Answer: A protein's specific shape determines its function.
Explanation: If the three-dimensional structure of the protein is altered because of a change in the structure of the amino acids, the protein becomes denatured and does not perform its function as expected.
A dog breathes in oxygen and then releases carbon dioxide when he exhales. Conversely, a tree gives off oxygen and takes in carbon dioxide. So the breath of the dog sustains the tree while the output of oxygen for the tree sustains the dog.
The stage that scientists begin to ask questions and attempt to explain observations is A. forming hypotheses. This is because a hypothesis is basically a testable question about observations scientists make.
