Answer: B
Explanation: The other answers are talking about similarities among different species.
1. Our results showed that test tube B contained end products of protein digestion, meaning that the isolated enzyme has the ability to break down protein. The end products of protein digestion include small polypeptides, dipeptides, and amino acids. In general, test tube B will contain the building blocks of proteins, which are the amino acids.
2. The two test tubes were placed in a hot water bath at 37oC. This is because the enzyme studied is a human enzyme and it works best at the human body temperature, which is approximately 37oC.
Enzymes are biological catalysts, which means that they accelerate chemical reactions. As a result, an enzyme's activity is greatly affected by temperature. Every enzyme, depending on each function and origin, has a specific range of ideal temperature conditions. If the temperature rises above the maximum accepted, then the enzyme denatures and loses its structure.
3. If the enzyme studied was added in a tube containing starch instead of proteins, then nothing would happen. This is because the enzymes are highly specialized and have very specific actions. It has been proved that this enzyme's activity involves the digestion of proteins.
Starch is a polysaccharide produced by plants, this means that starch is a carbohydrate. Given that starch is not a protein, it will not be digested by the enzyme. An enzyme digesting proteins, will not have any effect on carbohydrates.
4. The smaller molecules which are the result of the digestion happening in the digestive system are absorbed by the human body. More specifically, the products of protein digestion are absorbed by the intestine and then transported into the bloodstream. From the blood, they are then absorbed by other tissues.
After they are absorbed, they are used to build muscles or other compounds which can produce energy.
The correct answer is option C. Endocrine glands secrete hormones into the bloodstream because endocrine glands are ductless and the exocrine glands have ducts so they secrete their hormones into the ducts.
