Renal and Digestive Systems MCAT Biology Diagnostic Exam 4A

Question 1

The exocrine functions of the pancreas include chemical digestion of each of the following EXCEPT:

A. polypeptides.
B. carbohydrates.
C. nucleotides.
D. triglycerides.

Answer 1

C. Proteins (polypeptides) are chemically digested by pancreatic proteases such as trypsin and chymotrypsin (choice A is digested by pancreatic enzymes and can be eliminated). Some carbohydrate chemical digestion starts in the mouth, but much of it is done in the duodenum by enzymes such as pancreatic amylase (choice B can be eliminated). Triglycerides (lipids) are not digested until they reach the small intestine; this is mediated by pancreatic lipases after bile from the liver/gallbladder has emulsified the fat molecules (choice D can be eliminated). However, pancreatic nucleases digest DNA and RNA, not nucleotides (choice C is not digested by pancreatic enzymes and is the correct answer choice).

Concepts tested
Digestive System: Accessory Organs

Question 2

A drug is discovered that markedly increases hemoglobin’s affinity for oxygen. What physiological situation is this drug mimicking?

A. Hyperventilation
B. Rigorous exercise
C. Running a fever
D. Increased production of BPG at high elevation

Answer 2

A. Hyperventilation results in reduced blood carbon dioxide levels, which leads to an increase in blood pH and an increase in hemoglobin’s affinity for oxygen (choice A is correct). The other answer choices all result in a decrease in oxygen affinity (choices B, C and D are wrong).

Concepts tested
Respiratory System: Ventilation and pH Regulation

Question 3

Osteoclasts are stimulated to destroy bone and increase circulating levels of calcium by which hormones?

A. Parathyroid hormone and calcitonin
B. Calcitonin and calcitriol
C. Parathyroid hormone and calcitriol
D. Calcitonin and cortisol

Answer 3

C. Parathyroid hormone and calcitriol (the active form of vitamin D) are involved in stimulating the osteoclasts to phagocytically destroy bone, thus freeing up calcium to be transported by the bloodstream to other parts of the body (note however that calcitriol’s effect on bone is minor). They also promote the absorption of calcium from the gut (choice C is correct). Calcitonin inhibits osteoclasts, decreasing bone resorption (choices A and B are wrong), and cortisol is involved in long-term stress responses (choice D is wrong).

Concepts tested
Endocrine System: Hormones and Hormone Functions Skeletal System: Bone Structure/Turnover

Question 4

Which of the following is made up of pluripotent cells?

A. The mesoderm
B. The zygote
C. The morula
D. The inner cell mass

Answer 4

D. The cells of the inner cell mass differentiate into the three primary germ layers and have the ability to become any cell in the body; they are considered to be pluripotent cells (choice D is correct). The mesoderm is one of the three primary germ layers and can become many, but not all cell types in the body; it is considered to be multipotent (choice A is wrong). The zygote and morula are totipotent; they can become any of the cells in the body and can also form the trophoblast (choices B and C are wrong).

Concepts tested
Development: Embryology/Fetal Development

Question 5

Cartilage can play roles in support, flexibility, or a combination of the two. The strongest cartilage is fibrous, the most flexible is elastic, and hyaline cartilage is in between, both strong and somewhat flexible. Which of the following structures is most likely made of elastic cartilage?

A. Articular (joint) cartilage
B. Intervertebral disks
C. Pubic symphysis
D. Epiglottis

Answer 5

D. The epiglottis is found in the respiratory tract, above the opening to the trachea. When swallowing, the epiglottis must fold downward to seal off the trachea thus preventing food and liquid from entering. This requirement for flexibility makes the epiglottis most likely to be made of elastic cartilage. Articular cartilage needs to be strong but somewhat flexible and is made of hyaline cartilage (choice A is wrong), and both the intervertebral disks and the pubic symphysis must be very strong and are made of fibrous cartilage (choices B and C are wrong).

Concepts tested
Skeletal System: Connective Tissue/Bone

Question 6

Which of the following are involved in carrying blood to the kidneys?

A. Abdominal aorta and renal vein
B. Inferior vena cava and renal vein
C. Abdominal aorta and renal artery
D. Inferior vena cava and renal artery

Answer 6

C. The abdominal aorta carries blood away from the heart and into the trunk of the body. The renal artery branches off the aorta to supply the kidneys with blood (choice C is correct). The renal vein and inferior vena cava are both involved in returning blood back to the circulatory system after it has been filtered (choices A, B, and D are incorrect).

