In Escherichia coli, the synthesis of tryptophan is controlled by the tryptophan operon that is repressed in the presence of excessive tryptophan. When a mutant strain that has lost the regulatory gene of the tryptophan operon is placed in a medium that contains all nutrients the cells need to grow except tryptophan, which of the following will occur?

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#Question id: 2254

#Unit 2. Cellular Organization

If the intracellular [Ca2+] is 10⁻⁷ mol/L and the extracellular [Ca2+] is 2 × 10⁻³ mol/L, at what potential difference across the cell membrane will Ca2+ be at electrochemical equilibrium?

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#Question id: 2255

#Unit 2. Cellular Organization

Following statements are regarding to the Na+/K+ ATPase maintains the intracellular Na+ and K+ concentrations in animal cells. Which of the following statement is incorrect?

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#Question id: 2256

#Unit 2. Cellular Organization

Match the following inhibitors (Column I) with their effect (Column II).

Column I	Column II
A. A23187	I. endoplasmic reticulum Ca2+ ATPase inhibitor
B. valinomycin	II. Na+/K+ ATPase inhibitor
C. thapsigargin	III. K+ ionophore
D. ouabain	IV. Ca2+ ionophore

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#Question id: 2257

#Unit 2. Cellular Organization

Match the following property (Column I) with the transport mechanism (Column II).

Column I	Column II
A. Facilitated Transport	i. Requires specific protein
B. Active Transport	ii. Solute transported against its gradient
C. Cotransport	iii. Coupled to ATP hydrolysis
	iv. Driven by movement of a cotransported ion down its gradient

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#Question id: 2258

#Unit 2. Cellular Organization

The arrangement of microtubules in eukaryotic flagella is referred to as

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#Question id: 2259

#Unit 2. Cellular Organization

Which of the following is not a characteristic of prokaryotes?