What is the main function of the large intestine?

Correct Answer: B

Rationale: The main function of the large intestine is the absorption of water and electrolytes from indigestible food residues, helping to form solid waste (feces) for elimination. It mainly reabsorbs water and compacts the remaining material into feces, playing a crucial role in maintaining fluid balance in the body. Choices A, C, and D are incorrect because absorption of nutrients primarily occurs in the small intestine, secretion of digestive enzymes mainly occurs in the stomach and small intestine, and breaking down fats primarily occurs in the small intestine with the help of bile from the liver and enzymes.

Correct Answer: B

Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.

Correct Answer: C

Rationale: The main function of the adrenal glands is to produce hormones like adrenaline and cortisol. These hormones play a crucial role in regulating blood pressure, metabolism, and the body's stress response. While the adrenal glands do have some impact on metabolism, their primary function is not the direct regulation of metabolism. They are not involved in the production of bile or insulin. Therefore, the correct answer is the regulation of blood pressure.

Correct Answer: C

Rationale: The main function of the nervous system is to control and coordinate body activities by transmitting signals between different parts of the body and responding to internal and external stimuli. This allows for the regulation of body temperature, movement, sensory perception, and various other functions necessary for homeostasis. Choices A, B, and D are incorrect as they do not align with the primary role of the nervous system. Transporting blood is mainly carried out by the circulatory system, protecting the body from infection is a function of the immune system, and digesting food is the role of the digestive system.

Correct Answer: B

Rationale: The primary function of red blood cells, also known as erythrocytes, is to transport oxygen from the lungs to the body's tissues and organs. This is essential for cellular respiration and overall body functions. Red blood cells do not play a role in clotting blood, fighting infection, or carrying hormones. Choice A is incorrect because clotting blood is primarily done by platelets and other components of blood. Choice C is incorrect as fighting infection is a function mainly carried out by white blood cells. Choice D is incorrect because carrying hormones is primarily attributed to proteins like albumin and specific hormone-carrying proteins.