Apoenzyme and Cofactors — NEET Biology
✅ Asked in NEET 2019Consider the following statements. (A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group. (B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme. Select the correct option: (NEET 2019)
Consider the following statements. (A) Coenzyme or metal ion that is tightly bound to enzyme protein is called prosthetic group. (B) A complete catalytic active enzyme with its bound prosthetic group is called apoenzyme. Select the correct option: (NEET 2019)
Answer & NCERT explanation
Correct answer: C — is true but (B) is false
Statement A is true - prosthetic groups are tightly bound coenzymes or metal ions. Statement B is false - a complete enzyme with prosthetic group is called holoenzyme, not apoenzyme. Apoenzyme is the protein part without the prosthetic group. This is fundamental enzyme terminology from NCERT.
Read more NCERT concept on the PYQ
In these instances, the protein portion of the enzymes is called the apoenzyme. Three kinds of cofactors may be identified: prosthetic groups, co-enzymes and metal ions.
NTA tests your understanding of enzyme structure by distinguishing the protein part (apoenzyme) from non-protein helper molecules (cofactors). Students often confuse holoenzyme with apoenzyme—remember that holoenzyme = apoenzyme + cofactor (the complete, active enzyme), while apoenzyme alone is inactive. Cofactors come in three types: prosthetic groups (tightly bound), coenzymes (loosely bound, often vitamins), and metal ions (like Mg²⁺, Zn²⁺). The key to NEET success: know that an enzyme needs both parts to function—the protein structure provides specificity, while cofactors provide catalytic power.
What does NCERT say about these instances protein portion?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.