RBSE Solutions Class 9 Science Chapter 13 Environment

Question 1. Which of the following is not air pollutant:
(a) NO2
(b) SO2
(c) CO2
(d) DDT
Answer: (d) DDT
In simple words: DDT is a type of pesticide, not a gas that pollutes the air. The other options (NO2, SO2, CO2) are common gases that cause air pollution.

🎯 Exam Tip: Remember that air pollutants are usually gaseous substances or fine particulate matter released into the atmosphere, while DDT is a chemical compound primarily known for soil and water contamination.

Question 2. Who coined the term Ecology?
(a) Odum
(b) Tansley
(c) Haeckel
(d) Habber
Answer: (c) Haeckel
In simple words: Ernst Haeckel, a German biologist, was the first person to use the word "ecology." He brought this term into scientific study.

🎯 Exam Tip: When remembering key scientific terms and their originators, associating the name with the field (e.g., Haeckel with Ecology) can help. Ecology is the study of how living things interact with their environment.

Question 3. The main gas responsible for greenhouse effect is:
(a) CO2
(b) SOa
(c) NO2
(d) CO
Answer: (a) CO2
In simple words: Carbon dioxide (CO2) is the primary gas that causes the greenhouse effect. This effect traps heat in the Earth's atmosphere, making the planet warmer.

🎯 Exam Tip: While several gases contribute to the greenhouse effect, carbon dioxide is the most significant one due to its large emissions from human activities. Always remember the primary drivers of environmental phenomena.

Question 4. Which is an artificial ecosystem among the following:
(a) Forest
(b) Grass land
(c) Desert
(d) Crop land
Answer: (d) Crop land
In simple words: A crop field is an artificial ecosystem because humans create and manage it. Forests, grasslands, and deserts are all natural ecosystems.

🎯 Exam Tip: Artificial ecosystems are those created and maintained by humans, often for agricultural or urban purposes, differing from natural ecosystems which develop without human intervention.

Question 5. Adsorption, absorption and condensation are useful in control of which type of pollution?

🎯 Exam Tip: When a question lists processes, consider which type of pollution these processes are commonly used to manage. For example, gas filtration or water purification might involve these techniques.

Environment Very Short Answer Type Questions

Question 6. Define the term Ecology.
Answer: The word "ecology" comes from the Greek word "Oikos," meaning "a place to live," and "logos," meaning "to study." Ernst Haeckel, a German biologist, was the one who first used this term. Ecology is the study of how living things interact with each other and with their non-living environment. It helps us understand the delicate balance in nature.
In simple words: Ecology is the study of how living things like plants and animals live together and interact with their surroundings, like air, water, and soil.

🎯 Exam Tip: When defining scientific terms, explaining the origin of the word (if relevant) and mentioning key figures can add depth to your answer. Always include both biotic and abiotic components in the definition of ecology.

Question 7. Name the two main gaseous pollutant.
Answer: The two main gaseous pollutants are Sulphur dioxide (\( \text{SO}_2 \)) and Nitrogen dioxide (\( \text{NO}_2 \)). These gases are often released from industrial processes and vehicle emissions, contributing to acid rain and respiratory problems.
In simple words: Two main polluting gases are sulphur dioxide and nitrogen dioxide.

🎯 Exam Tip: When listing pollutants, it's good practice to provide their chemical formulas as well as their common names for accuracy.

Question 8. What are decomposers?
Answer: Decomposers, also called microorganisms or saprotrophs, are tiny living things like bacteria and fungi. They feed on the dead bodies of plants and animals. They break down complex organic materials into simpler inorganic substances. These simpler substances then return to the soil and are taken up by plants again, continuing the cycle of matter in the ecosystem. This process is essential for recycling nutrients.
In simple words: Decomposers are small living things like bacteria and fungi that break down dead plants and animals. They help put nutrients back into the soil.

🎯 Exam Tip: Emphasize the role of decomposers in nutrient cycling and their importance for maintaining a healthy ecosystem, as they prevent dead matter from accumulating and ensure resources are reused.

Question 9. Define Sound Pollution.
Answer: Sound pollution, also known as noise pollution, refers to unwanted noise that is unpleasant to the ears and is not needed or desired in a particular place at a specific time. For example, the sound of a loudspeaker might be normal during the day, but at midnight, it becomes a disturbance and is considered sound pollution. High levels of sound pollution can affect human health and wildlife.
In simple words: Sound pollution is simply unwanted loud or disturbing noise. If a sound is too loud or happens at the wrong time, making it annoying, it is called sound pollution.

🎯 Exam Tip: When defining pollution, always mention that it's "unwanted" or "undesirable" and specify its negative impact on living beings or the environment.

Question 10. Define the chemical condition caused by thermal pollution.

