Correct Answer: B

Rationale: The amplitude of a wave determines the loudness of sound when heard by the human ear. The greater the amplitude of a sound wave, the louder the sound will be perceived. Frequency (Choice A) refers to the number of wave cycles in a given time period. Wavelength (Choice C) is the distance between two corresponding points on a wave. Velocity (Choice D) is the speed at which the wave travels and does not directly affect the loudness of sound perceived by the human ear.

Correct Answer: B

Rationale: The scientific term for a broken bone is a fracture. Osteoporosis is a condition characterized by weak and brittle bones, not a broken bone. A sprain involves an injury to a ligament, not a bone. Dislocation occurs when the ends of bones are forced out of their normal positions at a joint, which is different from a fracture.

Correct Answer: B

Rationale: Antigenic variation is a strategy used by some viruses to evade the host's immune response. By constantly changing their surface antigens, viruses can avoid recognition and destruction by the immune system. This allows the virus to persist in the host and continue replicating, leading to prolonged infection and potential transmission to other hosts. Antigenic variation does not directly involve the production of toxins, survival outside a host, or rapid replication, making options A, C, and D incorrect in this context.

Correct Answer: D

Rationale: A) This statement is true. Fossils can provide evidence for the order of appearance of different species through the study of the fossil record. B) This statement is true. Fossils can be used to estimate the age of rocks and layers through relative dating methods such as stratigraphy and absolute dating methods like radiometric dating. C) This statement is true. Fossils can provide information about the behavior of extinct organisms through the study of their preserved remains and traces. D) This statement is NOT true. Fossils are not always perfectly preserved. In many cases, fossils are incomplete, fragmented, or altered over time due to geological processes. The level of preservation can vary depending on factors such as the type of organism, the environment in which it lived, and the processes involved in fossilization.

Correct Answer: A

Rationale: The main function of the stomach is to store food, churn it, and break it down into smaller pieces through mechanical digestion. This process is facilitated by the mixing of food with gastric juices, including stomach acid. The mechanical breakdown in the stomach helps initiate the digestion of food before it progresses to the small intestine for further digestion and nutrient absorption. Absorption of nutrients into the bloodstream primarily occurs in the small intestine, not the stomach. Enzymes that aid in digesting food are primarily produced in the pancreas and small intestine, not in the stomach. The elimination of waste products from the body mainly occurs through the large intestine and rectum, not the stomach.