A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
A&P 1 FINAL EXAM, STRAIGHTERLINE ANATOMY AND
PHYSIOLOGY 1, STRAIGHTERLINE A&P 1 CUMULATIVE FINAL
| 150 QUESTIONS | WITH COMPLETE SOLUTIONS | 2026/2027
EDITION
Aligned with Straighterline Anatomy & Physiology 1 Course Syllabus, HAPS (Human Anatomy and Physiology Society)
Learning Outcomes, and Standard A&P I Curriculum Guidelines (2026/2027 Edition)
EXAM FORMAT: 150 multiple-choice questions (4 options each, single best answer).
COGNITIVE DISTRIBUTION: ~25% recall, ~50% application, ~25% analysis.
QUESTION STYLE: ~70% scenario-based (clinical correlations, physiological processes, structural identification); ~30% direct
knowledge.
SPECIAL INCLUSIONS: 15 physiological-process questions, 15 structural-identification questions, 10 clinical-application questions
distributed across all 11 sections.
SCORING REFERENCE: Each question is worth an equal share of the cumulative total. Mark the single best answer; rationales follow
each question and reference HAPS learning outcomes.
ALIGNED STANDARDS: HAPS Learning Outcomes A1-A7 (Anatomy) and P1-P6 (Physiology); Straighterline A&P I module
objectives; standard A&P I curriculum guidelines (2026/2027).
Section 1: Introduction to Anatomy & Physiology / Homeostasis
Q1: A patient presents with a body temperature of 39.2°C (102.6°F). Which homeostatic control mechanism
components are actively engaged to restore normal body temperature?
A. Receptors in the spleen send signals to the hypothalamus; effectors are skeletal muscles that shiver
B. Thermoreceptors in the skin and hypothalamus detect the change; the hypothalamus (control center) signals sweat
glands and cutaneous blood vessels (effectors) to dissipate heat *[CORRECT]*
C. The cerebral cortex directly senses the fever and instructs sweat glands to secrete
D. Cutaneous blood vessels dilate without any control-center input because the response is purely local
Correct Answer: B
Rationale: Homeostasis follows the receptor → control center → effector loop (HAPS P1). Thermoreceptors in skin and hypothalamus
detect elevated core temperature; the hypothalamus acts as the control center and activates effectors (sweat glands, vasodilation of
cutaneous vessels) to dissipate heat. The spleen is not a thermoreceptor (eliminating A); the cerebral cortex is not the autonomic
thermoregulatory center (eliminating C); and although local responses exist, the integrated febrile response requires hypothalamic
coordination (eliminating D).
Q2: During active labor, oxytocin release causes uterine contractions that push the fetus against the cervix,
stretching it further and triggering additional oxytocin release. This is a classic example of which mechanism?
A. Negative feedback, because the system eventually returns to a set point
B. Positive feedback, because the response amplifies the original stimulus until a terminal event occurs
*[CORRECT]*
C. Feedforward regulation, because the body anticipates the stimulus
D. Acclimatization, because the body adapts over weeks to a new set point
Correct Answer: B
Rationale: Positive feedback loops amplify the original stimulus until a definite endpoint is reached — childbirth, blood clotting, and
ovulation are the textbook HAPS examples (HAPS P2). Negative feedback (A) returns the system toward a set point and would dampen
contractions; feedforward (C) anticipates rather than amplifies; acclimatization (D) is a long-term adjustment to environmental change,
not a single acute event.
Page 1
,A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
Q3: A surgeon making an incision to remove a tumor from the left kidney must pass through several body cavities.
The kidney is located in which cavity?
A. The abdominal cavity proper, because it is inferior to the diaphragm
B. The pelvic cavity, because it is bordered by the pelvic bones
C. The retroperitoneal space, posterior to the parietal peritoneum *[CORRECT]*
D. The vertebral canal, because it lies beside the spine
Correct Answer: C
Rationale: The kidneys are secondarily retroperitoneal organs — they develop behind the parietal peritoneum and remain outside the
peritoneal cavity (HAPS A1, body cavities). The abdominal cavity proper (A) contains intraperitoneal organs like the stomach; the pelvic
cavity (B) holds the bladder, rectum, and reproductive organs; the vertebral canal (D) houses the spinal cord, not the kidneys.
Q4: A patient reports pain in the right lower quadrant (RLQ) of the abdomen with rebound tenderness. Which
anatomical structure is most likely inflamed?
