Q: What kind of structure do purines have? Choices: - triple ring structure - single ring structure - helical stucture - double ring structure A:
double ring structure

(Question)
Q: What is the network of fibers that organizes structures and activities in the cell called? Choices: - enzymes - cytoplasm - DNA - cytoskeleton A:
(Answer)
cytoskeleton

Ques: Q: What are solutions that maintain a relatively constant ph when an acid or a base is added? Choices: - gases - water - liquids - buffer A:
Ans: buffer

(Q).
Q: When an action and reaction occur, what is transferred from one object to the other, yet in combination it remains the same? Choices: - matter - force - energy - momentum A:
(A).
momentum

Ques:Q: A life cycle continues through reproduction and what? Choices: - response - mechanical - example - development A:

Ans:development

Q: What do scientists use to help explain objects or systems in simpler ways? Choices: - theories - measurements - plants - models A:
models