PCAT Biological Practice Test

Question 1

During sympathetic stimulation, which of the following would NOT happen?

Accepted Answer

dilation of intestinal blood vessels

Answer

Sympathetic stimulation initiates the 'fight or flight' response, which prioritizes blood flow to vital organs like muscles, heart, and brain. This involves vasoconstriction of blood vessels to the digestive tract, not dilation, to redirect blood elsewhere. Dilation of bronchioles, secretion of glucagon, and dilation of pupils are all characteristic responses of the sympathetic nervous system.

Question 2

A disaccharide's breakdown releases energy, which is stored as ATP. This is an illustration of a (n)

Accepted Answer

Exothermic reaction

Answer

An exothermic reaction is a chemical process that releases energy into its surroundings, often in the form of heat. The breakdown of a disaccharide (catabolism) involves breaking chemical bonds, which releases stored energy that can then be captured to synthesize ATP. This energy release is the defining characteristic of an exothermic process.

Question 3

Which of the following would raise the blood's pH?

Accepted Answer

the digestion of a big meal

Answer

The digestion of a big meal, particularly one rich in protein, stimulates the stomach to produce large amounts of hydrochloric acid. This process, known as the 'alkaline tide,' involves the secretion of bicarbonate ions into the blood, which temporarily raises the blood's pH. The other options would generally lead to a decrease in blood pH (acidosis).

Question 4

Cyanide is a toxin that binds to the active site of the cytochrome c enzyme and stops it from working. Cyanide is a  (n)

Accepted Answer

Inhibitor

Answer

An inhibitor is a molecule that binds to an enzyme and reduces its activity. Since cyanide binds to the active site of the cytochrome c enzyme and prevents it from functioning, it acts as an inhibitor. This specific type of inhibition, where the inhibitor competes with the substrate for the active site, is known as competitive inhibition.

Question 5

Which of the following produces the least ATP?

Accepted Answer

TCA cycle

Answer

The TCA cycle (Krebs cycle) primarily functions to generate electron carriers (NADH and FADH2) for oxidative phosphorylation, along with one molecule of GTP (an ATP equivalent) per cycle. While glycolysis directly produces a net of 2 ATP, and oxidative phosphorylation yields the vast majority of ATP, the TCA cycle itself produces the least *direct* ATP compared to the other options.

PCAT - Pharmacy College Admission Test Practice Test

PCAT - Pharmacy College Admission Test Practice Test

PCAT Biological Practice Test