Structure & Requirements of Ecosystem - NEET Biology Class 12 Free MCQ

A biome is defined as a community of various plants and animals, that inhabit a particular type of geographic region of Earth. Biomes are often defined by their climate, rainfall/water characteristics, elevation, and plant characteristics (leaf type, spacing, etc). Biomes can be divided into two major classifications, terrestrial (land-based) and aquatic (water-based). 

Decomposition is the process that involves the breakdown of complex organic matter or biomass from the body of dead plants and animals with the help of decomposers into inorganic raw materials such as carbon dioxide, water, and other nutrients. The various processes involved in decomposition are as follows:

(1) Fragmentation: It is the first step in the process of decomposition. It involves the breakdown of detritus into smaller pieces by the action of detritivores such as earthworms.

(2) Leaching: It is a process where the water soluble nutrients go down into the soil layers and get locked as unavailable salts.

(3) Catabolism: It is a process in which bacteria and fungi degrade detritus through various enzymes into smaller pieces.

(4) Humification: The next step is humification which leads to the formation of a dark-coloured colloidal substance called humus, which acts as reservoir of nutrients for plants.

(5) Mineralization: The humus is further degraded by the action of microbes, which finally leads to the release of inorganic nutrients into the soil. This process of releasing inorganic nutrients from the humus is known as mineralization.

Decomposition produces a dark coloured, nutrient-rich substance called humus. Humus finally degrades and releases inorganic raw materials such as CO₂, water, and other nutrient in the soil.

The relationship between any system and its surrounding environment can be described in one of three ways. In an isolated system, neither matter nor energy is exchanged with its environment. In a closed system, energy, but not matter, is exchanged. In an open system, both matter and energy are exchanged between the system and its surrounding environment. Any ecosystem is an example of an open system. 

Biosphere is one of the layers surrounding the earth along with the lithosphere(land) ,hydrosphere(water),atmosphere (air).

Dry, freezed storage of germplasm at -196°C in liquid nitrogen is called cryopreservation. At such temperature, all biological activities are near stoppage. In situ conservation is the maintenance of biological diversity in natural habitats like national parks, wildlife sanctuaries and biosphere reserves. Ex situ conservation is the conservation of selected rare plants/animals in place outside their natural home.

Microorganisms like bacteria etc decompose organic matter.

Secondary productivity is the rate of formation of new organic matter by consumers. primary productivity depends on the producers inhabiting a particular area. Decomposers break down complex organic matter. Into inorganic substance like carbon dioxide water and nutrients. Parasitic species food on the body of other organisms.

An Ecotone describes an area that acts as a transition or boundary between two ecosystems. This could be, for example, an area of marshland between a river and the riverbank, a clearing within a forest or a much larger area such as the transition between Arctic Tundra and Forest biomes in Northern Siberia. As this area is inevitably Influenced by the two bordering ecosystems, it is therefore a consequence of this that a higher density of organisms and variety of species can be found within an Ecotone. This increase in biodiversity is referred to as the “edge effect”.

Fragmentation: Detritivores break down detritus into smaller particles. This process is called fragmentation. Earthworm is an example of detritivore.

Net Primary Productivity: When respiratory losses (R) is subtracted from GPP, we get Net Primary Productivity (NPP). Net primary productivity is the available biomass for the consumption of heterotrophs.

GPP – R = NPP

Secondary Productivity: The rate of formation of new organic matter by consumers is called secondary productivity.

The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of organic matter. Of this, the productivity of the oceans are only 55 billion tons.