What are the symptoms shown by a person if
$(i)$ Lungs get infected?
$(ii)$ Stomach is infected?

Choose the wrong statement.

Fill in the blanks:
$(a)$ Pneumonia is an example of . . . . . . disease.
$(b)$ Many skin diseases are caused by . . . . . . .
$(c)$ Antibiotics commonly block biochemical pathways important for the growth of . . . . . . .
$(d)$ Living organisms carrying the infecting agents from one person to another are called . . . . . . .

Which bacterium causes peptic ulcers? Who discovered the above pathogen for the first time?

State whether the following statement is true or false:
All viruses live outside host cells whereas bacteria very rarely do.

Explain giving reasons:
$(a)$ Balanced diet is necessary for maintaining a healthy body.
$(b)$ The health of an organism depends upon the surrounding environmental conditions.
$(c)$ Our surrounding area should be free of stagnant water.
$(d)$ Social harmony and good economic conditions are necessary for good health.