Olympiad Test : Ecosystem - 2 - Class 5 MCQ

Biological factors, also known as biotic factors, are living components of an ecosystem. They can include all living organisms, such as plants, animals, fungi, and microorganisms, and their interactions with each other and their environment. Biotic factors play a crucial role in shaping and maintaining the balance of an ecosystem. Answer: D: Saprophyte. A saprophyte is an organism that obtains nutrients by decomposing dead organic matter. It is a biotic factor because it is a living organism that interacts with its environment by breaking down and recycling organic material.

The number of links in a food chain
The number of links in a food chain refers to the number of organisms or species that are connected in a linear sequence, representing the transfer of energy and nutrients from one organism to another. Let's discuss the options given:
A: 0
- This is incorrect because a food chain must involve at least two organisms - a producer and a consumer.
B: 1
- This is incorrect because a food chain typically consists of multiple organisms or species.
C: 2
- This is incorrect because a food chain usually involves more than just two organisms. It generally consists of a producer, primary consumer, secondary consumer, and so on.
D: >2
- This is the correct answer. A food chain typically consists of multiple organisms or species, creating a series of links. The number of links can vary depending on the complexity of the ecosystem and the number of trophic levels present. In a simple food chain, there may be only a few links, while in a complex food web, there can be numerous links.
To summarize, the number of links in a food chain is generally greater than 2, as it involves multiple organisms or species in a linear sequence of energy and nutrient transfer.

The species that is threatened with extinction is called the "Endangered species." Here is a detailed explanation:
Definition of Endangered Species:
An endangered species refers to a population of organisms that is at risk of becoming extinct due to various factors such as habitat loss, environmental changes, pollution, overhunting, and climate change.

In an aqueous environment microscopic animals and plants are collectively known as planktons which are microscopic organisms. Producer planktons are called as phytoplanktons e.g., diatoms, dinoflagellates, algae etc., Consumer planktons are called as zooplanktons e.g., Protozoans, larvae of animals.

Biodegradable Waste:
Biodegradable waste refers to any waste material that can be broken down naturally by bacteria, fungi, or other living organisms. These waste materials can be decomposed and recycled into organic matter, contributing to the natural nutrient cycle. All of the following are examples of biodegradable waste:
1. Animal Excreta:
Animal waste, including feces and urine, is biodegradable. When properly managed, it can be used as a fertilizer or processed into biogas through anaerobic digestion.
2. Vegetable Scrap:
Vegetable scraps, such as leftover peels, leaves, and stems, are biodegradable. They can be composted to produce nutrient-rich soil or used as feedstock for biogas production.
3. Paper:
Paper is a biodegradable waste material that can be easily broken down by microorganisms. It can be recycled or composted to reduce environmental impact.
Therefore, the correct answer is Option D: All of the above. Animal excreta, vegetable scrap, and paper are all examples of biodegradable waste that can be decomposed naturally. Proper disposal and recycling of biodegradable waste help minimize pollution and promote sustainable waste management practices.

Greenhouse effect causes:
A: Melting of ice caps
- The greenhouse effect is responsible for the warming of the Earth's surface and atmosphere.
- As a result, the ice caps and glaciers in polar regions are melting at an accelerated rate.
- This leads to a decrease in the overall volume of ice, which contributes to rising sea levels.
B: Rise in the sea level
- The melting of ice caps and glaciers causes an increase in the volume of water in the oceans.
- This, combined with the expansion of seawater due to warming, leads to a rise in sea levels.
- Rising sea levels can result in coastal erosion, increased flooding, and the loss of coastal habitats.
C: Submerging of low lying areas
- Low-lying areas, such as coastal regions and islands, are particularly vulnerable to the impacts of rising sea levels.
- As sea levels rise, these areas become more prone to submersion and flooding.
- This can result in the displacement of communities, loss of infrastructure, and damage to ecosystems.
D: All of the above
- The greenhouse effect is responsible for all the mentioned consequences, including the melting of ice caps, rise in sea levels, and submerging of low-lying areas.
- These effects have significant implications for the environment, climate patterns, and human populations.
In conclusion, the greenhouse effect has multiple causes, which include the melting of ice caps, rise in sea levels, and submerging of low-lying areas. These consequences are interconnected and have far-reaching impacts on our planet. It is crucial to address and mitigate the greenhouse effect to minimize its detrimental effects on the environment and society.

An ecosystem is a community of living organisms (biotic factors) interacting with their physical environment (abiotic factors). Here are some key points to understand about ecosystems:

Producers:

• Producers, such as plants and algae, are the organisms that can convert sunlight energy into chemical energy through photosynthesis.


