question:
Which of the following is formed immediately after fertilization?
OPTIONS:
- egg
- sperm
- zygote
- embryo

answer:
zygote

question:
If wolves prey on deer for food, what will most likely happen to the deer population if wolves are removed from an area where deer live?
OPTIONS:
- The population of deer will increase.
- The population of deer will decrease.
- The population of deer will remain the same.
- The population of deer will become extinct.

answer:
The population of deer will increase.

question:
As the human population increases, more fossil fuels are being used. The burning of fossil fuels produces greenhouse gases. How might humans reduce greenhouse gases?
OPTIONS:
- Buy cars that use gasoline.
- Build power plants that use coal.
- Use renewable resources to generate power.
- Use nonrenewable resources to generate power.

answer:
Use renewable resources to generate power.

question:
Which human body system attacks viruses and bacteria once they have invaded the body?
OPTIONS:
- circulatory
- endocrine
- digestive
- immune

answer:
immune