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MCAT Biology Review

QuestionAnswer
1. All of the following are components of the Cell Theory EXCEPT A. all liviB. all living things posses mitochondria things are composed of cells.
2. Upon bacteriophage infection, the host cell is directed to sntesize viral protein. A scientist wishing to study the location of this process in the cell might use B. autoradiography.
3. A student determines type of membrane transport occurring in a cell.She finds that the molecule being transported's very large & polar,& when transported across the membrane,no ATP's used.Which of the following's the most mechanism of transport? C. Facilitated diffusion
4. Which of the following is NOT a type of tissue found in the human body? D. Cytoplasmic tissue
5. Which of the following types of nucleic acid will never be found in a virus? D. All of these can be found in a virus
6. Which of the following activities occurs in the Golgi apparatus? B. Modification and packaging of proteins
7. Mitochondrial DNA D. both (A) and (B)
8. Which of the following is NOT a function of the smooth endoplasmic reticulum? C. Protein synthesis
9. What is the main function of the nucleolus? A. Ribosomal RNA synthesis
10. In which of the following organelles is pH the lowest? A. Lysosomes
11. Which of the following is NOT a difference that would allow one to distinguish between a prokaryotic and a eukaryotic cell? C. Presence or absence of the cell wall
13. which of the following is NOT involved in cell movement? D. Centrioles
1. Consider a biochemical reaction A → B, which is catalyzed by A-B dehydrogenase. Which of the following statements is true? D. The free energy change (∆G) of the catalyzed reaction is the same as for the uncatalyzed reaction.
2. Consider the following enzyme pathway. A --1→ B --2→ C --3→ D --4→ E X --6→ Y An increase in [E] leads to the inhibition of enzyme 3. All of the following are results of the process EXCEPT A. an increase in [B].
3. Which of the following statements about enzyme kinetics is FALSE? A. An increase in the substrate concentration (at constant enzyme concentration) leads to proportional increases in the rate of the reaction.
4. At which pH would pancreatic 0oC. work at maximum activity? D. 8.5
5. Some enzymes require the presence of the nonprotein molecule to behave catalytically. An enzyme devoid of this molecule is called a(n) B. Apoenzyme.
6. Which of the following factors determine an enzyme’s specificity? A. The three-dimensional shape of the active site
7. Enzymes increase the rate of the reaction by A. Decreasing the activation energy
8. Bonding between atoms of an enzyme such as trypsin is best described as A. Peptide
9. In the equation below, substrate C is an allosteric inhibitor to enzyme 1. Which of the following is another mechanism caused by substrate C? A → enzyme 1 → B → enzyme 2→ C D. Negative feedback
10. When lactase hydrolyzes its substrate, lactose, which of the following occurs? A. Lactase retains its structure after the reaction
1. Which of the INCORRECTLY pairs a metabolic process with its site of occurrence? B. Citric acid cycle—mitochondrial membrane
2. Which of the following processes has a net reaction of 2Acetyl-CoA +6NAD+ + 2FAD + 2GDP + 2Pi + 4H2O → 4CO2 + 6NADH + 2FADH2 + 2GTP +4H- +2CoA C. Tricarboxylic acid cycle
3. In glucose degradation under aerobic conditions D. Both (A) and (C)
4. Fatty acids enter the catabolic pathway in the form of C. Acetyl-CoA
5. In which of the following reactions is the reactant oxidized? C. NADPH → NADP+
6. Which of the following statements correctly identifies the purpose of fermentation? B. To produce NAD+ in order to continue glycolysis
7. In which part of the cell would you expect to fine cytochrome c? C. Inner mitochondrial membrane
8. Which of the following is LEAST likely to occur during oxygen debt? B. Buildup of pyruvate
9. Autotrophic organisms, as compared to heterotrophs, convert sunlight into bond energy through photosynthesis. Which of the following best describes the type of process that photosynthesis is? A. Anabolic
10. In the course of glycolysis C. Glucose is degraded into two molecules of pyruvate
11. Which of the following correctly describes the amount of ATP produced from the high-energy carrier coenzymes? D. 1 NADH → 3 ATP
12. What is the total amount of ATP yielded by the catabolism of one glucose molecule via the Krebs cycle? C. 24 ATPs
1. Which is the following is the correct sequence of the development of a mature sperm cell? B – Diploid cells called spermatogonia differentiate into primary spermatocytes, which undergo the first meiotic division to yield two haploid secondary spermatocytes. These undergo a second meiotic division to become immature spermatids. The spermatids t
2. Which is the following is the correctly pairs the stage of development of an egg cell with the different periods in its life cycle? B – From the time of birth until a few hours before ovulation, all egg cells are arrested at the prophase stage of meiosis 1. These cells are referred to as primary oocytes. At ovulations, the egg cell has completed meiosis 1 and is now a haploid cell cal
3. Some studies suggest that in patients with Alzheimer’s disease, there is a defect in the way the spindle apparatus attaches to the kinetochore fibers. At which stage of mitotic division would you expect to see this problems? B – The spindle apparatus interacts with the kinetochore fibers in order to align the chromosomes on the equatorial plate during metaphase.
