CBSE 12th Biotechnology Question Paper 2026 (Set 1)

Inclusion bodies are aggregates formed inside microbial cells when recombinant proteins are produced in excess and are incorrectly folded. Hence, they are associated with incorrect folding and intracellular accumulation of recombinant proteins. Options B, C and D are incorrect because inclusion bodies are not formed due to extracellular secretion, enhanced growth, or lack of nutrients.

Mammalian cell cultures are maintained in incubators with about 5–10% CO$_2$, usually around 5%, to keep the pH of the culture medium stable. The other options are incorrect because 30%, 2%, and 15–20% CO$_2$ are not the standard conditions used for mammalian cell culture.

Monoclonal antibodies are preferred over polyclonal antibodies in diagnostics and therapeutics because they are highly specific, uniform, and can be produced in large amounts with consistent quality. Antibiotics are not substitutes for antibodies, and antibodies are definitely used in diagnosis and treatment. Polyclonal antibodies are less specific and therefore less preferred.

Single Nucleotide Polymorphisms (SNPs) can occur in both coding and non-coding regions of the genome. They are single base changes that may or may not affect protein function depending on their location. Therefore, option C is correct.

SCID is commonly caused by deficiency of adenosine deaminase (ADA). ADA deficiency leads to severe impairment of immune function, especially affecting T and B lymphocytes. The other enzymes listed—amylase, lipase, and reverse transcriptase—are not responsible for SCID.