STEM Unit 3
Three energy roles
producer, consumer, decomposer
How is an organism's energy role determined?
how it obtains food and how it interacts with other organisms
Producer
an organism that can make its own food
Consumer
an organism that obtains energy by feeding on other organisms
Herbivores
Consumers that eat only plants
Examples of Herbivores
cow, rabbit, chicken
Carnivores
Consumers that eat only animals
Examples of Carnivores
wolves, walruses, snakes
Omnivores
Consumers that eat both plants and animals
Examples of Omnivores
bears, crows, humans
Scavenger
A carnivore that feeds on the bodies of dead organisms
Examples of Scavengers
catfish, vulture, hyena
Decomposers
organisms that break down biotic wastes and dead organisms and return raw materials to the environment
Examples of Decomposers
mushrooms, bacteria, mold
How does energy enter into most ecosystems?
as sunlight and converted into food by producers
How does energy move through an ecosystem?
when one organism eats another
Food Chain
A series of events in which one organism eats another and obtains energy
Food Web
many overlapping food chains in an ecosystem
Energy Pyramid
A diagram that shows the amount of energy that moves from one feeding level to another in a food web
What type of consumer can be both a first and second level consumer at the same time?
omnivores
How much energy is transferred to the next level in an energy pyramid?
about 10%
What is most of the food energy converted to in each level?
Heat
Where is the most food energy available?
Producer level; first level consumers]
How do human activities affect ecosystems?
Human activities may affect the balance in an ecosystem and thereby change the ecosystem
Examples of human activities affecting ecosystems
overusing resources and using technology in agriculture
Ecosystem
An area where organisms interact with one another as well as with the nonliving parts of it.
How do populations change in size?
when new members join the population or when members leave the population.
Ecologists
scientists who study biotic and abiotic factors of an ecosystem and the interactions between them
Birth Rate
the number of births in a year per 1,000 individuals in a given time period
Death Rate
the number of deaths in a year per 1,000 individuals in a given time period
Population Statement
If birth rate > death rate, population size increases.
If death rate > birth rate, population size decreases.
Immigration
moving into a population
Emigration
leaving a population
Population Density
The number of individuals in an area of a specific size
Population density equation
number of individuals/unit area
Two ways to join a population
birth and immigration
Two ways to leave a population
death and emigration
Limiting Factors
environmental factors that causes a population to stop growing or decrease in size
Examples of limiting factors
food, water, space, weather conditions
Carrying Capacity
The largest population that an area can support
Natural Selection
A process in which an organism gets a characteristic which makes it better suited to a specific environment and may eventually become common in that species.
Adaptations
the behaviors and physical characteristics that allow organisms to live successfully in their environments
Examples of adaptations
giraffe's neck, human's brain, elephant's trunk
Niche
the role of an organism in its habitat
What does a niche include?
what type of food the organism eats, how it obtains this food, what other organisms eat it, when and how the organism reproduces, and the physical conditions it requires to survive.
Three major types of interactions among organisms
competition, predation, symbiosis
competition
the struggle between organisms to survive as they attempt to use the same limited resources
examples of competition
Weeds competing with crops for sunlight, water, and food
Predation
An interaction in which one organism kills another for food or nutrients
Predator
The organism that does the killing in a predation interaction
Prey
The organism that is killed in a predation interaction
Symbiosis
Any relationship in which two species live closely together and at least one of the species benefits
Types of symbiosis
mutualism, commensalism, parasitism
Mutualism
A relationship between two species in which both species benefit
Examples of mutualism
bees and flowers, birds and crocodiles, oxpecker and impala
Commensalism
A relationship between two organisms in which one organism benefits and the other is unaffected
Examples of commensalism
whales and barnacles, remora fish and sharks, trees and birds
Parasitism
A relationship between two organisms of different species with one living inside or on the other where one benefits and the other is harmed
Parasite
An organism that benefits in a parasitism relationship; usually smaller than host
Host
An organism that is harmed in a parasitism relationship
Examples of parasitism
fleas and dogs, cowbird and yellow warbler, fish lice and fish
Interspecific Competition
competition between members of different species
Intraspecific Competition
competition between members of the same species
Hypothesis Format
If, then, because
Examples of Producers
corn, apple, banana