primary cause of fish deaths. Fish have natural defenses against pathogens and can survive in water with a certain level of contamination.
- Reduction of dissolved oxygen caused by microbial activity: When sewage enters water bodies, it provides a high amount of organic matter. Microbes present in the water start breaking down this organic matter through microbial activity. This process consumes a large amount of dissolved oxygen in the water, leading to a decrease in oxygen levels. Fish require oxygen to survive, and low oxygen levels can lead to suffocation and death.
- Clogging of their gills by solid substances: While solid substances present in sewage can cause water pollution, leading to environmental degradation, they do not directly cause fish deaths by clogging their gills. Fish have adaptations to filter out solid particles and can tolerate a certain level of suspended solids.
- Foul smell: Foul smell is an indicator of pollution and the presence of harmful substances in water bodies, but it does not directly cause fish deaths.
In conclusion, the reduction of dissolved oxygen caused by microbial activity is the primary reason why fishes die in water bodies subjected to sewage pollution.

Answer:
DDT (Dichloro-Diphenyl-Trichloroethane) is a synthetic insecticide that was commonly used in the past for agricultural purposes. However, its use has been restricted or banned in many countries due to its harmful effects on the environment and human health. When DDT is sprayed on crops, it can lead to pollution of the following:
1. Air: DDT is volatile and can easily evaporate into the air. Once in the atmosphere, it can be carried over long distances by wind currents. Inhalation of DDT-contaminated air can be harmful to humans and animals.
2. Soil: DDT has a high persistence in the environment and can accumulate in the soil. It can persist in the soil for several years, causing contamination. Soil pollution with DDT can affect the growth and development of plants and can also be harmful to soil-dwelling organisms.
3. Water: DDT can enter water bodies through various routes such as surface runoff, leaching from soil, or direct application. DDT is highly soluble in water and can contaminate both surface water and groundwater. This can have detrimental effects on aquatic organisms and disrupt the balance of ecosystems.
Considering these points, the correct answer is D: Air, soil, and water. DDT spraying on crops can lead to pollution of all three components of the environment.

Insecticide is a type of pesticide. 
Pesticides can contaminate soil, water, turf, and other vegetation. In addition to killing insects or weeds, pesticides can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants.

Introduction:
In this question, we are asked to identify the disease that is not waterborne. To answer this question, we need to understand the nature of the mentioned diseases and determine which ones are transmitted through water.
Diseases:
The diseases mentioned in the question are:
A: Cholera: Cholera is a bacterial infection caused by the bacterium Vibrio cholerae. It is primarily transmitted through contaminated water or food.
B: Typhoid: Typhoid fever is caused by the bacterium Salmonella typhi. It is also transmitted through contaminated food and water.
C: Dysentery: Dysentery is an infection of the intestines, usually caused by bacteria or parasites. It can be transmitted through contaminated food or water.
D: Asthma: Asthma is a chronic respiratory condition characterized by inflammation and narrowing of the airways. It is not a waterborne disease and is not transmitted through water.
Conclusion:
Based on the information provided, the disease that is not waterborne is Asthma. Cholera, typhoid, and dysentery are all waterborne diseases that can be transmitted through contaminated water or food.

Supersonic Jets and Pollution
Introduction:
Supersonic jets, such as Concorde, can contribute to environmental pollution due to their unique characteristics and the emissions they produce. One of the key environmental concerns associated with supersonic jets is the thinning of the ozone layer.
Explanation:
Supersonic jets emit various pollutants into the atmosphere, including nitrogen oxides (NOx) and water vapor. These emissions can have a significant impact on the ozone layer, leading to its thinning. Here's a detailed explanation of the issue:
1. Ozone Layer:
The ozone layer is a region in the Earth's stratosphere that contains a high concentration of ozone (O3) molecules. It plays a crucial role in protecting life on Earth by absorbing a significant amount of the sun's ultraviolet (UV) radiation.
2. Ozone Depletion:
The emissions from supersonic jets, particularly nitrogen oxides (NOx), can contribute to the depletion of ozone in the stratosphere. NOx reacts with ozone and breaks it down, resulting in a decrease in the ozone layer's thickness.
3. Impact on UV Radiation:
Thinning of the ozone layer allows more UV radiation to reach the Earth's surface. Increased exposure to UV radiation can have harmful effects on human health, such as skin cancer, cataracts, and weakened immune systems. It can also impact ecosystems, including marine life and vegetation.
Conclusion:
Supersonic jets contribute to environmental pollution by thinning the ozone layer. The emissions they produce, particularly nitrogen oxides, react with ozone molecules, leading to a decrease in the ozone layer's thickness. This thinning can have adverse effects on human health and ecosystems due to increased exposure to UV radiation. It is crucial to address these environmental concerns when considering the use of supersonic jets and explore alternative technologies that have lesser environmental impacts.

