Answer:
The Laura tried to grow micro-organisms in culture broth medium in Petri-plates but the microbial growth was not observed even on the fourth day of culture which could be due to:
1. Laura could have not provided the correct broth medium maintaining the with pH and salt concentrations.
2. Microorganisms did not get optimal growth conditions.
3. The bacterial source could have died after the collection which could have lysed after their death and thus no longer visible.
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.