🎯 Exam Tip: Think about how changes in water temperature can affect the dissolved gases and chemical reactions in aquatic environments. Consider processes like solubility and metabolic rates.

Environment Short Answer Type Questions

Question 11. Explain abiotic components with example.
Answer: Abiotic components are the non-living parts of an environment that influence living organisms. They can be divided into a few types:
(a) Climatic or physical factors:
These include:
• Atmospheric factors: Such as temperature, sunlight, moisture, and rainfall.
• Edaphic factors: Such as the texture and composition of the soil. These factors play a big role in deciding what kinds of organisms can live in a specific area.
(b) Inorganic substances: These are different nutrient elements and compounds found in the environment. Examples include carbon (\( \text{C} \)), nitrogen (\( \text{N} \)), sulfur (\( \text{S} \)), phosphorus (\( \text{P} \)), carbon dioxide (\( \text{CO}_2 \)), oxygen (\( \text{O}_2 \)), and minerals like calcium (\( \text{Ca} \)), potassium (\( \text{K} \)), and magnesium (\( \text{Mg} \)). These substances are cycled through the ecosystem.
(c) Organic substances (Compounds): These include proteins, carbohydrates, fats, and amino acids. They are involved in the cycling of materials, appearing as lipids and humic substances. These substances enter living things through the soil and then return to the soil and environment after organisms die and decompose.
In simple words: Abiotic components are the non-living things in an environment, like weather (temperature, sun), soil, and basic elements (carbon, nitrogen, oxygen). They control where and how living things can exist and grow.

🎯 Exam Tip: When explaining abiotic components, provide clear examples for each category (climatic, inorganic, organic) and briefly state how each type influences living organisms in an ecosystem.

Question 12. What is Global warming?
Answer: Global warming is the increase in Earth's average temperature due to human activities. Humans release large amounts of carbon dioxide (\( \text{CO}_2 \)) and methane (\( \text{CH}_4 \)) into the atmosphere by burning fossil fuels in homes, factories, and vehicles, as well as through farming and cutting down forests. These "greenhouse gases" trap the heat reflected from the Earth's surface, similar to how a greenhouse works. This trapped heat causes the planet to get hotter, a phenomenon known as global warming, which is a direct result of the enhanced greenhouse effect.
In simple words: Global warming is when the Earth's temperature gets hotter because people put too many gases like carbon dioxide into the air. These gases trap heat and make our planet warmer.

🎯 Exam Tip: Clearly link global warming to the increase in greenhouse gases, primarily from human activities, and mention its direct impact on Earth's temperature. It's important to state the "why" behind the warming.

Question 13. What is an Artificial Ecosystem? Explain with example.

🎯 Exam Tip: Think about human-made environments designed to support life, and how they differ from natural systems in terms of maintenance and biodiversity. Crop fields or aquariums are common examples.

Question 14. Explain the causes and effects of Air Pollution?
Answer: Air pollution happens when there are unwanted changes in the air's natural composition, making it harmful for living things. These changes can be in the quality or quantity of gases in the air.
Following are the causes of air pollution:
(a) Burning of fuel in houses, furnaces, and factories: We use wood, charcoal, kerosene oil, coal, and diesel as fuel. When these fuels burn, they release carbon dioxide (\( \text{CO}_2 \)), sulphur dioxide (\( \text{SO}_2 \)), and carbon monoxide (\( \text{CO} \)) into the air, causing pollution.
(b) Smoke coming out from transport vehicles: Cars, buses, and trains burn diesel and petrol, which release CO, \( \text{CO}_2 \), \( \text{SO}_2 \), and \( \text{H}_2\text{S} \) into the air. Diesel vehicles, especially, release a lot of carbon monoxide, which is very polluting.
(c) Industrial wastes: Industries release waste products like carbon particles, chlorine, sulphur dioxide, and ammonia gas into the air. These are significant sources of air pollution.
(d) Cutting down of trees and clearing of forests: When trees are cut down rapidly, the amount of oxygen in the atmosphere decreases because trees produce oxygen. This also leads to an increase in carbon dioxide.
(e) The rapid growth of population: A quickly growing population leads to more resource consumption and waste production. This results in less oxygen and more carbon dioxide in the air.
Following are the harmful effects of air pollution on health:
• Gases from factories like carbon dioxide, chlorine, ammonia, and nitrous oxide can irritate the throat and eyes.
• Vapors from chemical factories can cause various lung diseases, such as coughing and asthma.
• Gases from aluminum and sulfur phosphate factories can lead to problems with teeth and bones.
• Smoke and dust particles in the air can cause coughs, asthma, and tuberculosis.
In simple words: Air pollution means dirty air that harms living things. It's caused by burning fuels in homes and cars, factory smoke, cutting down trees, and too many people. This dirty air can make us sick, causing problems with our breathing, eyes, and bones.

