Correct Answer: C

Rationale: Muscle contraction is the correct answer. It is the process by which muscles convert chemical energy (ATP) into mechanical energy (movement). During muscle contraction, the sliding filament theory explains how actin and myosin filaments slide past each other, causing muscle fibers to shorten and generate force. Photosynthesis (option A) is the process by which plants convert light energy into chemical energy. Cellular respiration (option B) is the process by which cells generate ATP from glucose and oxygen. The sliding filament theory (option D) is a detailed explanation of the molecular events that occur during muscle contraction but is not the overall process of converting energy into movement; it focuses on the mechanism within the process of muscle contraction.

Correct Answer: A

Rationale: The correct answer is A. The innate immune system provides nonspecific, immediate defense against pathogens. It is the body's first line of defense in responding to infections and does not involve memory cells or specific long-term immune responses like the adaptive immune system. Choice B is incorrect because specific, long-term immune responses through memory cells are characteristics of the adaptive immune system, not the innate immune system. Choice C is incorrect because the innate immune system does not provide specific, long-term immune responses. Choice D is incorrect because the innate immune system does provide an immediate defense against pathogens.

Correct Answer: C

Rationale: Food stores energy in the form of chemical potential energy. This energy is released during digestion and metabolism to provide the body with the energy it needs to function. It is derived from the bonds within the molecules of food, such as carbohydrates, fats, and proteins. Choice A, mechanical energy, is incorrect as food does not store energy in the form of mechanical energy. Choice B, kinetic energy, is incorrect as kinetic energy is associated with the motion of objects, not stored in food. Choice D, thermal energy, is incorrect as thermal energy relates to heat energy, which is not the primary form of energy stored in food.

Correct Answer: B

Rationale: The pitch of a sound wave is determined by its frequency. Frequency is the number of cycles of a wave that occur in a unit of time, usually measured in hertz (Hz). Higher frequencies correspond to higher pitches, while lower frequencies correspond to lower pitches. Amplitude refers to the height of a wave and is related to the loudness of the sound. Wavelength is the distance between two consecutive points in a wave that are in phase, and speed is the rate at which a wave travels through a medium. Therefore, the correct answer is frequency as it directly correlates with the pitch of a sound wave.

Correct Answer: B

Rationale: Enzymes are biological catalysts, not building blocks of muscle. They speed up chemical reactions in living organisms without being consumed in the process. Enzymes are not an energy source or antibodies. They play a crucial role in various biological processes by lowering the activation energy required for a reaction to occur, thereby increasing the rate of the reaction.