Food Webs & Food Chains
Explain why energy decreases as you move up an energy pyramid.
Energy decreases because some is lost as heat at each transfer.
Define what a trophic level is and give one example.
A trophic level is a feeding position in a food chain — producers are first level, consumers are higher.
Differentiate between herbivores, carnivores, and omnivores.
Herbivores eat plants; carnivores eat animals; omnivores eat both.
Identify which spheres interact when plants take in carbon dioxide and release oxygen.
The biosphere and atmosphere interact when plants release oxygen and absorb carbon dioxide.
List one positive and one negative way humans affect ecosystems.
Positive: conservation and recycling; Negative: pollution and deforestation.
Compare energy flow in a food chain vs. a food web.
A food chain is linear, while a food web shows multiple interconnections among organisms.
Explain how organisms at different trophic levels depend on each other.
Energy is transferred when one organism eats another, but some is always lost as heat.
Predict what would happen if decomposers were removed from an ecosystem.
Without decomposers, dead matter would accumulate and nutrients wouldn’t recycle.
Describe how the hydrosphere and atmosphere interact during evaporation.
Water from the hydrosphere evaporates into the atmosphere as vapor during the water cycle.
Predict the effect of deforestation on the carbon cycle.
If deforestation reduces photosynthesis, more CO₂ stays in the air, increasing the greenhouse effect.
Predict what would happen to a forest food web if the primary consumers disappeared.
If primary consumers disappeared, predators would decline from lack of food, and producers might temporarily increase.
Compare trophic levels in a desert and an ocean ecosystem.
Deserts often have shorter food chains; oceans have longer and more complex chains.
Explain how scavengers and decomposers both recycle matter.
Scavengers consume dead organisms; decomposers break them down chemically into nutrients.
Predict what would happen to the biosphere if volcanic eruptions increased globally.
Volcanic ash (geosphere) blocks sunlight (atmosphere), harming plants (biosphere).
Explain how pollution can alter energy flow in aquatic food webs.
Toxins bioaccumulate, moving up food webs and harming top predators.
Analyze how energy efficiency affects top predators in an ecosystem.
Low energy efficiency (only ~10% transfer) limits the population size of top predators.
If 10,000 kcal of energy enters an ecosystem, estimate how much reaches tertiary consumers.
If 1,000 kcal starts with producers, roughly 10 kcal reaches tertiary consumers.
Compare the role of a keystone species to that of a top predator.
Keystone species maintain ecosystem balance; losing them often collapses the system.
Analyze how erosion connects the geosphere and hydrosphere.
Moving water (hydrosphere) erodes rock (geosphere), showing the spheres’ interaction.
Compare renewable and nonrenewable resource use in terms of sustainability.
Renewable resources replenish naturally (like solar, wind); nonrenewables are finite (like coal, oil).
Evaluate why decomposers are essential for maintaining energy balance in ecosystems.
Decomposers recycle nutrients, allowing energy to continue cycling through the ecosystem.
Evaluate the impact of removing a trophic level on the stability of an ecosystem.
Removing a trophic level disrupts energy flow and can destabilize the whole ecosystem.
Assess how humans act as consumers and how this affects natural ecosystems
Humans disrupt food chains through pollution, overfishing, and altering natural habitats.
Evaluate how human activity in one sphere can disrupt another (give an example).
Example: Burning fossil fuels (geosphere) releases gases (atmosphere) that affect climate (biosphere).
Evaluate which human action (pollution, deforestation, overfishing) most threatens biodiversity and why.
Deforestation has the greatest impact — loss of habitat, biodiversity, and climate regulation.