Ecology
Ecology is the study of interactions or relationships of organisms with one another and with the biotic and abiotic environment.
Some terms used in Ecology
Habitat - a place where an organism lives
Population - a group of organisms of the same species living in a particular habitat
Community - All populations of organisms living and interacting with one another in a particular habitat
Ecosystem - a community and its abiotic environment, where :
· organisms are interdependent
· energy is transferred from one organism to another mainly through feeding
· The Sun is the main source of energy for our Earth
· solar energy from the Sun is absorbed by plants and passed on to other organisms as chemical energy
· most energy is lot as hear
· energy flow is non-cyclical
Abiotic factors
These are some abiotic factors that may influence the livelihood of organisms in a communiity or ecosystem:
Temperature and pH- affects the proper functioning of enzymes. Extreme temperatures and pH disrupts the hydrophobic, hydrophilic and ionic interactions in enzymes, causing them to lose their shape and functionality.
Oxygen content - oxygen is required for aerobic respiration. Lack of oxygen slows down metabolism.
Humidity - high humidity slows down the rate of transpiration in plants but is also critical to the survival of epiphytes and organisms living in arid places.
Amount of water - Affects the number and locations of flora and fauna. Dependent on rain pattern.
Wave action - prevents marine organisms from settling down and feeding.
Wind speed - high wind speed may break the stems of certain plant species and may dissipate humidity.
Light intensity - low light intensity retards plant growth, but high light intensity may bleach chlorophyll and impair the ability of plants to photosynthesise.
Salinity - affects osmotic balance in many aquatic animals and coastal plant species.
Type of substratum - Clayey, sandy or rocky substratum influences ability of plants and sessile organisms to anchor themselves.
Interactions
Mutualism - Both organisms benefit
Commensalism - One organism benefits while the other organism remains neutral
Exploitative Relationships - One organism benefit while the other organism is at a disadvantage
Competition - Both organisms are at a disadvantage
Ammensalism - One organism is at a disadvantage while the other remains neutral
*All interactions limit the distribution and abundance of organisms and are crucial elements which shape an ecosystem
Feeding relationship
Food chain - organisms consume one another, and energy is passed on as one organism consume another. A food chain starts with a producer ( usually a green plant which can photosynthesise and make food)
An example of a food chain:
Grass → Grasshopper→ Frog → Snake → Hawk
Food web - When organisms have more than one feeding relationship, food chains may be interconnected, thus forming a food web. A food web comprises interlinked food chains involving organisms from the same ecosystem.
An example of a food web:
Terms used in food web:
Autotrophs - An autotroph is an organism that produces complex organic compounds from simple inorganic molecules using energy from lighy (by photosynthesis) or inorganic chemical reactions (chemosynthesis). They are able to make their own food and do not use organic compounds as an energy source or a carbon source. Aututrophs can reduce carbon dioxide by adding hydrogen to it to make organic compounds.
Primary producers - Autotrophic organisms that supply energy to all other organisms in the food chain / food web.
Heterotrophs - Organisms which use organic molecules both as a source of carbon and energy, and acquire molecules by feeding on other organisms.
Consumers - Heterotrophic organisms that depend ultimately on producers as energy sources.
Herbivores - Organisms which feed on plants only.
Carnivores - Organisms which feed on other animals only.
Omnivores - Organisms which feed on both plants and animals.
Primary consumers - Organisms which feed on producers.
Secondary consumers - Organisms which feed on primary consumers.
Tertiary consumers - Consumers which feed on secondary consumers.
Decomposers - Organisms which release enzymes to break down large molecules in dead organic matter into smaller ones which can then be recycled.
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