PCAT Biological Processes Practice Test

Below is our free PCAT Biological Processes Practice Test. The PCAT Biology section covers general biology, microbiology, human anatomy, and physiology. Our PCAT Biology questions are designed to be very challenging, but answers and detailed explanations are included. Continue your test prep now with our free practice questions.

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Question 1
Which of the following would NOT occur during sympathetic stimulation?

A
secretion of glucagon
B
dilation of bronchioles
C
dilation of intestinal blood vessels
D
dilation of pupils
Question 1 Explanation: 
The correct answer is (C). 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.
Question 2
Which of the following would increase the pH of the blood?

A
severe damage to the kidneys
B
the digestion of a big meal
C
an increase in anaerobic respiration
D
an increase of the blood pCO2
Question 2 Explanation: 
The correct answer is (B). 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.
Question 3
Which of the following yields the least ATP directly?

A
TCA cycle
B
oxidative phosphorylation
C
glycolysis
D
Beta Oxidation
Question 3 Explanation: 
The correct answer is (A). 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.
Question 4
The T-tubules transmit an action potential, causing the opening of ____ channels in the ____.

A
Na+, Sarcoplasm
B
Ca2+, Sarcoplasmic Reticulum
C
Na+, Sarcoplasmic Reticulum
D
Ca2+, Sarcoplasm
Question 4 Explanation: 
The correct answer is (B). The T-tubules conduct action potentials that cause channels to open on the surface of the sarcoplasmic reticulum. The opening of these channels results in a release of Ca2+ into the sarcoplasm of the muscle fiber.
Question 5
Which of the following decompose disaccharides into monosaccharides?

A
salivary amalyse
B
pancreatic enzymes
C
gastrin
D
brush border enzymes
Question 5 Explanation: 
The correct answer is (D). 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.
Question 6
Which of the following does hemoglobin bond most strongly with?

A
oxygen
B
carbon dioxide
C
carbon monoxide
D
hydrogen
Question 6 Explanation: 
The correct answer is (C). 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.
Question 7
Which of the following is not secreted by the hypothalamus?

A
glucocorticoids
B
GnRH
C
Dopamine
D
GHIH
Question 7 Explanation: 
The correct answer is (A). Glucocorticoids are steroids synthesized and secreted by the adrenal cortex not the hypothalamus.
Question 8
A virulent phage is one which infects via:

A
the lysogenic cycle
B
phagocytosis
C
immunoglobins
D
the lytic cycle
Question 8 Explanation: 
The correct answer is (D). 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.
Question 9
Which is not a function of immunoglobins?

A
coagulation
B
assist in phagocytosis
C
attack pathogens
D
labeling of pathogens
Question 9 Explanation: 
The correct answer is (C). Antibodies or immunoglobins perform all of the functions except for directly attacking pathogens. Leukocytes, or white blood cells, are responsible for attacking pathogens.
Question 10
What results in extra or fewer chromosomes in a cell?

A
nondisjunction
B
double replication
C
double cytokinesis
D
epistasis
Question 10 Explanation: 
The correct answer is (A). 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.
Question 11
For vision, ___ must be converted to _____ in the cells of the retina.

A
vitamin C, retinal
B
vitamin E, biotin
C
vitamin A, retinal
D
vitamin A, biotin
Question 11 Explanation: 
The correct answer is (C). Vitamin A is a precursor of retinal, which is the chemical compound that enables animals to see. Biotin is associated with vitamin B. Carrots are known to be good for vision because they are high in vitamin A.
Question 12
Which of the following is involved in hearing?

A
microvilli
B
cilia
C
hair follicles
D
hair cells
Question 12 Explanation: 
The correct answer is (D). 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.
Question 13
Which is not active in bone resorption?

A
osteoblasts
B
osteoclasts
C
nephrons
D
small intestine
Question 13 Explanation: 
The correct answer is (A). Bone resorption, the decomposition of bone for absorption of minerals, including calcium, directly involves osteoclasts. Nephrons and the small intestine both absorb released Ca2+. Osteoblasts function to construct, not decompose, bones.
Question 14
Which of the following will result if there is a drop in blood pressure?

