Which scientist is associated with the discovery of the smallpox vaccine? MCQ with Answer and Explanation

Explanation:
The Sinoatrial (SA) node, the natural pacemaker of the heart, is a small, specialized mass of autorhythmic cardiac muscle cells located in the upper wall of the right atrium, just below the opening of the superior vena cava. It spontaneously generates electrical impulses at a regular rate, which spread through the atrial myocardium, causing the atria to contract and push blood into the ventricles. The impulse then reaches the AV node.

Explanation:
The large intestine does not produce digestive enzymes; it absorbs water and electrolytes. The small intestine and pancreas produce enzymes.

Explanation:
Tetracycline binds to the 30S ribosomal subunit, blocking attachment of aminoacyl-tRNA, thus inhibiting protein synthesis. Penicillin and cephalosporins inhibit cell wall synthesis, vancomycin also inhibits cell wall synthesis. Aminoglycosides like streptomycin also target 30S. Protein synthesis inhibitors exploit the difference between bacterial and human ribosomes.