4. If you wanted to incorporate a fluorescently labeled adenine into one of the two daughter cells that would arise as a result of mitosis, at which stage of cell development should you add in the nucleotide? D – To ensure that the labeled adenine will be incorporated into the DNA of one of the daughter cells, we have to insert the nucleotide when the DNA of the parent cell replicates. This way, when each chromosome is replicated, one of the chromatids will in
5. According to the endosymbiont hypothesis, mitochondria are bacterial descendants that formed as a result of a eukaryotic cell engulfing a prokaryotic cell. Based on this, what type of division would you expect to see in mitochondria? A – Since mitochondria are bacterial descendents and possess their own DANA, we would expect them to divide in the same fashion as any other prokaryote. As such, we would expect mitochondria to divide through binary fission, a simple form of sexual reprod
6. Upon ovulation, the oocyte is released into the C – This subtle point about ovulation eludes most students and remains hard to believe until the organs are examined in anatomy class in medical school. The ruptured ovarian follicle releases an oocyte into the abdominal cavity, close to the entrance of t
7. Cancer cells are cells in which mitosis has gone wild. If a cure were found that could target only cancer cells without affecting normal cells, at which point in the cell cycle would the treatment effectively prevent cancer cell division? D - All of the above
8. Which of the following INCORRECTLY pairs the term with its definition? C - Vas deferens - tube connecting the epididymis to the prostate
9. During which phase of the meiotic cycle does the cell have the diploid number of chromosomes? D - Both (A) and (B)
10. Which of the following does NOT contribute to genetic variability? D - The Interkinesis that occurs during telophase I
11. Which of the following statements correctly identifies a key difference between mitosis and meiosis? D - During metaphase of meiosis I, homologous pairs of replicated chromosomes line up
12. The chromosome number of an offspring produced via parthenogenesis would be B - haploid
13. Which of the following is true regarding prophase? D - The nucleoli disappear
14. Which of the following INCORRECTLY pairs the term with its definition? A - Seminal vesicles - secrete sperm
1. Which of the following developmental stages has the greatest nuclear-to-cytoplasmic material ratio? C - Blastula
2. Which of the following association is INCORRECT? B – endoderm – lens of the eye
3. Which of the following changes does NOT occur immediately after birth? D – Pressure in both the inferior vena cava and the right atrium increases
4. During which period of gestation is a teratogen most likely to affect brain development? A – First trimester
5. From which of the following germ layer does the notochord form? B - Mesoderm
6. The influence of a specific group of cells on the differentiation of another group of cells is referred to as D - induction
7. Which of the following structures in NOT formed from the endoderm? C – Circulatory system
8. Which of the following is true regarding fetal hemoglobin? C – It has a greater affinity for oxygen than adult hemoglobin
9. Which of the following may be found in the mother’s bloodstream? D – Two of the above
10. Which of the following INCORRECTLY pairs the fetal circulation shunt with its function? B – Ductus venosus – bypasses the pulmonary veins
11. Which of the following blood vessels do NOT contain deoxygenated blood? C – Fetal umbilical vein
12. Which of the following statements is FALSE? D – In fetal circulation, the blood delivered via the aorta has a higher partial pressure of oxygen than the blood that was delivered to the lungs
13. Which of the following changes to fetal circulation occurs after birth? D – All of the above
14. The placenta releases all of the following hormones EXCEPT B - LH
1. During muscle contraction, which of the following regions decrease(s) in length? D – 2, 3, and 4
2. Region 1 refers to C – the A band
3. Which region represents one sarcomere? D - 4
4. With which of the following molecules does Ca2- released from the sarcoplasmic reticulum bind? C - Troponin
5. Which of the following cells is correctly coupled with its definition? A – Osteoblasts – bone cells involved in the secretion of bone matrix
6. You are looking at a right leg X-ray of a child whose right femur has slowed its growth and is below the average length for a child of this age. To which region of the bone should you pay particular attention to see if there are any abnormalities? C – Epiphyseal plate
7. Which of the following INCORRECTLY pairs the type of fiber with its definition? D – White fibers – high levels of myoglobin
8. When the knee moves back and forth as a person walks, what keeps the surfaces of the leg bones from rubbing against each other? A – The articular cartilage
9. When a muscle fiber is subjected to very frequent stimuli, C – the contractions combine in a process known as summation
10. To facilitate the process of birth, the infant’s head is somewhat flexible. This flexibility is given in part by the two fontanelles, which are soft spots of connective tissue on the infant’s skull. With time, these fontanelles will ossify through a p B – intramembranous ossification
11. When a muscle is attached to two bones, usually only one of the bones moves. The part of the muscle attached to the stationary bone is always referred to as A – the origin
12. Which type of muscle is always multinucleated? I. Cardiac muscle II. Skeletal muscle III. Smooth muscle B – II only
13. Which type of muscle has myogenic activity? I. Cardiac muscle II. Skeletal muscle III. Smooth muscle D – I and III only
14. Red bone marrow is involved in erythrocyte function, whereas yellow bone marrow D – contains adipose tissue
15. Which of the following statements regarding the periosteum is INCORRECT? D – None of the above
1. Which of the following associations between the type of gastric cell or gland and its secretions is correct? B – Chief cells - pepsinogen
2. Which of the following is NOT part of the small intestine? B - Cecum
3. In an experiment, enterokinase secretion was blocked. As a direct result, levels of all of the following enzymes were affected EXCEPT B - Aminopeptidase
4. Which of the following INCORRECTLY pairs the digestive hormone with its function? D – Lipase – emulsifies fats
5. Where are proteins digested? C – Stomach and small intestine
6. Which of the following choices INCORRECTLY pairs a digestive enzyme with its site of secretion? A – Sucrase – salivary glands
7. You are looking at a CT scan of the abdomen of a child who presented to you with various symptoms, including projectile vomiting. You notice a constriction in the digestive system that prevents food from reaching the small intestine. Which structure is B – Pyloric sphincter
8. All of the following processes occurs in the mouth EXCEPT D – chemical digestion of proteins
9. The two graphs below show the relative activities of two enzymes in solutions of varying pH. Which of the following choices correctly identifies the two enzymes> B – 1-pepsin; 2-chymotrypsin