Concepts tested
Renal System: Kidney Functions

Question 7

Anatomical dead space is classified as that area of the respiratory pathway where no gas exchange occurs with the blood. Which of the following is part of the anatomical dead space?

A. Alveolar duct
B. Alveolus
C. Terminal bronchioles
D. Respiratory bronchioles

Answer 7

C. Anatomical dead space is the portion of the respiratory tree where gas exchange does not take place, also known as the conduction zone. The conduction zone includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles (choice C is correct). The respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveoli (choices A, B and D are wrong).

Concepts tested
Respiratory System: Conduction and Respiratory Zones

Question 8

A student becomes anxious during his final exam and begins hyperventilating. Which of the following is/are true?

Blood pH increases
Blood CO2 levels decrease
O2 saturation of hemoglobin increases
  	A.  I only 
  	B.  I and II only
  	C.  II and III only
  	D.  I, II, and III

Answer 8

D. Items I and II are true: hyperventilation causes the loss of excess carbon dioxide, which shifts the equilibrium of the respiratory equation (CO2 + H2OEquilibrium arrow.H2CO3Equilibrium arrow.H+ + HCO3–) to the left. As H+ and HCO3– combine to form H2CO3, blood pH increases (choices A and C can be eliminated). Item III is true: as blood pH increases, the oxygen saturation curve of hemoglobin shifts to the left. A left-shifted curve means that hemoglobin’s affinity for oxygen is increased, and it will be more saturated (choice B can be eliminated and choice D is correct).

Concepts tested
Respiratory System: Ventilation and pH Regulation

Question 9

Fully mature bone is composed of all of the following EXCEPT:

A. cartilage.
B. collagen.
C. calcium.
D. phosphate

Answer 9

A. Mature bone is made rigid by the inclusion of hydroxyapatite, a calcium-phosphate crystalline solid (choices C and D are found in bone and can be eliminated). Collagen forms the framework for mature bone and this framework is then hardened by the crystalline solid (choice B is found in bone and can be eliminated). Cartilage is deposited in growing bone, but is replaced with solid bone matrix as bone matures (choice A is not found in fully mature bone and is the correct answer choice).

Concepts tested
Skeletal System: Bone Structure/Turnover

Question 10

A patient is diagnosed with a connective tissue disorder that results in severe shedding of the skin. Which normal function of skin would be disrupted?

A. Maintaining blood pH
B. Preventing dehydration
C. Excreting excess water and salt
D. Hormone regulation

Answer 10

B. The skin provides a substantial barrier to water loss; patients with large quantities of skin that have been damaged or removed are at risk for dehydration (choice B is correct). The remaining answer choices list processes that are not significantly influenced by the skin. Note that sweating is a process designed to cool the body, not eliminate excess water and salt.

Concepts tested
Skin: Layers Skin: Thermoregulation

Question 11

Which of the following is NOT an accurate statement concerning the hydrochloric acid produced in the stomach?

A. HCl is produced by the parietal cells.
B. HCl converts the zymogen pepsinogen into the active enzyme pepsin.
C. HCl engages in acid hydrolysis of proteins, aiding in their elementary digestion.
D. HCl is part of the innate immune mechanisms present in the duodenum.

Answer 11

D. Hydrochloric acid is made by parietal cells in the stomach (choice A is an accurate statement and can be eliminated), causes zymogen conversion (choice B is an accurate statement and can be eliminated), and facilitates non-specific acid hydrolysis of proteins (choice C is an accurate statement and can be eliminated). However, while it plays a role in innate immune function of the stomach, HCl is neutralized by aqueous bicarbonate upon entry into the duodenum (choice D is not an accurate statement and is the correct answer choice).

Concepts tested
Digestive System: Alimentary Canal

Question 12

Labor and delivery depends on each of the following EXCEPT:

A. uterine smooth muscle excitability.
B. oxytocin release from the posterior pituitary.
C. uterine contractions and cervical pressure.
D. prolactin release from the anterior pituitary.

Answer 12

D. Choices A, B, and C all describe physiological components of the birthing process and can be eliminated. Prolactin is required for lactation, which occurs postpartum (labor does not depend on choice D so it is the correct answer choice).

