1
BIO 202L LAB 16 WORKSHEET 2026/2027 | The Digestive
System - Alimentary Canal & Accessory Organs | Complete
Answers | Pass Guaranteed - A+ Graded
SECTION 1: ALIMENTARY CANAL GROSS ANATOMY (Q1-15)
Q1. A student is examining a sagittal section of the head and neck. Which structure
forms the anterior boundary of the oral cavity and is composed of orbicularis oris
muscle covered by skin externally and mucous membrane internally?
A. Cheek
B. Hard palate
C. Uvula
D. Lips
C. Lips [CORRECT]
Rationale: The lips form the anterior boundary of the oral cavity and are composed of
the orbicularis oris muscle with skin externally and mucous membrane internally. The
vermilion border represents the transition zone between skin and mucous
membrane. Clinically, cleft lip results from failure of fusion of the maxillary and
medial nasal processes during embryonic development.
Correct Answer: C
Q2. During a cadaveric dissection, a student identifies a structure on the posterior
tongue that is arranged in an inverted V-shape and contains taste buds with bitter
receptors. Which papillae type is being described?
A. Filiform papillae
B. Fungiform papillae
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C. Circumvallate papillae
D. Foliate papillae
C. Circumvallate papillate [CORRECT]
Rationale: Circumvallate papillae are 8-12 large structures arranged in an inverted V-
shape anterior to the sulcus terminalis on the posterior tongue. They contain
numerous taste buds sensitive to bitter taste and are surrounded by a deep circular
groove. Clinically, inflammation of these papillae can cause glossitis and altered taste
perception.
Correct Answer: C
Q3. A 6-year-old patient presents with 20 teeth. Which dental formula correctly
describes the deciduous (primary) dentition?
A. 2-1-2-3 (per quadrant)
B. 2-1-2-0 (per quadrant)
C. 2-1-0-2 (per quadrant)
D. 2-1-2-3 (per quadrant, but 32 total)
B. 2-1-2-0 (per quadrant) [CORRECT]
Rationale: The deciduous dentition formula is 2 incisors, 1 canine, 2 premolars, and 0
molars per quadrant (2-1-2-0), totaling 20 teeth. Permanent dentition is 2-1-2-3 per
quadrant (32 teeth total). Clinically, premature loss of deciduous teeth can lead to
malocclusion and spacing problems for permanent teeth eruption.
Correct Answer: B
Q4. A patient undergoes endoscopy and the physician notes a narrowing at the
junction between the esophagus and stomach. Which sphincter is responsible for
preventing gastric reflux into the esophagus?
A. Upper esophageal sphincter (UES)
B. Pyloric sphincter
,3
C. Lower esophageal sphincter (LES)
D. Ileocecal valve
C. Lower esophageal sphincter (LES) [CORRECT]
Rationale: The lower esophageal sphincter (LES), also called the gastroesophageal
sphincter, is a physiological sphincter at the esophagogastric junction that prevents
gastric acid reflux. It is composed of smooth muscle and is tonically contracted
except during swallowing. Clinically, LES incompetence causes gastroesophageal
reflux disease (GERD) with heartburn and esophagitis.
Correct Answer: C
Q5. During a gastric endoscopy, a physician identifies the region of the stomach
immediately distal to the cardia and superior to the body. This dome-shaped area
receives air and gas during swallowing. Which gastric region is described?
A. Antrum
B. Fundus
C. Body
D. Pylorus
B. Fundus [CORRECT]
Rationale: The fundus is the dome-shaped superior portion of the stomach
immediately distal to the cardia and superior to the body. It is the most superior
gastric region and receives swallowed air and gas. Clinically, the fundus is the
common site for hiatal hernia protrusion through the esophageal hiatus.
Correct Answer: B
Q6. A surgical resident is preparing to perform a gastrectomy. The attending surgeon
asks which peritoneal fold connects the lesser curvature of the stomach to the liver
and contains the hepatic artery proper, portal vein, and common bile duct. Which
structure is being described?
, 4
A. Greater omentum
B. Falciform ligament
C. Lesser omentum
D. Mesentery proper
C. Lesser omentum [CORRECT]
Rationale: The lesser omentum is a double-layered peritoneal fold connecting the
lesser curvature of the stomach and duodenal bulb to the liver. It contains the portal
triad (hepatic artery proper, portal vein, common bile duct) within its free edge.
Clinically, the lesser omentum is a key surgical landmark for accessing the porta
hepatis and controlling bleeding during liver surgery.
Correct Answer: C
Q7. A patient presents with epigastric pain after meals. Imaging reveals a duodenal
ulcer at the major duodenal papilla. Which two ducts converge at this papilla to
empty into the duodenal lumen?
A. Cystic duct and common hepatic duct
B. Common bile duct and main pancreatic duct (duct of Wirsung)
C. Accessory pancreatic duct (duct of Santorini) and cystic duct
D. Hepatic duct and portal vein
B. Common bile duct and main pancreatic duct (duct of Wirsung) [CORRECT]
Rationale: The major duodenal papilla (ampulla of Vater) is the opening in the
duodenum where the common bile duct and main pancreatic duct (duct of Wirsung)
converge. The sphincter of Oddi controls the flow of bile and pancreatic juice.
Clinically, gallstones impacted at the ampulla can cause gallstone pancreatitis and
obstructive jaundice.
