Learning Targets: Organisms and the Environment – Relationships within Food Webs
ANSWER KEY
Objectives/TEKS
TEK 8.11A - Describe producer/consumer, predator/prey, and parasite/host relationships as they occur
in food webs within marine, freshwater, and terrestrial ecosystems.
TEK 8.11B – Investigate how organisms and populations in an ecosystem depend on and may compete
for biotic and abiotic factors such as quantity of light, water, range of temperatures or soil composition.
TEK 7.10B – Describe how biodiversity contributes to the sustainability of an ecosystem.
TEK 7.11C – Identify some changes in genetic traits that have occurred over several generations through
natural selection.
*Complete the following using your BOSS and science workbook.
*Write the page # that you found the information in the column to the right.
Describe the relationship between producers and consumers in a food web.
Producers are plants that are photosynthetic and get energy through photosynthesis. Consumers
are animals that have to eat to get energy.
Explain the difference between primary, secondary and tertiary consumers.
Primary consumers are the 1st consumer in a food chain that eat the producers. Secondary
consumers eat the primary consumer, the tertiary consumers eat the secondary consumers and so
on. Consumers can be more than one type depending on what all they eat.
Describe the relationship between a predator and prey in a food web.
Predators are animals that kill and eat another animal. Prey are the animals that are killed and
eaten by a predator.
Explain parasitism and describe the relationship between a parasite and a host in a food web.
Parasitism is a symbiotic relationship between organisms in which one organism, the parasite, is
benefited and the other organism, the host, is harmed. Parasites are like ticks, fleas or worms that
feed off a host organism for energy.
Explain what marine, freshwater and terrestrial ecosystems are.
Marine ecosystems are salt water/ocean ecosystems. Freshwater ecosystems are the lakes, ponds,
rivers, streams, wetlands, and estuary ecosystems that are freshwater. Terrestrial ecosystems are
any land ecosystem such as deserts, grasslands, forests etc.
Differentiate between abiotic and biotic factors organisms depend on and compete for in an ecosystem.
Abiotic factors are non-living things in the environment such as water, air, and heat. Biotic factors
are living things in the environment such as plants and animals needed for food, mates, and or
shelter.
Define an organism’s habitat and niche.
An organisms habitat is where it lives and its niche is the role it plays in its environment like what
it eats and where it lives.
Explain how an organism’s niche within an ecosystem affects other organisms.
Organisms that have the same niche compete more for resources because they have the same
habitat and eat the same food sources.
Define competition and explain how organisms may compete for resources.
Competition is when plants and animals compete for resources such as sunlight, water, food, space
etc.
Plants compete for sunlight, water, nutrients in soil and space
Animals complete for food, water, space, shelter and mates
Explain how resources in an ecosystem may be affected by competition.
If there is too much competition then available resources such as food and water will decrease and
may even be completely depleted
Define biodiversity and sustainability and explain how they relate in an ecosystem.
Biodiversity is the differences in living organism within an ecosystem. The greater the variety of
organisms the more sustainable the food web and survival of the ecosystem.
Page
#
Define natural selection and explain how it works.
Natural selection is the process in which organisms with favorable traits are able to survive and
reproduce and pass those favorable traits on to subsequent populations.
Explain favorable traits and how they help populations adapt over time?
Organisms with favorable traits are better able to survive and reproduce passing down those traits
to the next generation which allows a population to be better adapted to their environment over
time.
Explain what limiting factors are in an ecosystem and give examples
Limiting factors are factors that limit the population of a species such as food, water or space.
Explain what the carrying capacity of an ecosystem is and how it affects populations of organisms.
The carrying capacity of an ecosystem is the maximum number of a population that it can support.
If a population goes over the carrying capacity then organisms within that population will die or
have to migrate.
Vocabulary – Make sure that you can define all the following terms.
Ecology
Energy Pyramid
Niche
Prey
Resources
Limiting Factors
Ecosystem
Individual
Producer
Parasitism
Abiotic Factors
Carrying Capacity
Organism
Population
Consumer
Parasite
Biotic Factors
Natural Selection
Food Chain
Food Web
Community
Habitat
Decomposer
Predator
Host
Competition
Biodiversity
Sustainability
Favorable Genetic Traits