Q: Plants make sugars in the presence of sunlight in a process called photosynthesis. What form of carbon do the plants take in for this process?

OPTIONS:
- glucose molecule
- carbon dioxide
- single carbon atoms
- complex organic compounds
A: carbon dioxide
Q: Which human organ system primarily exchanges gases between the body and the atmosphere?

OPTIONS:
- excretory
- nervous
- skeletal
- respiratory
A: respiratory
Q: Which illness is always caused by an infection?

OPTIONS:
- a heart attack
- a broken bone
- influenza
- cancer
A: influenza
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.