A
formation of glucose
B
secretion of insulin
C
secretion of EPO
D
secretion of ANP
Question 14 Explanation: 
The correct answer is (C). 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.
Question 15
Which of the following occurs as a rise in intraocular pressure?

A
inflammation of the cornea
B
glaucoma
C
cataract
D
diabetic retinopathy
Question 15 Explanation: 
The correct answer is (B). 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.
Question 16
In which nonmembranous compartment are ribosomes made in a eukaryotic cell?

A
nucleus
B
rough ER
C
nucleolus
D
cytoplasm
Question 16 Explanation: 
The correct answer is (C). Ribosomes are manufactured inside of the nucleolus. RNA polymerases I and III work together to create ribosomes from rRNA and proteins.
Question 17
Which of the following lists the correct taxonomic order from most inclusive to least inclusive?

A
Kingdom, Order, Class, Species
B
Order, Family, Genus, Phylum
C
Order, Family, Genus, Species
D
Phylum, Order, Species, Genus
Question 17 Explanation: 
The correct answer is (C). Kingdom, Phylum, Class, Order, Family, Genus, Species. The mnemonic, “King Philip Came Over For Great Spaghetti,” is very useful for remembering the taxonomic order from most inclusive to least inclusive.
Question 18
Which of the following corresponds to the coding strand of the following mRNA?

5’-GUAACGUCA- 3’

A
5’-GTAACGTCA-3’
B
5’-CATTGCAGT-3’
C
5’- ACUGCAAUG- 3’
D
5’- TGACGTTAC- 3’
Question 18 Explanation: 
The correct answer is (A). The coding strand is NOT the complementary strand; it is the strand of DNA which is complementary to the strand from which mRNA is made. The coding strand will have the same sequence of bases as the produced RNA transcript except with thymine instead of uracil. A useful mnemonic for remembering the nucleotide bases in DNA and RNA is “GCAT PuPy” and “GCAU PuPy.” GCAT/U stand for guanine, cytosine, adenine, thymine, and uracil, and “Pu” and “Py” represent purine and pyrimidine, respectively.
Question 19
Which cells make up the insulated wrapping on axons?

A
Schwann cells
B
astrocytes
C
microglia
D
macrocytes
Question 19 Explanation: 
The correct answer is (A). Axons are surrounded by insulating cells called Schwann cells. This insulation enables action potentials to travel rapidly throughout the nervous system.
Question 20
Which of the following statements regarding energy production is true?

A
There is a net total of 4 ATP produced in glycolysis.
B
The GTP made in the TCA cycle does not become ATP.
C
The cell requires energy to move NADH into the mitochondria.
D
The net gain of ATP from each NADH is 2.
Question 20 Explanation: 
The correct answer is (C). 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.
Question 21
Blood flows from the mitral valve to the

A
left atrium
B
aorta
C
right ventricle
D
left ventricle
Question 21 Explanation: 
The correct answer is (D). 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.
Question 22
A female who is a carrier of an X-linked recessive disability produces an offspring with a normal male. What is the chance that the male offspring will have the disability?

A
0%
B
25%
C
50%
D
100%
Question 22 Explanation: 
The correct answer is (C). The situation presented is an Xx (female) crossed with an XY (male). Because the offspring is a male (XY), the X-chromosome must come from the mother. Consequently, there is a 50% chance of receiving the recessive x-chromosome.
Question 23
Energy for ATP synthesis is produced primarily by

A
NADH
B
proton gradient
C
ATP synthase
D
Na+
Question 23 Explanation: 
The correct answer is (B). 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.
Question 24
Which of the listed antibodies is released in response to an allergen?

A
IgA
B
IgE
C
IgG
D
IgM
Question 24 Explanation: 
The correct answer is (B). IgE is the antibody primarily involved in allergic reactions.
Question 25
A cross between red bean (RR) and a blue bean (UU) yields all purple beans. How many purple beans would result from a cross between two purple beans?

A
0.25 of the offspring
B
0.50 of the offspring
C
0.75 of the offspring
D
all of the offspring
Question 25 Explanation: 
The correct answer is (B). Begin by crossing a red bean with a blue bean: RR x UU gives all RU, also known as incomplete dominance. Next cross a purple bean with a purple bean: RU x RU yields 1 RR, 2 RU and 1 UU. Two out of the four offspring are purple beans. This is the same as 0.50, or 50%.
Question 26
The release of ____ into the blood would increase the heart rate.

