Consider statements about ecology: 1. A population includes all species in an area. 2. A community includes only interacting populations. 3. An ecosystem includes both biotic and abiotic components. Which are correct? MCQ with Answer and Explanation

Explanation:
The double helix structure of DNA was proposed by James Watson and Francis Crick in 1953, based on X-ray diffraction data produced by Rosalind Franklin and Maurice Wilkins. They proposed that DNA consists of two antiparallel polynucleotide chains coiled around a common axis, with specific base pairing (A-T, G-C) holding the strands together.

Explanation:
Vitamin C (ascorbic acid) is a cofactor for prolyl and lysyl hydroxylase enzymes that hydroxylate proline and lysine in collagen synthesis, necessary for stabilizing collagen triple helix. Deficiency leads to impaired collagen formation, causing scurvy—fragile blood vessels, bleeding gums, poor wound healing. Vitamin A is for vision, D for bone, K for clotting.

Explanation:
Polymerase Chain Reaction (PCR) is a powerful technique used to exponentially amplify a specific segment of DNA using primers and a thermostable DNA polymerase. Gel electrophoresis is a 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.