A. Stomach, in the left upper quadrant
B. Liver, in the right upper quadrant
C. Appendix, in the right lower quadrant *[CORRECT]*
D. Spleen, in the left upper quadrant
Correct Answer: C
Rationale: Using the four-quadrant abdominopelvic regional scheme (HAPS A1), the appendix lies in the right lower quadrant, and
RLQ pain with rebound tenderness is the hallmark of appendicitis. The stomach and spleen are left-upper-quadrant structures (A, D),
while the liver is right-upper-quadrant (B). Regional terminology directly translates to clinical localization of pain.
Q5: An MRI slice divides the brain into anterior and posterior portions along a plane that runs parallel to the
coronal suture. Which anatomical plane is being used?
A. Sagittal plane, because it divides the body into right and left portions
B. Frontal (coronal) plane, because it divides the body into anterior and posterior portions *[CORRECT]*
C. Transverse plane, because it divides the body into superior and inferior portions
D. Oblique plane, because it crosses both longitudinal and transverse axes
Correct Answer: B
Rationale: The frontal (coronal) plane divides the body into anterior and posterior sections and is named for its parallel relationship
with the coronal suture (HAPS A1, body planes). The sagittal plane (A) divides into right and left; the transverse/horizontal plane (C)
divides into superior and inferior; an oblique plane (D) is any plane not parallel to the three principal planes.
Q6: A patient has suffered a stroke and cannot identify objects placed in his left hand with eyes closed, although he
can do so with the right hand. The lesion most likely affects which anatomical directional relationship?
A. The contralateral somatosensory cortex, which is medial to the ipsilateral motor cortex
B. The ipsilateral thalamus, which is anterior to the contralateral cortex
C. The contralateral parietal lobe, which is superior to the lateral sulcus and posterior to the central sulcus
*[CORRECT]*
D. The ipsilateral cerebellar hemisphere, which is posterior to the brainstem
Correct Answer: C
Rationale: Sensory pathways decussate (cross over) in the spinal cord or brainstem, so a lesion in the right parietal lobe impairs
stereognosis in the left hand (HAPS A1 + P1, directional terms + sensory pathways). The contralateral parietal lobe is correctly located
superior to the lateral sulcus and posterior to the central sulcus. A and B misuse medial/anterior relationships; D would produce
ipsilateral motor signs, not sensory object-recognition deficits.
Q7: Which of the following best describes the relationship of the heart to the lungs within the thoracic cavity?
Page 2
,A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
A. The heart is superior to the lungs and anterior to the vertebral column
B. The heart is medial to the lungs and lies within the mediastinum *[CORRECT]*
C. The heart is lateral to the lungs and within the pleural cavity
D. The heart is inferior to the diaphragm and within the pericardial cavity only
Correct Answer: B
Rationale: The heart sits in the mediastinum, the central compartment of the thoracic cavity, and is therefore medial to the paired lungs
(HAPS A1, regional/directional terms). The heart is not superior to the lungs (A), not lateral (C), and certainly not inferior to the
diaphragm (D) — it sits in the mediastinum between the two pleural cavities.
Q8: A 56-year-old patient with type 1 diabetes reports polyuria, polydipsia, and fatigue. Her fasting blood glucose
is 312 mg/dL. Which homeostatic imbalance best explains this presentation?
A. Failure of the negative feedback loop regulating blood glucose due to insufficient insulin action *[CORRECT]*
B. Excess positive feedback from glucagon amplifying blood glucose
C. Receptor down-regulation causing hypercalcemia
D. Set-point shift to a higher glucose target value
Correct Answer: A
Rationale: Blood glucose is normally maintained by negative feedback between insulin and glucagon (HAPS P2). In type 1 diabetes, the
absence of insulin disables the corrective arm of the loop, producing sustained hyperglycemia, osmotic diuresis (polyuria), and thirst
(polydipsia). Glucagon does not drive positive feedback (B); hypercalcemia is unrelated to glucose regulation (C); and diabetes is not an
adaptive set-point shift (D) but a failure of the effector hormone.
Q9: Which structural level of organization encompasses the smallest functional unit that still exhibits all
characteristics of life?
A. Chemical level, because atoms are the building blocks of matter
B. Cellular level, because cells are the smallest living units capable of metabolism and reproduction *[CORRECT]*
C. Tissue level, because groups of similar cells perform shared functions
D. Organ level, because multiple tissues combine to perform complex tasks
Correct Answer: B
Rationale: The cellular level is the lowest level of structural organization that still satisfies all characteristics of life (HAPS A1, levels of
organization). Atoms (A) are non-living chemical units; tissues (C) and organs (D) are higher-order composites. A single isolated cell can
metabolize, reproduce, respond to stimuli, and maintain homeostasis, which is why the cell is the basic functional unit of life.
