JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year ENVIRONMENTAL STUDIES Previous Question Paper (March - 2022 - R13)

An ecosystem is a functional unit of nature where living organisms (biotic community) interact with each other and with their non-living (abiotic) physical environment. It encompasses the complex network of relationships between plants, animals, microorganisms, and their surroundings.

The ecosystem functions through two primary processes: energy flow and nutrient cycling. Energy enters the system primarily from the sun, is captured by producers through photosynthesis, and is transferred through various trophic levels via consumption. Simultaneously, essential nutrients (like carbon, nitrogen, and phosphorus) are recycled through the biotic and abiotic components, ensuring the system remains self-sustaining.

A food chain is a linear sequence of organisms through which energy and nutrients pass as one organism eats another. A food web is a complex, interconnected network of multiple overlapping food chains within an ecosystem, representing a more realistic view of feeding relationships.

In a terrestrial ecosystem, the components of a food chain are:

1. Producers (Autotrophs): Green plants and trees that convert solar energy into chemical energy through photosynthesis. They form the base of the food chain.
2. Primary Consumers (Herbivores): Animals such as insects, deer, or rabbits that feed directly on producers to obtain energy.
3. Secondary Consumers (Primary Carnivores): Organisms like frogs, small birds, or snakes that feed on primary consumers.
4. Tertiary Consumers (Secondary Carnivores): Top predators like hawks, lions, or eagles that feed on secondary consumers.
5. Decomposers (Detritivores): Organisms such as fungi, bacteria, and earthworms that break down dead organic matter, returning essential nutrients to the soil to be reused by producers, thus completing the cycle.