Test: Our Environment - 4 - UPSC MCQ

Non-biodegradable substances:

• Nylon: Nylon is a synthetic polymer that is not easily broken down by natural processes. It takes hundreds of years for nylon to decompose, making it non-biodegradable.

Biodegradable substances:

• Tea leaves: Tea leaves are organic materials that can be easily decomposed by bacteria, fungi, and other microorganisms. They are biodegradable and contribute to the natural nutrient cycle.


• Remains of animals: Animal remains, such as bones and flesh, are also organic materials that can be broken down by natural processes. They are biodegradable and play a role in the decomposition and recycling of nutrients in ecosystems.


• Fleece of sheep: Fleece, which is the wool obtained from sheep, is a natural fiber that can be broken down by microorganisms over time. It is biodegradable and does not contribute to long-term environmental pollution.

In conclusion, the non-biodegradable substance among the given options is nylon. It is a synthetic material that takes a long time to decompose, leading to potential environmental pollution if not properly disposed of.

Like other greenhouse gases, nitrous oxide absorbs radiation and traps heat in the atmosphere, where it can live for an average of 114 years, according to the EPA.

Incorrect Statement:

B: Soil provides disease resistant environment for plants.

Explanation:
The incorrect statement is B: Soil provides a disease-resistant environment for plants. This statement is incorrect because soil does not provide a disease-resistant environment for plants. In fact, soil can harbor various pathogens and pests that can cause diseases in plants. It is important for gardeners and farmers to take measures to prevent and manage plant diseases by practicing good sanitation, crop rotation, and using disease-resistant plant varieties.
Correct Statements:
- A: Soil provides water and minerals for the plant.
- C: Soil provides the substratum for plant growth.
- D: Soil provides necessary nutrients for plants.
Overall, soil plays a crucial role in supporting plant growth by providing water, minerals, nutrients, and a physical structure for plant roots to anchor and grow. However, it does not inherently provide a disease-resistant environment for plants.

The correct answer is D: Aquarium.
Terrestrial ecosystems are those that exist on land, so an aquarium, which is a man-made habitat for aquatic organisms, does not fall under this category.
Let's examine each option to demonstrate why D is the correct answer:
A: Grassland:
- Grasslands are vast areas covered with grasses and other herbaceous plants.
- They are found on every continent except Antarctica.
- Examples include the African savannah and the North American prairies.
B: Desert:
- Deserts are dry, arid regions that receive very little rainfall.
- They are characterized by extreme temperature variations and sparse vegetation.
- Examples include the Sahara Desert and the Mojave Desert.
C: Forest:
- Forests are areas with a high density of trees and other vegetation.
- They are home to a variety of plant and animal species.
- Examples include tropical rainforests, temperate forests, and boreal forests.
D: Aquarium:
- An aquarium is an enclosed habitat designed to house aquatic organisms.
- It typically contains fish, plants, and other underwater species.
- Aquaria can be found in homes, schools, and public institutions.
In conclusion, an aquarium is not a terrestrial ecosystem because it is a man-made aquatic habitat. The correct answer is D.

Food Chain Explanation:
A food chain represents the transfer of energy and nutrients from one organism to another in an ecosystem. It consists of a sequence of organisms, each serving as a source of food for the next organism. Let's analyze the options given:
Option A:
- Goat, cow, and elephant: While these organisms can coexist in an ecosystem, they do not form a food chain as they are not directly linked in terms of energy transfer from one to another.
Option B:
- Grass, goat, and human: This forms a food chain as it represents the flow of energy and nutrients. Grass is consumed by the goat, and the goat serves as food for humans.
Option C:
- Grass, fish, and goat: This does not form a food chain as there is no direct connection between grass and fish. The goat is not involved in the energy transfer between grass and fish.
Option D:
- Grass, wheat, and mango: This also does not form a food chain as there is no direct connection between grass and mango. Wheat is not involved in the energy transfer between these organisms.
Therefore, the correct answer is Option B: Grass, goat, and human, as it represents a food chain where energy and nutrients flow from grass to goat and then to humans.

Explanation:
The fourth trophic level is the level of top carnivores in a food chain or food web. These organisms are at the highest level of the trophic pyramid and feed on the organisms from the level below them. They are typically large predators that consume other carnivores or omnivores.
Key Points:
- The fourth trophic level consists of top carnivores.
- Top carnivores are the apex predators in a food chain or food web.
- They are typically large predators that feed on other carnivores or omnivores.
- Examples of top carnivores include lions, tigers, wolves, and sharks.
- Top carnivores have no natural predators and are at the top of the trophic pyramid.
Summary:
The fourth trophic level consists of top carnivores, which are apex predators that feed on other carnivores or omnivores. They occupy the highest level in the trophic pyramid and have no natural predators. Examples of top carnivores include lions, tigers, wolves, and sharks.

