ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B: Acting as a protective sac surrounding the heart. The pericardium is a double-walled sac that surrounds and protects the heart. It provides physical protection against external forces and prevents overfilling of the heart. Choices A, C, and D are incorrect as they do not accurately describe the function of the pericardium. Choice A refers to the role of heart valves, choice C refers to the role of the heart's electrical system, and choice D refers to the function of the atrioventricular node.

Correct Answer: A

Rationale: The main function of lysosomes is to break down and recycle cellular waste through the process of autophagy. Lysosomes contain enzymes that break down various molecules, organelles, and pathogens. This process helps maintain cellular homeostasis and provides the cell with raw materials for new cell components. Storing carbohydrates (B) is incorrect as lysosomes do not function in this capacity. Synthesizing lipids (C) is incorrect as this is typically the role of the endoplasmic reticulum and Golgi apparatus. Transcribing DNA into mRNA (D) is incorrect as this process occurs in the nucleus by RNA polymerase.

Correct Answer: B

Rationale: The correct answer is B: Pulmonary artery. The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. This is a crucial step in the pulmonary circulation system. The pulmonary vein carries oxygenated blood from the lungs back to the heart, so it does not transport blood from the heart to the lungs. The aorta is responsible for carrying oxygenated blood from the heart to the rest of the body, not to the lungs. The superior vena cava is a large vein that carries deoxygenated blood from the upper body to the heart, not to the lungs. Therefore, the pulmonary artery is the correct choice for transporting blood from the heart to the lungs.

Correct Answer: C

Rationale: The correct answer is C: Buffering system. The body maintains a relatively constant blood pH level through the buffering system, which involves the action of bicarbonate ions, carbonic acid, and other buffering molecules that help regulate pH by neutralizing excess acids or bases. This system acts quickly to prevent drastic changes in blood pH when there are fluctuations in blood carbon dioxide concentration. Cellular respiration (A) generates carbon dioxide, gas exchange (B) involves the exchange of gases in the lungs, and deoxygenation (D) refers to the loss of oxygen by the blood, but these processes are not primarily responsible for maintaining blood pH stability.

Correct Answer: C

Rationale: The correct answer is C because the main function of the pancreas is to produce enzymes that help digest food. These enzymes are released into the small intestine to break down carbohydrates, proteins, and fats. Choice A is incorrect as the pancreas does not store or break down food. Choice B is incorrect as nutrient absorption primarily occurs in the small intestine, not the pancreas. Choice D is incorrect as regulating blood sugar levels is primarily the role of the endocrine portion of the pancreas, not its main function.