Q: Which human organ system primarily exchanges gases between the body and the atmosphere?

OPTIONS:
- excretory
- nervous
- skeletal
- respiratory
A: respiratory
Q: A company plants trees on a bare hillside. Which of these is the BEST reason for planting the trees?

OPTIONS:
- The trees provide oxygen for the soil.
- The trees prevent soil from washing away.
- The trees make shade for animals living there.
- The trees cause animals to move to other places.
A: The trees prevent soil from washing away.
Q: Most of the concentration of which gas results from the activity of producer organisms?

OPTIONS:
- nitrogen
- oxygen
- water vapor
- carbon dioxide
A: oxygen
Q: A genetic mutation has caused the fur color of field mice to contrast with their environment. This type of mutation will most likely

OPTIONS:
- benefit the mice.
- harm the mice.
- increase reproductive rates.
- decrease competition for resources.
A:
harm the mice.