Given below are inhibitors of electron transport (Column X) and their target enzymes (Column Y)

Column X Inhibitors of electron transport		Column Y Respiratory chain complex enzymes
A.	Dicyclohexylcarbodiimide and Oligomycin	I.	NADH coenzyme Q reductase
B.	Rotenone and Demerol	II.	ATP Synthase
C.	Thenoyltrifluroacetone and Carboxin	III.	Succinate coenzyme Q reductase
D.	Cyanide and Azide	IV.	Cytochrome c oxidase

Which one of the following options represents all correct matches between Column X and Column Y?

Correct option is B

Explanation: This question asks to match the inhibitors of the electron transport chain with their target enzymes. Here’s the breakdown:

• A) Dicyclohexylcarbodiimide and Oligomycin inhibit ATP Synthase (complex V), which is responsible for synthesizing ATP during oxidative phosphorylation. Therefore, the correct match is (ii).

• B) Rotenone and Demerol inhibit NADH coenzyme Q reductase (complex I), which is responsible for transferring electrons from NADH to coenzyme Q. Therefore, the correct match is (i).

• C) Thenoyltrifluoroacetone and Carboxin inhibit Succinate coenzyme Q reductase (complex II), which is involved in transferring electrons from succinate to coenzyme Q. Therefore, the correct match is (iii).

• D) Cyanide and Azide inhibit Cytochrome c oxidase (complex IV), which is responsible for transferring electrons to oxygen. Therefore, the correct match is (iv).

Information Booster:

1. ATP Synthase (complex V) is essential for ATP production, and its inhibition leads to a halt in cellular energy production.

2. NADH coenzyme Q reductase (complex I) plays a crucial role in the electron transport chain by transferring electrons from NADH to coenzyme Q.

3. Succinate coenzyme Q reductase (complex II) is involved in the transfer of electrons from succinate to coenzyme Q and is a point of inhibition for substances like Carboxin and Thenoyltrifluoroacetone.

4. Cytochrome c oxidase (complex IV) is the terminal enzyme complex in the electron transport chain, responsible for transferring electrons to oxygen and completing the electron transfer process.