Correct Answer: B

Rationale: The correct answer is B: Esophagus. The esophagus is indeed the muscular tube that connects the mouth to the stomach. Food is transported down the esophagus via peristalsis, a series of muscle contractions. The pharynx is the area behind the mouth and nasal cavity, the trachea connects the larynx to the bronchi in the lungs, and the larynx is the voice box located in the throat. Therefore, choices A, C, and D are incorrect in the context of the question.

Correct Answer: C

Rationale: Smooth muscle is the type of muscle tissue that contracts involuntarily and is found in organs like the heart and intestines. Skeletal muscle is responsible for voluntary movements, like those involved in skeletal system actions. Cardiac muscle is found in the heart and contracts involuntarily, but it is distinct from smooth muscle. The heart's muscle is specialized and forms the myocardium, which is not the same as the smooth muscle found in organs like the intestines. Therefore, the correct answer is C) Smooth muscle.

Correct Answer: A

Rationale: Elements within the same group share similar electron configurations in their outermost shells, resulting in comparable chemical properties. Helium and Neon both belong to Group 18 (Noble Gases), explaining their similarities. Boron, Carbon, and Oxygen are not in the same group as Helium on the periodic table. Boron is in Group 13, Carbon is in Group 14, and Oxygen is in Group 16, which are different from Helium's Group 18.

Correct Answer: A

Rationale: The cell membrane, also known as the plasma membrane, serves as a protective barrier for the cell, separating the internal environment of the cell from the external environment. It is selectively permeable, meaning it controls the passage of substances in and out of the cell. This regulation of what enters and exits the cell is crucial for maintaining the cell's internal environment and ensuring proper functioning. Options B, C, and D are incorrect because storing energy, producing proteins, and synthesizing lipids are functions carried out by other cellular structures such as mitochondria, ribosomes, and endoplasmic reticulum, respectively, not the cell membrane.

Correct Answer: A

Rationale: Mitosis is the correct answer because it is the process of cell division that results in the production of two daughter cells with identical genetic material to the parent cell. Meiosis, while also involving cell division, leads to the formation of gametes with half the number of chromosomes as the parent cell. Differentiation is the specialization of cells for specific functions, not the process of cell division. Transformation involves a cell incorporating foreign DNA into its genome, which is unrelated to the division of a cell into two daughter cells.