*Question*
Q: What is most often the cause of encephalitis? Choices: - parasites - bacterial infections - calcium buildup - viruses A:
**Answer**
viruses

*Question*
Q: What is the enclosed, fluid-filled membrane that surrounds and protects the fetus and is attached to the placenta? Choices: - epithelial sac - umbilical sac - womb - amniotic sac A:
**Answer**
amniotic sac

*Question*
Q: In studying energy, what term do scientists use to refer to the matter and its environment involved in energy transfers? Choices: - molecule - ecosystem - world - system A:
**Answer**
system

*Question*
Q: What important liquid is stored throughout the earth in the oceans, underground, and in ice? Choices: - oil - lava - air - water A:
**Answer**
water