Module 3: Ecosystems Flashcards
What is an ecosystem?
Any group of living organisms and non living things occurring together, and the interrelationships between them.
components of an ecosystem = habitat + population + community
Habitat
The place where an organism lives
Population
All the organisms of one species that live in the same place at the same time and can breed together.
Community
All the populations of different species that live in the same place at the same time and can interact with each other,
Niche
The role that each species plays in an ecosystem.
e.g. how and what an organism feeds on, what it excretes, how it reproduces etc. It is impossible for two species to occupy exactly the same niche in the same ecosystem.
Biotic Factors
How living organisms in an ecosystem affect each other. e.g. food supply, predation and disease.
Abiotic Factors
the effects of the non living components of the ecosystem. e.g. pH, temperature and soil type.
Why are ecosystems considered ‘dynamic’?
As a result of the community of living things in an ecosystem interacting with one another and their physical environment, population sizes will rise and fall almost constantly. Any small changes in one population will affect another.
e. g.
- if a predators population size increases the population of the prey will decrease as more are being eaten (biotic factor)
- If nitrogen fixing plants begin to grown in nitrogen deficient soils, the soil nitrogen levels would increase, encouraging other plants to grow there as well. (abiotic factor…/biotic?)
Producers
Organisms that convert energy from the environment (and small inorganic molecules) in to large complex organic molecules. e.g. plants, algae and some bacteria. (Autotroph)
- Phototrophs- plants: convert light energy in to chemical energy
- Chemotrophs- bacteria: (near thermal oceanic vents) use chemical energy to from large complex organic molecules.
Consumers
Organisms that feed on other organisms and digest complex organic molecules- products are used for growth or as substances in respiration. (Heterotroph)
Decomposers
Organisms that feed on dead or waste organic material. They gain energy by digesting and respiring complex molecules in the organic matter. They cause decay and food to go off. e.g. bacteria, fungi and some animals
Why do two species never occupy exactly the same niche in the ecosystem?
If they occupy the same niche they will compete. One will be better at competing than the other, and will survive and reproduce whereas the other will fail to reproduce and will die out.