🎯 Exam Tip: When discussing environmental issues like air pollution, make sure to cover both its causes and its effects, providing specific examples for each to show a complete understanding.

Environment Additional Questions Solved

Multiple Choice Questions (MCQs)

Question 1. Abiotic factors of the environment are:
(a) Sunlight
(b) Temperature
(c) Rainfall
(d) All of the options
Answer: (d) All of the options
In simple words: Abiotic factors are all the non-living parts of an environment. Sunlight, temperature, and rainfall are all examples of these non-living factors.

🎯 Exam Tip: Remember that abiotic factors are physical and chemical elements like light, water, temperature, and soil, which are crucial for the survival and distribution of living organisms.

Question 2. The physical and biological world we live in is called:
(a) Environment
(b) Community
(c) Population
(d) Ecosystem
Answer: (d) Ecosystem
In simple words: An ecosystem includes both the living things (like plants and animals) and the non-living things (like air and water) in an area, all working together.

🎯 Exam Tip: Distinguish between terms: "Environment" is broader, "Community" is just living populations, "Population" is one species. "Ecosystem" specifically refers to the interaction of biotic and abiotic components.

Question 3. Biotic component of Ecosystem consists of:
(a) Producer
(b) Consumers
(c) Decomposers
(d) All of the options
Answer: (d) All of the options
In simple words: The living parts of an ecosystem, called biotic components, include producers (like plants), consumers (like animals), and decomposers (like fungi and bacteria).

🎯 Exam Tip: When defining biotic components, ensure you include all three main trophic levels: those that make their own food (producers), those that eat others (consumers), and those that break down dead matter (decomposers).

Question 4. What is common to the habitat and the environment?
(a) The biotic factors
(b) The abiotic components
(c) Both biotic and abiotic components
(A) A Biome
(B) A natural ecosystem
(C) An artificial ecosystem
(D) A community of plants and animals only
Answer: (B) A natural ecosystem
In simple words: A habitat is where an organism lives, and the environment is everything around it. A natural ecosystem brings together both living and non-living factors that affect a living thing.

🎯 Exam Tip: Understand that a habitat is a specific place, while an environment is the broader surroundings. An ecosystem describes the interaction of all components, making it a fitting common ground.

Question 6. A plant grown in the environment is related to:
(a) Other plants of area
(b) Soil of area
(c) Presence of light
(d) All of the options
Answer: (d) All of the options
In simple words: A plant growing in nature is connected to other plants, the soil it grows in, and the sunlight it gets. All these things work together.

🎯 Exam Tip: Remember that every living organism exists within a complex web of interactions, both with other living things (biotic) and with its physical surroundings (abiotic). All factors are interconnected.

Question 7. Example of sedimentary cycle in biosphere is:
(a) Phosphorus cycle
(b) Oxygen cycle
(c) Nitrogen cycle
(d) Carbon cycle
Answer: (a) Phosphorus cycle
In simple words: The phosphorus cycle is an example of a sedimentary cycle because phosphorus mainly moves through rocks, soil, water, and living things, staying mostly on land and in the ocean floor.

🎯 Exam Tip: Sedimentary cycles involve elements that are primarily stored in Earth's crust (rocks and soil), unlike gaseous cycles (like nitrogen or oxygen) where the atmosphere is the main reservoir.

Question 8. Which of the following is an abiotic component of the ecosystem:
(a) Bacteria
(b) Plants
(c) Humus
(d) Fungi
Answer: (c) Humus
In simple words: Humus is the decomposed organic matter in soil, which is a non-living part of the ecosystem. Bacteria, plants, and fungi are all living things.

🎯 Exam Tip: Clearly differentiate between biotic (living) and abiotic (non-living) components. Humus is a product of decomposition, making it a non-living organic material in the soil.

Question 9. The compound responsible for the depletion of ozone layer is:
(a) Sulphur dioxide
(b) Chlorofluorocarbon

🎯 Exam Tip: Recall the specific chemicals known to harm the ozone layer. Chlorofluorocarbons (CFCs) are particularly notorious for their role in ozone depletion.

Question. Polluted water can cause:
(a) Typhoid
(b) Kidney trouble
(c) Malaria
(d) Pulmonary disease
Answer: (a) Typhoid
In simple words: Drinking polluted water can lead to diseases like typhoid. This is a common illness spread through contaminated water.

🎯 Exam Tip: Be aware of the direct health consequences of consuming contaminated water. Typhoid is a classic example of a waterborne disease.

Question 11. The main cause of a cough, asthma and tuberculosis is:
(a) Air pollution
(b) Water pollution
(c) Noise pollution
(d) All of the options
Answer: (a) Air pollution
In simple words: Breathing dirty air from pollution is the main reason people get lung problems like coughs, asthma, and tuberculosis.

