Which of the following statements best describes endocrine glands?

The correct answer is choice D. Water is reabsorbed from the urinary filtrate. This is because ADH (antidiuretic hormone) increases the permeability of the cells in the collecting tubules to water, allowing more water to be reabsorbed back into the bloodstream and reducing urine volume.

Choice A is wrong because large quantities of dilute urine are formed when ADH is low or absent, not when it is secreted.

Choice B is wrong because the tubules become more permeable to water, not imper

The correct answer is choice B. Endocrine glands secrete chemicals into the blood. This is because endocrine glands are ductless glands that release their products (hormones) directly into the bloodstream, where they can reach their target cells throughout the body.

Choice A is wrong because salivary glands are exocrine glands, not endocrine glands. Exocrine glands secrete their products into ducts that lead to an internal or external surface.

Choice C is wrong because it describes exocrine glands, not endocrine glands. Exocrine glands release their secretions on an internal or external surface via ducts.

Choice D is wrong because it also describes exocrine glands, not endocrine glands. Endocrine glands do not secrete their products into ducts, but directly into the blood.

The correct answer is choice D. Thrombocytes, also known as platelets, are tiny components of your blood that help with clotting. They are your body’s natural bandage to stop bleeding. When a blood vessel tears, thrombocytes stick together to form a clot, plugging the tear to stop bleeding.

Choice A is wrong because defending against infection is the function of white blood cells, not thrombocytes.

Choice B is wrong because transporting respiratory gases is the function of red blood cells, not thrombocytes.

Choice C is wrong because forming connective tissue is not the function of any blood cells, but of specialized cells called fibroblasts.

A normal platelet count for adults ranges from 150,000 to 450,000 platelets per microliter of blood. Any count above 450,000 or below 150,000 would be risk factors for platelet-related conditions.

Digestion begins in the mouth, where the teeth break down the food and the saliva contains enzymes that start to break down carbohydrates. This process is called ingestion.

Choice A is wrong because the esophagus is a thin tube that connects the mouth to the stomach. It does not digest food, but moves it through peristalsis, which are wave-like contractions of the muscles in the gut wall.

Choice C is wrong because the stomach is a muscular bag that mixes food with acid and enzymes. It does not start digestion, but continues it, especially for proteins.

Choice D is wrong because the small intestine is where most of the digestion and absorption of nutrients takes place. It receives enzymes and bile from the pancreas and liver, which help to break down carbohydrates, proteins and lipids.