Agricultural Chemicals
Definition:
Agricultural chemicals refer to substances used in agriculture for various purposes such as pest control, nutrient supplementation, and growth regulation. They are essential for modern farming practices to increase crop productivity and protect plants from pests, diseases, and weeds.
Types of Agricultural Chemicals:
There are several types of agricultural chemicals, including:
1. Pesticides:
- Pesticides are substances used to control or kill pests that can cause damage to crops, livestock, or human health.
- They include insecticides (insect control), herbicides (weed control), fungicides (fungus control), and rodenticides (rodent control).
- Pesticides help farmers manage pests efficiently and sustainably.
2. Fertilizers:
- Fertilizers are substances applied to soil or plants to provide essential nutrients that are necessary for plant growth and development.
- They supply nutrients such as nitrogen, phosphorus, and potassium, which are vital for healthy plant growth and high crop yields.
- Fertilizers can be organic (derived from natural sources) or synthetic (manufactured chemically).
3. Growth Regulators:
- Growth regulators are chemicals that influence plant growth processes, such as stem elongation, flowering, fruit set, and ripening.
- They can be used to control plant height, increase fruit size, delay senescence (aging), and enhance crop quality.
- Growth regulators are valuable tools for managing plant growth and optimizing crop production.
Conclusion:
Agricultural chemicals encompass pesticides, fertilizers, and growth regulators, which play crucial roles in modern agriculture. These chemicals help farmers protect their crops from pests, supply essential nutrients to plants, and regulate plant growth processes. Their proper and responsible use ensures sustainable and efficient farming practices, leading to increased agricultural productivity and food security.

The logical sequence of the carbon cycle is:
- Producer: The carbon cycle begins with producers, such as plants and algae, that use photosynthesis to convert carbon dioxide into organic compounds, primarily glucose.
- Consumer: Consumers, including herbivores, carnivores, and omnivores, obtain carbon by consuming the producers. They break down the organic compounds through respiration, releasing carbon dioxide back into the atmosphere.
- Decomposer: Decomposers, such as bacteria and fungi, break down the remains of dead organisms and waste materials, releasing carbon dioxide as a byproduct.
- Return to the Producer: The carbon dioxide released by consumers and decomposers is taken up by the producers during photosynthesis, completing the carbon cycle.
Explanation:
- Producer: Producers play a crucial role in the carbon cycle as they are the primary source of organic compounds. They absorb carbon dioxide from the atmosphere and convert it into glucose through photosynthesis.
- Consumer: Consumers obtain carbon by consuming the producers. They break down the organic compounds through respiration, releasing carbon dioxide back into the atmosphere. This exchange of carbon between producers and consumers helps maintain the carbon cycle.
- Decomposer: Decomposers play a vital role in the carbon cycle by breaking down the remains of dead organisms and waste materials. During decomposition, they release carbon dioxide back into the atmosphere. This decomposition process ensures that carbon is recycled and made available for future use by producers.
- Return to the Producer: The carbon dioxide released by consumers and decomposers is taken up by the producers during photosynthesis, completing the carbon cycle. This continuous cycle ensures that carbon is constantly recycled and available for the growth and development of living organisms.

