PCAT Biological Practice Test

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

Correct! Wrong!

Explanation:
The blood flow to visceral organs decreases during sympathetic stimulation, but increases under parasympathetic stimulation. One function of the sympathetic nervous system is to increase blood flow to organs in demand of air or nutrients. During the fight-or-flight response, vasodilation works to move blood away from the digestive system and towards the muscles.

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

Correct! Wrong!

Explanation:
An exothermic reaction releases energy, whereas an endothermic reaction requires energy. The breakdown of a chemical compound is an example of a decomposition reaction (AB → A + B.. A combination reaction (A + B →AB. is the reverse of a decomposition reaction, and a replacement (displacement) reaction is one where compound breaks apart and forms a new compound plus a free reactant (AB + C →AC + B or AB + CD → AD + CB.

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

Correct! Wrong!

Explanation:
During the digestion of a large meal, parietal cells in the stomach generate hydrochloric acid (HCl) in exchange for a bicarbonate ion which enters the blood plasma, increasing the pH.

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

Correct! Wrong!

Explanation:
Enzyme inhibitors attach to an enzyme and block substrates from entering the active site, thereby preventing enzyme activity. As stated in the question, cyanide is a poison that irreversibly binds to an enzyme and blocks its active site, thus fitting the definition of an enzyme inhibitor.

Which of the following produces the least ATP?

Correct! Wrong!

Explanation:
The TCA cycle yields 2 GTPs (molecules that can be converted to ATP but are not ATP themselves), oxidative phosphorylation, which includes the ETC, can yield from 32 to 34 ATP. Glycolysis yields 2 ATP. Beta oxidation yields a range over 100 ATP that depends on the length of the fatty acid being degraded.

A virulent phage infects by:

Correct! Wrong!

Explanation:
Virulent phages use the lytic cycle to infect an organism. The lytic cycle is the process by which a phage DNA replicates itself via the host cell before causing the cell to lyse and release all of the phage’s replications.

Disaccharides are decomposed into monosaccharides via which of the following?

Correct! Wrong!

Explanation:
Disaccharides such as sucrose, maltose, and lactose, etc., are broken down further into monosaccharides (primarily glucose) in the small intestine by way of brush border enzymes lining microvilli of the small intestine.

Hemoglobin has the strongest bonds with which of the following?

Correct! Wrong!

Explanation:
Hemoglobin bonds most strongly with carbon monoxide as a result of the interaction of the orbitals of the hemoglobin and the carbon monoxide molecule. The carbon forms an ionic bond with the hemoglobin’s iron, and because of the joint configuration, the iron is able to donate additional electrons to the carbon monoxide.

What causes a cell to have extra or fewer chromosomes?

Correct! Wrong!

Explanation:
Nondisjunction is when chromosomes do NOT separate during anaphase. Consequently, the resulting cells display an unequal sharing of chromosomes, with some cells having too many, and others having too few.

Hearing involves which of the following?

Correct! Wrong!

Explanation:
Hair cells lining the basilar membrane utilize mechanotransduction to detect, to amplify, and to convert mechanical sound waves into electrical signals. The resulting action potential then passes through the cochlear nerve to reach the brain.

If blood pressure drops, which of the following will happen?

Correct! Wrong!

Explanation:
A drop in blood pressure causes the renal cortex of the kidney to secrete EPO (erythropoietin) in an effort to increase the blood pressure by increasing the synthesis of red blood cells. EPO is a necessary precursor for red blood cell production to take place.

When intraocular pressure rises, which of the following happens?

Correct! Wrong!

Explanation:
Intraocular pressure (IOP) poses the greatest risk of causing glaucoma. A reduction in the flow and drainage of aqueous humor leads to a rise in IOP. The built up pressure eventually results in glaucoma and optic nerve damage.

Ribosomes are generated in which nonmembranous compartment in a eukaryotic cell?

Correct! Wrong!

Explanation:
Ribosomes are manufactured inside of the nucleolus. RNA polymerases I and III work together to create ribosomes from rRNA and proteins.

The insulated wrapping on axons is made up of which cells?

Correct! Wrong!

Explanation:
Axons are surrounded by insulating cells called Schwann cells. This insulation enables action potentials to travel rapidly throughout the nervous system.

Which of the following energy production statements is correct?

Correct! Wrong!

Explanation:
Transport of the NADH into the mitochondria in most cases requires 1 ATP. This is the reason that prokaryotes often have a higher yield of ATP per glucose when compared to eukaryotes. Usually 38 ATP are produced per glucose for prokaryotes, and 36 per glucose for eukaryotes.

Blood goes from the mitral valve to the

Correct! Wrong!

Explanation:
The left atrium connects to the left ventricle by way of the mitral valve. The left ventricle connects to the aorta by way of the aortic valve. Blood flows from the pulmonary veins into the left atrium and through the mitral valve (bicuspid valve), to the left ventricle then out through the aorta.

The primary source of energy for ATP production is

Correct! Wrong!

Explanation:
Proton pumps located along the inner mitochondrial membrane enable the passage of H+ across a concentration gradient. These protons pass through ATP synthase in which an axel rotates to combine phosphate with ADP to form ATP. Without the proton gradient, ATP synthase could not create ATP.

Which of the following conditions is NOT caused by a viral infection?

Correct! Wrong!

Explanation:
Genital warts are caused by the Human papillomavirus. AIDS is a consequence of the Human Immunodeficiency Virus. The common cold is also a viral infectious disease. Syphilis, however, is the result of a bacterial infection.

The heart's rhythm is determined by:

Correct! Wrong!

Explanation:
The sinoatrial node (SA) is the main pacemaker of the heart, often initiating cardiac contraction due to generating impulses faster than other pacemaker areas. The SA is referred to as the primary pacemaker.

If the SA node stops operating, the heart will instantly stop: Is it true or false?

Correct! Wrong!

Explanation:
Although the SA node is the primary pacemaker of the heart, in the absence of its operation, the AV node will take over at a slower pace.

Which of the following organisms does not have mitochondria?

Correct! Wrong!

Explanation:
Unlike eukaryotes, prokaryotes do not possess organelles (excluding the ribosomes). Bacteria are categorized as prokaryotic and consequently do not possess a mitochondria

Both the liver and skeletal muscles have a high storage of

Correct! Wrong!

Explanation:
The liver and skeletal muscles are two of the major glycogen storage sites. The liver contains a high amount in order to regulate blood sugar levels. The skeletal muscles contain a high amount of glycogen in order to satisfy their energy demands.

For an egg to penetrate, which of the following is required?

Correct! Wrong!

Explanation:
In order to penetrate an egg, a spermatozoon must bind with the exterior of the egg. This binding takes place by way of the acrosome reaction, in which the sperm penetrates the jelly coat of the egg to breach and fuse with the egg plasma membrane before releasing its constituents into the eggs cytoplasm.

Following a high-carbohydrate meal, which hormone is released?

Correct! Wrong!

Explanation:
When the blood stream is over saturated with glucose (as a result of a meal high in carbohydrates), the pancreas releases insulin in order to regulate the glucose levels in the blood.

During inflammation, which of the following does NOT happen?

Correct! Wrong!

Explanation:
Inflammation causes dilation, not constriction of blood vessels. This dilation of blood vessels is designed to increase permeability across the blood vessels and facilitate mobility of white blood cells.

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