Flow of energy is unidirectional:
The statement "Flow of energy is unidirectional" means that energy flows in one direction only, and it does not come back to the previous levels. Let's understand this concept in detail:
Explanation:
1. Energy flow: Energy flows through various trophic levels in an ecosystem. It starts with the producers (autotrophs), which convert solar energy into chemical energy through photosynthesis.
2. Unidirectional: The flow of energy is unidirectional, meaning it moves from one trophic level to another and does not return to the previous levels. Once energy is transferred from one level to the next, it is used for various metabolic processes or lost as heat.
3. Higher trophic levels: As energy flows through the trophic levels, it is transferred from producers to primary consumers (herbivores), then to secondary consumers (carnivores), and so on. Each level feeds on the previous level, and energy is transferred along the food chain.
4. No return to lower trophic levels: Once energy is consumed by higher trophic levels, it is not returned to the lower trophic levels. The energy is used for growth, reproduction, and other metabolic activities of the organisms at each level. Some energy is also lost as heat in the process.
5. Energy loss: With each transfer of energy between trophic levels, there is a loss of energy. This loss occurs due to inefficient energy transfer, metabolic processes, and heat dissipation. As a result, the amount of energy available decreases with each level.
6. Energy input: The primary source of energy in ecosystems is the sun. The energy input from the sun is captured by autotrophs through photosynthesis and converted into chemical energy. This energy is then passed on to the rest of the food chain.
Therefore, the correct answer is option C: Energy which passes to the higher trophic levels doesn't come back to lower trophic levels.

The correct answer is option C: Dichloro diphenyl trichloroethane.
Here is a detailed explanation of the answer:
1. Understanding the question:
The question asks about the pesticide DDT and its chemical name.
2. Analyzing the options:
Let's analyze each option to determine the correct answer:
- Option A: Diphenyl dichlero trichleroethyne
- Option B: Dichlero diphenyl trichleroethyne
- Option C: Dichloro diphenyl trichloroethane
- Option D: Diphenyl dichlero trichleroethane
3. Identifying the correct option:
To determine the correct option, we need to know the chemical formula and name of DDT.
4. DDT's chemical formula and name:
DDT stands for Dichloro diphenyl trichloroethane.
- "Di" indicates the presence of two chlorine atoms.
- "Chloro" indicates a chlorine atom.
- "Diphenyl" refers to two benzene rings connected together.
- "Trichloroethane" indicates the presence of three chlorine atoms in an ethane molecule.
5. Comparing the options:
Now, let's compare the chemical name of DDT with each option:
- Option A: Diphenyl dichlero trichleroethyne - This option is incorrect because it does not match the correct chemical name of DDT.
- Option B: Dichlero diphenyl trichleroethyne - This option is incorrect because it does not match the correct chemical name of DDT.
- Option C: Dichloro diphenyl trichloroethane - This option is correct as it matches the correct chemical name of DDT.
- Option D: Diphenyl dichlero trichleroethane - This option is incorrect because it does not match the correct chemical name of DDT.
6. Conclusion:
Based on the analysis, we can conclude that the correct answer is option C: Dichloro diphenyl trichloroethane.

Greenhouse gases are:
- Gases used in house for cooking: This option is incorrect as greenhouse gases are not related to gases used for cooking in houses.
- Green in colour: This option is incorrect as the term "greenhouse" in greenhouse gases does not refer to the color, but rather to the concept of trapping heat.
- Traps solar radiations and increase temperature: This option is correct. Greenhouse gases are gases that absorb and emit infrared radiation within the thermal infrared range. They trap solar radiation in the Earth's atmosphere, which leads to an increase in temperature, known as the greenhouse effect.
- None of these: This option is incorrect as option C is the correct answer.
In summary, greenhouse gases are gases that trap solar radiation and increase the temperature of the Earth's atmosphere. They are not related to gases used for cooking in houses or their color.

Biodegradable Materials

• Paper: Paper is derived from plant fibers and is one of the most common biodegradable materials. It decomposes naturally over time when exposed to the environment.

Non-biodegradable Materials

• Plastic: Plastic is a synthetic material that is not easily broken down by natural processes. It can persist in the environment for hundreds of years.


• Polythene: Polythene, also known as polyethylene, is a type of plastic that is non-biodegradable.


• Aluminium foil: Aluminium foil is a metal material that is not biodegradable. It does not decompose naturally and can take a long time to break down.

