Assertion (A): The appendix is a vestigial organ. Reason (R): It has no known function in the human body. MCQ with Answer and Explanation

Explanation:
All are correct: producers make food, consumers eat other organisms, decomposers break down dead matter and return nutrients.

Explanation:
Diphtheria is a highly contagious bacterial infection caused by Corynebacterium diphtheriae. It primarily affects the mucous membranes of the nose and throat, producing a thick gray pseudomembrane. The bacteria also produce a potent exotoxin that can damage the heart, kidneys, and nervous system. It is preventable by the DPT vaccine.

Explanation:
AB positive blood has both A and B antigens and the Rh antigen, so it lacks antibodies against A, B, or Rh. Hence, individuals with AB+ can receive red blood cells from any donor without agglutination. O negative is the universal donor. Compatibility depends on antigens on donor RBCs and antibodies in recipient plasma.