Correct Answer: B

Rationale: The correct answer is B: To break down food. The stomach's primary function in digestion is to mechanically and chemically break down food. It achieves this by utilizing gastric acid and digestive enzymes to convert food into chyme, a semi-liquid mixture. The chyme is then passed to the small intestine for further processing and absorption of nutrients. Choices A, C, and D are incorrect because the stomach's main role is not to absorb nutrients, secrete digestive enzymes, or transport nutrients; instead, it primarily focuses on breaking down food.

Correct Answer: B

Rationale: The correct answer is B: Energy production. Mitochondria are known as the powerhouses of the cell because they generate adenosine triphosphate (ATP) through the process of cellular respiration. ATP is a molecule that stores and releases energy, providing the cell with the necessary energy for various activities and functions. Choices A, C, and D are incorrect. Protein synthesis primarily occurs in the ribosomes, breaking down waste is mainly carried out by lysosomes, and cell division is orchestrated by the nucleus and other organelles like the centrioles.

Correct Answer: A

Rationale: The spleen plays a crucial role in the lymphatic system by filtering blood, specifically removing old or damaged red blood cells. Additionally, the spleen produces lymphocytes, a type of white blood cell that plays a key role in the immune response by helping to fight off infections. Therefore, the correct answer is A, as the spleen is primarily involved in blood filtration and the production of lymphocytes rather than storing vitamins or regulating body temperature.

Correct Answer: B

Rationale: The adrenal cortex is the organ responsible for producing stress hormones like cortisol and aldosterone, which play a crucial role in the body's stress response. During stress, the adrenal cortex releases cortisol, a hormone that helps the body deal with stress by increasing blood sugar, suppressing the immune system, and aiding in metabolism. Parathyroid gland is responsible for calcium regulation, the posterior pituitary gland secretes hormones like oxytocin and vasopressin which are not directly related to the stress response, and the hypothalamus plays a role in regulating hormonal balance and various bodily functions but is not primarily responsible for producing stress hormones.

Correct Answer: C

Rationale: The correct answer is C: To store urine. The main function of the urinary bladder is to store urine produced by the kidneys before it is excreted from the body. It acts as a reservoir for urine until it is expelled during urination. Choices A, B, and D are incorrect because the urinary bladder does not filter blood, store or concentrate bile, or absorb nutrients. It is solely responsible for storing and releasing urine.