Which of the following diseases can be prevented by the BCG vaccine? MCQ with Answer and Explanation

Explanation:
Anabaena azollae lives in cavities of the water fern Azolla and fixes atmospheric nitrogen. It is used as a biofertilizer in rice paddies.

Explanation:
The double helix structure of DNA was elucidated by James Watson (an American biologist) and Francis Crick (a British physicist) in 1953 at the University of Cambridge. Their model was based on X-ray diffraction data produced by Rosalind Franklin and Maurice Wilkins. They proposed that DNA consists of two antiparallel strands held together by hydrogen bonds between complementary base pairs (A-T, G-C).

Explanation:
Sunlight is the ultimate source of energy for almost all ecosystems. Photosynthetic autotrophs (plants, algae, cyanobacteria) capture solar energy and convert it into chemical energy, which then flows through the food web. Some deep-sea ecosystems rely on chemosynthesis from hydrothermal vents, but globally, the sun drives the biosphere.