10. Which of the following choices correctly illustrates the course that a piece of bread takes through the digestive tract? B – Mouth → pharynx → esophagus → cardiac sphincter → stomach → pyloric sphincter → small intestine → large intestine → rectum → anus
11. The epiglottis is to the trachea as the lower esophageal (cardiac) sphincter is to the A - Stomach
12. Which of the following choices correctly pairs the nutrient with its site of absorption? A – Chylomicrons - lacteals
13. Starch is hydrolyzed into maltose by D – both (A) and (C)
14. The intestinal capillaries transport nutrients from the intestines to the B - liver
15. Which of the following choices INCORRECTLY pairs a digestive enzyme with its site of secretion? B – Aminopeptidase - stomach
16. Which of the following INCORRECTLY pairs a digestive enzyme with its function? B – Carboxypeptidase – hydrolyzes the terminal peptide bond at the amino end
1. All of the following facilitate gas exchange in the lungs EXCEPT D – active transport
2. Which of the following associations between the two stages of respiration and the contraction of muscles is correct? D – Exhalation – external intercostal muscles relax
3. What does negative-pressure breathing refer to? C - Inhalation
4. The intrapleural space in the lungs is bounded by the A – visceral pleura and the parietal pleura
5. Which of the following best describes the residual volume of the lungs? D – The volume of air that always remains in the lungs
6. The lungs can collapse from D – Both (A) and (B)
7. Which of the following mechanism exists in the respiratory system to ensure that inhalation occurs rapidly and safely? D – All of the above
8. Which of the correct sequence of passageways through which air travels during inhalation? D – Pharynx → larynx → trachea → bronchi → alveoli
9. Which of the following is generally a passive process? D – Both (B) and (C)
10. Total lung capacity is equal to the vital capacity plus the C – residual volume
1. Which of the following is FALSE statement regarding erythrocytes? C – Their nuclei are located in the middle of the cells’ dislike depressions
2. Which of the correct sequence of a cardiac impulse? C – SA node → AV node → Purkinje fibers → bundle of His → ventricles
3. Hemoglobin’s affinity for O2 C – decreases as blood pH decreases
4. Which of the following correctly traces the circulatory pathway? A – Superior vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary veins →left atrium → left ventricle → aorta
5. The tricuspid valve prevents backflow of blood from the D – right ventricle into the right atrium
6. At the venous end of a capillary bed, the osmotic pressure D – both (A) and (C)
7. A patient’s chart reveals that he has a cardiac output of 7,500 mL/min and a stoke volume of 50 mL. What is his pulse (in beats per minute)? C – 150 beats/min
8. An unconscious patient is rushed into the emergency room and needs an immediate blood transfusion. Because there is no time to check her medical history or determine her blood type, which type of blood should you, as her doctor, give her? D – O-
9. Which of the following is true regarding arteries and veins? C – The blood pressure in the aorta is always higher than the pressure in the superior vena cava
10. At any time, there is more blood in the venous system than the arterial system. Which of the following features of a vein allows this? A – Relative lack of smooth muscle in the wall
11. Which of the following is involved in the body’s primary blood-buffering mechanism? C – Carbon dioxide produced from metabolism
1. If a virus, such as HIV, destroys the body’s T-lymphocytes, to which type of diseases would the patient be most susceptible? A – Viral infections
2. Which of the following is NOT involved in cell-mediated immunity? B – Plasma cells
3. The lymphatic system B – transports hormones throughout the body
4. Which of the following is involved in antibody production? A - Plasma cells
5. Which of the following is true regarding passive and active immunity? A – Active immunity requires weeks to build, whereas passive immunity is acquired immediately
6. Which of the following is NOT an example of a nonspecific defense mechanism? D – Cytotoxic T-cells destroy foreign antigens
1. Which of the following would most likely be filtered through the glomerulus into Bowman’s capsule? B - Monosaccharides
2. In which of the following segments is sodium NOT actively transported out of the nephron? B – The thin segments of the loop of Henle
3. Which region of the kidney has the lowest solute concentration? B - Cortex
4. Which of the following sequences correctly shows the passage of blood flow through the vessels of the kidney? A – Renal artery → afferent arterioles→ glomerulus → efferent arterioles →vasa recta → renal vein
5. Which of the following statements is FALSE? C – ADH acts directly on the proximal convoluted tubule
6. In the nephron, amino acids enter the vasa recta via the process of D - reabsorption
7. On a very cold day, a man waits for over an hour at the bus stop. Which of the following structures helps his body set and maintain a normal body temperature? A - Hypothalamus
8. Glucose reabsorption in the nephron occurs in the C – proximal convoluted tubule
9. All of the following are functions of the liver EXCEPT B – storage of bile
10. The primary function of the nephron is to create urine that is A – hypertonic to the blood
11. The liver D – All of the above
1. Which of the following associations between the hormone and its classification is FALSE? C – ADH - mineralcorticoid
2. Which of the following hormones directly stimulates its target organ? D - GH
3. Increased activity of the parathyroid gland leads to A – an increase in blood Ca2+ concentration
4. Which of the following statements concerning growth hormone is NOT true? C – It is secreted by the hypothalamus
5. At which two points of the menstrual cycle are the levels of estrogen highest? A – Immediately before and after ovulation
6. Iodine deficiency may result in B - cretinism
7. Which of the following would NOT be seen during pregnancy? D – High levels of GnRH throughout the pregnancy
8. Which of the following associations between the hormone and its role is FALSE? D – FSH – maturation of the ovarian follicles into the corpus luteum
9. Which of the following hormones is NOT derived from cholesterol? C - Oxytocin
10. Which of the following is TRUE regarding pancreatic somatostatin? B – It is always inhibitory
11. Destruction of all beta cells in the pancreas would cause C – insulin secretion to stop and an increase in blood glucose
12. Which of the following associations regarding aldosterone regulation is FALSE? D – An increase in water reabsorption stimulates renin production
13. A scientist discovers a new hormone that is relatively large in size and that triggers the conversion of ATP to cAMP. Which of the following best describes the type of hormone that was just discovered? B – Peptide hormone
14. A patient presents to your office with muscle weakness, slowness in movement, and calcium deposits on his bones. A blood test reveals very low calcium levels in the blood. What is one treatment option for your patient? B – Increase PTH levels
