Correct Answer: B

Rationale: The correct answer is B: 'To absorb nutrients.' The small intestine is the primary site for nutrient absorption in the digestive system. It plays a crucial role in absorbing nutrients from digested food into the bloodstream, facilitating the delivery of essential nutrients to the body for various functions and processes. Choices A, C, and D are incorrect because while the small intestine does contribute to the breakdown of food and does secrete digestive enzymes, its primary function is to absorb nutrients, not to store glucose.

Correct Answer: A

Rationale: The cochlea, located in the inner ear, is responsible for detecting sound waves and converting them into neural signals that are sent to the brain for processing. It plays a crucial role in the process of hearing by translating mechanical vibrations into electrical signals that the brain can interpret as sound. The semicircular canals (Choice B) are responsible for balance and detecting head movements, not hearing. The ossicles (Choice C) are three tiny bones in the middle ear that transmit sound vibrations from the eardrum to the cochlea. The Eustachian tube (Choice D) helps equalize pressure between the middle ear and the atmosphere, but it is not directly involved in the process of hearing.

Correct Answer: B

Rationale: The parietal lobe is primarily responsible for processing sensory information related to touch, temperature, and body position. It plays a crucial role in interpreting sensations from different parts of the body, including proprioception, which is the awareness of body position. The frontal lobe is more associated with functions like decision-making and personality, the occipital lobe is primarily involved in visual processing, and the temporal lobe is responsible for auditory processing and memory. Therefore, the parietal lobe is the correct answer for this question.

Correct Answer: B

Rationale: Mitochondria are the organelles responsible for producing energy in the cell through a process called cellular respiration. They are often referred to as the powerhouses of the cell due to their role in generating ATP, the cell's energy currency. The nucleus is not involved in energy production but houses the cell's genetic material. Ribosomes are responsible for protein synthesis, not energy production. The Golgi apparatus is involved in processing and packaging proteins for secretion, not energy production.

Correct Answer: B

Rationale: The skin serves several crucial functions in protecting the body. One of its primary roles is to act as a physical barrier against pathogens, preventing harmful microorganisms from entering the body. Choice A, 'To produce vitamin D,' is incorrect because while the skin is involved in vitamin D synthesis upon exposure to sunlight, its primary protective role is against pathogens. Choice C, 'To store nutrients,' is incorrect as the skin is not a primary organ for nutrient storage. Choice D, 'To regulate body temperature,' is a function of the skin, but the primary role in protecting the body is to act as a barrier against pathogens.