Q10: A patient in shock has a blood pressure of 80/40 mmHg and a heart rate of 130 bpm. If we consider MAP
(mean arterial pressure) ≈ diastolic + 1/3 pulse pressure, what is the most likely effect on the baroreceptor reflex?
A. Increased firing of carotid sinus afferents, decreased sympathetic output, increased parasympathetic output
B. Decreased firing of carotid sinus afferents, increased sympathetic output, decreased parasympathetic output
*[CORRECT]*
C. No change in baroreceptor firing, because they respond only to oxygen tension
D. Increased firing of carotid sinus afferents with simultaneous increased sympathetic output
Correct Answer: B
Rationale: Baroreceptors in the carotid sinus and aortic arch detect stretch (HAPS P1, P2). When MAP falls, stretch decreases, afferent
firing drops, the cardiovascular control center in the medulla responds by increasing sympathetic outflow and decreasing
parasympathetic outflow, producing tachycardia and vasoconstriction. A describes the response to hypertension; C confuses
baroreceptors with chemoreceptors; D is physiologically contradictory.
Section 2: Chemistry of Life / Basic Biochemistry
Page 3
, A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
Q11: A solution has a hydrogen ion concentration of 1 × 10⁻⁴ M. What is the pH, and how does it classify relative to
neutrality (pH 7)?
A. pH 4, acidic *[CORRECT]*
B. pH 4, basic
C. pH 10, basic
D. pH 10, acidic
Correct Answer: A
Rationale: pH = -log[H⁺] = -log(10⁻⁴) = 4 (HAPS P3, chemistry of life). Values below 7 are acidic because the hydrogen ion
concentration exceeds the hydroxide ion concentration. Option B misclassifies pH 4 as basic; C and D invert the negative-log
relationship, mistakenly producing pH 10.
Q12: A biochemist is studying the bonding between two water molecules. Which type of bond forms between the
slightly positive hydrogen of one water molecule and the slightly negative oxygen of another?
A. Ionic bond, because electrons are completely transferred
B. Covalent bond, because electrons are shared equally
C. Hydrogen bond, an intermolecular attraction between polar molecules *[CORRECT]*
D. Peptide bond, because it links amino acid monomers
Correct Answer: C
Rationale: Hydrogen bonds form when a partially positive hydrogen atom of one polar molecule is attracted to a partially negative
atom (typically O, N, or F) of another molecule (HAPS P3). They are intermolecular and weaker than covalent bonds. Ionic bonds (A)
require complete electron transfer; covalent bonds (B) involve electron sharing within a molecule; peptide bonds (D) join amino acids in
proteins and are covalent amide linkages.
Q13: A patient overdoses on aspirin (acetylsalicylic acid), developing metabolic acidosis. The body's chemical
buffer system responds most rapidly. Which buffer is the primary intracellular buffer that binds H⁺ to mitigate pH
change?
A. Bicarbonate buffer, CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻
B. Phosphate buffer, HPO₄²⁻ + H⁺ ⇌ H₂PO₄⁻
C. Protein buffer, in which the side chain of histidine accepts H⁺ *[CORRECT]*
D. Ammonia buffer, NH₃ + H⁺ ⇌ NH₄⁺
Correct Answer: C
Rationale: Proteins are the most abundant intracellular buffers because their amino acid side chains (e.g., histidine's imidazole group,
with pKa near physiological pH) can accept or donate H⁺ (HAPS P3, buffers). Bicarbonate (A) is the principal extracellular/Ecf buffer;
phosphate (B) is important in renal tubules and urine; ammonia (D) is generated by the kidney for H⁺ excretion but is not a primary
intracellular buffer.
Q14: Which of the following is a disaccharide composed of glucose + fructose, commonly found in table sugar?
A. Lactose
B. Maltose
C. Sucrose *[CORRECT]*
D. Glycogen
Correct Answer: C
Rationale: Sucrose is a disaccharide of glucose + fructose (HAPS P3, carbohydrates). Lactose (A) is glucose + galactose and is milk
sugar; maltose (B) is glucose + glucose from starch digestion; glycogen (D) is a polysaccharide, the storage carbohydrate of animals, not
a disaccharide.
