Biology SS 1 Third Term
Week 7
Topic: Functioning Ecosystem
Introduction
An ecosystem is a basic functioning unit in nature. It is made up of living organisms (plants and animals) and their non-living environment. The biotic or living components such as the producers and consumers interact in their environment resulting in the ecosystem being a functional unit.
Autotrophs, Heterotrophs and Decomposers
Autotrophs
Autotroph is an organism that serves as a primary producer in a food chain. Autotrophs obtain energy and nutrients by harnessing sunlight through photosynthesis (photoautotrophs) or, more rarely, obtain chemical energy through oxidation (chemoautotrophs) to make organic substances from inorganic ones. Autotrophs do not consume other organisms; they are, however, consumed by heterotrophs.
Energy Production
Autotrophs produce their own energy by one of the following two methods:
- Photosynthesis – Photoautotrophs use energy from sun to convert water from the soil and carbon dioxide from the air into glucose. Glucose provides energy to plants and is used to make cellulose which is used to build cell walls. E.g. Plants, algae, phytoplankton and some bacteria. Carnivorous plants like pitcher plant use photosynthesis for energy production but depend on other organisms for other nutrients like nitrogen, potassium and phosphorous. Hence, these plants are basically autotrophs.
- Chemosynthesis – Chemoautotrophs use energy from chemical reactions to make food. The chemical reactions are usually between hydrogen sulfide/methane with oxygen. Carbon dioxide is the main source of carbon for Chemoautotrophs. E.g. Bacteria found inside active volcano.
Heterotrophs
Heterotrophs are organisms that survive by feeding on organic matter produced by or available in other organisms. It is an organism that consumes other organisms in a food chain, hence, they are called consumers. In contrast to autotrophs, heterotrophs are unable to produce organic substances from inorganic ones. They must rely on an organic source of carbon that has originated as part of another living organism. Heterotrophs depend either directly or indirectly on autotrophs for nutrients and food energy.
https://passnownow.com/lesson/functioning-ecosystem/
