AIPMT Biology Aspirants, read out the next topic AIPMT Biology Study material/ Notes of Ecosystem, important  for AIPMT Biology.

Ecosystem is the sum of all organisms living in a given area and the abiotic factors with which they interact. Abiotic factors consist of nonliving components such as water, air, nutrients, rocks, heat, and solar energy. Biotic factors consist of living and once living biological components like plants, animals, and microbes.

• Biotic and abiotic factors are linked by the flow of energy and the cycling of nutrients needed to sustain life.
• So, two processes help in sustaining the ecosystem in an efficient way: Energy flow and Nutrient cycling.
• Energy makes a one-way pass through ecosystems. Energy enters ecosystems of earth as sunlight (Solar energy). It is converted to chemical energy by biotic factors (plants) of ecosystem, transferred among various organisms and finally dissipated as heat back into space. This signifies that earth is an open system for energy.
• Energy is neither created nor destroyed, but it frequently changes form. Total amount of energy does not change (First law of thermodynamics). Energy is never recycled.
• Ecosystem needs a constant supply of energy from sun to synthesize the molecules they require, to counteract the universal tendency toward increasing disorderliness, maintaining second law of thermodynamics.

• Chemical elements, such as carbon, nitrogen and phosphorus, are cycled among abiotic and biotic components of the ecosystem as Nutrient cycle. Carbon atom in CO2 is released from the soil by a decomposer, taken up by a grass through photosynthesis, consumed by a grazing animal, and returned to the soil in the animal’s waste. Earth is a closed system with respect to matter.

Energy Flow and Nutrient Cycling through Ecosystem

• Energy flows through ecosystem, whereas matter cycles within and through ecosystem.
• Biotic factors of the ecosystem are grouped into trophic levels based on their main source of nutrition and energy.
• Much of the energy that enters each trophic level is used to power the metabolism of producers and consumers and this energy is eventually dissipated as heat and is lost from the ecosystem.
• Chemical elements are not altered when they are transferred between organisms, instead chemical elements cycle continuously between living organisms and the abiotic components of ecosystems.