Olympiad Test : Ecosystem - 2 - Class 5 MCQ

Biotic factors refer to the living components of an ecosystem, including organisms like plants, animals, fungi, and microorganisms. A saprophyte is an organism (such as fungi or certain bacteria) that decomposes dead organic matter, which classifies it as a biotic factor.

• Light, air, and soil are abiotic factors, as they are non-living components of the environment.
• A saprophyte interacts with its environment by breaking down and recycling organic material, thus being a living, biotic factor.

Therefore, the correct answer is D: Saprophyte.

A food chain typically consists of multiple trophic levels, each representing a different group of organisms involved in energy transfer (producers, primary consumers, secondary consumers, etc.). The number of links in a food chain usually exceeds 2, as it includes at least a producer and several consumers, making it greater than 2.

Thus, the correct answer is D: >2.

An endangered species is a species that is at risk of extinction due to a rapid decline in its population or habitat. These species are threatened by various factors like habitat loss, poaching, and environmental changes.

Thus, the correct answer is A: Endangered species.

Zooplankton are tiny aquatic animals that are found in both freshwater and marine environments. They drift with the water currents and are an important part of the food chain, serving as a food source for larger animals like fish. Zooplankton feed on microscopic plants called phytoplankton and can be herbivores, carnivores, or omnivores.

Biodegradable waste refers to materials that can be broken down by natural processes, such as the action of bacteria and fungi. Animal excreta, vegetable scraps, and paper are all examples of biodegradable waste because they decompose over time without causing long-term harm to the environment. Proper disposal of these materials helps reduce pollution and promotes recycling.

The greenhouse effect leads to global warming, which causes several environmental changes. It results in the melting of ice caps, which contributes to the rise in sea levels. As sea levels rise, low-lying areas are at risk of being submerged. These impacts of the greenhouse effect are a significant concern for the planet's future, highlighting the importance of reducing greenhouse gas emissions.

In an ecosystem, producers (plants, algae, etc.) form the base of the food chain and are more abundant than primary consumers (herbivores). Producers convert solar energy into chemical energy through photosynthesis, providing energy to primary consumers, who in turn support secondary consumers. This pyramid-like structure shows that the number of producers is typically higher than primary consumers.

The sum total of the populations of the same kind of organisms is referred to as a species. A species is a group of organisms that are capable of interbreeding and producing fertile offspring. All individuals within a species share similar characteristics and can reproduce with one another. For example, all lions are part of the species Panthera leo.

A nutrient is any chemical substance that an organism needs for survival. It helps in growth, energy production, and maintaining body functions. Nutrients include substances like carbohydrates, proteins, fats, vitamins, and minerals, which are essential for life. These substances can be obtained from food or the environment, and their availability influences the health of organisms.

The sum total of the variety of organisms in the biosphere is called biodiversity. It refers to the variety and variability of life forms, including plants, animals, and microorganisms, in a given area or on Earth as a whole. Biodiversity is crucial for ecosystem stability, resilience, and the functioning of ecological processes.

The total amount of living tissue within a given trophic level is known as biomass. Biomass refers to the mass of living organisms, such as plants, animals, and microorganisms, in a specific area or ecosystem at a given time. It is an important measure of energy available at different trophic levels in a food chain.

The term ‘detritivore’ refers to organisms that consume dead organic matter, such as decomposing plant and animal material. These organisms, like earthworms, fungi, and some insects, help in breaking down the remains of dead organisms into simpler substances, aiding in the recycling of nutrients within ecosystems. Therefore, detritivores are considered decomposers.

Biodiversity refers to the variety and variability of life forms within a given environment. It encompasses the different species of plants, animals, fungi, and microorganisms, and the ecosystems they form. This diversity is critical for the functioning of ecosystems and the well-being of life on Earth. Thus, option A—the range of different species in an environment—correctly describes biodiversity.

A correct food chain represents the flow of energy from one organism to another. In this case, Grass → Cow → Man is a correct food chain. Grass is eaten by the cow (herbivore), and the cow is consumed by humans (omnivore). The other options do not represent the natural flow of energy in an ecosystem.

A pyramid of biomass illustrates the total mass of living organisms at each trophic level in an ecosystem. It helps show how much biological material exists at each level, starting with producers at the base and moving upwards through consumers. This pyramid typically narrows as you go higher, indicating that biomass decreases as energy is transferred through the food chain. It provides insights into energy flow and ecosystem efficiency.

Bacteria and fungi are essential decomposers in ecosystems. They break down dead plants and animals into simpler substances, returning vital nutrients to the soil. This process helps recycle matter and ensures the continuity of nutrient cycles. Without decomposers, ecosystems would accumulate dead matter and lose vital nutrients.

The relationship between a human and a tapeworm is parasitism, where the tapeworm benefits by living inside the human's intestines and absorbing nutrients, while the human is harmed by the presence of the parasite. This can lead to various health problems for the human host, such as malnutrition and digestive issues. Parasitism is a type of symbiotic relationship where one organism benefits at the expense of the other.

The arrows in a food chain represent the movement of energy through different organisms. They indicate the direction in which energy is transferred as one organism consumes another. For example, when a herbivore eats a plant, the energy from the plant is transferred to the herbivore. The flow of energy in a food chain always moves from producers (plants) to consumers (herbivores, carnivores).

A fish tank is considered an ecosystem because it includes both the living community (fish, plants, bacteria, etc.) and a physical environment (water, rocks, light, temperature, etc.). Both biotic (living) and abiotic (non-living) factors work together to form the ecosystem, allowing interactions and energy flow within the system.

Detrivores feed on dead organic matter, including animal remains, animal faeces, and plant debris. They help in breaking down this material into smaller pieces, aiding in the recycling of nutrients in the ecosystem. Decomposers, on the other hand, are microorganisms like bacteria and fungi that further break down this material at the microscopic level.