The hormone that stimulates the secretion of testosterone from Leydig cells is: MCQ with Answer and Explanation

Explanation:
Iodine is essential for synthesis of thyroxine (T₄) and triiodothyronine (T₃). Deficiency leads to enlargement of the thyroid gland, known as goiter, as the gland tries to compensate. Anemia is due to iron deficiency, rickets to vitamin D deficiency, scurvy to vitamin C deficiency. Iodized salt is a public health measure to prevent goiter.

Explanation:
Diabetes mellitus is characterized by hyperglycemia due to insufficient insulin secretion (Type 1) or insulin resistance (Type 2). Diabetes insipidus is due to deficiency of ADH (vasopressin) affecting water reabsorption. Graves' disease is hyperthyroidism, Addison's is adrenal insufficiency. Insulin deficiency leads to inability of cells to uptake glucose.

Explanation:
Plasmids are small, circular, extrachromosomal DNA molecules in bacteria widely used as cloning vectors in genetic engineering. Restriction enzymes are part of the bacterial immune system, found in bacteria and archaea, not viruses, protecting them against bacteriophages. Polymerase Chain Reaction (PCR) requires a thermostable DNA polymerase (like Taq) to synthesize new DNA strands. Thus, statements 1 and 3 are correct.