a higher hydrostatic pressure at the arteriole end and a lower hydrostatic pressure at the venule end?. a higher osmotic pressure in its blood plasma than the osmotic pressure of the int
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Dear Future Doctor,
The following Subject Test and explanations contains questions not in test format and should be used to practice and to assess your mastery of the foundation content necessary for success on the MCAT Simply memorizing facts is not sufficient to achieve high scores; however, an incomplete understanding of basic science knowledge will limit your ability to think critically Think of building your content knowledge as learning the vocabulary and practicing MCAT-like questions as actually speaking
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Kaplan Test Prep
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Biology Subject Test 5
1 What is the principal function of NaHCO3?
A Dissolves CO2 better
B Inactivates bile
C Acts as a buffer
D Combines with oxygen when hemoglobin is
saturated
E Combines with CO2 in alveoli
2 Lacteals absorb
A carbohydrates
B proteins
C fatty acids
D salts
E Two of the above
3 If a strand of DNA underwent four rounds of
replication, what percentage of the total DNA present
would be comprised of the original DNA molecule?
A 0%
B 3.125%
C 6.25%
D 12.5%
E 25%
4 All of the following statements about the glycolytic
pathway are true EXCEPT
A It occurs in the cytoplasm
B Glycolysis is anaerobic
C 1 molecule of glucose breaks down into one
molecule of pyruvate
D 1 molecule of glucose results in the formation of 2
net ATP and 2 reduced molecules of NAD+
E Glucose is partially oxidized
5 Which of the following is NOT true regarding DNA?
A The basic unit is a nucleotide
B Adenine and guanine are pyrimidines
C The strands are anti-parallel
D Guanine always binds with cytosine with three
hydrogen bonds
E The sugar molecule is deoxyribose
6 You isolate a membrane bound vesicle containing hydrolytic enzymes It is most likely a
A chloroplast
B microbody
C phagosome
D vacuole
E lysosome
7 Which of the following does not occur immediately after birth?
A The infant begins to produce adult hemoglobin
B Resistance in the pulmonary arteries decreases
C Pressure in the left atrium increases
D Pressure in both the inferior vena cava and the right atrium increases
E The ductus arteriosus constricts
8 In a population in Hardy-Weinberg equilibrium, the frequency of the dominant allele D is three times that of the recessive allele d What is the frequency of
heterozygotes in the population?
A 6.25%
B 25%
C 37.5%
D 56.25%
E 75%
9 Shortly after gastrulation, a teratogen affects the development of the endoderm You will most likely see
a deformity in the
A lens of the eye
B gonads
C nervous system
D bladder lining
E connective tissue
10 Which component of blood is involved in clot formation?
A Erythrocytes
B Macrophages
C T cells
D B cells
E Platelets
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11 Which of the following is not secreted by the thyroid?
A Thyroxine
B Triiodothyronine
C TSH
D All of the above
E None of the above
12 Hypothyroidism is always associated with
A high blood pressure
B irritability
C low metabolic rate
D high body temperature
E decreased heart rate
13 Which of the following cellular substituents is made
within the nucleus?
A Lysosome
B Golgi apparatus
C Ribosome
D Smooth endoplasmic reticulum
E Cell membrane
14 A capillary has
A a higher hydrostatic pressure at the arteriole end
and a lower hydrostatic pressure at the venule end
B a higher osmotic pressure in its blood plasma than
the osmotic pressure of the interstitial fluid
bathing the tissues
C a hydrostatic pressure that results from the beating
of the heart
D Choices A and C only
E Choices A, B and C
15 Which of the following elements is not found in nucleic
acids?
A Sulfur
B Carbon
C Oxygen
D Nitrogen
E Phosphorus
16 A colorblind male XcY is crossed with a normal female who is a carrier of fragile X and colorblindness (XfXc) What is the probability that a male child will be phenotypically normal?
A 0%
B 25%
C 50%
D 75%
E 100%
17 Which of the following is NOT true regarding the cytoskeleton?
A It is composed of microtubules and microfilaments
B It gives the cell mechanical support
C It maintains the cell's shape
D It is not required for mitosis
E It is functional in the cell's motility
18 One molecule of glucose is catabolized via cellular respiration How many molecules of ATP are produced
by oxidative phosphorylation?
