Crossing over occurs between: MCQ with Answer and Explanation

Explanation:
Gene therapy involves correcting a genetic defect by introducing a functional gene into a patient's cells. The first clinical gene therapy was given in 1990 to a 4-year-old girl with Adenosine Deaminase (ADA) deficiency, a severe combined immunodeficiency (SCID) caused by a mutation in the ADA gene. The functional ADA gene was introduced into her lymphocytes using a retroviral vector.

Explanation:
In 1953, Stanley Miller and Harold Urey conducted an experiment to test the Oparin-Haldane hypothesis of chemical evolution. They simulated the reducing atmosphere of primitive Earth, which they believed lacked free oxygen. The gas mixture used was methane (CH4), ammonia (NH3), hydrogen (H2), and water vapor (H2O). By applying electrical sparks (simulating lightning), they successfully synthesized amino acids and other organic compounds.

Explanation:
Dermal tissue (epidermis in primary growth, periderm in secondary growth) forms the outermost protective layer of leaves, stems, and roots. It includes specialized cells like guard cells and root hairs. Vascular tissue (xylem, phloem) conducts, ground tissue fills and stores, meristematic is for growth.