15. Oxytocin and vasopressin are C – produced by the hypothalamus and released by the hypothalamus
16. If the thymus gland is taken out in a three-year-old child, what problems will the child experience later in life? B – He will be prone to viral and fungal infections
1. Resting membrane potential depends on D – All of the above
2. All of the following are associated with the myelin sheath EXCEPT C – increased energy output for nervous impulse conduction
3. The all-or-none law states that D – once an action potential is triggered, an impulse of given magnitude and speed is produced
4. Which of the following would NOT be observed in a patient with a cerebellar lesion? A – Memory impairment
5. By increasing the intensity of the stimulus, the action potential will B – increase in frequency,
6. Which of the following pairings is correct? A – Sensory nerves - afferent
7. When a sensory receptor receives a threshold stimulus, it will do all of the following EXCEPT C – inhibit the spread of the action potential to sensory neurons
8. Which of the following structures focuses light on the retina? D – Both (A) and (C)
9. A specific disease affects only the rods present in a patient’s retina. Which of the following will you most likely observe about the patient? C – His levels of rhodopsin are almost nonexistent
10. When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of B - hyperpolarization
11. Which of the following statements concerning the somatic division of the peripheral nervous system is INCORRECT? D – Its pathways always involve three neurons
12. In the ear, what structure transduces pressure waves to action potentials? B – Organ of Corti
1. What is the gene order of linked genes A, B, C, and D, given the following recombination frequencies? B - BDAC
2. In humans, the allele for black hair (B) is dominant to the allele to brown hair (b), and the allele for curly hair (C) is dominant to the allele for straight hair (c). When a person of unknown genotype is crossed against a straight-brown-haired indivi D - BbCc
4. Assuming classical Mendelian inheritance, how can one differentiate between a homozygous dominant individual and one who is heterozygous for the dominant trait? D – Both (B) and (C)
5. The distance between linked genes is directly proportional to A – the frequency of crossing over
6. If a male hemophiliac (XhY) is crossed with a female carrier of both color blindness and hemophilia (XcYh), what is the probability that a female child will be phenotypically normal? C – 50%
7. If a test cross on a species of plant reveals the appearance of a recessive phenotype in the offspring, what must be true of the phenotypically dominant parent? A – It must be genotypically heterozygous
8. Which of the following definition is FALSE? B – Expressivity – the degree to which the phenotype
9. In pea plants, the allele for round seeds (R) is dominant to the allele for wrinkled seeds (r), and the allele for yellow seeds (Y). A doubly heterozygous, round, yellow-seeded plant is crossed with a green, wrinkled-seeded plant. What percentage of t C – 50%
10. What are the genotypes of a, b, and c in the F3 generation? B – XCX, XCY, and XCY, respectively
11. What is the genotype of d in the F2 generation? B - XCX
12. What is the genotype of d in the F3 generation? D – Either XCX or XX
13. Which of the following definitions is INCORRECT? C – Translocation – the event by which a chromosomal fragment joins with its homologous chromosome
14. In a species of plant, a homozygous dominant red flower (RR) is crossed with a homozygous recessive yellow (rr). If the F1 generation is self-crossed and the F2 generation has a phenotype ratio of red:orange:yellow of 1:2:1, which event accounts for t B – Incomplete dominance
1. In the DNA of a fruit fly (Drosophila melanogaster), 20 percent of the bases are cytosines. What percent are adenines? B – 30%
2. In a single strand of a nucleic acid, nucleotides are linked by B – phosphodiester bonds
3. What role does peptidyl transferase play in protein synthesis? D – It catalyzes the formation of a peptide bond.
4. Which stage of protein synthesis does NOT require energy? D – All of the above require energy.
5. Topoisonmerases are enzymes involved in A – DNA replication.
6. You have just sequenced a piece of DNA that reads as follows: 5’—TCTTTGAGACATCC—3’ What would be the base sequence of the mRNA transcribed from this DNA? B – 5’ -TCTTTGAGACATCC-3’
7. Which of the following statements regarding differences between DNA and RNA is FALSE? D – DNA strands replicate in a 5’ to 3’ direction, whereas RNA is synthesized in a 3’ to 5’ direction.
8. When trypsin converts chymotrypsinogen to chymotrypsin, some molecules of chymotrypsin bind to a repressor, which in turn binds to the operator and prevents further transcription of trypsin. To which gene regulation system is this process most similar? C – trp operon
9. Which of the following DNA sequences would have the highest melting temperature? A – CGCAACCATGCG
10. Chemical analysis of some viral DNA has given the following results: 20 percent of the bases are adenines, 35 percent are thymines, 15 percent are cytosines, and 30 percent are guanines. What must be true of this DNA? C – It is single stranded.
11. Herpes is a virus that enters the human body and remains dormant in the nervous system until it produces an outbreak, without any particular stimulus. Which of the following statements correctly describes herpes? D – All of the above.
12. What does a polycistronic mRNA do? C – It codes for more than one polypeptide
13. Resistance to antibiotics is a well-recognized medical problem. What mechanisms account for a bacterium’s ability to increase its genetic variability and thus adapt itself to different antibiotics? D – Transduction.
14. Which of the following statement is INCORREC regarding inheritance of traits? B – The muscular strength gained by a weight lifter during his lifetime is inherited by his children.
15. Which of the following statements is FALSE based on Darwin’s theory of evolution? B – Favorable genetic variations become more and more common in individuals throughout their lives.
16. Which of the following is NOT a necessary condition for Hardy-Weinberg equilibrium? C – Monogamous mating partners.
17. As the climate got colder during the Ice Age, a particular species of mammal evolved a thicker layer of fur. This is an example of kind of selection? B – Directional selection.
18. At what point are two populations descended from the same ancestral stock considered separate species? A – When they can no longer produce viable, fertile offspring.
19. In a nonevolving population, there are two alleles, R and r, which code for the same trait. The frequency of R is 30%. What are the frequencies of all the possible genotypes? D – 9% RR, 42% Rr, 49% rr.
20. As the ocean became saltier, whales and fish independently evolved mechanisms to maintain the concentration of salt in their bodies; this can be explained by C – convergent evolution.
21. In a particular Hardy-Weinberg population, there are only two eye colors: brown and blue. Of the population, 36% has blue eyes, the recessive trait. What percentage of the population is heterozygous for brown eyes? B – 48%.
