Given below are two statements Statement (I): The active... | Agrigyan

• Carbonic anhydrase $\rightarrow$ (II) $\text{Zn}^{2+}$: Contains an essential zinc ion coordinated by three histidine residues that activates water for hydration of $\text{CO}_2$ to $\text{HCO}_3^-$.
• Hexokinase $\rightarrow$ (IV) $\text{Mg}^{2+}$: Requires magnesium ($ ext{Mg}^{2+}$) as a cofactor to chelate the negative charges of ATP, forming the true active substrate $\text{MgATP}^{2-}$.
• Nitrate Reductase $\rightarrow$ (I) Mo: Contains a molybdenum pterin cofactor (Moco) essential for transferring electrons to reduce nitrate ($\text{NO}_3^-$) to nitrite ($\text{NO}_2^-$).
• Urease $\rightarrow$ (III) $\text{Ni}^{2+}$: A nickel-dependent metalloenzyme that hydrolyzes urea into ammonia and carbon dioxide.

Correct option: (4) (A) - (II), (B) - (IV), (C) - (1), (DB) - (Ill)

• Discovery of Isozymes: The term isozyme (or isoenzyme) was coined and introduced by Clement L. Markert and Freddy Møller (1959).
• Definition: Isozymes refer to multiple distinct molecular forms of the same enzyme that occur within a single organism and catalyze the identical biochemical reaction, yet differ in amino acid sequence, electrophoretic mobility, and kinetic parameters (such as lactate dehydrogenase, LDH).

Correct option: (2) Market and Moller (1959)

• Characteristics of Ephemerals: Ephemerals are drought-escaping desert annuals that germinate, grow, flower, and set seeds rapidly (within 4 to 6 weeks) following sporadic desert rainfall, surviving dry spells as dormant desiccation-tolerant seeds.
• Succulents vs Ephemerals: Accumulating large quantities of water in fleshy tissues and consuming it conservatively is the hallmark of succulents / drought-enduring xerophytes (Opuntia, Agave, cacti), NOT ephemerals.
• Conclusion: Option 4 is NOT a characteristic of ephemerals.

Correct option: (4) They accumulate large quantity of water and use it slowly during dry periods