Question

Match the term to the correct definition:(5 points)
Predator
Competition
Mutualism
Abiotic Factor
Producer
Which example BEST represents commensalism?(1 point)

A tapeworm harming a human

A bird eating insects off a zebra

A remora attaching to a shark and eating leftover food

A bee pollinating a flower

What happens when a needed resource becomes scarce in an ecosystem?(1 point)

Populations increase

Competition decreases

Competition increases and some organisms die

All organisms adapt immediately
Predators help keep prey populations from becoming too large.(1 point)

True

False
Invasive species usually help native organisms survive.(1 point)

True

False
Explain how changes in resource availability can affect populations in an ecosystem. Include what happens when resources are plentiful versus scarce, and provide one example from the unit (e.g., garlic mustard, curlew population, drought, etc.)

​(4 points)

Answer 1

Match the term to the correct definition
- Predator — An organism that hunts, kills, and eats other organisms (its prey).
- Competition — Interaction in which two or more organisms vie for the same limited resources (food, space, light), reducing fitness of one or both.
- Mutualism — A relationship between two species in which both benefit.
- Abiotic factor — A nonliving physical or chemical part of the environment (temperature, water, sunlight, soil).
- Producer — An autotroph (e.g., plants, algae) that makes organic food from sunlight or chemicals (photosynthesis/chemosynthesis).

Which example BEST represents commensalism?
- A remora attaching to a shark and eating leftover food

What happens when a needed resource becomes scarce in an ecosystem?
- Competition increases and some organisms die

Predators help keep prey populations from becoming too large.
- True

Invasive species usually help native organisms survive.
- False

Explain how changes in resource availability can affect populations in an ecosystem (4 points)
- When resources are plentiful, organisms generally have higher survival and reproduction rates, so populations grow and can approach a higher carrying capacity; competition is low and more individuals survive to reproduce.
- When resources become scarce, competition intensifies; birth rates decline, death rates rise, some individuals migrate, and weaker populations can decline or go locally extinct.
- Scarcity can also change species interactions (e.g., increased predation or disease spread) and allow opportunistic or invasive species to take over.
- Example: Garlic mustard (an invasive plant) outcompetes native understory plants for light and nutrients; as garlic mustard spreads, native plant populations decline, which reduces food and habitat for native insects and animals, causing declines in those populations.