🎯 Exam Tip: Respiratory illnesses are primarily linked to the quality of the air we breathe. Pollutants in the air can directly damage the lungs and airways.

Question 12. Which is helpful in checking air pollution:
(a) Animals
(b) Factories
(c) Means of Transport
(d) Trees
Answer: (d) Trees
In simple words: Trees help reduce air pollution because they take in carbon dioxide and release oxygen. They also trap dust and other particles.

🎯 Exam Tip: Remember the vital role of plants and trees in filtering the air and producing oxygen through photosynthesis, making them natural allies against air pollution.

Environment Very Short Answer Type Questions

Question 1. Define Environment?
Answer: The environment is everything around us, including both the physical (non-living) and biological (living) elements. It is the complete set of conditions that influence the existence and development of an organism or a group of organisms.
In simple words: The environment is simply the physical and living world where we exist.

🎯 Exam Tip: A good definition of "environment" should encompass both the biotic (living) and abiotic (non-living) components that interact to form a system.

Question 2. Name the living components of the biosphere.
Answer: The living components of the biosphere are producers, consumers, and decomposers. Producers, like plants, make their own food. Consumers eat other organisms. Decomposers break down dead matter, recycling nutrients. These three groups interact to form food chains and webs.
In simple words: The living parts of the biosphere are producers (plants), consumers (animals), and decomposers (bacteria, fungi).

🎯 Exam Tip: Always remember the three main categories of living organisms in an ecosystem, based on their role in the food chain and energy flow.

Question 4. Name two types of Ecosystem.
Answer: Two main types of ecosystems are:
(a) Natural Ecosystems: These are ecosystems that exist and develop without significant human interference, such as forests, oceans, and deserts.
(b) Artificial Ecosystems: These are ecosystems created and managed by humans, such as croplands, gardens, and aquariums. They often require human maintenance to thrive.
In simple words: The two types of ecosystems are natural ones (like forests) and artificial ones (like farms), which are made by humans.

🎯 Exam Tip: When asked to classify ecosystems, distinguishing between those formed naturally and those influenced or created by humans is the primary division. Provide a clear example for each type.

Question 5. What is biosphere?
Answer: The biosphere is the part of Earth where life exists. It includes all the living organisms and the parts of the Earth's land, water, and atmosphere that support life. Essentially, it is the global ecological system integrating all living beings and their relationships with the lithosphere (land), hydrosphere (water), and atmosphere (air).
In simple words: The biosphere is the part of Earth that supports life, including all living things and the places they live in the air, on land, and in water.

🎯 Exam Tip: Emphasize that the biosphere is the "life-supporting zone" and mention its three main components: lithosphere, hydrosphere, and atmosphere, which all interact to allow life.

Question 6. What is thermal pollution?
Answer: Thermal pollution is when hot water from industries and power plants is released into natural water bodies like rivers or lakes. This changes the natural temperature of the water. Even water released from dams can affect temperature because deep reservoir water is colder than surface water. This change in temperature can harm aquatic life and disrupt the water ecosystem.
In simple words: Thermal pollution is when hot water from factories or power plants makes rivers and lakes warmer than they should be, harming living things in the water.

🎯 Exam Tip: When defining thermal pollution, focus on the introduction of heated water into natural systems and its direct impact on the water temperature, which then affects aquatic organisms.

Question 7. What is air pollution?
Answer: Air pollution is any undesirable change in the physical, chemical, or biological characteristics of the air. These changes are usually caused by harmful substances like gases and particles released into the atmosphere, making the air impure and dangerous for living things.
In simple words: Air pollution is when the air becomes dirty with harmful things, making it bad for breathing and the environment.

🎯 Exam Tip: A complete definition of air pollution should include the idea of "undesirable change" and the presence of "harmful substances" affecting the quality of the atmosphere.

Question 8. What is water pollution?
Answer: Water pollution is the contamination of water with unwanted and harmful substances. This occurs when pollutants, such as industrial waste, sewage, chemicals, and plastics, are released into water bodies, making the water unsafe for use and damaging aquatic ecosystems. The presence of these substances alters the water's natural quality.
In simple words: Water pollution is when water gets dirty because harmful and unwanted substances mix into it.

🎯 Exam Tip: Define water pollution by focusing on the introduction of "unwanted and harmful substances" into water bodies, leading to its contamination and negative impact.

