*Question*
Q: Cells must also be able to separate their relatively stable interior from what? Choices: - their habitat - predators - competition and chaos - the external environment A:
**Answer**
the external environment

*Question*
Q: Ultimately, most life forms get their energy from this? Choices: - heat - earth - food - sun A:
**Answer**
sun

*Question*
Q: What kind of a reaction occurs when a substance reacts quickly with oxygen? Choices: - invention reaction - Fluid Reaction - nitrogen reaction - combustion reaction A:
**Answer**
combustion reaction

*Question*
Q: What type of cellular respiration occurs in the presence of oxygen? Choices: - hyperbaric - anaerobic - extracellular - aerobic A:
**Answer**
aerobic