[Q]: The growth of which of the following usually occurs first in primary succession on a bare rock?
===
OPTIONS:
- Lichens
- Grasses
- Trees
- Shrubs
****
[A]: Lichens

[Q]: A sound is heard when you pluck a string on a guitar. What will happen to the sound if the same string is plucked harder?
===
OPTIONS:
- The volume will stay the same, and the pitch will be higher.
- The pitch will stay the same, and the volume will be higher.
- Both the pitch and the volume will be higher.
- Both the pitch and the volume will stay the same.
****
[A]: The pitch will stay the same, and the volume will be higher.

[Q]: Which situation is the best example of ecological succession?
===
OPTIONS:
- An organism survives a difficult winter.
- The populations in an area remain the same.
- One species replaces another species in an ecosystem.
- Each of several species uses the same amount of resources.
****
[A]:
One species replaces another species in an ecosystem.