Populations and Ecosystems Concepts
Initial perceptual naive misconceptions (any age)
- A change in a food web will only affect animals that prey on it.
- An animal that is high on the food web preys on all populations below it.
- A change in the prey population has no affect on the predator.
- If the size of one population in a food web is changed, all other populations in the web are changed in the same way.
- A food web is a food chain
- Animals are carnivores if they are big and ferocious. Herbivores are small and timid.
- Don't add plants to the web only prey and predator.
- See the top of the web as having the most energy. Or energy accumulates at the top.
- Populations on the top increase as the organisms below decrease.
- Characteristics of a population are created according to the needs of the individual or according to a predetermined grand plan.
- Characteristics are passed on by the bigger stronger organisms.
- Populations are either in equilibrium or decreasing depending on their position in the web.
- The needs and roles of a species are the same as those of similar species.
- Species live together in an ecosystem because they have compatible needs and behaviors.
- Plants rely on carbon dioxide from animals.
- Do not understand that animals energy comes from the sun.
- Deserts are dead waste lands where nothing could live or thrive.
Beginning (preschool - 7 years)
- A population consists of all individuals of a species that occur together at a given place and time
Intermediate (7 years - 11 years)
- Populations of organisms can be categorized by the function they serve in a community (producer and consumer).
- Plants and some microorganisms are producers- they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms.
- The population of an ecosystem depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition.
- Given adequate biotic and abiotic and no disease of predators, populations (including humans) increase at rapid rates.
- Lack of resources and other factors, such as predation and climate, limit the growth of a population in specific niches in the ecosystem.
- Relationships may be competitive or mutually beneficial.
- Some species have adapted to each other to the point that they could not survive without each other.
- Food chains identify the relationships among producers and consumers.
- Food cycle includes producers, consumers, and decomposers.
- Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem.
- An ecosystem includes all populations living together and the physical environmental factors with which they interact.
- For ecosystems, the major source of energy is sunlight which is transferred by producers into chemical energy through photosynthesis.
- That energy then passes from organism to organism in food webs.
- Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food.
- In the process of decomposing organic matter they create nutrients for plants.