Ecosystems
What term describes all the living things in an area and the nonliving parts they interact with?
Ecosystems
What is a food web?
A network of many interconnected food chains showing who eats whom
What word describes the process of creating offspring?
Reproduction
If a mouse is eaten by a snake, what is the mouse called?
Prey
What do food chains show?
Energy flow in a food chain (who eats whom)
Name one limiting factor that can reduce a population's size.
Example: food, water, shelter, space, disease, predators, climate
In a food web, which direction do arrows point: from the eater to what it eats, or from the eaten to its eater?
Arrows point from the organism being eaten to the organism that eats it (from resource → consumer).
If the number of births equals the number of deaths in a population over many years, what happens to the population size?
Population size stays about the same (stable).
What happens to a prey population if predator numbers increase? Choose: decrease, increase, remain the same.
Prey will decrease
Name three energy storage molecules broken down by organisms for energy.
Starch, glucose, and fats (or proteins, starch, fats — acceptable if students justify)
If plants in an ecosystem are removed, what immediate effect will primary consumers experience?
Primary consumers will have less food and likely decrease.
In a food web that shows grass → rabbit → hawk, what role does the rabbit play?
Primary consumer (herbivore
A deer population decreased over 50 years. Which explanation is best: more births than deaths, or fewer births than deaths?
Fewer deer were born than died (this explains a decrease
In a lake, small fish decline. Predict what will happen to large fish that eat them and explain why.
Large fish will decrease because their food source is reduced
Why do birds such as eagles and hawks need energy? Choose the best answer: breathing, flying, digesting food, or all of the above.
All of the above
Explain why biodiversity can help an ecosystem recover from a disturbance
Biodiversity provides multiple species that can fill roles; if one species declines others can help maintain ecosystem functions.
If a disease reduces the rabbit population, predict two likely changes elsewhere in the food web and explain why
Example: grass may increase (less eaten by rabbits); hawk population may decrease (less food). Explain: fewer rabbits = less food for predators; producers may face reduced grazing.
Define "competition" in an ecosystem and give one example from the unit.
Competition: when two or more populations use the same resource (example: rabbit and mouse both eat grasses).
Coyotes and wolves both eat deer. If wolf numbers increase, explain the likely effect on coyote numbers and why
Coyote population will likely decrease because wolves reduce deer numbers or outcompete coyotes for food; less food = fewer births than deaths.
In the sequence sun → grass → grasshopper → bird → cat, what is the cat’s role?
Predator (secondary/tertiary consumer depending on chain).
Describe how removing a top predator can cause a trophic cascade. Give one specific example
Removing a top predator often increases prey populations, which can overconsume producers (e.g., fewer wolves → more deer → overgrazing → loss of plant species).
Explain why a food web is better than a single food chain for predicting how species populations will change
Food webs include multiple feeding links so they show alternate food sources and indirect effects, giving more accurate predictions of population responses.
Describe how carrying capacity limits population growth and name two factors that determine carrying capacity
Carrying capacity is the max population an environment can support; determined by resources like food and water, and factors like space and predation.
Describe how predator-prey relationships can produce population cycles (two or three sentences; include the mechanism).
Predator increases reduce prey, causing predator numbers to fall later due to less food; then prey recover, producing cycles.
Explain how energy flows through an ecosystem and why there is less energy available at higher trophic levels
Energy enters as sunlight captured by producers, flows to consumers; energy is lost as heat at each transfer, so less is available at higher trophic levels.