Therefore, the only biodegradable material among the given options is paper.

Montreal Protocol Effective Date
The Montreal Protocol, an international environmental treaty designed to protect the ozone layer, became effective in 1989. The protocol was adopted on September 16, 1987, and entered into force on January 1, 1989. It has since been ratified by almost all countries around the world.
Details:
Here are some key points about the effective date of the Montreal Protocol:

Adoption: The Montreal Protocol was adopted on September 16, 1987, during a conference held in Montreal, Canada.

Effective Date: The protocol became effective on January 1, 1989, marking the official start of its implementation.

Objective: The primary objective of the Montreal Protocol is to phase out the production and use of substances that deplete the ozone layer, such as chlorofluorocarbons (CFCs) and halons.

Success: The Montreal Protocol is considered one of the most successful international environmental agreements. It has led to a significant reduction in the production and consumption of ozone-depleting substances globally.

Amendments: Over the years, the protocol has been amended several times to strengthen its provisions and address emerging ozone-depleting substances. These amendments include the London Amendment (1990), Copenhagen Amendment (1992), and Beijing Amendment (1999).

The Montreal Protocol serves as a crucial framework for international cooperation in protecting the ozone layer and has played a significant role in preventing further depletion.

Effects of Ozone Depletion:
There are several effects of ozone depletion on Earth's environment and climate. These include:
1. Increased Ultraviolet (UV) Radiation:
- Ozone depletion leads to an increase in the amount of UV radiation reaching the Earth's surface.
- This is because ozone molecules in the stratosphere absorb and block a significant portion of the UV radiation from the sun.
- With the depletion of ozone, more UV radiation penetrates the atmosphere, leading to potential harmful effects on human health and ecosystems.
2. Negative Health Effects:
- Increased UV radiation can have detrimental effects on human health, such as an increased risk of skin cancer, cataracts, and weakened immune system.
- UV radiation can also damage marine life, including coral reefs, phytoplankton, and other aquatic organisms.
3. Impact on Ecosystems:
- Ozone depletion can have severe consequences for ecosystems and biodiversity.
- UV radiation can inhibit photosynthesis and reduce plant growth, affecting the entire food chain.
- It can also harm plankton, which are vital for marine ecosystems and serve as a primary food source for many marine organisms.
4. Climate Change:
- While ozone depletion itself does not directly cause global warming, it can indirectly contribute to climate change.
- Ozone depletion affects atmospheric circulation patterns, leading to changes in wind patterns, temperature distribution, and precipitation.
- These changes in climate patterns can have subsequent impacts on weather systems and regional climates.
In conclusion, ozone depletion primarily results in an increase in UV radiation reaching the Earth's surface, which has negative consequences for human health, ecosystems, and climate.

Micro-organisms belong to the group of decomposers.

• Micro-organisms are small, single-celled organisms that are not visible to the naked eye.


• They play a crucial role in the ecosystem by breaking down organic matter and recycling nutrients.


• Decomposers, such as bacteria and fungi, are responsible for the process of decomposition.


• Decomposition is the breakdown of dead plants and animals into simpler substances, which can then be used by other organisms.


• Micro-organisms secrete enzymes that help in the breakdown of complex organic molecules into simpler compounds.


• They obtain their energy by breaking down organic matter.


• Micro-organisms are found in various environments, such as soil, water, and even inside the bodies of other organisms.


• They are essential for the nutrient cycling in ecosystems and help in maintaining the balance of nature.


• Examples of micro-organisms that act as decomposers include bacteria, fungi, and certain types of protozoa.

In conclusion, micro-organisms are a group of decomposers that play a vital role in the ecosystem by breaking down organic matter and recycling nutrients. They are found in various environments and are essential for maintaining the balance of nature.

Function of an ecosystem involves:
The function of an ecosystem is a complex process that involves various components working together to sustain life. The main functions of an ecosystem include:
1. Energy flow:
- Ecosystems are powered by the flow of energy through food chains and food webs.
- Producers (plants) convert sunlight into chemical energy through photosynthesis.
- Consumers obtain energy by consuming other organisms.
- Decomposers break down organic matter and release energy.
2. Nutrient movement:
- Nutrients are essential for the growth and development of organisms in an ecosystem.
- Nutrients are cycled through biogeochemical cycles, such as the carbon, nitrogen, and phosphorus cycles.
- Producers take up nutrients from the environment and incorporate them into their tissues.
- Consumers obtain nutrients by consuming other organisms.
- Decomposers break down organic matter and release nutrients back into the environment.
3. Interactions and relationships:
- Ecosystems are composed of numerous species that interact with each other.
- Predation, competition, symbiosis, and mutualism are common interactions in an ecosystem.
- These interactions help maintain the balance and stability of the ecosystem.
4. Ecological services:
- Ecosystems provide numerous benefits to humans and other organisms.
- They regulate climate, purify air and water, and provide habitats for various species.
- Ecosystems also provide resources such as food, timber, and medicines.
5. Biodiversity conservation:
- Ecosystems support a wide range of species, each with its own role and contribution.
- Conserving ecosystems is crucial for maintaining biodiversity and preventing species extinction.
In conclusion, the function of an ecosystem involves energy flow, nutrient movement, interactions and relationships, ecological services, and biodiversity conservation. These functions are interconnected and essential for the sustainability of life on Earth.