22. In a certain population, 64 of individuals are homozygous for curly hair (CC). The gene for curly hair is dominant to the gene for straight hair, c. what percentage of the population has curly hair? D – 96%.
23. Which of the following was NOT a belief of Darwin’s? C – Genetic mutation and recombination are the driving forces of evolution.
24. The proposed primordial soup was composed of organic precursor molecules formed by interactions between all of the following statements EXCEPT B – helium
25. Microspheres can be characterized by all of the following statements EXCEPT B – they are also known as colloidal droplets called coacervates.
1. Which of the following would be a reasonable null hypothesis for this experiment? A -Hermit crabs do not show preference for shells based on color.
2. Which of the following is not a legitimate concern over the experiment setup? D - The pink paint darkened after drying
3. Based on the data, which of the following conclusions is most likely to be true? A - Hermit crabs show a preference for color
4. Which of the following statements is LEAST likely to explain the data? C - Hermit crabs natural environment is light-colored
5. Based on the data, what evolutionary forces could be at play on these hermit crabs in an environment with many areas of pure pink rocks and many areas of pure black rocks? A - Disruptive selection
6. A hypothetical population of 89 black-shelled hermit crabs was discovered in the red sands of Jordan's Wadi Rum desert. Hermit crabs are not native to this region & experts believe they were introduced to the environment by South American tourists. Sci B - do not call into question the validity of the hypothesis that shell color affects hermit crab shell choice
7. The species of hermit crab used in the experiment & a second species of hermit crab are monophyletic. this second species is color-blind. Which of the following scenarios is most likely? C - This second species of hermit crab was influenced by evolutionary pressures of the founder effect
8. According to the pedigree, the disease alleles of the gene are most likely C - recessive
9. If male 7 from the pedigree marries a female carrier, the probability that they will have a healthy non-carrier child is A - 0%
10. According to the passage, what can be concluded about the expressivity of the disease? B - Expressivity varies
11. It can be inferred from the passage that a mutation leading to the most common form of cystic fibrosis can be classified as a(n) A - deletion
12. Based on the polymorphisms of DNA fragments, family member 7 is most likely I. heterozygous. II. homozygous recessive. III. homozygous dominant. B - II only
13. Which family member is not carrying the disease allele? B - 4
14. According to the passage, when compared to the fragment with the normal allele, the speed of movement through the gel of a DNA fragment containing the disease allele would be D - faster, as the disease allele fragment is shorter
15. According to its functional significance, the cystic fibrosis mutation can be referred to as D - silent
16. the researcher later used the restriction fragment length polymorphism method described to array 100 members of the U.S. population for cystic fibrosis. One person had the disorder. Identify the observed frequency of the disease allele. B -0.1
17. Family member 5 marries a carrier of the cystic fibrosis allele. On average, what proportion of their children will be affected? A - 1/4
18. Young patients can develop rheumatic heart disease later in life after an untreated throat infection with streptococci bacteria. Studies have shown that the heart disease primarily affects the mitral valve, whose surface cells have proteins similar to B -Hypersensitivity reaction such as an autoimmune disease
19. The activation of phosphofructokinase-1 (PFK-1) by glucagon-mediated increased in PKA activity is an example of what type of modulation of protein activity? D - Allosteric activation
20. What is the purpose of hexokinase? D - Phosphorylate glucose to glucose-6-phosphate
21. Both oxalacetate & acetyl-CoA can be generated from pyruvate. Which of the following ratios, if greater than one, would favor the production of pyruvate from oxalacetate & acetyl-CoA, rather than the usual forward reaction? A - Carbon dioxide/oxygen
22. According to the chemiosmotic hypothesis described in the passage, the electrical & pH gradients developed across the inner mitochondrial membrane can be described as having D -more positive charge and lower pH in the intermembrane space than in the matrix
23. Applying the information from the previous table, in cells treated with antimycin A, all of the following can be expected EXCEPT A -oxygen remains the final acceptor of electrons
24. While testing an unknown electron transport chain inhibitor, a researcher measured a high proton gradient while no ATP synthesis could be detected. Using the information in the previous table, what could be the unknown inhibitor? D -Oligomycin
25. Application of which of the following inhibitors will prevent electrons from reaching oxygen? B - II and III only
26. It can be inferred from the passage that the higher permeability of the inner mitochondrial membrane due to 2, 4-dinitrophenol most likely results in B - protons escaping the intermembrane space, decreasing the electric gradient
27. It can be inferred from the passage that the mitochondrial matrix contains D-ADP and phosphates
28. A researcher is interested in isolating fully reduced cytochrome a. Al of the following inhibitors can be used for this purpose EXCEPT C - rotenone
29. What additional variable could have affected the results? A - Presence of pre-existing lung disease beyond asthma
30. IgE is traditionally associated with which of the following immunocytes? D - Mast cells
31. Anticholinergic medication during an asthma attack is appropriate because D - the parasympathetic response encourages bronchoconstriction
32. Which inhaler, on average, was most effective in delivering bronchodilator to the lungs? A - A
33. Those with abetalipoproteinemia exhibit low levels of chylomicrons in their blood. Which of the following symptoms is likely caused by this metabolic disorder? B - Steatorrhea (excessive fat in the stool)
34. Which of the following DNA replication errors would be expected to have the LEAST severe consequence? B - A → G
35. The discovery of which of the following enzymes challenged the central dogma of molecular biology and why? A - Reverse transcriptase, because transcription was thought to be unidirectional from DNA to RNA only
36. The mass is determined to the gastrinoma (a gastrin secreting humor). The patient undergoes surgery and the tumor is removed. How does gastrin affect H+ secretion? A - Activates the cholecystokinin-B (CCK-B) receptor
37. The patient noted that her feces appeared "oily." When there is fat in the stool, this condition is called steatorrhea. This could be an indication of malabsorption of dietary lipids. How does the patient's condition affect her ability to absorb lipid B - Inactivation of pancreatic enzymes
