Choose the following statements which are correct with respect to con…

The correct answer is Option (3) → (B) and (C) only

(A) In simple stirred tank bioreactor, the stirring happens through sparging of air bubbles — False. In a simple stirred-tank bioreactor the contents are mixed by a stirrer (agitator). Bubbling sterile air through the medium is the sparged stirred-tank bioreactor, the other type.

(B) Bioreactor has an agitator system, oxygen delivery system and foam control system — True. These are three of its systems; a bioreactor also controls temperature and pH.

(C) Sampling ports provides vents to withdraw small volumes of culture periodically — True. This is what the sampling ports are for.

(D) Culturing in bio reactors is classified as downstream processing — False. Culturing is the biosynthetic stage. Downstream processing comes after it: the separation and purification of the product, its formulation with preservatives, and its clinical trials and quality control.

NCERT Extract:
Obtaining the Foreign Gene Product – “… A stirred-tank reactor is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents. The stirrer facilitates even mixing and oxygen availability throughout the bioreactor. Alternatively air can be bubbled through the reactor. If you look at the figure closely you will see that the bioreactor has an agitator system, an oxygen delivery system and a foam control system, a temperature control system, pH control system and sampling ports so that small volumes of the culture can be withdrawn periodically.”
Downstream Processing – “After completion of the biosynthetic stage, the product has to be subjected through a series of processes before it is ready for marketing as a finished product. The processes include separation and purification, which are collectively referred to as downstream processing. The product has to be formulated with suitable preservatives.”