During a lecture, a professor was talking about the potential that hydrogen has for exploding under certain conditions. Which was most likely the topic of the professor's lecture? OPTIONS:
- Conductivity of Gases
- Phase Changes in Matter
- Chemical Properties of Gases
- Physical Properties of Elements
A: Chemical Properties of Gases

Which type of water reservoir contains the largest volume of fresh water? OPTIONS:
- lakes
- rivers
- ice sheets
- aquifers
A: ice sheets

Which best describes two organ systems working together to help maintain homeostasis? OPTIONS:
- The reproductive organs produce sex cells.
- The nerves carry signals from the eye to the brain.
- The bones and muscles of the hand work together to grip a pencil.
- The muscles of the chest tighten to push carbon dioxide out of the lungs.
A: The muscles of the chest tighten to push carbon dioxide out of the lungs.

What is a benefit of the regulation of gene expression? OPTIONS:
- conservation of genetic information
- conservation of cell resources
- trait adaptation to environmental change
- trait inheritance in offspring
A:
conservation of cell resources