The scientist who discovered the first antibiotic, penicillin, was: MCQ with Answer and Explanation

Explanation:
Polymerase Chain Reaction (PCR) is a powerful molecular technique used to exponentially amplify a specific segment of DNA, creating millions of copies from a small initial sample. Gel electrophoresis is a laboratory method used to separate DNA, RNA, or protein molecules based on their size and charge by applying an electric field through a gel matrix. Restriction enzymes are molecular scissors that cut DNA at specific sequences; DNA ligase is the enzyme that joins DNA fragments together. Thus, statements 1 and 2 are correct.

Explanation:
The spleen is the largest lymphoid organ in the body. It is located in the abdominal cavity, specifically in the upper left quadrant, tucked between the stomach and the diaphragm, protected by the rib cage (ribs 9-11). It functions primarily in filtering blood, removing old or damaged red blood cells, storing platelets, and mounting immune responses against blood-borne pathogens. It is not located in the thoracic, pelvic, or cranial cavities.

Explanation:
Lamarck proposed that organs used extensively develop and those not used degenerate, and these acquired traits are inherited (inheritance of acquired characters). Darwin's theory is natural selection, Wallace independently proposed natural selection, Weismann disproved Lamarckism.