Q: Which list contains only things that are part of our solar system? ---- OPTIONS:
- planets, moons, comets
- galaxies, quasars, asteroids
- black holes, novas, stars
- clusters, asteroids, meteors

A: planets, moons, comets

Q: A scientist combines oxygen and hydrogen to form water. This combination illustrates that water is ---- OPTIONS:
- an atom.
- an element.
- a mixture.
- a compound.

A: a compound.

Q: Although change in multicellular species usually takes thousands of years, some species of bacteria undergo major changes in just a few years. One reason for this difference is that these bacteria ---- OPTIONS:
- are microscopic
- do not contain DNA
- reproduce very quickly
- cause infectious diseases

A: reproduce very quickly

Q: Which species have been on the Earth for the shortest amount of time? ---- OPTIONS:
- Humans
- Insects
- Fish
- Reptiles
A: Humans