‘Polio' is caused by
A bacteriophage
A virus with single strand $RNA$
A virus with single strand $DNA$
A virus with double strand $DNA$
''Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases''. Justify the statement giving suitable examples.
The spread of cancerous cells to distant sites is termed as
Morphine is extracted from
The depression of nervous activity is caused by which of the following drug