Welcome to Environment and Ecology Quiz – Test 2: Basics, a free online test designed to help you to understanding the important environmental concepts. This quiz covers fundamental areas of Environment and Ecology and is useful for learners preparing for TNPSC examinations and other competitive exams where General Science and environmental topics are included. Take the test to check your knowledge, identify areas that need more revision, and improve your confidence step by step. Read each question carefully, choose the most appropriate answer, and use the explanations after the test for effective revision and TNPSC preparation.
Note: Complete the test first, then use the detailed explanations below to review each question and strengthen your TNPSC preparation.
Environment and Ecology Test 2 (Basics) – Important Details & Quick Revision
This section explains the key concepts covered in the Environment and Ecology Test 2: Basics, including ecosystems, biotic and abiotic components, trophic levels, habitats, niches, decomposers, and ecological interactions. Reviewing these explanations will help strengthen your basics and support effective TNPSC preparation.
1. Which of the following best describes the term environment?
Answer: C. The surroundings and conditions that influence living organisms
Explanation:
The environment includes the surroundings and conditions that influence living organisms. It consists of both biotic factors, such as plants, animals, and microorganisms, and abiotic factors, such as air, water, soil, temperature, and sunlight. Therefore, the surroundings and conditions that influence living organisms best describe the term environment.
Why the other options are incorrect:
- A. The physical surroundings alone: The environment includes living as well as non-living factors.
- B. The living organisms alone: Living organisms are only the biotic part of the environment.
- D. The natural resources available to humans: Natural resources are only one part of the broader environment.
2. Which of the following is a biotic component of an ecosystem?
Answer: B. Bacteria
Explanation:
Bacteria are living organisms and therefore form part of the biotic components of an ecosystem. Biotic components include all living organisms such as plants, animals, fungi, and microorganisms.
Why the other options are incorrect:
- A. Soil: It is generally considered an abiotic component.
- C. Temperature: It is a non-living abiotic factor.
- D. Water: Water is a non-living abiotic factor.
3. Which term refers to the study of relationships between organisms and their environment?
Answer: A. Ecology
Explanation:
Ecology is the branch of biology that studies the relationships and interactions between organisms and their environment. It includes interactions among organisms and between organisms and their physical surroundings.
Why the other options are incorrect:
- B. Taxonomy: It deals with the identification, naming, and classification of organisms.
- C. Genetics: It deals with heredity and variation.
- D. Physiology: It deals with the functions and activities of living organisms.
4. Which of the following represents an abiotic factor of an ecosystem?
Answer: D. Sunlight
Explanation:
Sunlight is a non-living physical factor of an ecosystem and is therefore an abiotic component. It provides the energy required by producers for photosynthesis and influences various ecological processes.
Why the other options are incorrect:
- A. Fungi: Fungi are living organisms and form part of the biotic component.
- B. Plants: Plants are living organisms and are biotic components.
- C. Animals: Animals are living organisms and are biotic components.
5. Which group forms the primary source of food in most ecosystems?
Answer: C. Producers
Explanation:
Producers form the primary source of food in most ecosystems. They prepare their own food, mainly through photosynthesis, using sunlight, carbon dioxide, and water. They provide food and energy to other organisms in the ecosystem.
Why the other options are incorrect:
- A. Consumers: Consumers depend on other organisms for their food.
- B. Decomposers: Decomposers obtain nutrients by breaking down dead organic matter.
- D. Parasites: Parasites obtain nutrients from their host and do not form the primary food source of ecosystems.
6. What is the main role of decomposers in an ecosystem?
Answer: B. Breaking down dead organic matter and releasing nutrients
Explanation:
Decomposers such as bacteria and fungi break down dead plants, animals, and other organic matter. This process releases nutrients back into the environment, making them available for reuse by producers and helping maintain nutrient cycling.
Why the other options are incorrect:
- A. Converting sunlight into chemical energy: This is mainly carried out by producers through photosynthesis.
- C. Feeding directly on living plants: Herbivorous consumers feed directly on living plants.
- D. Controlling the temperature of the ecosystem: Temperature is an abiotic factor and is not controlled by decomposers.
7. Which statement correctly describes a habitat?
Answer: C. The place where an organism normally lives
Explanation:
A habitat is the natural place or environment where an organism normally lives and obtains the conditions and resources needed for survival, growth, and reproduction.
Why the other options are incorrect:
- A. The functional role of an organism in an ecosystem: This describes its ecological niche.
