Energy Flow
What is the ultimate source of energy for most ecosystems?
The sun
What do we call organisms that make their own food?
Producers (autotrophs)
What shape is used to represent energy flow in ecosystems?
A pyramid
What is the relationship called when both species benefit?
Mutualism
What do we call a species that has a large effect on its ecosystem?
Keystone species
What process do plants use to convert sunlight into chemical energy?
Photosynthesis
What type of consumer eats only plants?
Herbivores (primary consumers)
What percentage of energy typically moves from one trophic level to the next?
About 10%
What do we call it when one species hunts another for food?
Predation
What happens to biodiversity if a keystone species is removed?
Biodiversity often decreases
Explain how energy moves from the sun to a top predator.
Sun → producers → herbivores → carnivores
Compare the diets of omnivores and carnivores.
Omnivores eat plants and animals; carnivores eat only animals.
Why is the base of the energy pyramid wider than the top?
Producers capture the most energy, supporting higher levels.
Compare parasitism and commensalism.
Parasitism benefits one and harms the other; commensalism benefits one and doesn’t affect the other.
Predict what might happen to plants if top predators are removed from an ecosystem.
Herbivore populations increase, causing overgrazing.
Why does energy decrease as it moves through trophic levels?
Energy is lost as heat and used in metabolism at each level.
Predict what would happen to carnivores if herbivore populations declined.
Carnivores would decrease due to lack of food.
Compare an energy pyramid with a biomass pyramid.
Both show decreasing energy/biomass, but biomass is physical mass of organisms.
Predict how competition between two species might affect population size.
Both populations may decline due to limited resources.
Explain how invasive species can disrupt energy flow.
They outcompete natives, altering food webs.
Explain why ecosystems can only support a small number of top predators.
Limited energy transfer (≈10% rule) restricts biomass at higher trophic levels.
Argue whether humans should be considered top predators or omnivores in food webs.
Humans eat from multiple trophic levels but aren’t always apex predators.
Explain why eating at lower trophic levels (like plants) is more energy-efficient for humans.
Less energy is lost, so more available energy per calorie consumed.
Explain how species interactions help maintain ecosystem balance.
They regulate populations, control energy flow, and prevent dominance by one species.
Explain how removing one species can cause a trophic cascade.
The loss affects species at multiple levels, disrupting the entire ecosystem.