Q: What signals the secretion of gastric acid? Choices: - hormone - pepsin - leptin - gastrin A:
gastrin

Q: What is required to break bonds in reactants? Choices: - food - gas - protein - energy A:
energy

Q: Q: What basic structures are called the building blocks of life and comprise all living things? Choices: - pigments - seeds - lipids - cells A:
A: cells

Question: Q: The values of which factors are controlled by the experimenter over the course of an experiment? Choices: - other variables - independent elements - independent approaches - independent variables A:
Answer: independent variables

*Question*
Q: What is most of earth's surface covered with? Choices: - insects - sand - silicon - water A:
**Answer**
water

*Question*
Q: What is any nonmetallic, inorganic solid that is strong enough for use in structural applications called? Choices: - tissue - metallic - glass - ceramic A:
**Answer**
ceramic