Concepts tested
Endocrine System: Hormones and Hormone Functions Reproductive Systems: Female Reproductive System

Question 13

Spermatogenesis occurs:

A. throughout the male adult life, due to the ability of spermatogonia to perform binary fission.
B. in the seminiferous tubules, starting near the basement membrane and finishing near the lumen.
C. via two rounds of meiosis, and generates four reproductively mature spermatids.
D. in a testosterone and GnRH-dependent manner, during some phases of male adulthood.

Answer 13

B. Spermatogenesis occurs throughout male adulthood (choice D is wrong) because spermatogonia can undergo mitosis (to regenerate) and meiosis (to make primary spermatocytes). Note that only bacterial cells perform binary fission (choice A is wrong). Spermatogenesis involves two rounds of division during meiosis, not two rounds of meiosis, and generates four spermatids, but these cells are not mature (choice C is wrong). Choice B is true and the correct answer choice.

Concepts tested
Reproductive Systems: Spermatogenesis

Question 14

All of the following are components or types of loose connective tissue EXCEPT:

A. adipose tissue.
B. collagen.
C. ligaments.
D. the extracellular matrix.

Answer 14

C. Connective tissues are classified as “loose” or “dense” based on the amount of collagen they contain; those with a lot of collagen are dense tissues, and tend to play more supportive roles. Ligaments connect bones to bones and are made primarily of collagen, thus they are a type of dense connective tissue (choice C is not loose connective tissue and is the correct answer choice). Adipose tissue, or fat, contains virtually no collagen and is a type of loose connective tissue (choice A can be eliminated). Collagen is found in both loose and dense connective tissue; the difference between the two is the amount of collagen (choice B is a component of loose connective tissue and can be eliminated). The extracellular matrix is the mix of proteoglycans and glycosaminoglycans that exists as the tissue between cells, It is responsible for holding on to water (among other functions); it is a component of loose connective tissue and many other tissues (choice D can be eliminated).

Concepts tested
Skeletal System: Connective Tissue/Bone

Question 15

Which of the following is a true statement?

A. The release of secretin, triggered by high duodenal pH, causes the release of bicarbonate and enzymes from the pancreas.
B. The release of secretin, triggered by low duodenal pH, causes the release of bicarbonate and enzymes from the pancreas.
C. The release of secretin, triggered by low gastric pH, causes the release of bicarbonate and enzymes from the pancreas.
D. The release of secretin, triggered by high gastric pH, causes the release of bicarbonate and enzymes from the pancreas.

Answer 15

B. Secretin is released from duodenal cells when acidic chyme enters the duodenum from the stomach and duodenal pH drops (choice A is wrong). This causes the release of bicarbonate (and enzymes) from the pancreas to help neutralize that acid, bringing duodenal pH into a more neutral range. This provides a more optimal environment for the pancreatic enzyme to function in, as they do not work well at low (acidic) pH (choice B is true). Since the hormone is released by duodenal cells, and since the pH change must occur in the duodenum, it should not be affected by gastric pH (choices C and D are wrong).

Concepts tested
Digestive System: Accessory Organs

Question 16

All of the following are functions of the liver EXCEPT:

A. storage of glycogen.
B. synthesis of blood proteins.
C. bile production.
D. secretion of digestive enzymes.

Answer 16

D. The liver has a number of functions in the body, including synthesis of bile (choice C can be eliminated), glycogen storage and metabolism (choice A can be eliminated), synthesis of blood proteins (such as albumin, fibrinogen, angiotensinogen, lipoproteins, etc., choice B can be eliminated), amino acid metabolism, production of urea, vitamin storage, detoxification, etc. However, the liver does not secrete digestive enzymes (choice D is not a function of the liver and is the correct answer choice).

Concepts tested
Digestive System: Accessory Organs

Question 17

Which of the following does NOT refer to a region of the kidney?

A. Renal ductus
B. Renal cortex
C. Renal medulla
D. Renal pelvis

Answer 17

A. The renal cortex is the outermost layer of the kidney and the medulla is the inner region (choices B and C can be eliminated). The renal pelvis is a large space into which urine drains from the collecting ducts (choice D is part of the kidney and can be eliminated). There is no renal ductus (choice A is not a part of the kidney and is the correct answer choice).

Concepts tested
Renal System: Kidney Functions

Question 18

How does pulmonary surfactant function?