Question 9. What is a biogeochemical cycle?
Answer: A biogeochemical cycle describes the natural pathway through which essential nutrients and elements, like carbon, nitrogen, oxygen, and phosphorus, move between the living (biotic) and non-living (abiotic) parts of the environment. These cycles involve biological, geological, and chemical processes, ensuring that these elements are continuously recycled and available for life on Earth.
In simple words: A biogeochemical cycle is how important elements like carbon and nitrogen move in a circle between living things, rocks, air, and water in nature.

🎯 Exam Tip: Break down the term: "bio" (life), "geo" (Earth), "chemical" (elements). This highlights that these cycles involve the movement of chemicals through living organisms and Earth's physical systems.

Environment Short Answer Type Questions

Question 1. Differentiate between the lithosphere, hydrosphere and atmosphere.
Answer: The lithosphere, hydrosphere, and atmosphere are distinct layers of Earth:
(a) Lithosphere: This is the Earth's rigid outer layer, made up of soil, rocks, and minerals. It includes the crust and the uppermost part of the mantle. It is where landforms are found.
(b) Hydrosphere: This consists of all the water on Earth. It includes water vapor in the air, surface water (like oceans, lakes, and rivers), and underground water. Water is constantly moving and changing forms within this sphere.
(c) Atmosphere: This is the layer of gases that surrounds the Earth, like a blanket. It protects life on Earth by absorbing ultraviolet radiation and regulating temperature. It is mainly composed of nitrogen, oxygen, and small amounts of other gases.
In simple words: The lithosphere is the land part of Earth, the hydrosphere is all the water, and the atmosphere is the layer of air surrounding the planet. Each is a different part of our world.

🎯 Exam Tip: Clearly define each sphere by its composition and location. Highlighting a key characteristic or role for each (e.g., land for lithosphere, water for hydrosphere, air for atmosphere) helps differentiate them.

Question 2. List any three human activities which could lead to an increase in carbon dioxide content of air?
Answer: Three important human activities that increase the amount of carbon dioxide (\( \text{CO}_2 \)) in the atmosphere are:
• Combustion: Burning fuels like coal, petroleum products, and even cow dung for energy releases a lot of \( \text{CO}_2 \) into the air. This process powers industries, vehicles, and homes.
• Respiration: Humans and animals breathe out \( \text{CO}_2 \) as a natural by-product of their metabolic processes. As the global population grows, so does the total \( \text{CO}_2 \) released through respiration.
• Deforestation: Cutting down trees for human needs, such as for wood or to clear land for agriculture, removes natural absorbers of \( \text{CO}_2 \). Trees absorb \( \text{CO}_2 \) during photosynthesis, so fewer trees mean more \( \text{CO}_2 \) stays in the atmosphere.
In simple words: Three human actions that add more carbon dioxide to the air are burning fuels, breathing (by many people), and cutting down trees.

🎯 Exam Tip: When listing activities affecting climate, ensure you provide concrete examples for each. For instance, instead of just "burning," specify "burning fossil fuels" for better clarity.

Question 3. List three human activities responsible for water pollution.
Answer: Here are several human activities that cause water pollution:
(a) Disposal of industrial waste: Factories often release waste that contains poisonous substances directly into nearby water bodies, contaminating them.
(b) Excessive use of fertilizers and pesticides: When farmers use too many fertilizers and pesticides on crops, rainwater washes these chemicals into rivers and lakes, polluting the water.
(c) Hot water released from industrial units: Industries sometimes release hot water into natural water sources. This sudden temperature change can harm aquatic life and reduce oxygen levels in the water.
(d) Synthetic soap and detergents: Using synthetic soaps and detergents for washing in households introduces chemicals into the water system, which eventually reaches larger water bodies.
(e) Sewage discharged into sewers: Untreated or partially treated sewage from homes and cities often flows into rivers and oceans, bringing harmful bacteria and chemicals into the water.
In simple words: Water pollution happens because of many human activities. Some big ones are factories dumping waste, farmers using too many chemicals, hot water from industries, and sewage from homes.

🎯 Exam Tip: When listing causes of pollution, try to categorize them (e.g., industrial, agricultural, domestic) and provide specific examples for each type of activity to make your answer comprehensive.

Question 4. What is the difference between abiotic and biotic components?
Answer: The differences between abiotic and biotic components are fundamental to understanding ecosystems. Abiotic components are the non-living physical and chemical factors in an environment, such as sunlight, temperature, water, soil, and air. They provide the basic conditions for life. Biotic components, on the other hand, are all the living or once-living parts of an ecosystem, including plants, animals, fungi, and bacteria. These living components interact with each other and with the abiotic components to form a dynamic system. For example, sunlight (abiotic) helps plants (biotic) grow, which are then eaten by animals (biotic).
In simple words: Abiotic components are non-living things like air, water, and sun. Biotic components are all living things like plants and animals.

🎯 Exam Tip: Clearly state that abiotic means "non-living" and biotic means "living." Providing a couple of examples for each and a brief mention of their interaction strengthens your explanation.