A
rennin
B
ANP
C
norepinephrine
D
insulin
Question 26 Explanation: 
The correct answer is (C). Norepinephrine (as well as epinephrine), released by the adrenal glands, stimulates the sympathetic nervous system. A consequence of norepinephrine and epinephrine on the heart is an increase in the heart rate. The sympathetic nervous system is linked to the fight-or-flight response.
Question 27
Which of the following is NOT the result of a viral infection?

A
genital warts
B
Syphilis
C
AIDS
D
the common cold
Question 27 Explanation: 
The correct answer is (B). 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.
Question 28
The rhythm of the heart is set by the:

A
AV node
B
SA node
C
purkinje fibers
D
Heart valves
Question 28 Explanation: 
The correct answer is (B). 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.
Question 29
The heart will automatically stop if the SA node stops working:

True or False?

A
True
B
False
Question 29 Explanation: 
The correct answer is (B). 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.
Question 30
Which of the following lacks mitochondria?

A
fungi
B
protozoan
C
bacteria
D
amoeba
Question 30 Explanation: 
The correct answer is (C). Unlike eukaryotes, prokaryotes do not possess organelles (excluding the ribosomes). Bacteria are categorized as prokaryotic and consequently do not possess a mitochondria.
Question 31
The liver and skeletal muscles have a high storage of

A
glycogen
B
glucagon
C
ketone bodies
D
ammonia
Question 31 Explanation: 
The correct answer is (A). 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.
Question 32
What is the predominant source of progesterone after ovulation?

A
the oocyte
B
the ovary
C
the corpus callosum
D
the corpus luteum
Question 32 Explanation: 
The correct answer is (D). Recall that the luteal phase of the menstrual cycle occurs after ovulation which occurs after the follicular phase. Progesterone saturation is highest during the luteal phase, and the corpus luteum is most responsible for this increased amount. The oocyte is an egg, which isn’t responsible for progesterone. The ovary is a source of progesterone, but not the primary source. And the corpus callosum is the point of juncture between the hemispheres of the brain.
Question 33
Which of the following is necessary for the penetration of an egg?

A
the flagellum
B
mitochondria
C
acrosome
D
centriole
Question 33 Explanation: 
The correct answer is (C). 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.
Question 34
Which is the most inferior structure?

A
stomach
B
sigmoid colon
C
pancreas
D
small intestine
Question 34 Explanation: 
The correct answer is (B). Inferior refers to the area nearest the feet. Its opposite is superior, which refers to the area nearest the top of the head. In this case, the stomach is superior to both the pancreas and the small intestine which are both superior to the sigmoid colon. The sigmoid colon is nearest the feet of the options.
Question 35
Which hormone is released after a meal high in carbohydrates?

A
insulin
B
glucagon
C
EPO
D
gherlin
Question 35 Explanation: 
The correct answer is (A). 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.
Question 36
Which of the following does NOT happen during inflammation?

A
release of histamine
B
an increase of local temperature
C
migration of leukocytes
D
constriction of blood vessels
Question 36 Explanation: 
The correct answer is (D). 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 and other phages.
Question 37
Which of the following is NOT a result of sympathetic stimulation?

A
increase in blood pressure
B
increase of blood flow to intestines
C
increase in blood flow to the brain
D
dilation of pupils
Question 37 Explanation: 
The correct answer is (B). Sympathetic stimulation, associated with the fight-or-flight response, results in an increased blood pressure to help the body deal with a stressful situation. The body diverts blood away from digestion and the digestive system in favor of the skin, the muscles, and the brain.
Question 38
A virus contains all of the following except?

A
mitochondria
B
RNA
C
amino acids
D
DNA
Question 38 Explanation: 
The correct answer is (A). A virus is neither eukaryotic nor prokaryotic, but similar to prokaryotes, viruses lack organelles. They are composed primarily of nucleic acids, DNA and RNA, and proteins. Viruses lack mitochondria.
Question 39
Which of the following most recently evolved to its present state?

