September 9, 2022
Factors Affecting Living Organisms
Here's some highlights in IGCSE biology curriculum:
- Predators
- Parasites
- Disease
- Climate (i.e. Temperature, oxygen levels, rainfall quantity and light intensity)
- Intraspecific Competition (i.e. within the species for food, territory, shelter and mates)
- Interspecific Competition (i.e. between species for food, shelter and space)
- Soil/Substance (i.e. rock, sand, soil, clay or marsh)
Factors Affecting Population Size
Immigration (moving to)
- For the substance of the ground and the environment
- For food- quality, quantity, and what it is
- Space
Emigration (moving away)
- Because predators are in abundance
- Loss of habitat- either through human interference or naturally.
- Lack of food
- Lack of space
Birth
- Disease
- Predators
- Food
Death
- Disease
- Predators
- Food
Ecosystems
- Ecosystem - a distinct, self-supporting system of organisms interacting with each other and with their physical environment.
- Population - all the organisms of a specific species living in an ecosystem at a particular time.
- Community - all the populations of living organisms living in an ecosystem at a particular time.
- Habitat - a place where specific organisms live
- Quadrats - used to sample a distribution of organisms in their habitats and to estimate the population size of an organism in different areas.
- Substances and energy are transferred along food chains.
- Only about 10% of available energy is transferred.
In IGCSE biology, an ecosystem contains many living organisms that interact through feeding relationships. Plants are producers because they produce their food through photosynthesis. Animals are consumers- they eat other plants or animal to get their energy. Decomposers are organisms such as bacteria and fungi that breakdown and decompose dead materials and waste products to recycle their nutrients.
Feeding Relationships
There are four main ways to show feeding relationships in IGCSE biology:
- Food Chains
- Food webs
- Pyramids of number
- Pyramids of biomass
End of part I (remember to read part II)
Drafted by Gina (Biology)