The scientist who developed the first effective polio vaccine was: MCQ with Answer and Explanation

Explanation:
Vitamin D (calcitriol) stimulates the production of calcium-binding proteins in the intestinal lining, enhancing calcium absorption. Deficiency leads to rickets/osteomalacia. Vitamin A is for vision, C for collagen, B₁₂ for nerve function.

Explanation:
The plasma membrane (cell membrane) is selectively permeable, regulating the entry and exit of substances into and out of the cell, maintaining internal homeostasis. The nucleus is the membrane-bound organelle that houses the cell's genetic material (DNA) organized into chromosomes, directing cellular activities. Mitochondria are the double-membrane-bound organelles known as the 'powerhouses of the cell' because they are the primary site of aerobic respiration, producing the majority of the cell's ATP (energy currency). All statements are correct.

Explanation:
Rheumatoid arthritis is a chronic inflammatory autoimmune disease where the immune system mistakenly attacks the body's own healthy tissues, specifically the synovial membranes of joints. This leads to painful swelling, bone erosion, and joint deformity. Other examples of autoimmune diseases include Type 1 diabetes, multiple sclerosis, and systemic lupus erythematosus.