38. Which of the following substances does NOT stimulate H+ secretion by gastric parietal cells? A - Gastric inhibitory peptide (GIP)
39. Gastrin is secreted from G cells located in the antrum of the stomach. One function of gastrin is to D - stimulate gastric mucosa growth
40. The patient stated that she had been experiencing frequent diarrhea, and that the feces appeared to be oily. Why would someone with Zollinger_Ellison syndrome have frequent episodes of diarrhea? D - Malabsorption due to villi blunting
41. In Zollinger-Ellison syndrome, proper regulation over gastrin production and H+ secretion is lost. Normally, what type of physiologic control is exhibited once the proper gastric pH is reached? C - Negative feedback regulation
42. What is overall change in the free energy (∆G) of the catalyzed reaction? C - 35 kJ/mol
43. By approximately what percentage does aromatase lower the activation energy of the reaction? B - 33%
44. Studies have found that aromatase activity is high in obese individuals, yet in animal models, those lacking aromatase are obese. What is the best explanation for this? B - The reaction's product serves to inhibit aromatase when it is present at high levels
45. What type of regulation mechanism does letrozole use? D - None of the above
46. 'Male menopause' is characterized by unusually low androgen levels. How can androgen levels be increased in an affected man? B - Aromatase inhibition
47. The two sisters in generation I of this pedigree both have diabetes. What are the likely genotypes of individuals I-2 and I-3, respectively?(capital letter=dominant allele, lowercase=recessive allele) D - None of the above
48. Based on the available information, what forms of diabetes could individual II-1 have? I. Type I diabetes. II. Type II diabetes. III. MODY. IV. MIDD B - II IV only
49. What is the likelihood that individual IV-2 (the six-year-old boy) will develop diabetes before age 40? C - 50%
50. What is the likelihood that individuals III-12 and III-13 will both develop diabetes before age 40, assuming their mother has type II diabetes? A - 0%
51. If the penetrance of the MODY allele is 85%, what is likelihood that all of the nondiabetic children of individuals I-1 and I-2 are actually heterozygotes? A - 0.3%
52. A form of MODY called atypical diabetes mellitus (ADM), which has been identified only in African American & some Asian populations, is characterized by an initial need for insulin that eventually gives way to type II diabetic symptoms. If individual A -0%
1. The purpose of this experiment was most likely to B - contrast the different mechanisms of antiretroviral drugs
2. If the mechanism of drug A was related to its ability to mimic the nucleotide adenine and terminate the addition of further nucleotides to the nascent DNA strand, with in reverse transcription? C - Uracil
3. Given the results of the experiment, what is a possible mechanism for drug C? B - Binding and inhibition of reverse transcriptase activity
4.The experiment described in the passage was performed on drug D,a drug recently approved by the FDA to treat HIV.The results of the experiment show no change in viral RNA products or reverse transcriptase activity.Which of the following best explains th B - Drug D's mode of action is not related to reverse transcription
5. As described in the above passage, the action of non-nucleoside reverse transcriptase inhibitors is most similar to which of the following? B - II
6. Based on the info in the passage, which of the following is TRUE of nucleotide/nucleoside reverse transcriptase inhibitors? C - They cannot be removed after incorporation into the virus DNA
7. After cell entry and reverse transcription, HIV can become a latent provirus, inserting itself into the host genome. During this stage, where in the cell is viral DNA normally found? C - Nucleus
8. In the 1950s & 1960s, thalidomide was popularly prescribed to pregnant women suffering from morning sickness & difficulty seeping. The drug was never tested w/ that population, & after it has caused hundreds of birth defects, it was withdrawn. In gener B - Embryonic stage
9. Nondisjunction refers to wen chromosomal DNA does not separate appropriately, which can result in gametes containing either more or less than the standard amount of genetic material. Which of the following disorders is due to nondisjunction? C - Down syndrome
10. A newborn presents w/ a huge mass located at the anal region, which is identified as a sacrococcygeal teratoma. This mass is the persistence of the primitive streak, formed from the C - epiblast
11. A 4 year-old girl presents w/ 5 days of total blindness. There was no history of trauma, & intracranial pressure is normal. An MRI is taken & reveals a large suprasellar mass compressing the lateral ventricles & pituitary fossa. Emergency surgery is p A - Medulloblastoma
12. Which abdominal wall defect does not involve the umbilical cord? D - Gastroschisis
13. A young couple consult a physician about their concerns about miscarriage. They have heard stories about how person can suddenly lose her pregnancy,& they want to know as much as they can about the subject. They mention something about extra chromoso C - 69 XXX
14. An often-seen complication of pregnancy is that of a fertilized ovum implanting itself in tissue other than the uterine wall. There are multiple sites where this may occur, but the most common sit for an ectopic pregnancy is C - ampullary
15. A physician meets w/ young couple that hs been trying to get pregnant for the past year w/o success. During the initial workup, the woman states that she has a history of PID(pelvic inflammatory disorder) & wants to know if that could be the reason. w C - Chlamydia
16. A physician is worried that a fetus may be suffering from fetal erythroblastosis, a disease caused by D - anti-Rh antibodies
17. The usual result of an oocyte fertilized by two sperm is B - a partial mole
18. Recent studies have shown that viruses can make many DNA and/or RNA transcripts from the same genomic strand of either DNA or RNA, each of which has different frames. Which of the following organisms uses a process in translation that is most similar A - Eukaryote
19. Although many classes of bacteria exhibit antibiotic resistance, researchers have noted that more classes of gram-negative bacteria have antibiotic resistance than gram-positive. what is the unique structural feature of gram-negative bacteria which mo D - Outer cell wall
20. The lumen of the nuclear membrane is continuous w/ what organelle? B - Endoplasmic reticulum
21. Which type of cell releases glucagon? B - Alpha cell
22. Which of the following is NOT a phase of menstruation? C - Gestational
23. Below is a diagram of a menstrual cycle. How many ova does this woman produce per year? C - 13
24. The corpus luteum is D - the follicle following ovulation
25. Which is the following conditions would NOT contribute to infertility? D - Abnormally short luteal cycles coupled w/ long follicular cycles
