$A$ pure culture of bacteria was first obtained by..........

Assertion $(S)$: Alexander Fleming was the discoverer of antibiotics.
Reason $(R)$: Penicillin was obtained from $Penicillium \text{ } notatum$.

What did Fa-Hien and Wanse discuss?

Which one of the following organisms is used as an indicator of water quality?

Medicines are either man-made (i.e.,synthetic) or obtained from living organisms like plants,bacteria,animals,etc.,and hence,the latter are called natural products. Sometimes,natural products are chemically altered by man to reduce toxicity or side effects. Write against each of the following whether they were initially obtained as a natural product or as a synthetic chemical: $(a)$ Penicillin $(b)$ Sulphonamide $(c)$ Vitamin-$C$ $(d)$ Growth hormone.

What are organisms that cannot be seen with the naked eye called?