Practice Questions

TLS Online TPP Program

#Question id: 2870

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?

#Unit 2. Cellular Organization

The cells will continue to grow even though excess tryptophan is synthesized.
The cells will grow until excessive tryptophan arrests the expression of the operon.
The cells will not grow until enough tryptophan has been synthesized to activate the corepressor.
The cells will never grow unless tryptophan is added to the medium.

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TLS Online TPP Program

#Question id: 11140

#Unit 7. System Physiology – Animal

Although the membrane of a "resting" neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also ________.

TLS Online TPP Program

#Question id: 145

#Unit 1. Molecules and their Interaction Relevant to Biology

The pKaʹs of isoleucineʹs α-Carboxyl group and α-Amino group are 2.3 and 9.8, respectively. Calculate the isoelectric point.

TLS Online TPP Program

#Question id: 992

#Unit 1. Molecules and their Interaction Relevant to Biology

Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because:

TLS Online TPP Program

#Question id: 29582

#Unit 6. System Physiology – Plant

Quorum sensing in Erwinia carotovora is mediated by