1. Which statement best defines ecology?
ⓐ. It is the study of interactions among organisms and between organisms and their environment.
ⓑ. It is the study of internal tissues and organs in multicellular organisms.
ⓒ. It is the study of heredity and gene transmission across generations.
ⓓ. It is the study of chemical composition of living matter only.
Correct Answer: It is the study of interactions among organisms and between organisms and their environment.
Explanation: Ecology deals with relationships, not just the structure of organisms. It includes interactions among living organisms as well as their responses to non-living components such as temperature, water, light, and soil.
2. In ecological study, which sequence correctly arranges biological organisation from lower to higher level among the following?
ⓐ. Community → Population → Organism → Biome
ⓑ. Organism → Population → Community → Biome
ⓒ. Population → Organism → Biome → Community
ⓓ. Biome → Community → Population → Organism
Correct Answer: Organism → Population → Community → Biome
Explanation: Biological organisation in ecology proceeds from a single living individual to larger interactive groupings. An organism is one individual, a population is a group of individuals of the same species, a community includes populations of different species, and a biome covers a very large regional ecological unit. This order helps explain how ecological processes scale upward.
3. Which option represents an ecological level that includes populations of different species living together in an area?
ⓐ. Organism
ⓑ. Population
ⓒ. Community
ⓓ. Biome
Correct Answer: Community
Explanation: A community is formed when many populations occupy the same habitat and interact with one another. A population includes members of only one species, whereas a community includes multiple species together.
4. Which ecological level is most appropriate for studying how a group of deer increases, decreases, and responds to available resources in a forest?
ⓐ. Biome
ⓑ. Community
ⓒ. Organism
ⓓ. Population
Correct Answer: Population
Explanation: Questions about the number, density, growth, and resource use of members of one species belong to population-level study. The focus here is not on one deer alone and not on all species of the forest together. Instead, it concerns a single species as a group living in a defined area.
5. A student is comparing the effect of rainfall, temperature, and soil moisture on a cactus in its habitat. This mainly highlights interaction between the organism and
ⓐ. only other plants of the same species
ⓑ. the abiotic environment
ⓒ. the internal genetic system
ⓓ. the reproductive organs only
Correct Answer: the abiotic environment
Explanation: Rainfall, temperature, and soil moisture are non-living components of the environment. Ecology examines how organisms respond to such abiotic factors because these strongly influence survival, growth, and distribution.
6. Which of the following is the broadest ecological unit among the options given?
ⓐ. Population
ⓑ. Organism
ⓒ. Community
ⓓ. Biome
Correct Answer: Biome
Explanation: A biome is a large regional unit characterized by climate and dominant forms of life. It includes many communities spread across a wide area under similar environmental conditions. Population, organism, and community are all smaller units within ecological organisation.
7. Assertion: Ecology includes the study of interactions among organisms.
Reason: Living beings exist in isolation from both other organisms and physical surroundings.
ⓐ. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
ⓑ. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
ⓒ. Assertion is true, but Reason is false.
ⓓ. Assertion is false, but Reason is true.
Correct Answer: Assertion is true, but Reason is false.
Explanation: Interactions among organisms are a basic part of ecology, so the assertion is correct. The reason is incorrect because organisms do not live in complete isolation from other organisms or from physical conditions. Their survival depends on continuous interaction with both biotic and abiotic factors.
8. Which statement best explains why population is often a major level of ecological study?
ⓐ. It ignores environmental influences and studies only internal anatomy.
ⓑ. It deals only with the chemical composition of cells.
ⓒ. It focuses only on fossils and extinct forms.
ⓓ. It helps explain how groups of the same species behave in relation to resources and surroundings.
Correct Answer: It helps explain how groups of the same species behave in relation to resources and surroundings.
Explanation: Population-level study is useful because individuals of the same species in an area do not function as isolated units. Their numbers, growth, distribution, and use of resources can be understood more meaningfully when examined as a group. This level also connects ecology with broader processes such as survival and reproduction in nature.
9. Which level of ecological study is most suitable for understanding how the number of frogs in a pond changes with breeding and deaths over time?
ⓐ. Organism
ⓑ. Population
ⓒ. Community
ⓓ. Biome
Correct Answer: Population
Explanation: Change in the number of individuals of one species is studied at the population level. It includes births, deaths, movement, and resource use within a defined area. The focus is on the group as a unit rather than on a single organism or on all species together.
10. Which group best fits the definition of a population?
ⓐ. All grasses, shrubs, and trees in a meadow
ⓑ. All fishes living in different oceans of the world
ⓒ. All mango trees and neem trees in one orchard
ⓓ. All rabbits of the same species living in one grassland
Correct Answer: All rabbits of the same species living in one grassland
Explanation: A population consists of individuals of the same species living in a defined geographical area. These individuals usually share or compete for similar resources and may potentially interbreed. A group containing multiple species does not fit this definition.