The driving force of an ecosystem is solar energy.
Solar energy plays a critical role in sustaining life on Earth and is the primary driving force behind all ecosystems. Here's a detailed explanation:
1. Solar energy:
- The sun is the ultimate source of energy for all living organisms on Earth.
- Sunlight is composed of electromagnetic radiation, and it provides the energy required for photosynthesis, a process used by plants and other organisms to convert sunlight, water, and carbon dioxide into glucose (a carbohydrate) and oxygen.
- Solar energy is responsible for the production of food and the transfer of energy through various trophic levels in the ecosystem.
2. Producers:
- Producers, such as plants and algae, are organisms that convert solar energy into chemical energy through photosynthesis.
- They capture sunlight and convert it into glucose, which serves as a source of energy for themselves and other organisms in the ecosystem.
- Producers are the foundation of the food chain and provide energy for herbivores and ultimately for carnivores and decomposers.
3. Biomass:
- Biomass refers to the total mass of living organisms present in a particular area or ecosystem.
- Solar energy, through photosynthesis, drives the production of biomass in the form of plants, algae, and other photosynthetic organisms.
- Biomass serves as a source of energy and nutrients for other organisms in the ecosystem.
4. Carbohydrates in plants:
- Carbohydrates, such as glucose produced during photosynthesis, are essential for the growth and development of plants.
- They store energy and serve as a source of carbon compounds for other organisms.
- Carbohydrates are vital for the functioning of ecosystems, but they are ultimately derived from solar energy through the process of photosynthesis.
In conclusion, solar energy is the driving force of an ecosystem as it provides the energy required for photosynthesis, which drives the production of food and biomass. This energy flow through the ecosystem supports the growth, reproduction, and survival of all organisms within it.

Food Chain: Starting Point
The correct answer to the question is B: Photosynthesis. A food chain always starts with photosynthesis. Here is a detailed explanation of why photosynthesis is the starting point of a food chain:
1. What is Photosynthesis?
Photosynthesis is the process by which green plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose and oxygen. It takes place in the chloroplasts of plant cells.
2. Role of Photosynthesis in the Food Chain:
Photosynthesis is the primary source of energy for all living organisms on Earth. It is responsible for the production of organic compounds, primarily glucose, which serves as food for the entire food chain.
3. Producers:
Green plants, also known as producers, are the first trophic level in a food chain. They use photosynthesis to convert sunlight energy into chemical energy (glucose). They are self-sustaining and do not depend on other organisms for their energy.
4. Herbivores:
Herbivores are the primary consumers in a food chain. They consume plants, utilizing the energy stored in the glucose produced through photosynthesis. Examples of herbivores include cows, rabbits, and deer.
5. Carnivores and Omnivores:
Carnivores and omnivores are the secondary and tertiary consumers in a food chain. They obtain energy by consuming herbivores or other carnivores. Carnivores solely depend on the consumption of other organisms for their energy needs.
6. Decomposers:
Decomposers, such as bacteria and fungi, play a crucial role in the food chain. They break down the remains of dead organisms, including plants and animals, releasing nutrients back into the ecosystem. These nutrients are then used by plants for photosynthesis, completing the cycle.
In conclusion, photosynthesis is the starting point of a food chain. It provides the energy needed for the growth and survival of all living organisms in an ecosystem. Without photosynthesis, the food chain would cease to exist, and life on Earth would not be sustainable.

According to the 10% law, the energy available to each successive level is 10% of the previous level.

Explanation:

• The 10% law: The 10% law is a principle in ecology that states that only 10% of the energy available at one trophic level is transferred to the next trophic level.


• Trophic levels: In an ecosystem, organisms are organized into trophic levels, which represent the different levels of the food chain. The first trophic level consists of producers (plants), followed by primary consumers, secondary consumers, and so on.