A. By increasing alveolar elasticity
B. By increasing the cohesive force of water
C. By increasing the surface tension of water
D. By decreasing the surface tension of

Answer 18

D. Pulmonary surfactant decreases water’s surface tension (decreasing the cohesive forces of water) to help prevent collapse of the small airways in the lung (choice D is correct, and choices B and C are wrong). Pulmonary surfactant does not have a direct impact on alveolar elasticity although the decrease in cohesive force effectively reduces alveolar collapsing forces (i.e., a decrease in alveolar elasticity; choice A is wrong).

Concepts tested
Respiratory System: Conduction and Respiratory Zones

Question 19

Which of the following best describes the organization of striated muscle tissue from large scale structures to small scale structures?

A. Fascicles, myofibers, myofibrils, sarcomeres
B. Fascicles, myofibrils, myofibers, sarcomeres
C. Sarcomeres, myofibers, myofibrils, fascicles
D. Sarcomeres, myofibrils, myofibers, fascicles

Answer 19

A. Since the question asks for structures from largest to smallest, the biggest structures are the bundles of muscle tissue called fascicles (choices C and D are wrong). Fascicles are composed of fine muscle fibers called myofibers which are individual muscle cells that contain myofibrils. Finally, the myofibrils are subdivided into many sarcomeres (choice B is wrong and choice A is correct).

Concepts tested
Muscular System: Skeletal Muscle Structure and Sarcomeres

Question 20

Advertising and public health campaigns have long been trying to minimize drug and alcohol use in pregnant women. It is most important to limit the ingestion of these substances during the:

A. second trimester, since this is when the fetus undergoes the most extensive growth.
B. first trimester, since this is when all major organ systems develop.
C. second trimester, since this is when organ systems finish development.
D. third trimester, since this is when the mother is most uncomfortable and therefore most prone to taking pain-relieving drugs.

Answer 20

B. The basic development of all major organ systems is done in the first trimester of pregnancy, which is why drug or toxin exposure during this time can have major negative effects (choice B is correct). While drug exposure can harm a fetus at any point in development, the first trimester is crucial in development (choice B is better than choices A, C, and D). Most of these developmental pathways near completion in the second trimester, and the fetus increases drastically in size in the third trimester.

Concepts tested
Development: Embryology/Fetal Development

Question 21

When is meiosis II of oogenesis considered complete?

A. After the first polar body is secreted and disintegrates
B. After the primary oocyte completes cytokinesis
C. After the secondary oocyte is fertilized
D. When four ootids are generated from one oogonium

Answer 21

C. The secondary oocyte starts meiosis II before ovulation but freezes in metaphase II. Meiosis II is completed (and the second polar body is secreted) only if fertilization occurs (choice C is correct). Note that only one ootid is generated from a oogonium, because of polar body secretion (choice D is wrong). The disintegration of the first polar body is not part of meiosis II (choice A is wrong), and the division of the primary oocyte is part of meiosis I (choice B is wrong).

Concepts tested
Reproductive Systems: Oogenesis

Question 22

What type of ion channel is unique to cardiac muscle as opposed to skeletal or smooth muscle?

A. Voltage-gated sodium channel
B. Voltage-gated potassium channel
C. Voltage-gated calcium channel
D. Potassium leak channel

Answer 22

C. All types of muscle depend on voltage-gated sodium channels for depolarization (choice A is wrong) and voltage-gated potassium channels for repolarization (choice B is wrong). Potassium leak channels are important in establishing the resting membrane potential in all muscle types (choice D is wrong). However, only cardiac muscle cells have voltage-gated calcium channels; these are used to extend depolarization and create the distinctive plateau phase seen in cardiac muscle action potentials (choice C is correct).

Concepts tested
Muscular System: Cardiac and Smooth Muscle

Question 23

During the sliding filament cycle, which portions of the sarcomere experience a change in length?

A. A band and H zone
B. H zone and I band
C. I band and Z lines
D. A band and Z lines

Answer 23

B. The A band represents the complete length of the thick filament (myosin) which is neither shortened nor lengthened during contraction (choices A and D are wrong). The Z lines demarcate the individual sarcomeres and are also not altered by contraction (choice C is wrong). The H zone is the region measuring thick filament only with no overlap and this does change as sliding occurs; similarly, the I band is the region measuring the thin filament only (actin) and also changes as sliding occurs (choice B is correct).