Page 4
A&P 1 FINAL EXAM, STRAIGHTERLINE ANATOMY AND
PHYSIOLOGY 1, STRAIGHTERLINE A&P 1 CUMULATIVE FINAL
| 150 QUESTIONS | WITH COMPLETE SOLUTIONS | 2026/2027
EDITION
Aligned with Straighterline Anatomy & Physiology 1 Course Syllabus, HAPS (Human Anatomy and Physiology Society)
Learning Outcomes, and Standard A&P I Curriculum Guidelines (2026/2027 Edition)
EXAM FORMAT: 150 multiple-choice questions (4 options each, single best answer).
COGNITIVE DISTRIBUTION: ~25% recall, ~50% application, ~25% analysis.
QUESTION STYLE: ~70% scenario-based (clinical correlations, physiological processes, structural identification); ~30% direct
knowledge.
SPECIAL INCLUSIONS: 15 physiological-process questions, 15 structural-identification questions, 10 clinical-application questions
distributed across all 11 sections.
SCORING REFERENCE: Each question is worth an equal share of the cumulative total. Mark the single best answer; rationales follow
each question and reference HAPS learning outcomes.
ALIGNED STANDARDS: HAPS Learning Outcomes A1-A7 (Anatomy) and P1-P6 (Physiology); Straighterline A&P I module
objectives; standard A&P I curriculum guidelines (2026/2027).
Section 1: Introduction to Anatomy & Physiology / Homeostasis
Q1: A patient presents with a body temperature of 39.2°C (102.6°F). Which homeostatic control mechanism
components are actively engaged to restore normal body temperature?
A. Receptors in the spleen send signals to the hypothalamus; effectors are skeletal muscles that shiver
B. Thermoreceptors in the skin and hypothalamus detect the change; the hypothalamus (control center) signals sweat
glands and cutaneous blood vessels (effectors) to dissipate heat *[CORRECT]*
C. The cerebral cortex directly senses the fever and instructs sweat glands to secrete
D. Cutaneous blood vessels dilate without any control-center input because the response is purely local
Correct Answer: B
Rationale: Homeostasis follows the receptor → control center → effector loop (HAPS P1). Thermoreceptors in skin and hypothalamus
detect elevated core temperature; the hypothalamus acts as the control center and activates effectors (sweat glands, vasodilation of
cutaneous vessels) to dissipate heat. The spleen is not a thermoreceptor (eliminating A); the cerebral cortex is not the autonomic
thermoregulatory center (eliminating C); and although local responses exist, the integrated febrile response requires hypothalamic
coordination (eliminating D).
Q2: During active labor, oxytocin release causes uterine contractions that push the fetus against the cervix,
stretching it further and triggering additional oxytocin release. This is a classic example of which mechanism?
A. Negative feedback, because the system eventually returns to a set point
B. Positive feedback, because the response amplifies the original stimulus until a terminal event occurs
*[CORRECT]*
C. Feedforward regulation, because the body anticipates the stimulus
D. Acclimatization, because the body adapts over weeks to a new set point
Correct Answer: B
Rationale: Positive feedback loops amplify the original stimulus until a definite endpoint is reached — childbirth, blood clotting, and
ovulation are the textbook HAPS examples (HAPS P2). Negative feedback (A) returns the system toward a set point and would dampen
contractions; feedforward (C) anticipates rather than amplifies; acclimatization (D) is a long-term adjustment to environmental change,
not a single acute event.
Page 1
,A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
Q3: A surgeon making an incision to remove a tumor from the left kidney must pass through several body cavities.
The kidney is located in which cavity?
A. The abdominal cavity proper, because it is inferior to the diaphragm
B. The pelvic cavity, because it is bordered by the pelvic bones
C. The retroperitoneal space, posterior to the parietal peritoneum *[CORRECT]*
D. The vertebral canal, because it lies beside the spine
Correct Answer: C
Rationale: The kidneys are secondarily retroperitoneal organs — they develop behind the parietal peritoneum and remain outside the
peritoneal cavity (HAPS A1, body cavities). The abdominal cavity proper (A) contains intraperitoneal organs like the stomach; the pelvic
cavity (B) holds the bladder, rectum, and reproductive organs; the vertebral canal (D) houses the spinal cord, not the kidneys.
Q4: A patient reports pain in the right lower quadrant (RLQ) of the abdomen with rebound tenderness. Which
anatomical structure is most likely inflamed?
