Shankar IAS Test: Ecology - UPSC MCQ

1. Population is a group of organisms occupying a defined area during a specific time.

   • This statement is correct. In ecology, a population refers to a group of individuals of the same species living in a specific area at a given time.

2. Population growth rate is the percentage variation between the number of individuals in a population at two different places.

   • This statement is incorrect. Population growth rate refers to the change in the number of individuals in a population over time, typically expressed as a percentage per unit time. It is not about the variation between two different places but rather the change over time in the same place.

3. The main factors that make the population decrease are death and emigration.

   • This statement is correct. The primary factors leading to a decrease in population size are death (mortality) and emigration (the movement of individuals out of a population).

Based on the evaluation:

• Statement 1 is correct.
• Statement 2 is incorrect.
• Statement 3 is correct.

Thus, the correct answer is:

1. 1 and 3 Only

1. Caraka-Samhita - Classification of animals based on habitat: Correct. The Caraka-Samhita indeed contains classifications of animals based on habit and habitat.

2. Abiotic component - Plants: Incorrect. Plants are part of the biotic components of the environment, not the abiotic components. Abiotic components include non-living factors such as energy, radiation, temperature, and water.

3. Major Community - Relatively independent, large-sized: Correct. Major communities are large-sized, well-organized, and relatively independent, relying primarily on the sun's energy.

4. Minor Community - Dependent on neighboring communities: Correct. Minor communities depend on neighboring communities and are not completely independent units in terms of energy and nutrient dynamics.

Thus, pairs 1, 3, and 4 are correctly matched, while pair 2 is incorrectly matched.

Hence, the correct answer is Option B.

The Temperate Deciduous Forest biome extends over Central and Southern Europe, Eastern North America, Western China, Japan, New Zealand, among other regions. It is characterized by moderate average temperature and abundant rainfall, making it one of the most productive agricultural areas on Earth. This biome's flora includes trees like beech, oak, maple, and cherry. The diverse array of familiar vertebrates and invertebrates further enriches this biome, making it a vital part of the global ecosystem.

• Structure of a community: In a community, the number of species and size of their population vary greatly. A community may have one or several species. The environmental factors determine the characteristic of the community, as well as the pattern of organisation of the members in the community.

• The characteristic pattern of the community is termed as the structure which is reflected in the roles played by various population, their range, the type of area they inhabit, the diversity of species in the community and the spectrum of interactions between them.

1. Precipitation that falls near the equator is most likely to fall as rain into the ocean. This statement is partially true because while a significant amount of precipitation near the equator does fall into the ocean, a considerable amount also falls on land, particularly in tropical rainforest regions like the Amazon Basin and the Congo Basin. However, since the statement emphasizes the likelihood of rain falling into the ocean without negating the substantial rainfall on land, its accuracy can be contextually accepted given the vast expanse of oceans around the equatorial belt.

2. Water vapor is a greenhouse gas that helps to regulate the temperature of the earth's atmosphere. This statement is correct. Water vapor is indeed a significant greenhouse gas, contributing to the natural greenhouse effect that helps regulate the Earth's temperature. Without this effect, the planet would be much colder and less hospitable to life as we know it.

3. Globally, precipitation far exceeds evaporation. This statement is incorrect. The global water cycle is balanced over time, meaning that the amount of water that evaporates from the Earth's surface (including both land and oceans) approximately equals the amount of precipitation that falls back to Earth. If precipitation far exceeded evaporation globally and consistently, we would see a continuous increase in the volume of water in the Earth's surface reservoirs, which is not the case.

Therefore, the correct answer is: 1 and 2 only

Statement-I correctly highlights the significant coverage of the earth's surface by tropical rain forests and the proportion of plant and animal species they harbor. Statement-II complements this by describing the unique structure of tropical rain forests with multiple layers of vegetation and the concentration of animals and epiphytes in the canopy. The second statement provides further details supporting the first statement, hence both statements are correct, and Statement-II elaborates on Statement-I, making option A the correct choice.

1. Herbivores : Primary consumers

Correct. Herbivores feed mainly on plants and are primary consumers. Examples include cows and rabbits.

2. Wolves : Secondary consumers

Correct. Wolves feed on primary consumers and are considered secondary consumers.

3. Algae : Primary producers

Correct. Algae, like green plants, perform photosynthesis and are primary producers in aquatic ecosystems.

4. Earthworm : Macro consumers

Incorrect. Earthworms are not macro consumers; they are detritivores, which helps in the decomposition of organic matter. They are considered micro consumers as they decompose dead organic substances.

Thus, three pairs are correctly matched.

Both Statement-I and Statement-II are correct. Statement-II provides additional context and elaborates on the significance of the ecological concepts discussed in the Vedic texts. The Caraka-Samhita indeed underscores the vital role of environmental factors like air, land, water, and seasons for sustaining life, while also cautioning against the adverse effects of polluted environments. Hence, Statement-II complements and explains Statement-I, making Option A the correct answer.

The abiotic components of an ecosystem, including energy, temperature, atmosphere, and substratum, collectively play a crucial role in determining the range and survival of organisms. While each factor influences organisms differently, their combined effects shape the distribution and adaptability of species within an ecosystem.

- Statement-I correctly defines abiotic components as non-living parts like soil, water, air, and light energy that impact ecosystems through physical processes.
- Statement-II correctly explains how biotic components (plants and animals) depend on abiotic factors such as soil nutrients and sunlight for growth and reproduction.
- Both statements are accurate, and Statement-II provides a clear illustration of how abiotic components support life, making it explanatory of Statement-I.

Thus, option A is correct: Both statements are correct, and Statement-II explains Statement-I.