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Organisms and Environment - I

Organisms and Environment

  • Ecology deals with interactions among different organisms and their environment.

  • Organisms get adapted to their environment for their survival and reproduction.

  • The rotation of the earth about its axis brings about changes in the environment, leading to different seasons. This leads to the formation of various biomes such as desert, grassland, etc.

  • Life not only exists in favourable habitats, but also in harsh and extreme conditions.

  • The environment of an organism can be divided into:

    • Abiotic factors

    • Biotic factors

Abiotic Factors

  • Some of the major abiotic factors that interact with the organisms are:

    • Temperature − It is the most relevant abiotic factor since all organisms require an optimum temperature for their metabolism and other body functions. Depending upon their ability to tolerate temperature range, organisms are of two types- stenothermal (restricted to a narrow range of temperature) and eurythermal (can tolerate a wide range of temperature).

 
 
  • Water − Water also is a major influencing factor. Life on earth is impossible without water as it forms the major constituent of all living cells. In oceans where quantity of water is not a limitation, the quality of water becomes one. Depending upon the ability to tolerate salinity, organisms can be stenohaline (restricted to narrow range of salinity) and euryhaline (tolerant to wider range of salinity).

  • Soil − The nature and composition of soil differs from one place to another depending upon the climate, weathering process, and soil development method. The characteristic features such as soil composition, grain size, percolation, water holding capacity, etc. determine the native of the organisms it can support.

  • Light − The major source of light on earth is the Sun. Light is essential for plants to perform photosynthesis. Certain plants become adapted to perform photosynthesis under very low light since they are constantly overshadowed by tall trees. Many plants also depend on light for their flowering (photoperiodism). The availability of light on land is comparatively higher than that in water.

 

  • All organisms in order to sustain maximum functionality maintain a constant internal environment (homeostasis). An organism may adopt one of the following strategies for homeostasis:

    • Regulate − Certain animals have the ability to maintain a constant temperature and a constant osmolarity to keep up their homeostasis. Mammals have a constant body temperature (37°C) irrespective of the outside temperature. In summers, to maintain the temperature, we sweat and in winters we shiver, which produces heat.

    • Conform − Animals and plants except mammals do not have a constant body temperature and their body temperature changes in accordance with the outside temperature. Such organisms are called conformers. Conformers have not evolved. They have not become regulators since regulation is energetically more expensive.

  • Migrate − The organism can move temporarily from stressful habitats to more hospitable areas and return once the period changes. Birds can migrate from cold regions to relatively warmer regions during winter and vice-versa during summers.

  • Suspend − Some organisms cease to be metabolically active during stressful period. They suspend all activity and enter a period of dormancy. For example − Spores in bacteria and lower plants; and hibernation (winter sleep) and aestivation (summer sleep) in animals Similarly, zooplankton enter diapause, a stage of suspended development during unfavourable conditions.

Solid Waste

  • Consists of all the unwanted undesired materials thrown into the dustbin
  • It may be composed of biodegradable or non-biodegradable wastes.
  • Open dumps used for disposing solid waste serves as breeding ground for rats and flies. Therefore, sanitary landfills are used as a substitute for these.
  • Biodegradable wastes can be either aerobically on anaerobically broken down using microbes. The non-biodegradable waste can be recycled, reused, or dumped in landfills.
  • Hospital wastes also contain hazardous materials, which have to be disposed properly. Hospital wastes are generally incinerated.
  • Irreparable computers and other electronic goods make up e-wastes, which are either dumped in land fills or are incinerated. E-waste can be recycled also to recover metals such as copper, iron, silicon, gold, etc.
  • To use the plastic waste in an efficient way, polyblend, a fine powder of recycled modified plastic, has been developed. When polyblend is mixed with bitumen, it can be used to lay roads with greater water repellent capacity and greater life.

Solid Waste

  • Consists of all the unwanted undesired materials thrown into the dustbin
  • It may be composed of biodegradable or non-biodegradable wastes.
  • Open dumps used for disposing solid waste serves as breeding ground for rats and flies. Therefore, sanitary landfills are used as a substitute for these.
  • Biodegradable wastes can be either aerobically on anaerobically broken down using microbes. The non-biodegradable waste can be recycled, reused, or dumped in landfills.
  • Hospital wastes also contain hazardous materials, which have to be disposed properly. Hospital wastes are generally incinerated.
  • Irreparable computers and other electronic goods make up e-wastes, which are either dumped in land fills or are incinerated. E-waste can be recycled also to recover metals such as copper, iron, silicon, gold, etc.
  • To use the plastic waste in an efficient way, polyblend, a fine powder of recycled modified plastic, has been developed. When polyblend is mixed with bitumen, it can be used to lay roads with greater water repellent capacity and greater life.
Phosphorus cycle is a sedimentary cycle.

Phosphorus Cycle

  • Phosphorus is an important constituent of cell membranes, nucleic acids, and cellular energy transfer systems.

  • Rocks contain phosphorus in the form of phosphate.

  • When rocks are weathered, some of the phosphate gets dissolved in the soil solution …

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