11. Which statement is essential for a group of organisms to be considered a population?
ⓐ. All individuals must have identical body size.
ⓑ. All individuals must belong to the same species.
ⓒ. All individuals must be of the same age.
ⓓ. All individuals must occupy different habitats.
Correct Answer: All individuals must belong to the same species.
Explanation: Species identity is one of the basic requirements in defining a population. The members should belong to the same species and occur within a defined area. They need not be identical in age, size, or sex.
12. Which of the following is not necessary for identifying a population?
ⓐ. The individuals should occur in a defined area.
ⓑ. The individuals should be exactly the same age.
ⓒ. The individuals should belong to the same species.
ⓓ. The individuals should share or compete for similar resources.
Correct Answer: The individuals should be exactly the same age.
Explanation: Members of a population can belong to different age groups, so identical age is not required. What matters is that they are individuals of the same species living in a particular area. They also tend to use similar resources or compete for them.
13. A biologist studies all lotus plants of the same species growing in a particular lake. This group is best described as a
ⓐ. community
ⓑ. biome
ⓒ. population
ⓓ. habitat
Correct Answer: population
Explanation: The group includes individuals of one species confined to a defined area, which matches the idea of a population. A community would include many species living together, while habitat refers to the place where organisms live. A biome is a much larger ecological unit.
14. Which example represents a community rather than a population?
ⓐ. All pine trees of one species on a mountain slope
ⓑ. All bacteria of one species in a culture flask
ⓒ. All fish of one species in a pond
ⓓ. All algae, snails, fishes, and frogs in a pond
Correct Answer: All algae, snails, fishes, and frogs in a pond
Explanation: A community includes populations of different species living in the same area. The pond group listed here contains many kinds of organisms, not just one species. A population, in contrast, includes only members of a single species.
15. Which statement about a population is correct?
ⓐ. It always includes all organisms living in a habitat.
ⓑ. It contains members of several species sharing one food source.
ⓒ. It is limited to sexually reproducing organisms only.
ⓓ. It consists of individuals of one species occupying a defined area.
Correct Answer: It consists of individuals of one species occupying a defined area.
Explanation: Population is a species-specific grouping within a defined geographical region. The members may share or compete for similar resources and are studied together as an ecological unit.
16. Why can an asexually reproducing group of organisms also be treated as a population in ecology?
ⓐ. Because ecological study requires only the same habitat, not the same species
ⓑ. Because they are always genetically identical in every condition
ⓒ. Because they occur as a group in an area and interact with similar resources
ⓓ. Because they can never increase in number without mutation
Correct Answer: Because they occur as a group in an area and interact with similar resources
Explanation: Ecological study often focuses on how a group of organisms occupies space and uses resources in nature. Even if reproduction is asexual, the group can still behave as a population when it consists of members of the same species in a defined area. Such organisms may show density, growth, and resource competition like other populations.
17. Which feature best distinguishes a population from a mere random collection of organisms?
ⓐ. Presence of individuals of the same species in a defined area
ⓑ. Presence of only young individuals in one season
ⓒ. Presence of organisms from different trophic levels
ⓓ. Presence of organisms with identical body mass
Correct Answer: Presence of individuals of the same species in a defined area
Explanation: A population is not just any grouping of organisms seen together. It must involve individuals of the same species that occur in a specific geographical area. They usually share or compete for similar resources and function as a meaningful ecological unit.
18. Population ecology is especially important because it provides a link between ecology and
ⓐ. embryology
ⓑ. physiology
ⓒ. taxonomy
ⓓ. evolution
Correct Answer: evolution
Explanation: Population-level study helps explain how ecological conditions affect survival, reproduction, and variation in groups of organisms. These same processes are closely related to evolutionary change over time.
19. Which of the following can be called a population?
ⓐ. All rose plants, hibiscus plants, and jasmine plants in one garden
ⓑ. All birds visiting a lake during winter, regardless of species
ⓒ. All tigers of one species living in a particular reserve
ⓓ. All insects found in crop fields across several countries
Correct Answer: All tigers of one species living in a particular reserve
Explanation: The tigers form a group of the same species confined to a clearly defined geographical area. This satisfies the main requirements of a population. A mixture of many species, even in one area, represents a broader ecological grouping.
20. Potential interbreeding is included in the idea of population mainly because the members
ⓐ. belong to a single reproductive unit of the same species
ⓑ. must remain equal in number throughout the year
ⓒ. always occupy exactly the same shelter site
ⓓ. can survive without using common resources
Correct Answer: belong to a single reproductive unit of the same species
Explanation: Members of a population are usually considered part of the same species and therefore part of a common reproductive pool. The phrase “potentially interbreeding” reflects this biological unity.