A 2
B 4
C 32
D 36
E 40
19 Drosophila melanogaster can have several eye colors
Red eyes are dominant over white eyes and sepia eyes If
a red eyed fly that resulted from a mating of red eyed and sepia eyed parents is crossed with a sepia eyed fly, what percentage of the offspring will have sepia eyes?
A 0%
B 25%
C 50%
D 75%
E 100%
20 The retina of the eye is a derivative of the
A endoderm
B ectoderm
C mesoderm
D ectoderm and mesoderm
E mesoderm and endoderm
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21 Vitamin K absorption occurs mainly in the
A duodenum
B jejunum
C stomach
D large intestine
E mouth
22 All of the following are characteristics of osmosis
EXCEPT
A Passive transport
B Occurs with water
C Solvent will spontaneously move from a hypertonic
environment to a hypotonic environment
D Solvent spontaneously moves from an area of high
solvent concentration to low solvent concentration
E Is a special form of diffusion
23 What region of the brain controls the breathing rate?
A Medulla oblongata
B Hypothalamus
C Cerebrum
D Cerebellum
E Pituitary gland
24 Which type of muscle is always multinucleated?
A Cardiac muscle
B Skeletal muscle
C Smooth muscle
D A and B
E B and C
25 Which of the following hormones is released from the
posterior pituitary?
A Oxytocin
B FSH
C Glucagon
D Estrogen
E Calcitonin
26 All of the following occur in the mouth except
A mechanical digestion
B moistening of food
C chemical digestion of proteins
D bolus formation
E chemical digestion of starch
27 Which of the following is TRUE about the role of LH in the menstrual cycle?
A LH inhibits the secretion of GnRH
B LH is secreted by the ovary
C LH induces the ruptured follicle to become the corpus luteum and secrete progesterone and estrogen
D LH stimulates the development and maintenance of the endometrium in preparation for implantation of the embryo
E LH stimulates milk production after birth
28 Cardiac muscle
A Is innervated by the somatic motor nervous system
B Is not striated
C Is multi-nucleated
D Has voluntary contraction
E Does not require Ca2+
29 Which of the following statements about the glycolytic pathway is true?
A Oxygen serves as a major reactant in glycolysis
B During glycolysis, glucose is partially reduced
C For each molecule of glucose that undergoes glycolysis, two net molecules of ATP and two molecules of reduced NAD are produced
D For each molecule of glucose that undergoes glycolysis, one molecule of pyruvic acid is formed
E Pyruvic acid, the final product of the Krebs cycle, serves as the immediate fuel for the next series of cellular reactions
30 Which region of the kidney has the lowest solute concentration?
A Nephron
B Cortex
C Medulla
D Pelvis
E Epithelia
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31 Which of the following hormones raises the
concentration of blood calcium?
A Glucagon
B Insulin
C Parathyroid hormone
D Aldosterone
E Anti-diuretic hormone
32 If a person lacks gamma globulin, he would have
A severe allergies
B low resistance to infection
C diabetes
D hemophilia
E None of the above
33 Resting membrane potential depends on
A The differential distribution of ions across the axon
membrane
B Active transport
C Selective permeability
D The Na+/K+ pump
E All of the above
34 Which of the following is generally a passive process
A Inhalation
B Exhalation
C Gas exchange
D A and B
E B and C
35 Which of the following is NOT true regarding the
circulatory system?