• Energy transfer: As energy flows through the food chain, it is transferred from one trophic level to another. However, not all the energy is transferred. According to the 10% law, only 10% of the energy is passed on to the next trophic level.


• Example: To illustrate the 10% law, let's consider a simple food chain. Suppose there are 1000 units of energy available at the producer level (plants). According to the 10% law:




• Only 10% (100 units) of the energy will be available to the primary consumers (herbivores) at the next trophic level.


• Then, only 10% (10 units) of the energy will be available to the secondary consumers (carnivores) at the next trophic level.


• Finally, only 10% (1 unit) of the energy will be available to the tertiary consumers (top carnivores) at the highest trophic level.

Therefore, the correct answer is A: 10%.

The formula of Ozone is O₃.
Explanation:
- Ozone is a molecule composed of three oxygen atoms.
- The chemical symbol for oxygen is "O".
- The subscript "3" indicates that there are three oxygen atoms in the molecule.
- Therefore, the formula of ozone is O₃.
- It is important to note that ozone is different from molecular oxygen (O₂), which consists of only two oxygen atoms bonded together.

The decomposers in an ecosystem play a crucial role in breaking down organic material and recycling nutrients. They are responsible for the decomposition process, which converts complex organic compounds into simpler inorganic forms that can be utilized by other organisms. Here is a detailed explanation of the role of decomposers in an ecosystem:
1. Convert organic material to inorganic forms:
- Decomposers such as bacteria, fungi, and certain types of insects break down dead plants, animals, and other organic matter.
- They release enzymes that break down complex organic compounds, such as proteins and carbohydrates, into simpler forms.
- This process releases inorganic nutrients, such as nitrogen, phosphorus, and carbon, back into the soil or water.
2. Release nutrients for use by other organisms:
- Decomposers play a crucial role in nutrient cycling by releasing essential elements from organic matter.
- These nutrients are then available for uptake by plants, which form the base of the food chain.
- In this way, decomposers help to maintain the overall balance and productivity of the ecosystem.
3. Improve soil fertility:
- Decomposers contribute to the formation of humus, a dark, organic-rich substance that improves soil fertility.
- As decomposers break down organic matter, they release nutrients that are absorbed by plants, promoting their growth.
- The organic matter also improves the soil's ability to retain water, nutrients, and support a diverse range of plant life.
4. Enhance ecosystem resilience:
- Decomposers play a vital role in recycling nutrients and breaking down dead organisms.
- This helps to prevent the accumulation of organic waste, which could lead to the release of harmful substances or the spread of diseases.
- By efficiently decomposing organic matter, decomposers contribute to the overall health and resilience of the ecosystem.
In conclusion, decomposers in an ecosystem are responsible for converting organic material into inorganic forms, releasing nutrients for use by other organisms, improving soil fertility, and enhancing the overall resilience of the ecosystem. Their role is essential in maintaining the balance and sustainability of the ecosystem.

Only 10% of the energy present is given to the consumer at the next level, of the total energy the level/animal has.
Therefore, if 4th Level = 5kJ
3rd Level = 50kJ
2nd Level = 500kJ
Producer = 5,000kJ

To determine which group contains only non-biodegradable items, we need to analyze each group of materials and identify the non-biodegradable items present in each group.
Group A:
- Polythene: Non-biodegradable
- Detergent: Non-biodegradable
- PVC: Non-biodegradable
Group B:
- Plastic: Non-biodegradable
- Bakelite: Non-biodegradable
- Leaf: Biodegradable
Group C:
- Plastic: Non-biodegradable
- Detergent: Non-biodegradable
- Grass: Biodegradable
Group D:
- Wood: Biodegradable
- Paper: Biodegradable
- Leather: Biodegradable
From the analysis, we can see that only Group A (Polythene, detergent, PVC) contains only non-biodegradable items. The other groups have at least one biodegradable item present.
Therefore, the correct answer is Group A.

Examples of man-made ecosystems are orchards, home aquarium, zoo, botanical gardens and park. These ecosystems are sustained by human interventions. Aquarium and zoo ecosystem, for example, cannot survive without the care of humans. Man-made ecosystems are created for specific purposes.

A food chain is a series of plants/animals which are interrelated in the form of an organism being eaten as food by the other. A food chain consists of producers and consumers. In the given food chain, plants are producers. The animals eating plants are called primary consumers and animals eating primary consumers are called secondary consumers. 

Thus, the correct answer is 'Producers and consumers.'

The food chain is a sequence of populations or organisms through which food and energy are passed on an ecosystem with the members of each trophic levels. A food chain shows who is eating whom. Here, organisms of higher trophic level derive its nutrients from organisms of a lower trophic level.