Fact 1: Roundworms may be free-living or parasitic. Fact 2: Nematodes are microscopic roundworms. Given the two facts above, what may be free-living or parasitic?
OPTIONS:
- insects
- parasites
- bushes
- nematodes
- trees
- bacteria
- animals
- Most plants

Answer: nematodes

Fact 1: Having no natural predators increases population size. Fact 2: Population size is a function of natality and mortality. Given the two facts above, having what is a cause of mortality?
OPTIONS:
- natural predators
- seasons
- Abnormal cell growth
- liver cancer
- insects
- chickenpox
- influenza
- sunlight

Answer: natural predators

Fact 1: Mammals have a layer of fat under the skin to help insulate the body. Fact 2: Of the sea mammals, especially the seal and walrus are hunted. Given the two facts above, what has a layer of fat under the skin to help insulate the body?
OPTIONS:
- walruses
- bears
- the Sun
- water
- rabbit
- ice
- animals
- humans

Answer:
walruses