Consider statements about cell biology: 1. The plasma membrane is selectively permeable. 2. The nucleolus is the site of protein synthesis. 3. Lysosomes contain digestive enzymes. Which are correct? MCQ with Answer and Explanation

Explanation:
Urobilin is derived from bilirubin, a heme breakdown product, and gives urine its yellow color. R is true and explains A.

Explanation:
The aorta is the main and largest artery originating from the left ventricle, distributing oxygenated blood to all parts of the body through its branches. The pulmonary artery carries deoxygenated blood to lungs. Coronary arteries supply the heart muscle, carotid arteries supply the brain. The aorta has a diameter of about 2-3 cm in adults.

Explanation:
The endocrine part of the pancreas—the islets of Langerhans—contains β-cells that secrete insulin (lowers blood glucose), α-cells secrete glucagon (raises blood glucose), and δ-cells secrete somatostatin. Exocrine pancreas secretes digestive enzymes (trypsin, lipase, amylase). Pepsin is from stomach, bile from liver, gastrin from stomach. Insulin deficiency causes diabetes mellitus.