A
pons
B
cerebrum
C
cerebellum
D
medulla oblongata
Question 39 Explanation: 
The correct answer is (B). The medulla oblongata and the pons make up the brain stem, which evolved earliest. The cerebellum evolved next, followed by the cerebrum.
Question 40
The oxidation of NADH occurs in which of the following?

A
glycolysis
B
TCA cycle
C
ETC
D
photosynthesis
Question 40 Explanation: 
The correct answer is (C). NADH is the reduced form of nicotinamide adenine dinucleotide and contains an electron that can be donated in the ETC. In the ETC, NADH is oxidized to NAD+.
Question 41
Why does the lactic acid pathway predominate in anaerobic respiration?

A
because the lactic acid can be made into oxygen when needed
B
because O2 is needed for the creation of NADH
C
because O2 is required for glycolysis
D
without O2 there is no electron acceptor for the ETC
Question 41 Explanation: 
The correct answer is (D). Lactic acid fermentation, a method of anaerobic respiration, is relied upon to generate energy for cells in the absence of oxygen. However, because oxygen acts as the primary electron acceptor in aerobic respiration, the lactic acid pathway, lacking oxygen, contains no electron acceptor in the process.
Question 42
Which pathway accounts for the least amount of ATP generated (by the pathway)?

A
glycolysis
B
TCA cycle
C
ETC
D
all have an equal number of ATP made
Question 42 Explanation: 
The correct answer is (B). The generation of most to least ATP is as follows: ETC, which can produce 32 ATP; Glycolysis, which produces 2 ATP, and the TCA cycle, which produces 2 GTP in addition to electron carriers that are used in the ETC to generate ATP.
Question 43
An action potential would travel fastest in

A
unmyelinated, thick axon
B
myelinated, thick axon
C
unmyelinated, thin axon
D
myelinated thin axon
Question 43 Explanation: 
The correct answer is (B). Axons are thin or thick bundles of nerve fibers. The thicker an axon is, the more quickly an action potential will travel through it. Additionally, a myelin sheath functions as an insulator that also facilitates the rapid transmission of an action potential.
Question 44
Where is the ETC located in bacteria?

A
mitochondria
B
Golgi apparatus
C
peroxisome
D
plasma membrane
Question 44 Explanation: 
The correct answer is (D). Eukaryotes house the ETC in their mitochondria, but bacteria, which are prokaryotic, do not possess mitochondria or organelles. The ETC in prokaryotic bacteria is located along the cell membrane.
Question 45
Which of the following is NOT made by the pituitary gland?

A
ACTH
B
ADH
C
FSH
D
LH
Question 45 Explanation: 
The correct answer is (B). The list of hormones made by the pituitary gland can be recalled with the mnemonic FLATPOG, signifying: FSH, LH, ACTH, TSH, GH, MSH (melanocyte stimulating hormone), and prolactin. ADH is made by the hypothalamus and is only secreted by the posterior pituitary.
Question 46
Which of the following is found in the plasma membrane of a cell?

A
phospholipid
B
glycoprotein
C
cholesterol
D
all of the above
Question 46 Explanation: 
The correct answer is (D). The plasma membrane of a cell is composed of a phospholipid bilayer, a double layer of lipids combined with phosphate groups. The hydrophilic nature of the phosphate heads and the hydrophobic nature of the lipids create a double sided membrane with phosphates on both sides and lipids trapped between. Cholesterol and glycoprotein molecules are embedded inside the phospholipid bilayers.
Question 47
Which of the following should be added to denature a protein all the way back to primary structure?

A
reducing agent
B
oxidizing agent
C
water
D
ether
Question 47 Explanation: 
The correct answer is (A). In order to denature proteins to their primary structure, a reducing agent is necessary to cleave the disulfide bonds in protein’s secondary structure.
Question 48
What is the role of a nurse cell?

A
secrete testosterone
B
secrete sperm
C
nurture maturing red blood cells
D
activate sperm motility
Question 48 Explanation: 
The correct answer is (C). Nurse cells aid in the maturation of red blood cells. They are macrophages that absorb immature red blood cells and facilitate the growth of red blood cells.
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