26. The combination birth control pill is a mixture of estradiol and progesterone taken to prevent pregnancy. This drug affects a woman's menstrual flow by A - making it lighter through mimicking the circulating levels of progesterone and estradiol during pregnancy, preventing the proliferative uterine phase
27. Which of the following is NOT contained in menstrual discharge? D - Zygote
28. At the beginning of the follicular phase, circulating estradiol levels are low. However, by the midfollicular phase, estradiol has reached moderately high circulating levels. Which of the following is TRUE of the follicular phase? B - FSH levels are lower at the midpoint of the follicular phase than at the end
29. Which of the following graphs accurately depicts the relationship between serum levels of FSH & estradiol in the follicular phase? A -
30. Studies have shown that a combination of estradiol & progesterone causes release of FSH & LH before ovulation, yet a combination of estradiol & progesterone inhibits release of FSH &LH after ovulation. Which of the following is TRUE? C - Very high estradiol and very low progesterone levels cause the FSH and LH surges that lead to ovulation. The opposite conditions contribute to FSH and LH suppression after ovulation
31. There is a 0.3 to 0.5 degree Celsius rise in basal body temperature immediately after ovulation during a woman's menstrual cycle. If a couple wanted to use the basal body temperature method as a form of birth control, which of the following minimum co A - Only have sexual intercourse during a 21-day timespan, starting three days after the basal temperature rise
32. Given the results regarding the control gene & the gene from family 2, which of the following explains the presence of a mitochondrial inheritance disorder in family 2? D - I and II
33. On further investigation, it is found that gene X produces a transmembrane protein. taking this into account along w/ the info in the passage, what is the most likely location of this protein in the cell? C - Inner mitochondrial membrane
34. If we assume that a specific mitochondrial inheritance disorder affects the ability of the electron transport chain to donate electrons to oxygen, the compound(s) most likely to increase in someone w/ this disorder is A - lactic acid
35. According to the passage, mitochondrial inheritance disorders have A - multiple genotypes and multiple phenotypes
36. Consider a scenario where scientists have just discovered a mitochondrial inheritance disorder that does not obey the traditional maternal inheritance pattern. It's found to be due to a mutation in the nuclear DNA of the cell. Which of the following e C - Certain nuclear DNA products are transported to the mitochondria where they ply a vital role in mitochondrial function
37. The family tree below depicts the inheritance of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes), mitochondrial inheritance disorder. Which of the following contributes to this inheritance pattern? I. Maternal inher C - I and II
38. Which of the following is TRUE of mitochondrial DNA and eukaryotic nuclear DNA? A -Mitochondrial DNA and nuclear DNA each encode their own ribosomes
39. Which of the following enzymes decomposes polysaccharides into maltose? A - Amylase
40. Which of the following mutations in an RNA codon would be expected to produce the LEAST severe result? B - AAA → AAG
41. What is the genetic basis for the statement "males drive evolum C - Gametogenesis in the male produces four unique sperm cells whereas in the female it produces only one ovum
42. Based on the passage, which of the two mechanisms would be supported by a finding that carbamazepine, an anticonvulsive medication commonly used to treat epilepsy, was found to stabilize the inactivated state of the voltage-gate sodium channels respon B - Kindling model
43. Which of the following accurately describes the differences between the previous tow models of epileptogenesis? C - Excitotoxicity is concerned w/ a possible chemical process by which epileptogenesis occurs, whereas the kindling model is mainly concerned w/ a possible electrical process by which epileptogenesis occurs
44. Assuming you accept the excitotoxicity view of epileptogenesis,which of the following methods would best treat acute seizure activity in a patient w/ an extremely elevated concentration of glutamate? A - Extracellular administration of an enzyme that degrades glutamate
45. Glutamate is known to be the major excitatory neuro-transmitter in mammals. glutamate does NOT A - depend on its receptors to determine whether it will be excitatory or inhibitory
46. Based on the given information, Which of the following is a plausible mechanism by which trauma to the brain results in epilepsy? A - Ischemia depletes the metabolic nutrients necessary for production of uptake carriers
47. Which of the following phenomena could plausibly explain the kindling model? D - None of the above
48. Which of the following could possibly explain an abrupt loss of balance in someone w/ elevated levels of glutamate in his brain? A - Trauma to the cerebellum
49. Given the information in Figure 1, what is the ratio of the H2O concentration inside the cell to the concentration outside the cell, respectively? B - 2:3
50. What molecule is required to control the balance of sodium and water within a cell? C - ATP
51. Hyponatremic encephalopathy has particularly severe consequences for women, as evidenced by the sole death in the Boston Marathon. What is the most likely explanation for this? D - Vasopressin is present at high levels in affected women
52. While intravenous sodium is necessary to reverse the effects of hyponatremia, doing so too rapidly can cause a serious problem in the myelin sheath. What part of the neuron does myelin insulate? C - Axon
1. What further data would best support hypothesis 2 w/o refuting the results of hypothesis 1? A - Post-translational alterations in tyrosinase that change its activity levels differ w/ varying melanin levels
2. From the passage, one could locally infer that the metabolic activity of tyrosinase in Himalayan rabbits is D - more active at cooler body temperatures
3. Based on the data presented in the passage, which region of the rabbit is likely to be dark in color at 25 degrees Celsius C - Limb
4. Which portion of tyrosinase is most important in terms of its overall functioning? A - Active site
5. What level of structural organization of tyrosinase is first and most substantially affected by temperature changes? D - 3 degrees
6. If a future study were conducted on chemical activity in melanin-producing cells, which finding would best support hypothesis 2 while accepting the stipulations of hypothesis 1? B - Allosteric interactions w/ tyrosinase
7. Based on findings from the passage, what is TRUE about the thermolability of tyrosinase between 10 and 32 degrees Celsius? B - Its active site is partially denatured at 10 degrees Celsius
8. What other physical factors might likely determine tyrosinase activity? A - pH
