What do positive feedback mechanisms do?

Correct Answer: B

Rationale: Positive feedback mechanisms amplify or increase changes in a system, moving conditions away from the normal state. This makes choice B the correct answer. Choice A is incorrect as positive feedback does not cause long-term changes but rather accelerates deviations from the norm. Choice C is incorrect because positive feedback does not bring conditions back to normal; instead, it amplifies deviations. Choice D is incorrect as positive feedback does not usually lead to stable conditions but rather to further deviations from the normal state.

Correct Answer: B

Rationale: Homeostasis is the body's ability to maintain stable internal conditions despite external changes. To achieve this balance, concentrations of essential substances must remain within specific ranges. Choice A is incorrect because decreasing concentrations would not maintain stability. Choice C is incorrect as increasing concentrations when the body is stressed would disrupt homeostasis. Choice D is incorrect as fluctuating greatly between high and low values would also not support the body's stability. Therefore, the correct answer is B, as it aligns with the concept of homeostasis by emphasizing the need for stability within certain limits.

Correct Answer: A

Rationale: The correct answer is A: visceral pleura. The membrane covering the surface of the lungs is called the visceral pleura. It is a serous membrane that is in direct contact with the lung tissue. Choices B, C, and D are incorrect because the parietal pleura covers the inner surface of the chest wall and diaphragm, the visceral pericardium covers the surface of the heart, and the parietal pericardium is the outer layer of the pericardium surrounding the heart, respectively.

Correct Answer: A

Rationale: The parietal pericardium is a tough, fibrous outer layer that is attached to the diaphragm and the sternum but not directly to the surface of the heart. It forms a sac around the heart known as the pericardial sac. Therefore, the statement that the parietal pericardium is attached to the surface of the heart is false.

Correct Answer: D

Rationale: Cell death, also known as apoptosis, first occurs during fetal development when specific cells are programmed to die. This process is essential for shaping and organizing tissues and organs. Choices A, B, and C are incorrect because cell death begins much earlier, during fetal development, rather than later in life or at puberty. Understanding the timing of cell death in different stages of life is crucial in developmental biology.

Correct Answer: D

Rationale: The correct answer is 'the cell.' Cells are considered the basic unit of structure and function in all living organisms. While atoms are the smallest units of matter, they do not represent the basic unit of structure and function in organisms. Molecules are made up of atoms and can vary in size and complexity, but they are not the fundamental unit of life. Macromolecules are large molecules essential for life processes, but they are composed of atoms and do not function as the basic unit of structure and function in organisms. Therefore, the cell, with its organelles and specialized functions, is the correct answer.

Correct Answer: A

Rationale: Patterns of growth in preserved bones and tooth decay can indeed reflect the health of the individuals they belonged to. Growth patterns can indicate malnutrition or diseases during childhood, while tooth decay can signify dietary habits and overall health. Therefore, the correct answer is 'Yes.' 'No' is incorrect because these factors can provide valuable information about the health of individuals. 'Not enough information to determine' is incorrect as these indicators are commonly used in anthropological and archaeological studies to understand health conditions in past populations. 'Not applicable' is also incorrect as the information from bones and tooth decay is relevant to assessing the health of individuals.

Correct Answer: B

Rationale: The statement that the parietal pleura is a visceral membrane is false. The parietal pleura is actually a membrane that lines the thoracic cavity and is responsible for protecting and cushioning the lungs. Visceral pleura, on the other hand, is the membrane that covers the surface of the lungs. Therefore, the parietal pleura is not a visceral membrane, making the correct answer 'False.' Choices C and D are not relevant as the question is asking for a true/false statement.

Correct Answer: A

Rationale: The statement is true. The field of medicine evolved as early healers moved away from superstition and magic, instead focusing on natural chemicals to treat illnesses. This transition marked a shift towards a more scientific and evidence-based approach to healthcare. Choice B is incorrect because the statement accurately reflects the historical development of medicine. Choice C is incorrect as the historical transition from superstition to natural chemicals is a well-documented aspect of the evolution of medicine. Choice D is incorrect as the statement provided is true.