A Mammals have a four chambered heart
B Veins have a strong pulse
C Arteries typically carry oxygenated blood
D The lymphatic system intersects with the circulatory
system at the thoracic duct
E The pumping chambers of the heart are called
ventricles
36 Which of the following is NOT made of cartilage?
A Nose
B Middle ear
C Outer ear
D Skeletal Joint
E Larynx
37 Which of the following hormones directly affects blood sugar level?
A Oxytocin
B Calcitonin
C Estrogen
D Glucagon
E Thyrotropin
38 At the arterial end of a capillary bed, the osmotic pressure
A Is greater than the hydrostatic pressure
B Results in a net outflow of fluid
C Is less than the hydrostatic pressure
D Two of the above
E None of the above
39 Which of the following is NOT true about aldosterone?
A Stimulates reabsorption of Na+
B Stimulates secretion of K+
C Results in the production of concentrated urine
D Produced by the adrenal cortex
E Known as vasopressin
40 The function of the lymph nodes is to
A Filter lymph
B Break down hemoglobin
C Increase glucose concentrations in blood
D Facilitate the absorption of amino acids
E Carry oxygen
STOP! END OF TEST
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THE ANSWER KEY AND EXPLANATIONS BEGIN ON THE FOLLOWING PAGE
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BIOLOGY SUBJECT TEST 5
ANSWER KEY
1 C
2 C
3 C
4 C
5 B
6 E
7 D
8 C
9 D
10 E
11 C
12 C
13 C
14 E
15 A
16 A
17 D
18 C
19 C
20 B
21 D
22 C
23 A
24 B
25 A
26 C
27 C
28 D
29 C
30 B
31 C
32 B
33 E
34 E
35 B
36 B
37 D
38 D
39 E
40 A
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Explanations
The principal function of sodium bicarbonate in the blood is to serve as a buffer to maintain a slightly basic (7.2) pH
of the blood NaHCO3 is the conjugate base to H2CO3, which results from the combination of carbon dioxide and water:
CO2 + H2O →
← H2CO3 →
← H+ + HCO3
The small intestine are lined with finger-like projections called villi which serve to increase the absorptive surface area Within the core of the villi are capillaries and lacteals, which are lymphatic vessels Amino acids and glucose pass through the villi walls into the capillary Large fatty acids and glycerol pass into the lacteals and are then reconverted into fats Lymph and the absorbed fats will later empty into the central circulatory system
With each round of replication the original DNA material gets halved After 4 rounds of replication the amount of original DNA will = (12)4 = 161 = 6.25%
The original strand of DNA is comprised of two sister strands After four rounds of replication, you would have 16 strands of DNA comprised of 32 sister strands The two original sister strands are 6.25% of the 32 sister strands that you have at the end of the replication
The statement in choice C is false: One molecule of glucose (6 carbon sugar) breaks down into two molecules of pyruvate (pyruvate is a 3 carbon molecule) Hence this is the choice we are looking for
Choice A is a true statement and therefore NOT the correct response: Glycolysis occurs in the cytoplasm
Choice B is also true Glycolysis is anaerobic and occurs in both eukaryotes and prokaryotes In anaerobic conditions
or in anaerobic bacteria, it is the first step in fermentation In eukaryotes, pyruvate is reduced to lactic acid and in
prokaryotes, it is reduced to ethanol
Choice D is an accurate statement In glycolysis, one molecule of glucose is broken down and 4 ATP are formed However, due to the initial investment of 2 ATP, the net production of ATP is 2 Also, two molecules of NAD+ are reduced to NADH These molecules will later enter the electron transport chain to produce ATP
Adenine and guanine are purines while cytosine, uracil and thymine are pyrimidines
Choice A is an accurate statement The basic unit of DNA is a nucleotide which is made up of a phosphate group, a deoxyribose sugar, and a nucleic acid
Choice C is also a true statement: The strands are antiparallel, that is, one strand has a 5’ ∅ 3’ polarity and its complementary strand has a 3’ ∅ 5’ polarity
Choice D is correct Guanine always bonds with cytosine with three hydrogen bonds Adenine will bond with either thymine or uracil with two hydrogen bonds
Choice E is correct The sugar molecule in DNA is deoxyribose while in RNA it is ribose
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The lysosome is like the stomach of the cell and is characterized as a membrane bound organelle that stores
hydrolytic enzymes
Choice A is incorrect because chloroplasts are found only in algae an plant cells They contain chlorophyll and are the site of photosynthesis Chloroplasts contain their own DNA and ribosomes and may have evolved by symbiosis Choice B is incorrect because microbodies are membrane bound organelles specialized as containers for metabolic reactions
Choice C is incorrect because phagosomes are vesicles that are involved in the transport and storage of materials that are ingested by the cell through phagocytosis
Choice D is incorrect Vacuoles and vesicles are membrane bound sacs involved in the transport and storage of materials that are ingested secreted, processed, or digested by the cells Vacuoles are larger than vesicles and are more likely to be found in plant cells
