Correct Answer: D

Rationale: The upper respiratory tract includes structures such as the nose, nasal cavity, pharynx, and larynx. These structures are responsible for filtering, warming, and humidifying the air. The lower respiratory tract comprises the trachea, bronchi, bronchioles, alveolar ducts, and alveoli. Bronchioles, alveolar ducts, and alveoli are all part of the lower respiratory system, involved in gas exchange. Therefore, the correct answer is 'None of the above' as none of the listed options are part of the upper respiratory tract.

Correct Answer: D

Rationale: Progesterone initiates the preparation of the endometrium of the uterus for pregnancy. It promotes the growth of blood vessels and glands in the endometrial lining, making it conducive for implantation and supporting early pregnancy. While estrogen helps in thickening the endometrium, it is progesterone that plays a crucial role in preparing it for pregnancy. FSH (Follicle-stimulating hormone) is involved in stimulating ovarian follicles, not directly in preparing the endometrium. LH (Luteinizing hormone) triggers ovulation but does not primarily prepare the endometrium for pregnancy.

Correct Answer: D

Rationale: The correct answer is D because the urinary system eliminates some waste products of digestion. After digestion in the digestive system, nutrients are absorbed into the bloodstream, and waste products are transported to the kidneys via the urinary system to be excreted as urine. This process helps eliminate waste products generated during digestion, illustrating the coordination between the digestive and urinary systems. Choices A, B, and C are incorrect. Choice A is incorrect as the ureter is part of the urinary system, not controlled by the digestive system. Choice B is incorrect as the urinary system primarily removes metabolic waste, not toxins from digestion. Choice C is incorrect because the digestive system mainly aids in digestion and nutrient absorption, not hormone production affecting urination.

Correct Answer: D

Rationale: The correct answer is D: T4. The primary hormone secreted by the thyroid gland is thyroxine, also known as T4. T4 plays a crucial role in regulating metabolism, growth, and energy levels in the body. It is converted into the more active form, triiodothyronine (T3), which exerts most of the biological effects of thyroid hormones. Choices A, B, and C are incorrect. Oxytocin is not produced by the thyroid gland but by the pituitary gland, TSH (thyroid-stimulating hormone) is secreted by the pituitary gland to stimulate the thyroid gland, and adrenaline is produced by the adrenal glands, not the thyroid gland.

Correct Answer: B

Rationale: The normal pH of human arterial blood is approximately 7.4. This slightly alkaline pH is crucial for the proper functioning of enzymes and biochemical processes in the body. Any significant deviation from this pH level can result in serious health issues such as acidosis or alkalosis. Choice A (6.8) is incorrect as it is lower than the normal pH of arterial blood, indicating acidity. Choice C (7.9) and Choice D (8.2) are incorrect as they are higher than the normal pH of arterial blood, indicating alkalinity.