• They are the foundation of the food chain, as they provide energy and nutrients for other organisms.


• Producers are usually the most abundant organisms in an ecosystem.

Species:
- The sum total of the populations of the same kind of organisms constitute a species.
- A species is a fundamental unit of biological classification.
- It refers to a group of organisms that can interbreed and produce fertile offspring.
- The population of a species consists of all the individuals of that species living in a particular area or habitat.
Colony:
- A colony refers to a group of organisms, usually of the same species, living together in a close association.
- It typically involves a division of labor and cooperation among the individuals in the colony.
- Examples of colonies include ant colonies, bee colonies, and some species of bacteria.
Genus:
- A genus is a taxonomic rank used in biological classification.
- It represents a group of species that are closely related and share common characteristics.
- Several species can belong to the same genus.
Community:
- A community refers to the assemblage of populations of different species living together in a particular area or habitat.
- It includes all the interacting populations of organisms within that area.
- A community can consist of various species, each with its own population.
Conclusion:
- The correct answer is C: Species. The sum total of the populations of the same kind of organisms constitutes a species.

Answer:
Nutrient
- A nutrient is any chemical substance that an organism requires to live.
- It is an essential component of an organism's diet.
- Nutrients provide energy, support growth and development, and maintain overall health.
- They are required in varying quantities and play different roles in the body.
- Nutrients include carbohydrates, proteins, fats, vitamins, minerals, and water.
- Carbohydrates, proteins, and fats are macronutrients, which are required in larger amounts.
- Vitamins and minerals are micronutrients, which are required in smaller amounts.
- Water is a vital nutrient that is necessary for many bodily functions.
- Nutrients are obtained through the consumption of food and beverages.
- They are broken down and utilized by the body to support various physiological processes.
- A balanced diet that includes a variety of nutrient-rich foods is essential for overall health and well-being.

Explanation:
The sum total of the variety of organisms in the biosphere is called biodiversity. Biodiversity refers to the existence of a wide range of living organisms, including plants, animals, fungi, and microorganisms, in a particular habitat or ecosystem. It encompasses the diversity of species, genetic diversity within species, and the diversity of ecosystems.
Importance of Biodiversity:
Biodiversity is crucial for the functioning and stability of ecosystems. It provides various benefits, including:
1. Ecosystem Services: Biodiversity supports numerous ecosystem services, such as air and water purification, soil fertility, pollination, and climate regulation.
2. Food Security: Biodiversity is essential for maintaining agricultural productivity, as different species of plants and animals contribute to diverse food sources.
3. Medicine and Biotechnology: Many pharmaceutical drugs and medicinal compounds are derived from biodiversity. It has immense potential for future discoveries in medicine and biotechnology.
4. Ecological Balance: Biodiversity helps maintain the balance between different species and their interactions within an ecosystem, ensuring its stability and resilience.
5. Aesthetic and Cultural Value: Biodiversity provides aesthetic and cultural value, as it contributes to the beauty and uniqueness of natural landscapes and plays a significant role in cultural practices and traditions.
6. Economic Value: Biodiversity supports various economic sectors such as tourism, fisheries, forestry, and agriculture, contributing to livelihoods and economic development.
Conclusion:
Biodiversity is a fundamental aspect of the biosphere, encompassing the variety of organisms and their interactions within ecosystems. It is crucial for the functioning and sustainability of our planet, providing essential ecosystem services, food security, medicines, and cultural value. Protecting and conserving biodiversity is crucial for maintaining the balance of life on Earth and ensuring a sustainable future for generations to come.

The total amount of living tissue within a given trophic level is known as biomass.
Explanation:
- Biomass refers to the total mass of living organisms within a specific trophic level in an ecosystem.
- It represents the collective weight of all the living organisms, including plants, animals, and microorganisms, within a particular trophic level.
- Biomass is usually measured in terms of dry weight or carbon content and is typically expressed in units such as grams per square meter or kilograms per hectare.
- It provides an indication of the amount of energy and nutrients available within a trophic level and is an important factor in understanding the structure and dynamics of ecosystems.
- Biomass can vary significantly between different trophic levels, with higher trophic levels generally having lower biomass due to the energy loss and inefficiencies in transferring energy from one trophic level to the next.
- Understanding the biomass distribution within an ecosystem is crucial for studying ecological processes, such as energy flow, nutrient cycling, and population dynamics.

Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition. Detritivores (e.g., earthworm) break down detritus into smaller particles , a process called fragmentation. This process is a very important step in the decomposition cycle enhancing the process of decomposition. Hence, they are included in the category of decomposers alongwith other bacteria and fungi.

Biodiversity is described as:

• The range of different species in an environment: Biodiversity refers to the variety of different species present in a particular environment. It includes all living organisms such as plants, animals, fungi, and microorganisms.


• The seasonal and daily changes in an environment: This statement is incorrect. Biodiversity is not related to the seasonal or daily changes in an environment, but rather focuses on the variety of species.


• The way species differ from one another: While species do differ from one another, this statement does not fully capture the concept of biodiversity. Biodiversity encompasses not only the differences between species but also the overall variety and abundance of species.


• The influence of physical factors on an environment: This statement is also incorrect. Biodiversity is primarily concerned with the variety of species and their interactions, rather than the influence of physical factors on the environment.

Therefore, the correct answer is A: The range of different species in an environment. Biodiversity is a measure of the variety and abundance of different species in a given area, and it is an important aspect of ecological health and stability.

Correct Food Chain:

The correct food chain out of the given options is:

• Grass → Cow → Man

Explanation:

A food chain represents the flow of energy and nutrients from one organism to another within an ecosystem. In a food chain, each organism serves as a source of food for the next organism in the chain.

The correct food chain in this case is:

• Grass → Cow → Man

Here is the breakdown of the food chain:

• Grass: Grass is a producer that converts sunlight into energy through photosynthesis.


• Cow: The cow is a primary consumer that feeds on grass.


• Man: The man is a secondary consumer that consumes the cow for food.

This food chain represents a natural flow of energy and nutrients, where the grass is eaten by the cow, and the cow is consumed by the man. This sequence shows how energy is transferred from one organism to another.

It is important to note that food chains can be more complex in nature, with multiple organisms involved. However, in the given options, the correct food chain is Grass → Cow → Man.

The pyramid of biomass represents the total mass of living organisms at each trophic level in an ecosystem. It provides a visual representation of the amount of living material or biomass present at each level of a food chain or food web. Here is a detailed explanation of what the pyramid of biomass represents:
The concept of biomass:
- Biomass refers to the total mass of living organisms in a given area or ecosystem.
- It includes the mass of living organisms like plants, animals, and microorganisms.
Understanding the pyramid of biomass:
- The pyramid of biomass is a graphical representation of the biomass present at different trophic levels in an ecosystem.
- It is constructed by arranging the organisms from different trophic levels in decreasing order of their biomass.
- Each level of the pyramid represents a different trophic level, starting from the primary producers at the bottom and moving up to the top-level consumers.
Interpreting the pyramid of biomass:
- The width of each level of the pyramid represents the amount of biomass or total mass of organisms present at that trophic level.
- The wider the level, the greater the biomass at that trophic level.
- Generally, the pyramid of biomass becomes narrower at higher trophic levels, indicating a decrease in biomass as we move up the food chain.
Significance of the pyramid of biomass:
- It helps in understanding the energy flow and transfer between different trophic levels in an ecosystem.
- It highlights the relationship between producers, consumers, and decomposers in terms of biomass and energy.
- It shows the relative importance of different trophic levels in terms of biomass and the overall structure of the food web.
In conclusion, the pyramid of biomass represents the total mass of living organisms at each trophic level in an ecosystem. It provides valuable insights into the energy flow and structure of food webs, helping us understand the dynamics of ecosystems.

Bacteria and Fungi as Decomposers

1. Introduction: Bacteria and fungi play a crucial role in ecosystems as decomposers.


2. Decomposition: Decomposition is the breakdown of organic matter into simpler compounds, which are then recycled back into the environment.


3. Process: Bacteria and fungi decompose dead plants, animals, and other organic materials through the following process:




• Enzyme Production: Bacteria and fungi produce enzymes that break down complex organic compounds into simpler forms.


• Feeding: They absorb the simpler compounds released by the enzymes as a food source.




4. Importance of Decomposition: Decomposition is vital for several reasons:




• Nutrient Recycling: Bacteria and fungi break down organic matter and release nutrients, such as nitrogen, phosphorus, and carbon, back into the soil. These nutrients are then available for plants and other organisms.


• Waste Removal: Decomposers help remove dead organisms and waste materials, preventing the accumulation of organic matter in the environment.


• Ecosystem Balance: By breaking down dead matter, decomposers help maintain a balance in the ecosystem and prevent the spread of diseases.




5. Examples: Examples of decomposers include:




• Bacteria: Bacteria like Bacillus and Clostridium are involved in the decomposition of organic matter.