After birth, a number of changes occur in the circulatory system as the fetus adjusts to breathing on its own The lungs expand with air and rhythmic breathing begins Resistance in the pulmonary blood vessels decreases, causing an increase in blood flow through the lungs When the umbilical blood flow stops, blood pressure in the inferior vena cava decreases, causing a decrease in pressure in the right atrium In contrast, left atrial pressure increases due to increased blood flow from the lungs Increased left atrial pressure coupled with decreased right atrial pressure causes the foramen ovale to close In addition, the ductus arteriosus constricts and later closes permanently The ductus venosus degenerates over a period of time, completely closing in most infants three months after birth The infant begins to produce adult hemoglobin, and by the end of the first year of life, little fetal hemoglobin can be detected in the blood
If the frequency of the dominant allele is three times that of the recessive allele, then p = 3q According to Hardy-Weinberg equilibrium, p + q = 1 so 3q + q =1 Solving for q we get 4q = 1; q = 0.25 and p = 0.75 Again according to Hardy-Weinberg, the frequency of the heterozygotes is equal to 2pq Substituting in our values for p and q we have the equation 2(0.75)(0.25) which equals 0.375 or 37.5%
The endoderm will develop into the epithelial linings of the digestive and respiratory tracts, parts of the liver, pancreas, thyroid, and the bladder lining
Choice A is incorrect because the lens of the eyes will develop from the ectoderm
Choice B is incorrect because the gonads are developed from the mesoderm
Choice C is incorrect because the nervous system is developed from the ectoderm
Choice E is incorrect because the connective tissue is developed from the mesoderm
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Choice A, erythrocytes, are the oxygen carrying components of the blood They contain hemoglobin which can bind
up to four molecules of oxygen
Choice B, macrophages, carry out phagocytosis of foreign particles and bacteria, digest them, and present the
fragments on their cell surface
Choice C, T cells, lyse virally infected cells or secrete proteins which stimulate the development of B or other types of
T cells
Choice D, B cells, mature into memory cells or antibody producing cells during immune responses
The thyroid hormone, thyroxine, or tetraiodothyronine, is simply an amino acid containing four atoms of iodine Another thyroid hormone, triiodothyronine, contains three atoms of iodine Both of these hormones accelerate oxidative metabolism throughout the body Thyroid-stimulating hormone (TSH) is secreted by the anterior pituitary to stimulate the thyroid gland
Hypothyroidism is caused by inflammation of the thyroid or iodine deficiency Thyroid hormones are undersecreted
or not secreted at all Common symptoms of hypothyroidism include a slowed heart rate and respiratory rate, fatigue, cold intolerance, and weight gain In newborns, it is termed cretinism and is characterized by mental retardation and short stature Hyperthyroidism occurs when the thyroid is over-stimulated, and symptoms often include increased metabolic rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, and protruding eyes
The two ribosomal subunits are manufactured in the nucleolus, a region within the nucleus The ribosomes are the sites of protein production The fact that ribosomes are partly composed of RNA could have clued you in to the correct answer Choices A, B, D, and E are all incorrect because they refer to organelles that are composed of phospholipid membranes and protein, so they are not manufactured in the nucleus Rather, they are synthesized in regions of the cell (specifically the smooth endoplasmic reticulum and the ribosomes) other than the nucleus Choice A, the lysosome, contains hydrolytic enzymes involved in digestion Choice B, the Golgi apparatus, is a membrane-bound organelle that sorts and packages proteins made by the ribosomes Choice D, the smooth endoplasmic reticulum, is a portion of the endoplasmic reticulum that does not have ribosomes and is involved in lipid synthesis and drug detoxification Choice E, the cell membrane, is a barrier between the interior and exterior of the cell
Choices A, B, and C are all true statements about capillaries Choice A is correct because a capillary has a higher hydrostatic pressure at the arteriole end and a lower hydrostatic pressure at the venule end As blood flows from arterioles
to capillaries, blood pressure gradually drops due to friction between the blood and the walls of the vessels and the increase
in cross-sectional areas provided by numerous capillary beds Choice B is correct as well Blood plasma in the capillaries has a higher osmotic pressure than the pressure in interstitial fluid This is a result of the greater amount of dissolved solutes in the blood plasma of the capillaries Choice C is correct because the pumping force of the heart through the blood vessels creates hydrostatic pressure Hydrostatic pressure is defined as the force per area that blood exerts on the walls of the blood vessels Again, choice E is the correct answer because choices A, B, and C are all true statements
Sulfur is sometimes found in proteins but never in nucleic acids The famous Hershey-Chase experiment took advantage of this to determine whether proteins or nucleic acids carried the genetic information of the cell