Concepts tested
Muscular System: Skeletal Muscle Structure and Sarcomeres Muscular System: Sliding Filament Theory/Excitation-Contraction Coupling

Question 24

A patient presents with a severe hypodermis infection he developed from contact with another infected patient. What path did the bacteria most likely follow?

A. Epidermis → Hypodermis
B. Epidermis → Dermis → Hypodermis
C. Dermis → Hypodermis
D. Hypodermis → Dermis → Epidermis

Answer 24

B. The most likely path of infection for the bacteria would be to begin at the skin surface (epidermis), choices C and D can be eliminated) and end at the hypodermis, which necessitates passing through the dermis (choice B is correct and choice A is wrong). Note that the likelihood of bacteria finding a path between the epidermis and hypodermis without passing through the dermis is incredibly unlikely in the typical patient.

Concepts tested
Skin: Layers

Question 25

Which of the following is the correct order of reproductive structures through which sperm must travel, from their generation to their exit from the male body?

A. Seminiferous tubules, vas deferens, ejaculatory duct, urethra
B. Epididymis, seminiferous tubules, ejaculatory duct, vas deferens
C. Seminiferous tubules, epididymis, urethra, ejaculatory duct
D. Urethra, vas deferens, ejaculatory duct, epididymis

Answer 25

A. Sperm are made in the seminiferous tubules of the testes (choice B can be eliminated), mature in the epididymis (choice C can be eliminated), and are stored in the vas deferens or ductus deferens (choice D can be eliminated). During ejaculation, they travel with the rest of semen through the ejaculatory duct and then the urethra. Overall, choice A is the best answer.

Concepts tested
Reproductive Systems: Male Reproductive System

Question 26

Expiration is a passive process due to which of the following?

A. Elasticity of the lungs
B. Decreased atmospheric pressure
C. Decreased intrapulmonary pressure
D. Contraction of expiratory muscles

Answer 26

A. Expiration occurs primarily due to the elasticity of the lungs, which increases intrapulmonary pressure and causes air to be expelled to the lower-pressure atmosphere (answer A is correct and choice C is wrong). Atmospheric pressure remains relatively constant from breath to breath, and does not play a role in passive expiration (choice B is wrong). While muscular contraction can take part in forced expiration, this question was specifically asking about passive expiration, which does not involve muscle contraction (choice D is wrong).

Concepts tested
Respiratory System: Ventilation and pH Regulation

Question 27

After ovulation, the follicular cells remaining in the ovary:

A. differentiate into the corpus luteum and secrete high levels of progesterone.
B. secrete FSH and LH until GnRH levels decrease in response to negative feedback.
C. differentiate into the corona radiata and induce endometrial thickening.
D. secrete progesterone which induces menstruation after LH levels reach a critical threshold.

Answer 27

A. Only answer choice A is an accurate statement. FSH and LH are secreted from the anterior pituitary (choice B is wrong). The corona radiata is composed of layered granulosa cells and surrounds the secondary oocyte after ovulation (choice C is wrong). Progesterone inhibits menstruation, and dropping progesterone levels in fact induce menstruation (choice D is wrong).

Concepts tested
Reproductive Systems: The Menstrual Cycle

Question 28

What regulates the contraction of skeletal muscle fibers?

A. Decreasing cytoplasmic concentrations of potassium
B. Increasing cytoplasmic concentrations of potassium
C. Decreasing cytoplasmic concentrations of calcium
D. Increasing cytoplasmic concentrations of calcium

Answer 28

D. Calcium regulates the contraction of skeletal muscle fibers (choices A and B are wrong) because of its interaction with troponin. When calcium levels rise in the cell, troponin (bound to tropomyosin) binds calcium and changes shape; this shape change shifts the position of tropomyosin and uncovers the myosin binding sites on actin, allowing contraction to proceed (choice C is wrong and choice D is correct).

Concepts tested
Muscular System: Sliding Filament Theory/Excitation-Contraction Coupling

Question 29

Which of the following is a correct timeline for first trimester fetal development?

A. Fetus – morula – blastocyst – trophoblast
B. Zygote – trophoblast – morula – embryo
C. Fertilization – morula – blastocyst – fetus
D. Zygote – morula – placenta – blastocyst

Answer 29

C. Gametes fuse in fertilization to form the zygote, which undergoes cleavage to form the morula. Next the blastocyst forms, which includes the trophoblast (choice B can be eliminated). Placental development starts once the blastocyst has implanted in the uterine wall (or endometrium; choice D is wrong). The developing human is called an embryo for the first two months, and is called a fetus after this (choice A is wrong). Choice C presents the correct order of development.

