Energy & Matter
What process do plants use to make glucose and oxygen from sunlight, CO₂, and water?
Photosynthesis
What is it called when one animal eats another animal?
Predation (predator–prey)
If a population’s resource availability increases, what usually happens to population size?
It usually increases (population growth)
What two components together make an ecosystem?
Living organisms (biotic) and the physical environment (abiotic).
Which of the following is a producer: rabbit, owl, human, or grass?
Grass (producer).
In a food web, what percent of energy is typically passed from one trophic level to the next?
10%
Name the three types of symbiosis and give an example for each.
Mutualism (both benefit — e.g., impala & oxpecker), Commensalism (one benefits, other neutral — e.g., bird using abandoned woodpecker hole), Parasitism (one benefits, other harmed — e.g., roundworms in intestines)
Name two abiotic factors that can affect population size.
Rainfall and sunlight.
Give an example of an abiotic disruption and one biotic disruption.
Abiotic: volcano eruption or fire; Biotic: introduction of invasive species (Nile perch).
Give one clear example of a consumer and say whether it is a herbivore, carnivore, or omnivore.
Example: Rabbit — herbivore; Owl — carnivore; Human — omnivore.
Write the chemical equation (words or symbols) for cellular respiration.
Oxygen + glucose → carbon dioxide + water + energy (ATP)
Define competition and give an example (include organisms)
Competition: species require same limited resources (example: Nile perch competing with cichlids for food)
Look at a population graph that fluctuates (goes up and down). Explain two biological reasons the population might rise and fall over time.
Predator–prey cycles (predator numbers up → prey down → predator down → prey up); resource availability (food, water) fluctuates with seasons or disturbances.
After a large volcanic eruption covers a river and forest with ash, who is more likely to re-establish the base of the food web first: plants or animals? Explain using matter and energy.
Plants — producers must establish to capture sunlight and create matter/energy base for consumers; without producers, consumers cannot be sustained.
Explain how photosynthesis and cellular respiration connect producers and consumers in terms of matter (CO₂, O₂) and energy.
Photosynthesis: producers use CO₂, H₂O, and sunlight to make glucose and O₂. Consumers use O₂ and glucose in cellular respiration to produce CO₂, H₂O, and energy — linking matter and energy flow between producers and consumers.
Explain why energy cannot be recycled in an ecosystem but matter can.
Energy enters ecosystems (sunlight), flows through trophic levels, and is lost as heat so it does not return. Matter (elements like C, H, O) is transformed between organisms and recycled by decomposers.
Describe one way an introduced (invasive) species can change a food web. Provide a short ecological consequence.
An introduced predator can reduce or extirpate prey species without defenses, causing cascading declines or shifts in other species and changing energy pathways.
Describe the transect sampling method in one or two sentences and explain why scientists use it.
Transect: sampling along a line/area to estimate species abundance and spatial patterns; used to compare environments and monitor restoration.
Explain the role of decomposers in cycling matter in an ecosystem. Include two examples of decomposers.
Decomposers break down dead matter and return nutrients to soil/water for producers (examples: fungi, bacteria).
Describe an experiment that shows plants both produce and break down sugars (hint: BTB indicator). What result shows photosynthesis? What result shows respiration?
Experiment: Place a plant in BTB solution in a capped vial. During photosynthesis BTB turns blue (CO₂ used). When plant respires (no light), BTB turns yellow (CO₂ produced).
Using the energy pyramid idea, explain why adding more trophic levels (more predators above existing ones) usually cannot be supported.
About 90% of energy is lost at each transfer; higher trophic levels receive too little energy to support many organisms, so extra levels are unsustainable.
Compare and contrast parasitism and mutualism in terms of benefit/harm to the species involved; include a specific example for each.
Parasitism harms host while benefiting parasite; mutualism benefits both
A species introduced to a lake lacks natural predators and outcompetes native fish. Predict and explain three likely long-term effects on the lake ecosystem (include effects on matter or energy flow).
Effects: native species decline or extinction; altered food web and predator declines or diet shifts; disrupted nutrient cycling and possible economic impacts for humans.
Describe trade-offs people must consider when deciding whether to remove an invasive species. Include at least three different constraints or consequences (e.g., economic, ecological, legal/social).
Trade-offs: ecological risks (non-target harm), economic costs/benefits, legal or social constraints (laws, people depending on invasive species for income), and potential unintended consequences of control methods.
Explain how decomposers support producers and the cycling of matter; include a short chain example starting with producers and ending with decomposers.
Decomposers return nutrients to soil so producers can use them; example chain: Grass (producer) → Grasshopper (consumer) → Mouse (consumer) → Fungi/bacteria (decomposers) → nutrients back to soil for grass.