Ecosystem Nutrition and Energy Flow

Anaerobic bacteria is the connecting link between sludge and biogas production.

Plants that make their own food are called autotrophs.

Some plants do not get all the required nutrients from the soil in which they grow. The Pitcher plant is insectivoroui because it gets nutrients like nitrogen from the insects.

Bread yeast and fungi secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it. This mode of nutrition in which organisms take in nutrients in solution form from dead and decaying matter is called saprotrophic nutrition.

Algae contain chlorophyl, which gives them the green colour. Algae can also prepare their own food by photosynthesis.

Primary consumers are the herbivores, which feed on the producers.

In a food chain, omnivores occupy more than one trophic level and some organisms grab different trophic positions in different food chains.

Decomposers are heterotrophic organisms, mainlyfungi and bacteria. They meet their energy and nutrient requirements by degrading dead organic matter or detritus. Decomposers secrete digestive enzymes that breakdown dead and waste materials into simple, inorganic materials, which are subsequently absorbed by them. In terrestrial ecosystems roughly 90% of the net primary production ends up being broken down by them.

Viruses are not living and do not carry out any type of respiration. They require no nutrients using energy acquired by their host cell. They cannot reproduce inside nonliving organic matter. Viruses reproduce at the expense of a host. Thus, they most closely resemble parasites.

Chemoautotrophs are organisms that are capable of manufacturing their organic food utilising chemical energy released in the oxidation of some inorganic substances. The process of manufacture of food in such organisms is called chemosynthesis. It includes some acrobic bacteria.

Nitrogen is a vital ingredient to plant life. Most industrial fertilisers contain high concentrations of nitrogen compounds, such as ammonium nitrate. Animals eat plants and turn the nitrogen into proteins. When the animals die, bacteria break down the proteins, releasing N₂ back into the atmosphere to begin the cycle again.

In ecological energy pyramids, trophic level 1 has producers, level 2 has herbivores, level 3 has carnivores, and level 4 has top carnivores that prey on other carnivores. This is the standard sequence. Top carnivores (like lions, eagles, or sharks) occupy the apex position in food chains.

Biological magnification (or biomagnification) refers to the increasing concentration of non-biodegradable substances like pesticides, mercury, or heavy metals at each successive trophic level in a food chain. Substances accumulate in higher concentrations as you move up. Food web is the feeding network, decomposition is breakdown, and fermentation is a microbial process.

Nitrogen, water, and carbon all have complete biogeochemical cycles (nitrogen cycle, water cycle, carbon cycle) where elements are continuously recycled through ecosystems. Sodium does not have a complete biological cycle - it accumulates primarily in oceans and is part of mineral sedimentation cycles but not actively recycled like the other three.

Energy flows from autotrophs (producers that make their own food) to heterotrophs (consumers that eat other organisms) and finally to decomposers (bacteria and fungi that break down dead matter). This is the correct sequence. Option A incorrectly reverses the flow, and other options misplace the components.