Concepts tested
Development: Embryology/Fetal Development

Question 30

Which of the following describes the route via which urine leaves the kidney and is voided from the body?

A. Ureter, involuntary urinary sphincter, bladder, voluntary urinary sphincter
B. Ureter, bladder, involuntary urinary sphincter, voluntary urinary sphincter
C. Ureter, bladder, voluntary urinary sphincter, involuntary urinary sphincter
D. Bladder, ureter, involuntary urinary sphincter, voluntary urinary sphincter

Answer 30

B. Urine leaves the kidneys via the ureters and travels to the bladder where it is stored prior to excretion (choices A and D are wrong). When voiding, urine passes through the internal urinary sphincter, which is composed of smooth muscle and is therefore under autonomic (involuntary) control and then the external urinary sphincter, which is composed of skeletal muscle under voluntary control (choice C is wrong and choice B is correct).

Concepts tested
Renal System: Kidney Functions

Question 31

Cardiac, skeletal, and smooth muscle cells share all of the the following EXCEPT:

A. troponin.
B. actin.
C. myosin.
D. regulation by increased cytoplasmic calcium.

Answer 31

A. All types of muscle cells contain the proteins actin and myosin (choices B and C are shared and can be eliminated). Calcium plays a role in the regulation of all muscle types (choice D is shared and can be eliminated). Troponin is a regulatory protein in cardiac and skeletal muscle, but not in smooth muscle, which utilizes calmodulin instead (choice A is not shared and is the correct answer choice).

Concepts tested
Muscular System: Cardiac and Smooth Muscle

Question 32

Estrogen levels gradually increase throughout the first half of the menstrual cycle. Which of the following is true about estrogen?

A. It is produced by the oocyte in the follicle of the ovary.
B. It induces thickening of the endometrial wall.
C. It feeds back positively to the posterior pituitary.
D. Its secretion is due to increased release of vesicles containing estrogen.

Answer 32

B. Estrogen levels increase in the first half of the menstrual cycle. This hormone comes from the granulosa cells of the follicle, not the oocyte (choice A is wrong). Initially, estrogen feeds back negatively to the hypothalamus and anterior pituitary, and closer to ovulation, it triggers a positive feedback loop. However, any feedback loop between estrogen and the pituitary gland would only involve the anterior pituitary gland, not the posterior pituitary (choice C is wrong). Increasing estrogen favors endometrial thickening and remodeling, in preparation for implantation (choice B is correct). Note that estrogen is a steroid hormone and these are made in the SER of cells and secreted immediately. Unlike peptide hormones, steroid hormones are not stored in vesicles (choice D is wrong).

Concepts tested
Reproductive Systems: The Menstrual Cycle

Question 33

The neurotransmitter used at the neuromuscular junction (NMJ) is:

A. acetylcholine.
B. norepinephrine.
C. dopamine.
D. serotonin.

Answer 33

A. Acetylcholine (ACh) is the neurotransmitter used to communicate between effector neurons and skeletal muscle (choice A is correct). Norepinephrine is a neurotransmitter involved in stress responses (choice B is wrong). Both dopamine and serotonin play significant roles in regulating brain chemistry, but do not play a direct role in transmitting signals to muscles (choices C and D are wrong).

Concepts tested
Muscular System: Motor Units

Question 34

Which of the following is true about the renin-angiotensin axis?

A. The juxtaglomerular cells in the afferent arteriole are baroreceptors that sense low pressure, ACE converts angiotensinogen to angiotensin I, and renin converts angiotensin I to angiotensin II.
B. The juxtaglomerular cells in the afferent arteriole are baroreceptors that sense high pressure, ACE converts angiotensinogen to angiotensin I, and renin converts angiotensin I to angiotensin II.
C. The juxtaglomerular cells in the afferent arteriole are baroreceptors that sense low pressure, renin converts angiotensinogen to angiotensin I, and ACE converts angiotensin I to angiotensin II.
D. The juxtaglomerular cells in the afferent arteriole are baroreceptors that sense high pressure, renin converts angiotensinogen to angiotensin I, and ACE converts angiotensin I to angiotensin II.

