Free Biology Worksheets
Decomposers in Nature:
Q.1. What are decomposers?
Ans: Organisms that break down dead organic matter, feeding on some of the remains and releasing the rest. Some microorganisms, like bacteria and fungus, get their food from the waste of plants and animals and their dead bodies, and as a consequence, they are mixed with the soil and water by being decomposed. These mixed components can be again consumed as food components. This is why these microorganisms are called decomposers or transformers.
Q.2. How do decomposers play an essential role in the cycling of nutrients in nature?
Ans:
Decomposers feed on dead and decaying organisms and their feces. They secrete enzymes onto their food source such as a decaying leaf. These enzymes break down complex organic compounds (food), like carbohydrates and proteins, into simple soluble or gaseous inorganic compounds. The decomposers absorb only a small amount of energy and nutrients are released into the surrounding soil, air, and water.
The inorganic compounds released during decay include gases like carbon dioxide, hydrogen sulfide, water vapour, salts like nitrates, sulfates, phosphates and potassium ions. These are reused by green plants during photosynthesis and other synthetic processes.
Sewage is normally decomposed by saprophytic microorganisms. In towns and cities, sewage from households is drained into large settling tanks. Bacteria present in the sewage secrete enzymes to digest the solid organic matter into soluble, harmless substances and the gas, carbon dioxide. Bateria also feeds on such digested products.
By enabling the recycling of nutrients, decomposers play an important role in maintaining life on Earth.
Q.3. What are microorganisms?
Ans:
The invention of the microscope opened up the world of very minute living organisms called microorganisms. Known commonly as germs or microbes, they are found almost everywhere in nature. eg. viruses, bacteria, fungi.
The Carbon Cycle
How is carbon transformed between organisms and their surroundings?
1. Plants use CO2 from the atmosphere to produce food through photosynthesis.
2. Carbon enters the food chain when animals eat producers and other consumers.
3. organisms release CO2 into the atmosphere during respiration.
4. The decomposition and formation of fossil fuels allow carbon to enter rocks and soil.
5. The combustion of fossil fuels in factories and automobiles releases carbon into the atmosphere.
