Salmonella bacteria can cause humans to have stomach cramps, vomiting, diarrhea, and fever. The effect these bacteria have on humans indicates that Salmonella bacteria are

Answer Explanation

A) The stomach - This is an organ of the digestive system. It plays a crucial role in breaking down food through the secretion of gastric juices, which contain enzymes and acids to begin the process of digestion. Therefore, option A is correct.

B) The mouth - The mouth is also an organ of the digestive system. It is where the process of digestion begins, as it is responsible for chewing and breaking down food into smaller pieces. Additionally, saliva produced in the mouth contains enzymes that start the chemical breakdown of food. Therefore, option B is correct.

C) The intestines - Both the small intestine and the large intestine are essential organs of the digestive system. The small intestine is where most of the absorption of nutrients from food occurs, while the large intestine absorbs water and salts from the material that has not been digested. Therefore, option C is correct.

D) The heart - The heart is not an organ of the digestive system. Instead, it is a part of the circulatory system responsible for pumping blood throughout the body. While the circulatory system works in conjunction with the digestive system to transport nutrients absorbed from the intestines to various tissues and organs, the heart itself is not directly involved in digestion. Therefore, option D is incorrect.

Answer Explanation

The action of enzymes vary with pH. Enzymes are proteins that catalyze biochemical reactions, and their activity is influenced by various factors including pH.

The pH level affects the ionization state of amino acid residues within the enzyme's active site. This, in turn, can affect the enzyme's ability to bind substrate molecules and catalyze reactions.

Different enzymes have different optimal pH ranges at which they exhibit maximum activity. This optimal pH range is determined by the specific environment in which the enzyme typically functions. For example, pepsin, which is involved in digesting proteins in the stomach, works optimally at an acidic pH around 2, whereas enzymes in the small intestine function optimally at a slightly alkaline pH around 7 to 8.

Extreme deviations from the optimal pH can denature enzymes, causing them to lose their structure and function. Therefore, maintaining the appropriate pH level is crucial for ensuring the proper functioning of enzymes in biochemical reactions.

Answer Explanation

C) polysaccharide that is synthesized and stored within the human liver

- Correct: Glycogen is a polysaccharide, which means it is a complex carbohydrate composed of many glucose molecules linked together. It is synthesized and stored primarily in the liver and muscles of humans and other vertebrates. Glycogen serves as a form of energy storage, allowing organisms to store glucose for later use when energy demands are high or when glucose availability is low.

A) complex carbohydrate that is often stored in red blood cells

- Incorrect: While glycogen is a complex carbohydrate, it is not stored in red blood cells. Red blood cells do not contain nuclei or organelles, including glycogen storage structures.

B) complete protein necessary for the synthesis of cell membranes

- Incorrect: Glycogen is not a protein. It is a carbohydrate used for energy storage. Proteins are composed of amino acids and are involved in various cellular functions, including the synthesis of cell membranes, but glycogen does not play a direct role in this process.

D) by-product of sucrose digestion within the pancreas

- Incorrect: Glycogen is not a by-product of sucrose digestion within the pancreas. Sucrose is a disaccharide composed of glucose and fructose, and it is broken down into its component sugars by enzymes in the small intestine, not the pancreas. Glycogen is synthesized and stored in the liver and muscles as a form of energy storage.