Published: Published Date – 11:15 PM, Sun – 15 May 22
Hyderabad:
Ecosystem Elementary Aspects
An ecosystem consists of both structural & functional components. The ecosystem components of ecosystem are of two types – Abiotic factors and Biotic factors. Abiotic factors are again of two types – Physical factors and Chemical factors. Lights, temperature, soil, and pressure are all physical factors. The chemical factors include oxygen, carbon dioxide, and various mineral nutrients in soil/water.
These factors have a significant impact on the lives of organisms in an ecosystem. An ecosystem’s functional aspect is energy transfer and mineral recycling.
Light
Photosynthesis is the process by which plants produce food. This is possible only if there is enough sunlight. It is easy to see the importance of light in all living organisms, especially the autotrophs.
Many species of small plants (herbs, shrubs) that grow in forests can photosynthesise well under low light conditions. This is because they are constantly overshadowed by tall trees with many branches.
Many plants are also dependent upon sunlight to fulfill their photoperiod requirements for flowering.
Many animals consider light important because they use the seasonal and diurnal variations in the intensity and duration of light (photoperiod) as cues to determine when to forage (collect food) or when to migrate.
Since the sun is the source for both light and temperature, the availability of light on the ground is closely tied to that of the air temperature.
Deep under the oceans, however, the environment is always dark, and its inhabitants don’t experience light. Life depends on the spectral quality. Many organisms are vulnerable to the UV portion of the spectrum. Marine plants living at different depths of water have to be able to access all the visible spectrum colours.
Biological effects of sunlight: Light has many biological effects and activates such as pigmentation, movement, vision and metabolism.
Effect of light upon pigmentation
The colour of the skin is affected by light
Animals that live in low-intensity areas of light, such as caves, have less pigmentation than animals that are exposed to light.
For example: – A cave dwelling amphibian, proteus anguinus, has pale coloured skin because of less pigmentation. After a certain time, the skin colour will darken as it is exposed to sunlight.
Photo Response: An organism’s reaction to changes in the light intensity and direction is called photoresponse. Motile organisms have the following photo responses:
Phototaxis:Phototaxis is the oriented loco-motor movement of an organism in the opposite direction to light as seen by euglenas or cockroaches (positive response).
Plotokinesis:Photokinesis refers to the influence of light on the non-directional movement and movement of organisms. This is evident in the larvae pinnotheres Maculatus-the mussel car-in which the intensity of the light influences the speed of the organism’s movement.
Phototropism:Phototropism refers to the orientation of light by a non-motile organism like a plant/plant component.
Phototropism is responsible for the growth of plants that are influenced by sunlight.
To be continued …
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