A. Stomach, in the left upper quadrant
B. Liver, in the right upper quadrant
C. Appendix, in the right lower quadrant *[CORRECT]*
D. Spleen, in the left upper quadrant
Correct Answer: C
Rationale: Using the four-quadrant abdominopelvic regional scheme (HAPS A1), the appendix lies in the right lower quadrant, and
RLQ pain with rebound tenderness is the hallmark of appendicitis. The stomach and spleen are left-upper-quadrant structures (A, D),
while the liver is right-upper-quadrant (B). Regional terminology directly translates to clinical localization of pain.
Q5: An MRI slice divides the brain into anterior and posterior portions along a plane that runs parallel to the
coronal suture. Which anatomical plane is being used?
A. Sagittal plane, because it divides the body into right and left portions
B. Frontal (coronal) plane, because it divides the body into anterior and posterior portions *[CORRECT]*
C. Transverse plane, because it divides the body into superior and inferior portions
D. Oblique plane, because it crosses both longitudinal and transverse axes
Correct Answer: B
Rationale: The frontal (coronal) plane divides the body into anterior and posterior sections and is named for its parallel relationship
with the coronal suture (HAPS A1, body planes). The sagittal plane (A) divides into right and left; the transverse/horizontal plane (C)
divides into superior and inferior; an oblique plane (D) is any plane not parallel to the three principal planes.
Q6: A patient has suffered a stroke and cannot identify objects placed in his left hand with eyes closed, although he
can do so with the right hand. The lesion most likely affects which anatomical directional relationship?
A. The contralateral somatosensory cortex, which is medial to the ipsilateral motor cortex
B. The ipsilateral thalamus, which is anterior to the contralateral cortex
C. The contralateral parietal lobe, which is superior to the lateral sulcus and posterior to the central sulcus
*[CORRECT]*
D. The ipsilateral cerebellar hemisphere, which is posterior to the brainstem
Correct Answer: C
Rationale: Sensory pathways decussate (cross over) in the spinal cord or brainstem, so a lesion in the right parietal lobe impairs
stereognosis in the left hand (HAPS A1 + P1, directional terms + sensory pathways). The contralateral parietal lobe is correctly located
superior to the lateral sulcus and posterior to the central sulcus. A and B misuse medial/anterior relationships; D would produce
ipsilateral motor signs, not sensory object-recognition deficits.
Q7: Which of the following best describes the relationship of the heart to the lungs within the thoracic cavity?
Page 2
,A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
A. The heart is superior to the lungs and anterior to the vertebral column
B. The heart is medial to the lungs and lies within the mediastinum *[CORRECT]*
C. The heart is lateral to the lungs and within the pleural cavity
D. The heart is inferior to the diaphragm and within the pericardial cavity only
Correct Answer: B
Rationale: The heart sits in the mediastinum, the central compartment of the thoracic cavity, and is therefore medial to the paired lungs
(HAPS A1, regional/directional terms). The heart is not superior to the lungs (A), not lateral (C), and certainly not inferior to the
diaphragm (D) — it sits in the mediastinum between the two pleural cavities.
Q8: A 56-year-old patient with type 1 diabetes reports polyuria, polydipsia, and fatigue. Her fasting blood glucose
is 312 mg/dL. Which homeostatic imbalance best explains this presentation?
A. Failure of the negative feedback loop regulating blood glucose due to insufficient insulin action *[CORRECT]*
B. Excess positive feedback from glucagon amplifying blood glucose
C. Receptor down-regulation causing hypercalcemia
D. Set-point shift to a higher glucose target value
Correct Answer: A
Rationale: Blood glucose is normally maintained by negative feedback between insulin and glucagon (HAPS P2). In type 1 diabetes, the
absence of insulin disables the corrective arm of the loop, producing sustained hyperglycemia, osmotic diuresis (polyuria), and thirst
(polydipsia). Glucagon does not drive positive feedback (B); hypercalcemia is unrelated to glucose regulation (C); and diabetes is not an
adaptive set-point shift (D) but a failure of the effector hormone.
Q9: Which structural level of organization encompasses the smallest functional unit that still exhibits all
characteristics of life?
A. Chemical level, because atoms are the building blocks of matter
B. Cellular level, because cells are the smallest living units capable of metabolism and reproduction *[CORRECT]*
C. Tissue level, because groups of similar cells perform shared functions
D. Organ level, because multiple tissues combine to perform complex tasks
Correct Answer: B
Rationale: The cellular level is the lowest level of structural organization that still satisfies all characteristics of life (HAPS A1, levels of
organization). Atoms (A) are non-living chemical units; tissues (C) and organs (D) are higher-order composites. A single isolated cell can
metabolize, reproduce, respond to stimuli, and maintain homeostasis, which is why the cell is the basic functional unit of life.
