Which type of organism would most likely benefit directly from increased levels of CO_{2}? OPTIONS:
- fish
- bird
- tree
- mushroom
A: tree

Sodium bicarbonate (NaHCO_{3}) is commonly known as baking soda. Sodium bicarbonate is a white solid that can dissolve in water. Under the proper conditions, sodium bicarbonate can release carbon dioxide (CO_{2}) gas. Which of the following is not a physical property of sodium bicarbonate? OPTIONS:
- It is white.
- It is a solid.
- It can dissolve in water.
- It releases carbon dioxide.
A: It releases carbon dioxide.

A solar cell turns sunlight into another form of energy. A solar cell is most like what natural structure? OPTIONS:
- an elephant's ears
- a plant's leaves
- a deer's hooves
- a tree's roots
A: a plant's leaves

An atom will always have OPTIONS:
- a single, negatively-charged nucleus.
- equal numbers of protons and electrons.
- "shared" electrons from another atom.
- a stable number of charged neutrons.
A:
equal numbers of protons and electrons.