Energy and Sun
What is the main source of energy for almost all ecosystems?
The sun!
What do we call organisms that make their own food using sunlight?
Producers
What is a food chain?
A single linear sequence showing who eats whom.
What does the term "habitat" mean?
The physical place where an organism lives and gets its needs met.
What do decomposers do to help cycle matter in an ecosystem?
They break down dead organisms and return nutrients to the soil for plants to reuse.
Plants capture energy from the sun and store it in their bodies through what process?
Photosynthesis
Give one example of a primary consumer and one example of a carnivore (secondary/tertiary consumer) that might live in a forest.
Primary consumer example: rabbit;
carnivore example: fox or hawk.
What is a food web and how is it different from a single food chain?
A network showing many interconnected food chains; it shows multiple feeding relationships.
Name two resources animals need from their habitat
Food and water (also shelter, space, light, soil nutrients).
Why is it true that "the food of almost any kind of animal can be traced back to plants"?
Because plants capture sunlight to make food; herbivores eat plants and carnivores eat those herbivores — energy traces back to plants.
Explain how energy that animals get from food originally comes from the sun. *keep it brief but accurate!*
Plants capture sunlight and convert it into energy; animals eat the plants - so the energy came from the sun.
Define "omnivore" and give one example
Omnivore: eats both plants and animals, e.g., raccoon or bear.
On a small pond food web, algae are eaten by tiny water animals, which are eaten by fish, which are eaten by herons. If a pesticide kills many tiny water animals, predict two effects on the pond food web.
Fewer tiny animals → less food for fish (fish decrease) → herons may have less food; algae might increase because fewer tiny animals to eat them; overall imbalance.
Define "niche" in one sentence.
A niche is the role an organism plays in its ecosystem, including how it gets food and interacts with others.
Describe in one sentence how nutrients from dead plants return to the soil and become available to new plants.
Decomposers break down dead material into simpler nutrients that are incorporated into soil and taken up by plant roots.
Name two ways energy can be transferred in an ecosystem besides eating (hint: think non-living transfers).
Movement (motion) transfers energy; heat (thermal) energy; light, sound or electrical currents in human-made systems.
Explain why decomposers are sometimes considered "hidden" but essential producers of nutrients.
Decomposers (fungi, bacteria) break down dead material into nutrients that return to soil; they are often microscopic or hidden in soil.
Draw (describe) a simple 3-step food chain that starts with grass and ends with a hawk, naming each level (producer → consumer → consumer).
Example: Grass (producer) → Rabbit (primary consumer) → Hawk (secondary consumer/top predator).
Give an example of how two species might compete in the same ecosystem and one way they could avoid direct competition.
Example: Two bird species eat the same seeds; one feeds at ground level, the other in shrubs (resource partitioning reduces competition).
Explain how energy and matter move differently through an ecosystem (one sentence each).
Energy flows one-way (enters as sunlight, moves through organisms, exits as heat) — Matter cycles (nutrients are reused, recycled through decomposition and uptake).
A wolf catches a rabbit and runs away. Describe two places the rabbit's energy goes after the wolf catches it.
Energy used for wolf's motion and body processes (heat, growth); some lost as heat to the environment; some transferred to decomposition after consumption or when uneaten parts decompose.
A plant is eaten by an insect, which is eaten by a bird, and later the bird dies and is broken down by fungi. Label each organism as producer, consumer (with type), or decomposer.
Plant = producer; insect = primary consumer; bird = secondary consumer; fungi = decomposer.
Explain how removing a top predator from an ecosystem can cause a trophic cascade — give one specific example (brief).
Removing top predator can increase prey populations, which may overconsume plants, reducing habitat and resources for other species (example: wolves removed → deer increase → overgrazing → loss of plant diversity).
An invasive plant species spreads rapidly and replaces native plants. Explain two ways this can affect the local food web and ecosystem health.
Native species loss reduces food sources for native consumers; reduced biodiversity can weaken ecosystem resilience and nutrient cycling; invasive plants may change soil nutrients or shade out young plants.
Design a short investigation idea (2–3 sentences) that uses a model to show how energy moves through a local food web (what you would model and what you'd look for).
Example investigation: Build a paper-model food web of local pond species showing arrows for energy flow; simulate removal of one species and observe predicted changes in energy flow and population sizes.