• Fungi: Fungi such as mushrooms and molds play a key role in decomposition.

Therefore, the correct answer is D: Decomposers.

The relationship between a human and a tapeworm is parasitism.
- Definition of parasitism: Parasitism is a type of symbiotic relationship in which one organism, known as the parasite, benefits at the expense of the other organism, known as the host. The parasite typically lives in or on the host, obtaining nutrients and shelter while causing harm or damage to the host.
Explanation:
- Human as the host: In this relationship, the human serves as the host for the tapeworm.
- Tapeworm as the parasite: The tapeworm is a parasitic organism that lives in the intestines of its host, the human.
- Tapeworm benefits: The tapeworm benefits from the nutrients and shelter provided by the human host.
- Human harm: The tapeworm can cause various health problems in the human, including digestive issues and nutrient deficiencies.
- Asymmetrical relationship: The relationship between the human and the tapeworm is asymmetrical because the tapeworm benefits while the human is harmed.
- Dependence: The tapeworm is dependent on the human host for its survival and reproduction.
Conclusion:
The relationship between a human and a tapeworm is an example of parasitism, as the tapeworm benefits at the expense of the human host.

The arrows in a food chain represent:
The correct answer is D: The movement of energy through different organisms.
Explanation:
Food chains are a way of representing the flow of energy in an ecosystem. They show how energy is transferred from one organism to another as they consume and are consumed by other organisms. The arrows in a food chain indicate the direction of energy flow, specifically:
- From the prey to the predator: The arrows point from the organism being eaten (prey) to the organism that consumes it (predator). This represents the transfer of energy from one organism to another.
- Energy transfer: As each organism consumes another, energy is transferred from the consumed organism to the consumer. The arrows illustrate this movement of energy through different organisms in the food chain.
- Energy loss: Energy is not transferred in its entirety from one organism to another. With each transfer, some energy is lost as heat or used for the organism's own metabolic processes. The arrows help to represent this energy loss as the food chain progresses.
- Energy pyramid: The arrows also contribute to the construction of an energy pyramid, which represents the decreasing amount of energy available at each trophic level. The length of the arrows in a food chain can reflect the amount of energy being transferred.
In conclusion, the arrows in a food chain represent the movement of energy through different organisms, showing the flow of energy from prey to predator and illustrating the transfer and loss of energy as the food chain progresses.

Explanation:

A fish tank is considered an ecosystem because it includes both a living community and a physical environment. Here's a breakdown of why each option is correct:

A: The living community
- A fish tank typically contains various living organisms such as fish, plants, and microorganisms.
- These organisms interact with each other, forming a complex web of relationships within the tank.
B: A physical environment
- A fish tank provides a physical space for the living organisms to inhabit.
- It includes elements such as water, substrate, rocks, and decorations that create a suitable habitat for the organisms.
C: The living community as well as a physical environment
- As mentioned above, a fish tank encompasses both the living organisms and the physical components of the tank.
- The organisms rely on the physical environment to meet their basic needs, such as food, shelter, and oxygen.
Therefore, the correct answer is option C: the fish tank is an ecosystem because it includes both a living community and a physical environment.

Detrivores feed on the waste material in an ecosystem including animal remains, animal faeces, and plant debris. They play an important role in the ecosystem by breaking down organic matter and recycling nutrients back into the environment. Here is a detailed explanation of why detrivores are the correct answer:
Definition of detrivores:
- Detrivores are organisms that obtain their energy by consuming dead organic material.
- They are commonly found in soil, water, and other habitats where organic matter accumulates.
Functions of detrivores:
- Detrivores help in the decomposition process by breaking down complex organic compounds into simpler forms.
- They play a crucial role in nutrient cycling by releasing nutrients back into the ecosystem.
- By feeding on dead organic matter, detrivores help to prevent the accumulation of waste material in the environment.
Examples of detrivores:
- Earthworms: They consume dead plant material and enhance soil fertility through their burrowing activities.
- Dung beetles: They feed on animal faeces, helping to break it down and recycle nutrients.
- Woodlice: They consume decaying plant material and contribute to the breakdown of dead wood.
Difference between detrivores and decomposers:
- Detrivores are organisms that directly consume dead organic matter, while decomposers are mainly microorganisms (such as bacteria and fungi) that break down organic matter.
- Decomposers work on a microscopic level by secreting enzymes to break down complex organic compounds, while detrivores physically consume the organic matter.
Therefore, the correct answer is option B: Detrivores.