Biogeochemical cycles, also known as material cycling, refer to the movement and transformation of essential elements and compounds through biotic and abiotic components of the Earth's ecosystems. These cycles play a crucial role in maintaining the balance of nutrients and sustaining life on Earth. The four major biogeochemical cycles are the carbon cycle, nitrogen cycle, phosphorus cycle, and sulfur cycle.
- Sedimentary Cycles: This term refers to the fact that many elements involved in biogeochemical cycles are stored in sedimentary rocks, which act as long-term reservoirs for these elements. However, this term does not encompass the full scope of biogeochemical cycles.
- Gaseous Cycles: This term refers to the fact that some elements, such as carbon and nitrogen, primarily exist in gaseous forms in the atmosphere and undergo cycling through various processes, including photosynthesis, respiration, and decomposition. While gaseous cycles are an important aspect of biogeochemical cycles, they do not encompass the entirety of these cycles.
- Material Cycling: This term is a more comprehensive and accurate description of biogeochemical cycles as it encompasses the movement and transformation of various elements and compounds through different components of ecosystems, including the atmosphere, lithosphere, hydrosphere, and biosphere. Material cycling accurately reflects the interconnected nature of these cycles and the exchange of materials between living organisms and their environment.
- Cycles of Water: While the water cycle is an essential part of the biogeochemical cycles, it is only one component among several others. Biogeochemical cycles involve the cycling of multiple elements and compounds, not just water.
In conclusion, the most appropriate and inclusive term to describe biogeochemical cycles is "Material Cycling." This term acknowledges the complex and interconnected nature of these cycles and encompasses the movement and transformation of various elements and compounds through different components of ecosystems.

Azotobacter: A Free Living Nitrogen Fixing Bacterium
Azotobacter is a free-living nitrogen-fixing bacterium that is commonly found in soil. It is known for its ability to convert atmospheric nitrogen into a form that is usable by plants. Here is some information about Azotobacter:
1. Nitrogen Fixation: Azotobacter has the unique ability to fix atmospheric nitrogen into ammonia, which can be taken up by plants. This process is essential for the nitrogen cycle and plays a crucial role in maintaining soil fertility.
2. Free-Living Bacterium: Unlike other nitrogen-fixing bacteria, such as Rhizobium, Azotobacter does not form a symbiotic relationship with plants. It is considered a free-living bacterium as it can survive and thrive in the soil without relying on a specific plant host.
3. Soil Habitat: Azotobacter is commonly found in agricultural soils, as well as natural environments such as forests and grasslands. It prefers well-drained soils with good organic matter content.
4. Beneficial Effects: Azotobacter contributes to soil fertility by fixing nitrogen, which enhances plant growth and productivity. It also produces growth-promoting substances like auxins, gibberellins, and vitamins, which further benefit plant development.
5. Environmental Conditions: Azotobacter can tolerate a wide range of environmental conditions. It can survive in both aerobic (oxygen-rich) and anaerobic (oxygen-poor) soil conditions. However, it thrives best in well-aerated soils.
In conclusion, Azotobacter is a free-living nitrogen-fixing bacterium that plays a significant role in soil fertility and plant growth. Its ability to convert atmospheric nitrogen into a usable form makes it an essential component of the nitrogen cycle.

Foot and Mouth Disease:

Foot and Mouth Disease (FMD) is a highly contagious viral disease that primarily affects cloven-hoofed animals such as cattle, sheep, swine, goats, and other animals in the same family. It is important to note that FMD can also affect humans, although it is extremely rare.

Cause of Foot and Mouth Disease:

The disease is caused by a virus known as the Foot and Mouth Disease Virus (FMDV). This virus belongs to the Picornaviridae family and is classified into seven different serotypes: O, A, C, Asia 1, SAT 1, SAT 2, and SAT 3.

Transmission and Spread:

The FMDV is highly contagious and can spread through various means:

• Direct contact with infected animals: The virus can be transmitted through nasal secretions, saliva, milk, urine, and feces of infected animals.


• Contaminated objects: The virus can survive for extended periods in the environment and can be spread through contaminated equipment, vehicles, clothing, and even feed or water.


• Aerosol transmission: The virus can be spread through respiratory droplets, allowing it to travel short distances and infect nearby susceptible animals.