- B. The feeding relationship between two organisms: This refers to a type of ecological interaction.
- D. The movement of nutrients between organisms: This is related to nutrient cycling within an ecosystem.
8. The term “niche” of an organism mainly refers to its
Answer: B. Functional role and position in an ecosystem
Explanation:
An organism’s niche refers to its functional role and position within an ecosystem. It includes how the organism uses resources, interacts with other organisms, and contributes to the functioning of the ecosystem.
Why the other options are incorrect:
- A. Physical appearance and body structure: These describe an organism’s physical characteristics, not its ecological niche.
- C. Geographical location alone: Location may be associated with an organism’s habitat, but it does not fully define its niche.
- D. Reproductive age and lifespan: These are biological characteristics and do not describe an organism’s ecological role.
9. Which of the following is an example of an artificial ecosystem?
Answer: C. Aquarium
Explanation:
An aquarium is an artificial ecosystem created and maintained by humans. It can contain living organisms such as fish and aquatic plants along with non-living components such as water, light, and dissolved substances.
Why the other options are incorrect:
- A. Pond: A naturally occurring pond is generally considered a natural aquatic ecosystem.
- B. Forest: A naturally occurring forest is a natural terrestrial ecosystem.
- D. Grassland: A naturally occurring grassland is a natural terrestrial ecosystem.
10. Which of the following is a natural aquatic ecosystem?
Answer: D. Pond
Explanation:
A pond is a natural aquatic ecosystem where organisms interact with one another and with non-living factors such as water, sunlight, temperature, and dissolved nutrients.
Why the other options are incorrect:
- A. Crop field: A crop field is a terrestrial ecosystem that is managed by humans.
- B. Aquarium: An aquarium is an artificial aquatic ecosystem maintained by humans.
- C. Garden: A garden is a terrestrial environment generally created and maintained by humans.
11. Which of the following is a terrestrial ecosystem?
Answer: C. Grassland
Explanation:
A grassland is a terrestrial ecosystem dominated mainly by grasses and other herbaceous vegetation. It supports various plants, animals, and microorganisms that interact with one another and with abiotic factors.
Why the other options are incorrect:
- A. Lake: A lake is an aquatic ecosystem.
- B. Ocean: An ocean is a marine aquatic ecosystem.
- D. Pond: A pond is a freshwater aquatic ecosystem.
12. Which organisms occupy the first trophic level in a typical ecosystem?
Answer: D. Producers
Explanation:
Producers occupy the first trophic level because they produce organic food from inorganic substances, mainly through photosynthesis. They form the starting point of most food chains and provide energy and food for organisms at higher trophic levels.
Why the other options are incorrect:
- A. Herbivores: Herbivores feed on producers and therefore occupy the second trophic level.
- B. Carnivores: Carnivores generally occupy higher trophic levels because they feed on other consumers.
- C. Decomposers: Decomposers break down dead organic matter and are not assigned to the first trophic level in a typical food chain.
13. Which of the following is an example of a primary consumer?
Answer: A. Grasshopper feeding on grass
Explanation:
A primary consumer is an organism that feeds directly on producers. Since grasshopper feeds on grass, which is a producer, the grasshopper acts as a primary consumer and occupies the second trophic level.
Why the other options are incorrect:
- B. Snake feeding on a frog: A snake feeding on a frog is a secondary consumer because the frog commonly feeds on primary consumers.
- C. Eagle feeding on a snake: An eagle feeding on a snake occupies a higher consumer level in the food chain.
- D. Mushroom growing on dead matter: Mushroom is a decomposer that obtains nutrients from dead organic matter.
14. Which ecological interaction benefits both participating organisms?
Answer: B. Mutualism
Explanation:
Mutualism is an ecological interaction in which both participating organisms benefit from the relationship. Examples include the association between flowering plants and pollinators, where both organisms gain benefits.
Why the other options are incorrect:
- A. Predation: One organism benefits by capturing and feeding on another organism, which is harmed.
- C. Parasitism: The parasite benefits while the host is harmed.
- D. Competition: Organisms compete for limited resources, and neither participant receives a mutual benefit from the interaction.
15. A tiger hunting and killing a deer is an example of
Answer: C. Predation
Explanation:
Predation is an ecological interaction in which one organism, called the predator, captures and kills another organism, called the prey, for food. A tiger hunting and killing a deer is a typical example of predation.
Why the other options are incorrect:
- A. Mutualism: Mutualism benefits both organisms involved in the interaction.