Q10: A patient in shock has a blood pressure of 80/40 mmHg and a heart rate of 130 bpm. If we consider MAP
(mean arterial pressure) ≈ diastolic + 1/3 pulse pressure, what is the most likely effect on the baroreceptor reflex?
A. Increased firing of carotid sinus afferents, decreased sympathetic output, increased parasympathetic output
B. Decreased firing of carotid sinus afferents, increased sympathetic output, decreased parasympathetic output
*[CORRECT]*
C. No change in baroreceptor firing, because they respond only to oxygen tension
D. Increased firing of carotid sinus afferents with simultaneous increased sympathetic output
Correct Answer: B
Rationale: Baroreceptors in the carotid sinus and aortic arch detect stretch (HAPS P1, P2). When MAP falls, stretch decreases, afferent
firing drops, the cardiovascular control center in the medulla responds by increasing sympathetic outflow and decreasing
parasympathetic outflow, producing tachycardia and vasoconstriction. A describes the response to hypertension; C confuses
baroreceptors with chemoreceptors; D is physiologically contradictory.
Section 2: Chemistry of Life / Basic Biochemistry
Page 3
, A&P 1 Final Exam | Straighterline Anatomy & Physiology 1 | 2026/2027 Cumulative Final - 150 Questions
Q11: A solution has a hydrogen ion concentration of 1 × 10⁻⁴ M. What is the pH, and how does it classify relative to
neutrality (pH 7)?
A. pH 4, acidic *[CORRECT]*
B. pH 4, basic
C. pH 10, basic
D. pH 10, acidic
Correct Answer: A
Rationale: pH = -log[H⁺] = -log(10⁻⁴) = 4 (HAPS P3, chemistry of life). Values below 7 are acidic because the hydrogen ion
concentration exceeds the hydroxide ion concentration. Option B misclassifies pH 4 as basic; C and D invert the negative-log
relationship, mistakenly producing pH 10.
Q12: A biochemist is studying the bonding between two water molecules. Which type of bond forms between the
slightly positive hydrogen of one water molecule and the slightly negative oxygen of another?
A. Ionic bond, because electrons are completely transferred
B. Covalent bond, because electrons are shared equally
C. Hydrogen bond, an intermolecular attraction between polar molecules *[CORRECT]*
D. Peptide bond, because it links amino acid monomers
Correct Answer: C
Rationale: Hydrogen bonds form when a partially positive hydrogen atom of one polar molecule is attracted to a partially negative
atom (typically O, N, or F) of another molecule (HAPS P3). They are intermolecular and weaker than covalent bonds. Ionic bonds (A)
require complete electron transfer; covalent bonds (B) involve electron sharing within a molecule; peptide bonds (D) join amino acids in
proteins and are covalent amide linkages.
Q13: A patient overdoses on aspirin (acetylsalicylic acid), developing metabolic acidosis. The body's chemical
buffer system responds most rapidly. Which buffer is the primary intracellular buffer that binds H⁺ to mitigate pH
change?
A. Bicarbonate buffer, CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻
B. Phosphate buffer, HPO₄²⁻ + H⁺ ⇌ H₂PO₄⁻
C. Protein buffer, in which the side chain of histidine accepts H⁺ *[CORRECT]*
D. Ammonia buffer, NH₃ + H⁺ ⇌ NH₄⁺
Correct Answer: C
Rationale: Proteins are the most abundant intracellular buffers because their amino acid side chains (e.g., histidine's imidazole group,
with pKa near physiological pH) can accept or donate H⁺ (HAPS P3, buffers). Bicarbonate (A) is the principal extracellular/Ecf buffer;
phosphate (B) is important in renal tubules and urine; ammonia (D) is generated by the kidney for H⁺ excretion but is not a primary
intracellular buffer.
Q14: Which of the following is a disaccharide composed of glucose + fructose, commonly found in table sugar?
A. Lactose
B. Maltose
C. Sucrose *[CORRECT]*
D. Glycogen
Correct Answer: C
Rationale: Sucrose is a disaccharide of glucose + fructose (HAPS P3, carbohydrates). Lactose (A) is glucose + galactose and is milk
sugar; maltose (B) is glucose + glucose from starch digestion; glycogen (D) is a polysaccharide, the storage carbohydrate of animals, not
a disaccharide.
Page 4
