*Question*
Q: Each endocrine hormone affects only certain "target" cells, which have molecules of what on the surface that enable binding of a given hormone? Choices: - lipids - rna - gas - protein A:
**Answer**
protein

*Question*
Q: What is another name for mother of pearl? Choices: - pigment - enamel - calcium - nacre A:
**Answer**
nacre

*Question*
Q: What are used to balance chemical equations? Choices: - isotopes - densities - outputs - coefficients A:
**Answer**
coefficients

*Question*
Q: What does a healthy immune system fight off? Choices: - microorganisms and other dieases - respiratory and other dieases - bacteria and viruses - infections and other dieases A:
**Answer**
infections and other dieases