Answer:
1- It's often impossible to repeat trials on the same subjects. 2-Subjects may report an inaccurate medical history. 3-It can be difficult to control all possible variables. 4-It's impossible to come up with testable scientific questions for human subjects.
Explanation:
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Answer:
The fact that both strands are used as templates for DNA replication the response would be the first one.
The cytoskeleton helps the cell maintain its shape and internal organization.