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MCAT practice test online – MCAT prep

Free MCAT practice test online

Q6: An enzyme was assayed in the absence (−) or presence (+) of an allosteric effector, and the following Lineweaver-Burk plot was obtained:

MCAT practice tests

Which statement about the allosteric effector is correct?

A.The effector is an activator that increases both Vmax and Km.

B.The effector is an activator that increases Vmax but decreases Km.

C.The effector is an inhibitor that decreases both Km and Vmax.

D.The effector is an inhibitor that increases Km but decreases Vmax.

View Answer

Answer: C.The effector is an inhibitor that decreases both Km and Vmax.

Q7: Consider the following reaction:

Which parameter would NOT be affected by the addition of phosphoglycerate mutase?

A.The stability of the transition state between 3-phosphoglycerate and 2-phosphoglycerate

B.The equilibrium concentrations of 2-phosphoglycerate and 3-phosphoglycerate

C.The activation energy barrier between 3-phosphoglycerate and 2-phosphoglycerate

D.The rate constant for conversion of 2-phosphoglycerate to 3-phosphoglycerate

View Answer

Answer: B.The equilibrium concentrations of 2-phosphoglycerate and 3-phosphoglycerate

Q8: A single-stranded DNA oligonucleotide composed of which of the following would move most slowly down an alkaline agarose gel during electrophoresis?

A.Deoxyadenosine monophosphate

B.Deoxythymidine monophosphate

C.Deoxycytidine monophosphate

D.Deoxyguanosine monophosphate

View Answer

Answer: D.Deoxyguanosine monophosphate

Q9: A scientist sequences the genomes of several species and analyzes their evolutionary relationships to a single common ancestor.  The percentage of similarity between the genome of each species to the genome of this ancestor is calculated and shown in the table below.

Genomic similarity
to common ancestor
Species A 95%
Species B 88%
Species C 35%
Species D 22%

Which species diverged from the common ancestor first?

A.Species A

B.Species B

C.Species C

D.Species D

View Answer

Answer:

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