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. Why does compartmentalization require energy?

because a negative gradient in chemical potentials across cellular membranes must be maintained correct incorrect

because a zero gradient in chemical potentials across cellular membranes must be maintained correct incorrect

because ions must be pumped against a gradient in chemical potential spanning across cellular membranes correct incorrect

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. Which biologically active species control important cellular process such as oxidation/reduction, hydrolysis, and methyl group transfer?

metalloproteins correct incorrect

free proteins correct incorrect

free metal ions correct incorrect

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. Which statement is correct?

Both passive and active ion transport modes occur in the cell. correct incorrect

Only passive ion transport mode occurs in the cell. correct incorrect

Only active ion transport mode occurs in the cell. correct incorrect

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. Siderophores are small polydentate ligands with high iron affinity. Their role is to aid iron _____ in organisms.

storage correct incorrect

uptake correct incorrect

transport correct incorrect

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. How is acid-base catalysis accomplished in organisms?

through free H⁺ or OH^– correct incorrect

through metal ions built into protein structures correct incorrect

Acid-base catalysis is absent from organisms since they rarely possess the extreme pH conditions that enable catalysis by free H⁺ or OH^–. correct incorrect

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. Methyl transfer reactions of cobalamines rely on the:

high nucleophilicity of square-planar Co(I) correct incorrect

high electrophilicity of square-planar Co(I) correct incorrect

low nucleophilicity of square-planar Co(I) correct incorrect

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. The enzyme nitrogenase is of great interest to industrial chemists because:

It reduces nitrates present in waste water to nitrogen gas, thus reducing the potential for nitrate pollution of the environment. correct incorrect

It oxidizes nitrites to nitrates at normal conditions; the nitrates are then used in the production of nitric acid. correct incorrect

It reduces nitrogen to ammonia at normal conditions. correct incorrect

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. Both Zn and Cu in living systems are coordinated by cysteine thiolates; the geometry of these coordination compounds is:

tetrahedral for both metals correct incorrect

tetrahedral for Cu; linear for Zn correct incorrect

tetrahedral for Zn; linear for Cu correct incorrect

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. What is biomineralization?

Biomineralization is crystallization of inorganic materials under biological control. correct incorrect

Formation of fossil materials from dead organizms (particularly shells) under anaerobic conditions is called biomineralization. correct incorrect

The process of biomineralization is a cellular process found in some bacteria that converts minerals from the environment into source of biologically important metals. correct incorrect

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. What are oxygenases?

Oxygenases are redox metalloenzymes that behave as reducing agents. correct incorrect

Oxygenases are metalloenzymes responsible for the catalytic insertion of one O atom ore both O atoms from a dioxygen molecule into substrates. correct incorrect

Oxygenases catalytically convert O₂ to H₂O or, less frequently, H₂O₂. correct incorrect