Correct Answer: B
BIO 202L LAB 16 WORKSHEET 2026/2027 | The Digestive
System - Alimentary Canal & Accessory Organs | Complete
Answers | Pass Guaranteed - A+ Graded
SECTION 1: ALIMENTARY CANAL GROSS ANATOMY (Q1-15)
Q1. A student is examining a sagittal section of the head and neck. Which structure
forms the anterior boundary of the oral cavity and is composed of orbicularis oris
muscle covered by skin externally and mucous membrane internally?
A. Cheek
B. Hard palate
C. Uvula
D. Lips
C. Lips [CORRECT]
Rationale: The lips form the anterior boundary of the oral cavity and are composed of
the orbicularis oris muscle with skin externally and mucous membrane internally. The
vermilion border represents the transition zone between skin and mucous
membrane. Clinically, cleft lip results from failure of fusion of the maxillary and
medial nasal processes during embryonic development.
Correct Answer: C
Q2. During a cadaveric dissection, a student identifies a structure on the posterior
tongue that is arranged in an inverted V-shape and contains taste buds with bitter
receptors. Which papillae type is being described?
A. Filiform papillae
B. Fungiform papillae
,2
C. Circumvallate papillae
D. Foliate papillae
C. Circumvallate papillate [CORRECT]
Rationale: Circumvallate papillae are 8-12 large structures arranged in an inverted V-
shape anterior to the sulcus terminalis on the posterior tongue. They contain
numerous taste buds sensitive to bitter taste and are surrounded by a deep circular
groove. Clinically, inflammation of these papillae can cause glossitis and altered taste
perception.
Correct Answer: C
Q3. A 6-year-old patient presents with 20 teeth. Which dental formula correctly
describes the deciduous (primary) dentition?
A. 2-1-2-3 (per quadrant)
B. 2-1-2-0 (per quadrant)
C. 2-1-0-2 (per quadrant)
D. 2-1-2-3 (per quadrant, but 32 total)
B. 2-1-2-0 (per quadrant) [CORRECT]
Rationale: The deciduous dentition formula is 2 incisors, 1 canine, 2 premolars, and 0
molars per quadrant (2-1-2-0), totaling 20 teeth. Permanent dentition is 2-1-2-3 per
quadrant (32 teeth total). Clinically, premature loss of deciduous teeth can lead to
malocclusion and spacing problems for permanent teeth eruption.
Correct Answer: B
Q4. A patient undergoes endoscopy and the physician notes a narrowing at the
junction between the esophagus and stomach. Which sphincter is responsible for
preventing gastric reflux into the esophagus?
A. Upper esophageal sphincter (UES)
B. Pyloric sphincter
,3
C. Lower esophageal sphincter (LES)
D. Ileocecal valve
C. Lower esophageal sphincter (LES) [CORRECT]
Rationale: The lower esophageal sphincter (LES), also called the gastroesophageal
sphincter, is a physiological sphincter at the esophagogastric junction that prevents
gastric acid reflux. It is composed of smooth muscle and is tonically contracted
except during swallowing. Clinically, LES incompetence causes gastroesophageal
reflux disease (GERD) with heartburn and esophagitis.
Correct Answer: C
Q5. During a gastric endoscopy, a physician identifies the region of the stomach
immediately distal to the cardia and superior to the body. This dome-shaped area
receives air and gas during swallowing. Which gastric region is described?
A. Antrum
B. Fundus
C. Body
D. Pylorus
B. Fundus [CORRECT]
Rationale: The fundus is the dome-shaped superior portion of the stomach
immediately distal to the cardia and superior to the body. It is the most superior
gastric region and receives swallowed air and gas. Clinically, the fundus is the
common site for hiatal hernia protrusion through the esophageal hiatus.
Correct Answer: B
Q6. A surgical resident is preparing to perform a gastrectomy. The attending surgeon
asks which peritoneal fold connects the lesser curvature of the stomach to the liver
and contains the hepatic artery proper, portal vein, and common bile duct. Which
structure is being described?
, 4
A. Greater omentum
B. Falciform ligament
C. Lesser omentum
D. Mesentery proper
C. Lesser omentum [CORRECT]
Rationale: The lesser omentum is a double-layered peritoneal fold connecting the
lesser curvature of the stomach and duodenal bulb to the liver. It contains the portal
triad (hepatic artery proper, portal vein, common bile duct) within its free edge.
Clinically, the lesser omentum is a key surgical landmark for accessing the porta
hepatis and controlling bleeding during liver surgery.
Correct Answer: C
Q7. A patient presents with epigastric pain after meals. Imaging reveals a duodenal
ulcer at the major duodenal papilla. Which two ducts converge at this papilla to
empty into the duodenal lumen?
A. Cystic duct and common hepatic duct
B. Common bile duct and main pancreatic duct (duct of Wirsung)
C. Accessory pancreatic duct (duct of Santorini) and cystic duct
D. Hepatic duct and portal vein
B. Common bile duct and main pancreatic duct (duct of Wirsung) [CORRECT]
Rationale: The major duodenal papilla (ampulla of Vater) is the opening in the
duodenum where the common bile duct and main pancreatic duct (duct of Wirsung)
converge. The sphincter of Oddi controls the flow of bile and pancreatic juice.
Clinically, gallstones impacted at the ampulla can cause gallstone pancreatitis and
obstructive jaundice.
Correct Answer: B
