Molybdoenzymes can both oxidize as well as reduce the substrates, because

1. Mo(VI) is more stable than Mo(IV)

2. Mo(IV) can transfer oxygen atom to the substrate and Mo(VI) can abstract oxygen atom from the substrate

3. Conversion of Mo(VI) to Mo(IV) is not favoured

4. Mo(VI) can transfer oxygen atom to the substrate and Mo(IV) can abstract oxygen atom from the substrate

The metal present at the active site of the protein carboxypeptidase A is

1. Zinc

2. molybdenum

3. magnesium

4. Cobalt

The red colour of oxyhaemoglobin is mainly due to the

1. d-d transition

2. metal to ligand charge transfer transition

3. ligand to metal charge transfer transition

4. intraligand $\mathrm{\pi }-\mathrm{\pi }*$ transition

Hemoglobin is an oxygen carrying protein. The correct statement about oxyhemoglobin is that

1. the metal is low-spin in +3 oxidation state while dioxygen is in ${{\mathrm{O}}_2}^{-}$ form

2. the metal is high spin in +3 oxidation state while dioxygen is in ${{\mathrm{O}}_2}^{-}$ form

3. the metal is low spin in +3 oxidation state while dioxygen is in neutral form

4. the metal is high spin in +3 oxidation state while dioxygen is in neutral form

Oxymyoglobin Mb(O₂) and oxyhaemogolbin Hb(O₂)₄, respectively, are

1. Paramagnetic and paramagnetic

2. Diamagnetic and diamagnetic

3. Paramagnetic and diamagnetic

4. Diamagnetic and paramagnetic

The cooperative binding of O₂ in hemogoblin is due to

1. a decrease in size of iron followed by changes in the protein conformation

2. an increase in size of iron followed by changes in the protein conformation

3. a decrease in size of iron that is NOT accompanied by the protein conformational changes

4. an increase in size of iron that is NOT accompanied by the protein conformational changes

Oxidized form of enzyme catalase (structure A); prepared by the reaction of [Fe(P)]⁺ (P=porphyrin) with H₂O₂ has a green colour because of

1. Oxidation state of iron changed from Fe^III to Fe^IV.

2. Porphyrin ring is oxidized by one electron.

3. $\mathrm{\pi }-\mathrm{\pi }*$ transition appears in the visible region

4. Fe^IV is coordinated with anionic tyrosinate ligand in axial position.

The extent of $\mathrm{\pi }$ electron conjugation in macrocyclic rings (i) heme, (ii) coenzyme B₁₂ and (iii) chlorophyl follows the order

1. (i)>(iii)>(ii)

2. (i)>(ii)>(iii)

3. (iii)>(i)>(ii)

4. (ii)$\approx$(i)>(iii)

Patients suffering from Wilson's disease have

1. Low level of Cu-Zn superoxide dismutase

2. High level of Cu-Zn superoxide dismutase

3. Low level of copper-storage protein, ceruloplasmin

4. High level of copper storage protein ceruloplasmin

Iron-sulphur clusters in biological systems are involved in

1. proton transfer

2. atom transfer

3. group-transfer

4. e^- transfer