- B. Commensalism: In commensalism, one organism benefits while the other is generally neither significantly benefited nor harmed.
- D. Parasitism: In parasitism, the parasite benefits by living on or in a host without normally killing it immediately.
16. Which interaction occurs when two organisms compete for the same limited resource?
Answer: A. Competition
Explanation:
Competition occurs when organisms require the same limited resource, such as food, water, space, or nutrients. The organisms may compete with one another when the available resource cannot adequately meet their needs.
Why the other options are incorrect:
- B. Mutualism: Both organisms benefit from a mutualistic relationship rather than competing for a limited resource.
- C. Commensalism: One organism benefits while the other is generally neither significantly benefited nor harmed.
- D. Predation: Predation involves a predator capturing and feeding on prey, rather than two organisms competing for the same resource.
17. Which combination correctly represents the major components of an ecosystem?
Answer: B. Biotic components and abiotic components
Explanation:
An ecosystem consists of two major components: biotic components, which include living organisms, and abiotic components, which include non-living factors such as air, water, soil, temperature, and sunlight. Both components interact with each other within an ecosystem.
Why the other options are incorrect:
- A. Producers, consumers and only animals: An ecosystem includes abiotic factors as well as different groups of living organisms.
- C. Plants, animals and microorganisms only: These are biotic components, but an ecosystem also includes abiotic factors.
- D. Soil, water and air only: These are abiotic factors and do not represent the living component of an ecosystem.
18. Which of the following is an example of a decomposer?
Answer: A. Mushroom
Explanation:
A mushroom, representing a fungus, acts as a decomposer by breaking down dead organic matter and obtaining nutrients from it. Decomposers play an important role in returning nutrients to the ecosystem.
Why the other options are incorrect:
- B. Grasshopper: A grasshopper is a primary consumer that feeds on plants.
- C. Eagle: An eagle is a carnivorous consumer that feeds on other animals.
- D. Grass: Grass is a producer that makes its own food through photosynthesis.
19. Ecological balance is best maintained when
Answer: B. Organisms and environmental factors remain in a relatively stable relationship
Explanation:
Ecological balance refers to a relatively stable condition in an ecosystem in which organisms and environmental factors interact in a way that supports the continued functioning of the ecosystem. Changes in one component can affect other components and disturb this balance.
Why the other options are incorrect:
- A. One species dominates all other organisms: Dominance of one species can disrupt relationships and reduce ecological stability.
- C. Only producers are present in an ecosystem: A functioning ecosystem requires interactions among different living components along with abiotic factors.
- D. All organisms compete for the same resources: Excessive competition for limited resources does not represent ecological balance.
20. How does energy flow through an ecosystem?
Answer: A. In one direction
Explanation:
Energy generally flows through an ecosystem in one direction, from the Sun to producers and then through consumers. At each transfer, some energy is lost as heat, so energy is not recycled in the same way as nutrients.
Why the other options are incorrect:
- B. In two directions: Energy transfer through an ecosystem does not normally proceed in two opposite directions.
- C. In a circular pattern: Unlike nutrients, energy is not continuously recycled through the ecosystem.
- D. In a random pattern: Energy follows a directional flow through producers and successive consumer levels.
Revision Tips
- Environment: Remember that it includes both biotic (living) and abiotic (non-living) factors.
- Ecology: Focus on the study of relationships between organisms and their environment.
- Habitat vs Niche: Habitat is where an organism lives, while niche is its functional role in the ecosystem.
- Biotic vs Abiotic: Plants, animals, fungi, and bacteria are biotic; sunlight, water, soil, and temperature are abiotic.
- Producers and Trophic Levels: Producers occupy the first trophic level and form the foundation of most food chains.
- Consumers: Primary consumers feed directly on producers.
- Decomposers: Remember bacteria and fungi as important decomposers that break down dead organic matter and help recycle nutrients.
- Ecosystems: Revise the difference between natural and artificial ecosystems and between aquatic and terrestrial ecosystems.
- Ecological Interactions: Clearly distinguish mutualism, competition, predation, and parasitism.
- Energy Flow: Remember that energy flows in one direction, whereas nutrients are recycled within ecosystems.
Further Reference – Environment and Ecology
For further reading and concept clarity, learners can refer to the NCERT textbooks, which provide useful foundational information on environment, ecology, ecosystems, and related topics. This official NCERT resource “Our Environment” can be used alongside the explanations in this quiz for deeper understanding and revision.
