Correct Answer: A

Rationale: A saturated solution is defined as a solution that has dissolved the maximum amount of solute possible at a specific temperature and pressure. In a saturated solution, any additional solute added will not dissolve, resulting in a visible precipitate. Choice B, unsaturated solution, refers to a solution where more solute can still be dissolved. Choices C and D, dilute solution and concentrated solution, do not specifically refer to the maximum amount of solute that can be dissolved at a given temperature and pressure, making them incorrect in this context.

Correct Answer: B

Rationale: Hospital-acquired infections (HAIs), also known as nosocomial infections, are infections that patients acquire during the course of receiving treatment in a healthcare facility. Among the options provided, bacteria are the most common cause of HAIs. Bacteria such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa are known to cause a wide range of infections in healthcare settings. While viruses, fungi, and parasites can also cause HAIs, bacteria are the most prevalent and significant pathogens responsible for these infections. Proper infection control measures, including hand hygiene, environmental cleaning, and antimicrobial stewardship, are essential in preventing and controlling HAIs caused by bacteria.

Correct Answer: C

Rationale: Estrogen is the hormone responsible for the characteristic changes experienced during puberty in females, such as breast development and menstruation. Estrogen plays a crucial role in the development of secondary sexual characteristics and the regulation of the menstrual cycle. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are primarily involved in the regulation of the menstrual cycle and ovulation. Progesterone, on the other hand, is important for preparing the uterus for pregnancy and maintaining pregnancy, but it is not the primary hormone responsible for the changes seen during puberty in females.

Correct Answer: A

Rationale: Aerobic respiration is the process by which cells use oxygen to convert glucose into energy. This process occurs in the mitochondria of cells and is the most efficient way to produce energy during exercise. Anaerobic respiration and glycolysis are alternative pathways for energy production when oxygen is limited, typically occurring during high-intensity exercise. Lactic acid fermentation, on the other hand, occurs in the absence of oxygen and leads to the production of lactic acid, causing muscle fatigue and soreness.

Correct Answer: A

Rationale: Mass is a measure of the amount of matter in an object and remains constant regardless of changes in gravity. Weight, on the other hand, is a measure of the gravitational force acting on an object and varies with changes in gravity. Volume is the amount of space occupied by an object and can change with changes in gravity. Density is the mass of a substance per unit volume and can also change with changes in gravity if the volume changes. Therefore, the correct answer is mass as it remains the same regardless of the gravitational force acting on the object, making it an intrinsic property of the substance.