Carbohydrate absorption:

Correct Answer: B

Rationale: The correct answer is B because glucose, galactose, and fructose are transported across the basolateral membrane by the GLUT2 transporter. This occurs after they are absorbed into enterocytes through various transport mechanisms. Choice A is incorrect because SGLT-2 transporter is responsible for glucose and galactose absorption, not fructose. Choice C is incorrect as fructose is absorbed through facilitated diffusion, not secondary active transport. Choice D is incorrect because insulin actually increases carbohydrate absorption by upregulating GLUT2 expression.

Correct Answer: D

Rationale: Step-by-step rationale for choice D being correct: 1. ATP is an energy carrier molecule. 2. Adenosine triphosphate (ATP) is a precursor of cyclic AMP. 3. Cyclic AMP is a secondary messenger involved in cellular signaling. 4. Therefore, choice D is true. Summary of incorrect choices: A: Adenosine triphosphate is a high-energy phosphate, not low. B: Reduction involves gain, not loss, of electrons. C: Oxidative phosphorylation occurs in the mitochondria, not the endoplasmic reticulum.

Correct Answer: B

Rationale: The correct answer is B because antidiuretic hormone (ADH) actually causes urine volume to decrease as blood volume decreases, not increase. ADH acts on the kidneys to reabsorb water, leading to concentrated urine and conservation of body fluids. Rationale summary: A: True, hyposecretion of FSH or LH can lead to sterility in both males and females. C: False, oxytocin is also released during sexual activity, breastfeeding, social bonding, and stress responses, not just during childbirth and nursing. D: True, luteinizing hormone triggers ovulation and stimulates the production of progesterone and some estrogens.

Correct Answer: D

Rationale: The correct answer is D: insulin. Elderly individuals are more likely to develop type 2 diabetes due to a decrease in insulin production by the pancreas and decreased sensitivity to insulin in tissues. Insulin plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into cells for energy production. A decline in insulin production or sensitivity can lead to elevated blood sugar levels, contributing to the development of type 2 diabetes. Estrogen (choice A), thyroid hormone (choice B), and follicle-stimulating hormone (choice C) do not directly impact insulin production or sensitivity in the context of type 2 diabetes development in elderly individuals.

Correct Answer: A

Rationale: The correct answer is A: The mouth. Starch digestion begins in the mouth due to the enzyme amylase present in saliva. Amylase breaks down starch into maltose. This process initiates digestion before food reaches the stomach or small intestine. The other choices are incorrect because oesophagus primarily serves as a passage for food, the small intestine is where most digestion and nutrient absorption occur, and the stomach's main role is to break down proteins with the enzyme pepsin, not starch.