Consider statements about human circulation: 1. Arteries carry oxygenated blood. 2. Veins have valves to prevent backflow. 3. Capillaries have thick walls. Which are correct? MCQ with Answer and Explanation

Explanation:
Plasma makes up ~55% of blood; albumin is the main protein. Mature human RBCs are anucleate. So 3 is incorrect.

Explanation:
Osteomalacia is softening of bones in adults due to vitamin D deficiency, leading to bone pain and muscle weakness. Rickets is the childhood equivalent, affecting growth plates. Scurvy is vitamin C deficiency, kwashiorkor is protein deficiency. Vitamin D is essential for calcium absorption and bone mineralization.

Explanation:
The femur (thigh bone) is the longest, heaviest, and strongest bone in the human skeleton. The stapes (stirrup) is a small bone in the middle ear and is the smallest bone in the human body. The hyoid bone is a U-shaped bone in the neck that supports the tongue; it is unique because it is not articulated (jointed) with any other bone, but is suspended by muscles and ligaments. Thus, statements 1 and 2 are correct.