Question 5. Define biosphere?
Answer: The biosphere is the total sum of all physical and biological conditions on Earth that support life and influence organisms. It represents the global ecological system that brings together all living things and their relationships, including their interactions with the Earth's land (lithosphere), water (hydrosphere), and air (atmosphere). The biosphere is considered the largest self-sustaining biological system on our planet. It is usually divided into these parts:
Lithosphere: This includes all the solid parts of the Earth, like rocks and soil.
Hydrosphere: This comprises all the liquid parts of the Earth, including oceans, lakes, and rivers.
Atmosphere: This is the gaseous layer surrounding the Earth.
In simple words: The biosphere is the part of Earth where all living things exist. It includes all the land, water, and air that support life.

🎯 Exam Tip: When defining the biosphere, emphasize that it's the "life-supporting zone" and clarify its main subdivisions (lithosphere, hydrosphere, atmosphere) to show a comprehensive understanding.

Question 6. What is soil pollution? How does it cause?
Answer: Soil pollution happens when harmful substances are added to the soil, or useful components are removed, which negatively affects its fertility and harms the living organisms within it.
Causes of Soil Pollution:
Soil pollution is mainly caused by solid wastes and chemicals.
• Industrial waste: Slag heaps from mines and waste from industries like pulp and paper mills, sugar mills, oil refineries, power plants, chemical and fertilizer factories, and plastic and rubber industries all contribute significantly to soil pollution.
• Fly ash: Most industrial furnaces and thermal power stations produce fly ash, which is a fine, powdery residue from unburnt materials. This ash contains various pollutants that contaminate the soil.
• Domestic waste: Household waste includes a lot of solid waste, such as food scraps, vegetable remains, packaging, cans, paper, ash, broken gadgets, wood, metals, plastics, and construction debris. These materials are often dumped in landfills, leading to soil contamination.
In simple words: Soil pollution is when dirt becomes unhealthy because of harmful substances, making it hard for plants and animals to live there. It's caused by factory waste, fly ash, and household trash.

🎯 Exam Tip: For soil pollution, distinguish between the direct addition of pollutants (like industrial waste) and the indirect effects (like removal of useful components). Give concrete examples of waste types.

Environment Long Answer Type Questions

Question 1. Define the classification of biotic factors in an ecosystem? Explain the importance of each factor?
Answer: Biotic components are the living parts of an ecosystem. They are classified based on their food relationships and how they get energy. Here are the main categories:
(a) Producers: These are living members of an ecosystem, mainly green plants and some bacteria, that create their own food through processes like photosynthesis. They convert sunlight or chemical energy into organic compounds, forming the base of the food chain.
(b) Consumers or Heterotrophs: These are animals that cannot make their own food. They get energy by eating other organisms. Consumers are further divided into types based on what they eat:
1. Primary Consumers: These are herbivores that eat producers (green plants). Examples include insects, goats, cows, rabbits, and deer.
2. Secondary Consumers: These are carnivores that eat primary consumers (herbivores). Examples include snakes, frogs, foxes, and lizards.
3. Tertiary Consumers: These are large carnivores that eat secondary consumers. Lions and tigers are common examples of tertiary consumers.
4. Omnivores: These animals eat both plants and other animals. Humans are a good example of omnivores.
(c) Decomposers or Micro consumers or Osmotrophs or Saprotrophs: These are microorganisms like bacteria and fungi that feed on dead plants and animals. They break down complex organic substances into simpler inorganic ones. This process returns essential nutrients to the soil, which plants can then reuse, thus continuing the cycle of matter.
In simple words: Biotic factors are the living parts of an ecosystem, grouped by how they get food. Producers (like plants) make food. Consumers (like animals) eat other living things and are split into primary (eat plants), secondary (eat herbivores), tertiary (eat other carnivores), and omnivores (eat both plants and animals). Decomposers (like bacteria) break down dead stuff. Each group is important for the flow of energy and nutrients.

🎯 Exam Tip: For each biotic factor, clearly define its role in the food chain (producer, consumer, decomposer) and provide several distinct examples. Emphasize their interconnectedness in nutrient cycling and energy flow.

