3.3 Flashcards
Trophic Levels
Levels in a food chain or web that represent an organism’s position in the transfer of energy. Primary producers (autotrophs) make up the first trophic level, followed by primary consumers (herbivores), secondary consumers (carnivores), and so on.
Autotroph vs. Heterotroph
Autotroph: Organisms that produce their own food, typically through photosynthesis (e.g., plants).
Heterotroph: Organisms that cannot produce their own food and must consume other organisms (e.g., animals).
Herbivore vs. Omnivore vs. Carnivore vs. Detritivore
Herbivore: Organisms that primarily eat plants.
Omnivore: Organisms that eat both plants and animals.
Carnivore: Organisms that eat only animals.
Detritivore: Organisms that feed on dead organic material, such as decomposing plants and animals.
Keystone Species
A species that plays a critical role in maintaining the structure of an ecological community. Its removal can cause significant changes in ecosystem composition and dynamics.
Trophic Cascade
A phenomenon where changes at one trophic level cause cascading effects at other trophic levels, often initiated by the addition or removal of a top predator.
Describe the differences between food web and trophic cascade diagrams.
Food Web: A network of interconnected food chains showing how different species are related through feeding interactions. It illustrates the flow of energy and nutrients across multiple trophic levels.
Trophic Cascade Diagram: Focuses on the impacts of a top predator on lower trophic levels, emphasizing how changes in one part of the food web can ripple through the system, often leading to indirect effects on other species.
Compare and contrast autotrophs and heterotrophs with examples.
Autotrophs produce their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis); examples include plants and algae.
Heterotrophs obtain energy by consuming other organisms; examples include lions (carnivores), deer (herbivores), and humans (omnivores).
Explain how detritivores and decomposers differ in their ecological roles.
Detritivores consume large pieces of dead organisms or organic waste (e.g., earthworms, woodlice).
Decomposers (e.g., fungi, bacteria) break down complex organic matter into simpler substances, playing a critical role in nutrient cycling.
Identify the trophic levels of organisms in a simple food web including grass, rabbits, foxes, and hawks.
Grass: Primary producer (1st trophic level).
Rabbits: Primary consumers (herbivores, 2nd trophic level).
Foxes: Secondary consumers (carnivores, 3rd trophic level).
Hawks: Tertiary consumers (top predators, 4th trophic level).
Predict how the removal of a top predator, like wolves, would affect a food web.
The removal of wolves could cause an overpopulation of herbivores like deer, which would lead to overgrazing of vegetation. This could reduce plant biodiversity, affect other species dependent on plants, and potentially lead to a trophic cascade.
Using a trophic cascade model, predict how an increase in a keystone predator affects herbivore and primary producer populations.
An increase in a keystone predator typically reduces the herbivore population, allowing primary producers (plants) to flourish due to decreased grazing pressure.
How does the introduction of an invasive species affect trophic levels in a food web?
An invasive species can outcompete native species, disrupt predator-prey relationships, or introduce new diseases, leading to imbalances in the food web and possibly triggering a trophic cascade.
Construct a simple food web involving a keystone species and describe its role.
Sea otters (keystone species) → sea urchins (herbivores) → kelp (primary producers).
Sea otters keep the sea urchin population in check, preventing overgrazing of kelp. Without otters, kelp forests would decline, reducing habitat for other marine species.
Analyze how the introduction of a non-native predator could cause a trophic cascade in an ecosystem.
The introduction of a non-native predator could decimate prey populations, indirectly leading to overpopulation of certain species lower in the food web, or even the decline of key plant species, altering the entire ecosystem structure.
