The process of artificially introducing weakened pathogens to stimulate immunity is called: MCQ with Answer and Explanation

Explanation:
Phloem transports organic solutes (mainly sucrose) from source to sink. Xylem transports water and minerals. Phloem is composed of sieve tubes and companion cells.

Explanation:
Robert Koch, a German physician and microbiologist, formulated Koch's postulates in the late 19th century. These four criteria are designed to establish a causal relationship between a specific microbe and a specific disease. The postulates require that the microbe must be found in all cases of the disease, isolated and grown in pure culture, cause the disease when inoculated into a healthy susceptible host, and be re-isolated from the experimentally infected host.

Explanation:
Vitamin C is chemically L-ascorbic acid. It is water-soluble, an antioxidant, and required for collagen synthesis. Deficiency causes scurvy. It is found in citrus fruits, amla, and green vegetables.