In genetics, the 'Operon model' was proposed by: MCQ with Answer and Explanation

Explanation:
The Ti (tumor-inducing) plasmid from Agrobacterium tumefaciens is a natural plant genetic engineer. It transfers T-DNA into the plant genome, making it an effective vector for introducing foreign genes in plant genetic engineering. pBR322 is a common E. coli cloning vector. Bacteriophage lambda and cosmids are used in animal/bacterial systems. Ti plasmid has revolutionized GM crop development.

Explanation:
The fossil record shows a chronological sequence of life forms, providing direct evidence of evolutionary changes over time. Embryological similarities, such as the presence of pharyngeal slits and a notochord in early vertebrate embryos, support the idea of common ancestry. Biogeography, the study of species distribution, shows that species are not randomly distributed but are related to their geographic origins and evolutionary history. Thus, statements 1 and 2 are correct.

Explanation:
Vaccination introduces antigens (weakened or killed pathogens) to stimulate the body's own immune system to produce antibodies and memory cells without causing disease. This is artificial active immunity. Natural active immunity is acquired by recovering from infection. Artificial passive immunity is direct administration of antibodies (e.g., antiserum). Natural passive immunity is transfer of maternal antibodies to fetus.