Populations & Ecosystems Test - 8

Decomposers breaks the complex organic matter present in dead plants and animals into simpler form that can be reused. They acts as reducer of dead and decaying matters.

The rate at which solar energy is converted and stored by the producers per unit area over a time period is called primary productivity. The solar energy is converted into usable form by plants with the help of photosynthesis.

The chemical energy of food is the main source of energy required by all living organisms. This energy is transmitted to different trophic levels along the food chain. This energy flow is based on two different laws of thermodynamics:

• First law of thermodynamics, that states that energy can neither be created nor destroyed, it can only change from one form to another.
• Second law of thermodynamics, that states that as energy is transferred more and more of it is wasted.

Ecosystem consists of biotic component producer, consumer and decomposer. Producer fix solar energy into useable forms and decomposer breaks the complex organic matter into simpler forms but consumer do not perform specific function so non-essential.

In most of the food chain of ecosystem only 4 to 5 trophic levels are present because loss of energy at successive levels is very high. Only 10% of energy is transferred to next trophic level.

A detritus food chain begins with dead organic matter. It is made of decomposers which are heterotrophic organism fungi and bacteria.Rhizophora species is a saprophyticheterotrophs.

Food web is formed by interaction between a numbers of food chains having common members. Stability of ecosystem largely depends upon the kinds of food web exists in it for proper flow of energy.

For greater efficiency a food chain must have three to four trophic levels. At each trophic levels loss of energy is very high so very small amount of energy is left after there trophic level.

At each trophic level only ten percent of energy is transferred from one trophic level to next trophic level from producer to consumers. So, only 20J of energy is available to tertiary consumers.

Productivity is the rate of new biomass production by an individual, population, community within an ecosystem. The productivity of an ecosystem depends on several environmental factors such as light, water, temperature, precipitation, etc.