Free Practice Test Prep MCAT Exam Questions 2025

Stay ahead with 100% Free Medical College Admission Test: Verbal Reasoning, Biological Sciences, Physical Sciences, Writing Sample MCAT Dumps Practice Questions

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Total 815 Questions | Updated On: Mar 25, 2025

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Question 1

Which of the following molecules will stop being produced first when oxygen is no longer supplied to the cell?

Section: Biological Sciences

A : Oxaloacetate

B : Pyruvate

C : Water

D : Adenosine triphosphate

Answer: C

Question 2

Which of the following will halve the magnitude of the electrostatic force of attraction between two charged

particles?

Section: Physical Sciences

A : Doubling the distance between the particles

B : Halving the charge on each particle

C : Halving the charge on only one of the particles

D : Placing a positively charged particle midway between the particles

Answer: C

Question 3

All of the following are true regarding the function of neurons EXCEPT:

Section: Biological Sciences

A : Hyperpolarization at the end of an action potential is one mechanism by which neurons limit the rate atwhich action potentials may fire.

B : The flow of sodium into the neuron depolarizes the membrane in the first phase of an action potential.

C : The transmitting neuron secretes neurotransmitters into the synaptic cleft from its dendrites.

D : An action potential is initiated when the axon hillock reaches the threshold potential.

Answer: C

Question 4

Synthetic dyes constitute a commercially significant area of organic chemistry. The color producing properties

of these compounds are the result of highly delocalized electron systems giving rise to electronic transitions

whose absorptions occur in the visible region. Most commercially useful dyes can be classified as one of three

types – anthraquinones, azo dyes, or triarylmethyl salts. Examples of each type are illustrated in Figure 1.

Figure 1

In order for a dye to be useful in the fabric industry, it must have sufficient affinity for the polymeric fibers of

which the material is composed; the dye must not only impart a color to the fabric, but must also do so in a

relatively permanent manner (color fastness). Proper design of synthetic polymers requires the placement of

acidic or basic side chains along the polymer backbone such that binding sites are available for dying. Similarly,

dyes must be produced not only with the appropriate color-producing structure, but also with an affinity for the

fabric in question. The structural units of several common synthetic fibers are shown in Figure 2.

Figure 2

Dacron belongs to which of the following general classifications?

Section: Biological Sciences

A : Polyamide

B : Polyester

C : Polyurethane

D : Polypeptide

Answer: B

Question 5

Compounds containing a hydroxyl group attached to a benzene ring are called phenols. Derivatives of phenols,

such as naphthols and phenanthrols, have chemical properties similar to those of phenols, as do most of the

many naturally-occurring substituted phenols. Like other alcohols, phenols have higher boiling points than

hydrocarbons of similar molecular weight. Like carboxylic acids, phenols are more acidic than their alcohol

counterparts. Phenols undergo a number of different reactions; both their hydroxyl groups and their benzene

rings are highly reactive. A number of chemical tests can be used to distinguish phenols from alcohols and

carboxylic acids.

Thymol, a naturally occurring phenol, is an effective disinfectant that is obtained from thyme oil. Thymol can

also be synthesized from m-cresol, as shown in Reaction A below. Thymol can then be converted to menthol,

another naturally-occurring organic compound; this conversion is shown in Reaction B.

Reaction A

Reaction B

Comparing the Ka values for cyclohexanol (Ka = 10−13) and phenol (Ka = 1.3 × 10−10) reveals that phenol is more

acidic than cyclohexanol. Which of the following explain(s) the acidity of phenol?

I. The exceptionally strong hydrogen bonding possible with phenol facilitates the loss of a proton, making it

more acidic than cyclohexanol.

II. Phenol’s conjugate base, phenoxide, is stabilized by resonance to a greater extent than phenol itself.

III. The negative charge of the oxygen atom on the phenoxide ion is delocalized over the benzene ring.

Section: Biological Sciences

A : I only

B : II only

C : II and III only

D : I, II, and III

Answer: C

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Total 815 Questions | Updated On: Mar 25, 2025

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