Correct Answer: B

Rationale: The correct answer is B: '
To detoxify harmful substances.' The liver is primarily responsible for detoxifying harmful substances present in the blood as part of its role in metabolism. While the liver does produce bile to aid in digestion and stores glucose for energy regulation, its main function in metabolism is detoxification. The liver does not produce insulin; insulin is produced by the pancreas to regulate blood sugar levels.

Correct Answer: B

Rationale: The glomerulus is a key structure in the kidney responsible for filtering blood. It consists of a network of capillaries that filter waste products and excess substances from the blood, allowing the formation of urine. While the nephron, Bowman's capsule, and Loop of Henle are also essential components of the kidney's filtration system, the glomerulus is specifically involved in the initial blood filtration process. The nephron is the functional unit of the kidney, Bowman's capsule surrounds the glomerulus and collects the filtrate, and the Loop of Henle is responsible for reabsorption and concentration of urine, not the initial blood filtration.

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.

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 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.