Question 2. Explain the causes of water pollution. Discuss how you can contribute in reducing water pollution.
Answer: Water pollution is caused by various factors, and we can all help reduce it. Here are some causes and control measures:
(a) Microbial growth: Sewage from large cities is often dumped into rivers. This sewage contains nutrients that make tiny bacteria grow rapidly. This excessive growth uses up the oxygen in the water, causing other aquatic organisms to die.
(b) Oil: Oil spills from ships and the washing of automobiles can pollute rivers and other water bodies. Oil creates a layer on the water surface, blocking sunlight and harming marine life.
(c) High Temperature: Hot water released from factories and power generators into water bodies causes thermal pollution. This raises the water temperature, which reduces the amount of dissolved oxygen and harms aquatic ecosystems. The release of cold water from deep dam reservoirs into rivers can also alter natural temperatures.
Some of the control measures of water pollution are as follows:
• Effluent Treatment: All wastewater from factories should be treated and cleaned before it is released into rivers or other water bodies. This removes harmful chemicals and pollutants.
• Sewage Treatment: Sewage should be fully treated before being released into rivers or used for irrigation. Biogas can be produced from sewage in treatment tanks, serving as a valuable cooking gas, and the leftover solid can be used as rich manure.
• Avoid fertilizers and pesticides: Farmers should reduce their use of chemical fertilizers and pesticides, or use organic alternatives, to prevent these chemicals from washing into water sources.
• No garbage in water bodies: People should not throw garbage or waste directly into rivers, lakes, or other water bodies.
In simple words: Water gets polluted by city sewage, oil spills, hot factory water, and harmful chemicals. To stop this, factories must clean their waste, sewage should be treated, we should use fewer farm chemicals, and never throw trash into water.

🎯 Exam Tip: When explaining water pollution, provide examples of both point sources (like factory discharge) and non-point sources (like agricultural runoff). Always include practical steps individuals and industries can take to reduce pollution.

Question 3. (a) Draw a labelled diagram of the oxygen cycle in nature and explain?
(b) How does replenishment take place?
Answer:
(a) The oxygen cycle shows how oxygen moves through the air, water, and living organisms. Oxygen makes up about 21% of the gases in the atmosphere. It is also present in water and helps aquatic life survive. Oxygen is found in combined forms like carbon dioxide (\( \text{CO}_2 \)) and water (\( \text{H}_2\text{O} \)). It is a vital part of biological molecules like proteins and fats. All living things, including plants, animals, and decomposers, use oxygen from their environment for breathing. Plants also use \( \text{CO}_2 \) during photosynthesis, and this process releases oxygen into the atmosphere. Oxygen is also used when dead organisms decay and when fuels like wood and coal burn, releasing \( \text{CO}_2 \) and \( \text{H}_2\text{O} \) back into the air. The oxygen cycle is a continuous natural process that keeps oxygen levels balanced for life on Earth.

🎯 Exam Tip: When asked to explain a natural cycle like the oxygen cycle, describe the main stages and the key elements involved, such as the role of plants, animals, and the atmosphere. If a diagram is requested but not provided in the source, focus on giving a very thorough textual explanation.

Question 3. (a) Draw a labelled diagram of the oxygen cycle in nature and explain? (b) How does replenishment take place?
Answer:
(a) Oxygen makes up about 21% of all the gases in the air. It is also found dissolved in water, which helps aquatic life survive. Oxygen is also present in combined forms, like carbon dioxide (\( \text{CO}_2 \)) and water (\( \text{H}_2\text{O} \)). It is also part of the earth's crust as oxides of metals and silicon. Oxygen is a key part of most important biological molecules such as proteins, carbohydrates, nucleic acids, and fats.
All living things (plants, animals, and decomposers) take oxygen from their surroundings to use for breathing (respiration). Plants also take in \( \text{CO}_2 \) during photosynthesis, and oxygen becomes part of all organisms through water. Oxygen is used when dead organisms decay and decompose, and also when fuels like wood, coal, and petroleum are burned. During these processes, \( \text{CO}_2 \) and \( \text{H}_2\text{O} \) are released back into the air. Green plants use carbon dioxide and water to make food (carbohydrates) through photosynthesis, releasing oxygen as a byproduct. Green plants are a major source of oxygen in the atmosphere.
(b) Replenishment: Photosynthesis is how atmospheric oxygen is restored. During photosynthesis, carbon dioxide is used with water, and oxygen gas is released. The oxygen gas released during photosynthesis comes from water. So, the oxygen used in the form of \( \text{H}_2\text{O} \) and \( \text{CO}_2 \) is put back into the earth's atmosphere.
In simple words: The oxygen cycle shows how oxygen moves between the air, living things, and the environment. Plants release oxygen during photosynthesis, which is then used by all living things for breathing. This cycle keeps the oxygen levels balanced on Earth.

🎯 Exam Tip: When explaining cycles, always mention the key forms of the element and the main processes (like respiration and photosynthesis for oxygen) that drive its movement. Ensure you include how oxygen is both consumed and replenished.