9. Which of the following must be true when GFR = C? D - All of the above
10. Which of the following is TRUE when C < GFR? A - Reabsorption of the solute has occurred
11. Which of the following must be assumed when using inulin to measure glomerular filtration rate? A - The filtered concentration of inulin is exactly the same as the plasma concentration
12. Which of the following statements about inulin is most likely true? C - It is bigger than glucose
13. No known solute is completely filtered from the blood after a single pass through the glomerular apparatus. PAH is most likely C - both filtered and secreted by the kidney
14. Which of the following is RUE when C > GFR? A - The solute is being secreted into the tubules of the nephron
15. A patient has a plasma creatinine concentration of 4 mg/dL. Her clearance of PAH is 550 mL/min. Approximately what percent of plasma is filtered by the patient's kidneys per minute? A - 5.5%
16. Which of the following statements describes renal blood flow in relation to PAH clearance? A - It is greater
17. The following are the results of an experiment to test interferon production in response to various pathogens A - Fungi and protozoa are generally extracellular pathogens
18. The following are the results of an experiment where interferon was added to plates of virally infected cells two hours after initial inoculation with high titers of a virus. The control represents a plate of virally infected cells before and 2 hours D -
19. Which of the following findings on microscopy would provide proof that interferons inhibited viral RNA synthesis? D - Lack of viral capsid protein
20. Gamma inferno, synthesized by T-lymphocytes, stimulates the humoral immune system to fight viral infections. Which of the following findings would provide evidence that the humoral immune system has be recruited? D - Increased concentration of immunoglobulins at the site of viral entry
21. Cytotoxic T-cells are capable of killing virally infected cells via a number of ways. Interferon production by cytotoxic T-cells leads to Which of the following? D - Recruitment of macrophages to the site of infection
22. People born w/o a thymus would have Which of the following laboratory derangements? A - Low lymphocyte count
23. Certain diseases affecting tissue perfusion can have a profound effect on the efficiency of the immune system. Poor oxygen delivery would hamper Which of the following immunoprotective events? B - Respiratory burst by macrophages
24. Which of the following describes the central reaction of a Western blot? D - Nucleotide hybridization
25. Which of the following is an assumption of the Hardy-Weinberg model? D - The population being studied is large and stable
26. Angiotensin directly causes the release of Which of the following from the adrenal cortex? B - Aldosterone
27. Cystic fibrosis is a genetic disorder inherited through an autosomal recessive gene C - 25%
28. Given the principle of independent assortment, how many unique gametes could be produced from the genotype AaBbCc? C - 8
29. Some types of mammals have especially long loops of Henle that maintain a steep osmotic gradient. this adaptation enables the organism to A - excrete urine of higher osmolarity
30. Mice are administered A - steroid hormone
31. The lung is a more common site for primary tuberculosis than the duodenum because D - the low pH of the digestive secretions in the stomach kills mycobacteria before they enter the duodenum
32. An MRI scan of a child's brain reveals a tumor growing on her posterior pituitary gland. Which of the following symptoms might have predicted this finding? A - Hypertension
33. A researcher investigates the cells involved in bone formation and resorption. From Which of the following types of cells are osteoclasts most likely to be differentiated? D - Macrophages
34. Many runners find that smoking cigarettes decreases their speed and endurance. This finding is due to all of the following effects of nicotine EXCEPT B - increase in surfactant section by type II alveolar epithelial cells
35. Which of the following structures is found in bacterial cells? A - Ribosome
36. One type of DNA mutation that can occur as a result of environmental toxin exposure is a deletion, in which one or more nucleotides are deleted during the replication of the cell's genome. However, in mutations in which three base pairs are deleted, t C - retention of the original reading frame
37. In the healthy human adult, erythropoiesis occurs in Which of the following locations? C - III only
38. the kidney is also involved in the processing of Which of the following substances? B - Vitamin D
39. Which of the following laboratory findings would you expect in a patient w/ chronic kidney disease who is unable to produce adequate EPO levels? C - Normal sized (normocytic) red blood cells
40. Which of the following laboratory techniques would be most useful for distinguishing exogenous from endogenous EPO? D - Enzyme-Linked immunoabsorbant assay (ELISA)
41. The following data were obtained in a mouse population exposed to varying levels of oxygen. Biologically active HIF was measured by ELISA. Red blood cell percentage by volume was measured by centrifuging a blood sample and comparing the volume of sedi B - exhaustion of iron stores in chronic low oxygen states
42. Genetic mutations resulting in insuppressible HIF would directly result in C - abnormally high levels of EPO at elevated oxygen concentrations
43. Which of the following properties of the red blood cell allows it to complete its course through the circulation? A - Lack of nucleus
44. According to the passage, HIF acts at which of the following steps? Hypoxia--A → EPO --B → Erythropoiesis ---D → RBC Heme precurors --C → Heme↑ A - Hypoxia → EPO (A)
45. Epinephrine works systemically to shunt blood to the skeletal muscles, brain, and heart away from nonessential organs such as the stomach, intestine, and kidneys. One would expect which of the following responses to a prolonged administration of epine A - Increase in EPO production
46. In order to bind oxygen, the iron contained in heme needs to be retained in the Fe2+ state. Which of the following enzymes is likely responsible for returning Fe3+ to its most efficient oxygen-binding state? C - Reductase
47. why might bone development be hampered in cloudy climates? D - Less sunlight to produce vitamin D from endogenous precursors
48. Bone loss would result from over activity of which of the following cells? B - Osteoclasts
49. It can be inferred from the passage that the majority of bone healing occurs by D - secondary healing
50. A patient who has had her thyroid removed complains of nausea, tetany, numbness, and tingling around her lips. Excess of what mineral most likely contributes to these symptoms? D - Calcium
51. Vitamin D is stored in Which of the following? B - Fat
52. T- and B-cells are both developed in the bone, but T-cells mature in Which of the following? C - Thymus
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