Biogeochemical cycles biology homework help from Tutorspoint tutors at an affordable price to students.
Biogeochemical Cycles
Biogeochemical cycles are cycles that combine both biotic and abiotic components of our planet through the aid of various cycles namely – water cycle, nitrogen cycle, carbon cycle, and oxygen cycle. Since these cycles are inter-dependent, instability of these cycles tends to damage the life on our planet earth.
Water Cycle:
The water that falls on land in the form of rain, snow or hailstones, flows back into seas and other water bodies. The water is then evaporated from these water bodies, resulting in the formation of water vapor and clouds. This completes the whole water cycle.
Water is also used up by living organisms – plants and animals for transpiration and respiration processes respectively. Some of the water falling on land seeps into the ground and is used up by roots of plants to conduct water through the stem, while some water is evaporated by the sun’s heat.
Nitrogen Cycle:
Our air is composed of 79% nitrogen, but it cannot be used directly by the plants. But there are some micro-organisms which have the ability to fix the nitrogen from the atmosphere into the soil. Thus, they are called biological nitrogen fixers. Once the microbes fix the nitrogen as nitrogenous compounds like nitrates and nitrites, these compounds are used up by the plants during the process of food preparation and storage (nitrification).
The animals obtain nitrogen directly or indirectly from the plants. After a certain period of time, the death of plants and animals results in the decomposition of dead and decaying matter by specialized micro-organisms that release ammonia and other nitrogen compounds into the air and soil (de-nitrification). This completes the nitrogen cycle.
Carbon Cycle:
Carbon is found in the form of diamonds and graphite in the crust of the earth and in the form of carbohydrates, nucleic acids, and fats in all living creatures. Carbohydrates and fats are energy-rich food and their basic component is carbon, hydrogen, and oxygen. Carbon is also found in exoskeleton and endoskeleton in the form of carbonate salts. The percentage of carbon dioxide present in the atmosphere is very small about 0.03%.
The carbon dioxide in the air is taken up by plants during the photosynthesis process. The carbon dioxide along with water forms simple and complex carbohydrates. The carbohydrates are prepared by plants and stored in various parts of the plant. All animals depend on plants for food sources directly or indirectly. The animals release carbon in the form of carbon dioxide during respiration and decomposition. Other than this, carbon compounds from plants and animals are also used to prepare fossil fuels like coal, limestone and petroleum and carbonate shells.
The Greenhouse Effect:
A greenhouse is a place where plants are grown in a house that is completely surrounded by glass. Greenhouses are seen in countries with extremely colder climate during the winter season. In a greenhouse, the glass traps the sun’s heat, thus resulting in increasing the temperature of the greenhouse compared to its surroundings.
Thus, these keep the plants warm and ensures the growth and development of plants during the winter season. A drawback of greenhouses is that some gases cannot prevent the heat escape from the planet earth. Hence these gases remain in the atmosphere, resulting in increasing the temperature of the atmosphere. This phenomenon is known as global warming.