Answer 34

C. Juxtaglomerular cells are baroreceptors and secrete renin in response to low blood pressure (choices B and D are wrong). Renin converts the zymogen angiotensinogen into angiotensin I. Angiotensin I is further converted to angiotensin II by ACE (angiotensin converting enzyme, choice A is wrong and choice C is correct). Angiotensin II is a powerful vasoconstrictor that quickly increases blood pressure.

Concepts tested
Renal System: Renal Regulation of Blood Pressure

Question 35

An elderly patient presents with chronic renal failure and metabolic acidosis. What impact would this have on oxygen delivery to tissues?

A. Increased oxygen delivery due to hemoglobin’s increased oxygen affinity
B. Increased oxygen delivery due to hemoglobin’s decreased oxygen affinity
C. Decreased oxygen delivery due to hemoglobin’s increased oxygen affinity
D. Decreased oxygen delivery due to hemoglobin’s decreased oxygen affinity

Answer 35

B. Metabolic acidosis (decreased blood pH) will decrease hemoglobin’s affinity for oxygen (choices A and C can be eliminated) and subsequently increase oxygen delivery to tissues (choice D can be eliminated and choice B is correct). Other causes of decreased oxygen affinity include elevated body temperature and increased production of BPG.

Concepts tested
Renal System: Renal Regulation of pH

Question 36

The nephrons of the kidney are responsible for filtering blood and modifying the filtrate to produce urine. Which of the following provides the best description of the initial composition of filtrate in a healthy individual?

A. Water, glucose, ions
B. Water, ions, cells
C. Water, cells, proteins
D. Water, proteins, glucose

Answer 36

A. The glomerular basement membrane is only permeable to water and small, hydrophilic molecules, such as glucose, amino acids, and ions (choice A is correct). Whole cells or whole proteins should not be able to cross through this filter (choice B, C, and D are wrong).

Concepts tested
Renal System: Nephron Structure/Function

Question 37

In males:

A. the Wolffian duct develops into male external genitalia, and spermatogonia regenerate via mitosis throughout adult life.
B. the Wolffian duct develops into male internal genitalia, and spermatogonia regenerate via mitosis throughout adult life.
C. the Wolffian duct develops into male external genitalia, and spermatogonia regenerate via meiosis throughout adult life.
D. the Wolffian duct develops into male internal genitalia, and spermatogonia regenerate via meiosis throughout adult life.

Answer 37

B. All fetuses begin with both Mullerian ducts and Wolffian ducts. The Mullerian ducts regress in males, and the Wolffian ducts develop into male internal genitalia (choices A and C are wrong). Spermatogonia regenerate through the male adult life, by performing mitosis (choice B is correct and choice D is wrong).

Concepts tested
Development: Embryology/Fetal Development

Question 38

What effect does growth hormone have on the epiphyseal plate during childhood development?

A. Collagen is deposited at the epiphyseal plate, extending the length of the bone and becoming part of its infrastructure.
B. Collagen is deposited at the epiphyseal plate, extending the length of the bone before being replaced by cartilage and hydroxyapatite.
C. Cartilage is deposited at the epiphyseal plate, extending the length of the bone and becoming part of its infrastructure.
D. Cartilage is deposited at the epiphyseal plate, extending the length of the bone before being replaced by collagen and hydroxyapatite.

Answer 38

D. During the primary bone growth and development of childhood, growth hormone causes the deposition of cartilage at the epiphyseal plate to lengthen the bone (choices A and B are wrong). This cartilage is soon replaced with the long-term bone components of collagen and hydroxyapatite (a calcium-phosphate crystalline solid) (choice C is wrong and choice D is correct).

Concepts tested
Skeletal System: Connective Tissue/Bone Skeletal System: Bone Structure/Turnover

Question 39

Which of the following is a correct pairing of female reproductive structure and function?

A. Uterus – site of fertilization
B. Vagina – high pH as part of innate immunity
C. Fallopian tubes – becomes the birth canal during labor and delivery
D. Ovary – site of oogenesis

Answer 39

D. The site of fertilization is a fallopian tube (choice A is wrong). The vagina has a low pH, as part of innate immunity (choice B is wrong). The vagina becomes the birth canal (choice C is wrong). The ovary is the site of oogenesis (choice D is correct).

Concepts tested
Reproductive Systems: Female Reproductive System

Question 40

Which of the following are the functions of the large intestine?