Question 4. (a) With the help of well-labelled diagram, explain the water cycle in nature? (b) Explain how is greenhouse effect related to global warming?
Answer:
(a) In nature, water constantly moves in a cycle. Hydrogen is a main element of water and moves with it. Water comes from many places as water vapor. This vapor forms when water evaporates from bodies like oceans, lakes, and rivers, and also from living things. Animals release water through urine and sweat, which then evaporates. Plants release water through transpiration. All this water vapor contributes to the air. This vapor cools down at higher altitudes and forms tiny droplets. These droplets gather to make clouds. When clouds get heavy, water falls back to Earth as rain or snow. This process is called precipitation. This way, water returns to the earth, making fresh water available. The water cycle also helps move hydrogen, which plants need. Plants use water to get hydrogen for reducing carbon dioxide during photosynthesis. During this process, water breaks into \( \text{H}^+ \) and \( \text{OH}^- \) ions. Hydrogen is used to fix carbon dioxide, and oxygen is released as a byproduct.
(b) Carbon dioxide (\( \text{CO}_2 \)) and methane in the atmosphere absorb infrared radiation from Earth. They trap this heat, stopping it from escaping into space. The carbon dioxide acts like the glass in a greenhouse, keeping the earth warm. This is why it is called the greenhouse effect. Without it, Earth would be too cold for life. However, when there is too much \( \text{CO}_2 \) and methane, it causes global warming, which means the earth's average temperature goes up. This increase in temperature can lead to polar ice caps melting and sea levels rising.
In simple words: The water cycle shows how water moves from Earth to the sky and back again, like a continuous loop. The greenhouse effect is when certain gases, like carbon dioxide, trap heat in Earth's atmosphere, keeping our planet warm. Too much of these gases leads to global warming, which makes Earth hotter.

🎯 Exam Tip: When explaining cycles, describe each stage clearly (evaporation, condensation, precipitation). For the greenhouse effect, highlight the role of gases in trapping heat and differentiate between the natural effect and its human-caused increase leading to global warming.

Question 5. Make a schematic diagram of the carbon cycle? What are the two ways in which carbon dioxide is fixed in the environment?
Answer: The air has about 0.03% carbon dioxide. The carbon cycle shows how carbon moves around, as it is a basic part of all organic compounds in living things. Carbon dioxide in the air and dissolved in water are the main sources of carbon. Carbon moves from the air to producers (plants), then to consumers (animals), and then from both back to decomposers, and finally into the atmosphere again. Carbon is also found in water, fossil fuels, and sedimentary rocks.
Carbon dioxide is fixed in the environment mainly in two ways:
1. Photosynthesis: Green plants take \( \text{CO}_2 \) from the air and use it to make their own food (carbohydrates) during photosynthesis. This is the first step where \( \text{CO}_2 \) is removed from the atmosphere and used by living organisms.
2. Absorption by water bodies: Carbon dioxide also dissolves directly into water bodies like oceans, where it can be used by aquatic plants and other organisms.
In simple words: The carbon cycle explains how carbon moves between the air, living things, and the ground. Plants fix carbon dioxide from the air during photosynthesis to make food. Also, carbon dioxide can dissolve in water.

🎯 Exam Tip: Remember the two main processes that fix atmospheric carbon dioxide: photosynthesis by plants and absorption into water. Emphasize how carbon moves through producers, consumers, and decomposers.

Question 6. What is ozone? Discuss its role in protecting the life on earth. Which human activities are depleting ozone layer? Show a picture of the ozone hole over Antarctica.
Answer: Ozone is a form of oxygen made of three oxygen atoms (\( \text{O}_3 \)). It is very poisonous to living things. There is an ozone layer, about 5 km thick and 25-30 km above Earth's surface, that surrounds our planet. The ozone layer is crucial because it blocks some of the sun's harmful ultraviolet (UV) light. UV light is bad for humans and crops; long exposure can cause skin cancer, eye damage, and weaken the immune system. Too much UV light also kills tiny aquatic plants (phytoplankton), can disrupt global rainfall, and cause other ecological problems, affecting food supplies.
The main reasons for the ozone layer getting thinner (depletion) are:
1. Chlorofluorocarbons (CFCs): These are man-made chemicals that are very stable. When they reach the ozone layer, they react with ozone molecules and destroy them, making the layer thinner.
2. Nitrogen monoxide (NO): This pollutant also causes ozone destruction.
Years ago, a hole in the ozone layer was found over Antarctica, showing the extent of this depletion. This helps us understand the importance of reducing such emissions.
In simple words: Ozone is a special type of oxygen that forms a protective shield high above Earth. This shield stops harmful sunlight from reaching us. Human activities, especially using chemicals called CFCs, are making this ozone shield thinner, which is a big problem for all life on Earth.

🎯 Exam Tip: When discussing ozone, define it, explain its protective role against UV radiation, and clearly identify the main human-caused chemicals (CFCs, nitrogen monoxide) responsible for its depletion.