Biodiversity & Survival
A population survives a new disease because some individuals possess different alleles that provide resistance. What characteristic makes this possible?
Genetic diversity
A bacterial population doubles every hour. What type of growth does this represent when resources are unlimited?
Exponential growth
What term describes the maximum population size an environment can sustainably support?
Carrying capacity (K)
A bird eats parasites off a mammal, and both organisms benefit. What type of symbiosis is this?
Mutualism (+/+)
Oak trees occasionally produce unusually large crops of acorns. What is this called?
Bumper crop / mast year
A bird can eat many different foods and survive in forests, cities, and grasslands. Is it a generalist or specialist?
Generalist
A population increases by 50 individuals every year. What growth model describes this pattern?
Linear growth
A mosquito produces hundreds of eggs, matures quickly, and provides little parental care. Is it r-selected or K-selected?
r-selected
A horsehair worm lives inside a praying mantis and harms it. What relationship is this?
Parasitism (+/−)
A large acorn crop allows more mice to survive and reproduce. What might happen to gypsy moth populations?
Moth populations may decrease because mice eat their pupae
A wildfire reduces a population from 3,000 to 40. It eventually recovers to 2,000. Why might it remain vulnerable to environmental changes?
Genetic bottleneck reduced genetic diversity
A deer population increases rapidly, then slows and stabilizes near 800. What growth model does this represent, and why?
Logistic growth; population approaches carrying capacity
A hurricane destroys 40% of a bird population's nesting habitat regardless of population density. Is this density-dependent or independent?
Density-independent
Remoras create drag on sharks, increasing their energy use. Why might commensalism no longer be the best classification?
The shark experiences a cost, suggesting a potentially parasitic relationship
Why can a growing white-footed mouse population increase the risk of Lyme disease?
Mice are reservoirs of Lyme disease bacteria that ticks can acquire
A Canadian lynx relies heavily on snowshoe hares, while a wolf eats many prey species. If hare populations collapse, which predator is more affected, and why?
Canadian lynx; it depends heavily on one prey species
A bacterial population begins with 100 organisms and doubles every hour. How many bacteria will there be after 4 hours?
1,600 bacteria
A contagious disease spreads faster as deer become crowded together. Explain why this is density-dependent.
Higher density increases contact and disease transmission
After wolves return to Yellowstone, elk browsing decreases and willow trees recover. How could this increase beaver populations?
More willow trees provide food and building materials for beavers
If most mice disappear from an oak forest, predict one possible benefit and one ecological cost.
Benefit: potentially less Lyme transmission; cost: more moths and defoliation
Conservation managers can breed 20 closely related endangered animals or 20 genetically diverse animals. Which strategy better supports population resilience, and why?
Genetically diverse animals; preserves alleles and reduces inbreeding risks
Two populations start with 100 animals. Population A increases by 20 annually; Population B increases by 20% annually. Which eventually grows faster, and why?
Population B; exponential growth adds increasingly larger numbers
A lake supports 500 fish. After pollution reduces food and oxygen, the population stabilizes around 300. What happened to carrying capacity, and why?
Carrying capacity decreased because resources became limited
Scientists observe more beavers after wolves return to Yellowstone. Why is this correlation insufficient to prove wolves caused the increase?
Other factors could explain the increase; correlation alone does not establish causation
Why might eliminating mice to reduce Lyme disease be a poor long-term strategy for managing an oak forest?
Mice control moth populations while also serving as reservoirs of Lyme disease bacteria