A. Digest and absorb nutrients and water, store feces
B. Absorb nutrients and store feces
C. Digest macromolecules and absorb nutrients
D. Reabsorb water and store feces

Answer 40

D. The large intestine does not participate in any digestion (choices A and C are wrong), and only very minimal nutrient absorption (some vitamins, choice B is wrong). The main function of the large intestine is to reabsorb the large amounts of water that enter from the small intestine. This helps prevent dehydration by compacting and solidifying waste products into feces, which is then stored in the large intestine until elimination (choice D is correct).

Concepts tested
Digestive System: Alimentary Canal

Question 41

Which of the following must happen before fertilization?

A. The spermatozoa swim through the vagina, cervix, uterus, and one fallopian tube.
B. The slow block triggers pH changes in the oocyte cytoplasm.
C. The secondary oocyte completes meiosis II and secretes the second polar body.
D. The endometrial wall thickens and prepares for morula implantation

Answer 41

A. Choice A describes the path sperm must take to reach an oocyte (choice A is correct). pH changes and the slow block occur after fertilization and function to prevent more than one sperm from fusing with the oocyte (choice B is wrong). The oocyte completes meiosis II only after the sperm has fused (choice C is wrong). While it is true that the endometrial wall thickens before fertilization (in preparation for implantation), the blastocyst – not the morula – embeds into the uterine wall (choice D is wrong).

Concepts tested
Development: Embryology/Fetal Development

Question 42

Red, slow-twitch muscle fibers would likely be found in:

the posture muscles of the back.
the thigh muscles of marathon runners.
the calf muscles of pole-vaulters.
  	A.  I only
  	B.  I and II only 
  	C.  II and III only
  	D.  I, II, and III

Answer 42

B. Red slow-twitch muscle fibers have many mitochondria and a good blood supply so they are very fatigue-resistant. Item I is true: the posture muscles of the back need to be fatigue-resistant because they are in use consistently (choice C can be eliminated). Item II is true: the thigh muscles of marathon runner participate in endurance activity and need fatigue-resistant fibers (choice A can be eliminated). Item III is false: the calf muscles of pole-vaulters are in use for a very short period of time and likely contain white fast-twitch fibers (Type IIB fibers; choice D can be eliminated and choice B is correct).

Concepts tested
Muscular System: Skeletal Muscle Fiber Types

Question 43

The mouth is NOT responsible for which of the following functions?

A. Mastication
B. Bolus creation
C. Saccharide absorption
D. Carbohydrate digestion

Answer 43

C. The mouth breaks up food via chewing (i.e. mastication; choice A is a function of the mouth and can be eliminated). It then forms the fragments into a smooth ball, or bolus, and lubricates that ball with saliva (choice B is a mouth function and can be eliminated). Salivary amylase (ptyalin) is responsible for carbohydrate digestion into disaccharides (choice D is a function and can be eliminated), however no nutrient absorption occurs in the mouth (choice C is not a function of the mouth and is the correct answer choice).

Concepts tested
Digestive System: Alimentary Canal

Question 44

Semen contains:

A. glucose as a primary food source for spermatozoa.
B. mucus, secreted from the prostate gland, to help with lubrication.
C. alkaline secretions to help neutralize the low pH in the male urethra and the female vagina.
D. water, secreted from only the seminal vesicles.

Answer 44

C. Besides spermatozoa, semen contains: mucus from the bulbourethral glands for lubrication (choice B is wrong); water (which is secreted from all three accessory glands) to provide the liquid medium (choice D is wrong); alkaline secretions (from the prostate and bulbourethral glands) to neutralize acidic environments (choice C is correct); nutrients (primarily fructose) secreted from the seminal vesicles (choice A is wrong).

Concepts tested
Reproductive Systems: Male Reproductive System

Question 45

What is selectively reabsorbed by the proximal convoluted tubule?

A. Water and ions only
B. Glucose and amino acids only
C. Water, ions, glucose, amino acids
D. Water, ions, glucose, proteins

Answer 45

C. Selective reabsorption begins immediately after filtration and starts in the proximal convoluted tubule. Much of the water and ions in the filtrate are returned to the circulatory system (choice B is wrong). Glucose and amino acids are also reabsorbed (choice A is wrong and choice C is correct). A healthy kidney does not allow proteins to enter the filtrate, as they are too big to pass through the glomerular basement membrane (choice D is wrong).

Concepts tested
Renal System: Nephron Structure/Function