Ecology

Definitions: 
Habitat - where an organism lives
Population -  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


Abiotic factors:

Factor	Examples of how factor influences life
Temperature	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.
pH
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 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 impairs the ability of plants to photosynthesize.
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.

Biotic factors:

Interaction	Organism A	Organism B	Example
Mutualism	+	+	Lichen
Commensalism	+	0	Remora fish and Shark
Exploitative Relationships (Predation, Parasitism, Herbivory)	+	-	Snake and Rabbit
Competition	-	-	Snake and Eagle have similar feeding habits
Ammensalism	-	0

Food Chain


Definition:


A food chain is a diagram, of some sort, that describes how energy is passed from one living thing to the other in a community.



Food Web


Definition:


A food web comprises interlinked food chains involving organisms from the same ecosystem.


The need to conserve environment

We conserve to:

• prevent extinction of plant and animal species
• maintain a stable and balanced ecosystem, prevents disruption of natural cycles such as water and carbon cycles; also prevents global warming
• maintain large gene pool, preserve favourable genes; helps to improve agricultural produce or crops with better resistance to diseases 
• conserve marine life as a food source
• scientific value – study of evolution
• nature appreciation – recreational purposes such as hiking, fishing, skiing
• maintain biodiversity – economical, medical and industrial uses

Carbon Cycle

• photosynthesis
• respiration
• excretion and egestion
• decomposition
• destruction of vegetation
• sedimentation and mineralization
• dissolution (chemical weathering)
• combustion