Symptoms and Effects:

FMD can cause various symptoms and effects in affected animals:

• Fever


• Blister-like sores on the tongue, lips, gums, and hooves


• Lameness and reluctance to move


• Loss of appetite and weight loss


• Reduced milk production (in dairy cattle)

Prevention and Control:

Preventing and controlling the spread of FMD involves implementing strict biosecurity measures:

• Isolation of infected animals


• Quarantine of affected premises


• Disinfection of equipment and facilities


• Restricting animal movement


• Vaccination of susceptible animals

It is important for farmers and livestock owners to report any suspected cases of FMD to the relevant authorities to prevent its further spread and minimize the economic impact on the livestock industry.

Agroforestry and social forestry both include:
- Production forestry: Both agroforestry and social forestry involve the management and cultivation of trees for various purposes, including timber production and other forest products.
- Commercial forestry: Agroforestry and social forestry practices can also have commercial aspects, such as the sale of forest products or the establishment of tree plantations for economic gain.
- Afforestation: Both agroforestry and social forestry aim to increase forest cover and promote the establishment of trees in areas where they were previously absent or sparse.
- Plantation of trees: Both agroforestry and social forestry involve the deliberate planting of trees, either in mixed cropping systems or in dedicated tree plantations.
In summary, Agroforestry and social forestry encompass various activities related to the management, cultivation, and utilization of trees for productive, commercial, and environmental purposes.

Answer:
Anthrax is a serious disease that affects various animals, including cattle, poultry, and fish. It is caused by the bacterium Bacillus anthracis and can be transmitted to humans as well. Let's break down the options given:
A: Cattle
- Anthrax is a well-known disease in cattle.
- It can cause high mortality rates in infected cattle.
- Cattle can contract anthrax by ingesting spores from contaminated soil or plants.
B: Poultry
- Anthrax is less common in poultry compared to cattle.
- Poultry can become infected with anthrax by consuming contaminated feed or water.
C: Fish
- Anthrax is not a common disease in fish.
- Fish are not typically affected by Bacillus anthracis.
D: All of these
- This option is incorrect because anthrax does not affect fish.
Therefore, the correct answer is A: Cattle. Anthrax is a serious disease of cattle, and it can also affect other animals like poultry. However, it does not affect fish.

Viral diseases are severe infectious diseases which spread rapidly from one person to the other. Pancreatic necrosis (IPN) is a viral disease which occurs in salmon fish. It is mainly caused due to the premature killing of the cells in the living tissues.

Viral haemorrhagic septicemia (VHS) is a deadly infectious fish disease caused by the viral hemorrhagic septicemia virus. It afflicts over 50 species of freshwater and marine fish in several parts of the northern hemisphere.

Therefore, the correct answer is option A.

Energy flow in the ecosystem is unidirectional.


Explanation:

The energy flow in an ecosystem refers to the movement of energy from one organism to another through food chains and food webs. This flow of energy is unidirectional, meaning it moves in one direction only.

Here is a detailed explanation of why energy flow in the ecosystem is unidirectional:
1. Trophic levels:

The energy flow in an ecosystem occurs through different trophic levels. These levels include producers, primary consumers, secondary consumers, and so on. Each trophic level represents a different level of energy transfer.
2. Energy transfer:

The energy flow starts with the producers, which are usually plants that convert sunlight into chemical energy through photosynthesis. This energy is then passed on to the primary consumers, which are herbivores that consume plants. The energy continues to flow through the different trophic levels as organisms are consumed by other organisms.
3. Energy loss:

As energy moves up the food chain, there is a loss of energy at each trophic level. This loss occurs due to metabolic processes, heat loss, and incomplete digestion. Only a fraction of the energy from one trophic level is transferred to the next.
4. Energy transfer efficiency:

The efficiency of energy transfer between trophic levels is low, usually ranging from 5-20%. This means that a significant amount of energy is lost as it moves through the food chain. This low transfer efficiency contributes to the unidirectional flow of energy.
5. Decomposers and detritivores:

In addition to the energy flow through the trophic levels, energy is also returned to the ecosystem through decomposers and detritivores. These organisms break down dead organic matter and waste, releasing energy back into the ecosystem. However, this energy is still part of the unidirectional flow, as it ultimately moves through the food chain again.
In conclusion, energy flow in the ecosystem is unidirectional, moving from producers to consumers and eventually being lost or returned to the environment through decomposers. This unidirectional flow is influenced by the trophic levels, energy loss, transfer efficiency, and the role of decomposers and detritivores.