Human Digestive System Quiz – 1st Year Biology | Chapter 9 Study Tool
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Total Marks: 50
Time: 60 min
Questions: 25

Biology (SNC) – 1st Year

Chapter: #9 – Human Digestive System
Subject: Biology
Level: 1st Year Science
Type: Practice Quiz
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Chapter 9: Human Digestive System

Multiple Choice Questions (10×1=10)

1
Why is lipase not active in the stomach?
A It is destroyed by acid
B It needs alkaline pH to work
C It is secreted by the liver
D It digests only proteins
2
Which stomach secretion activates pepsin and kills bacteria?
A Bile
B Hydrochloric acid (HCl)
C Sodium bicarbonate
D Mucus
3
Which of the following is not the part of the gastrointestinal (GI) tract?
A Stomach
B Liver
C Small intestine
D Esophagus
4
Which enzyme in saliva begins the digestion of carbohydrates?
A Pepsin
B Lipase
C Salivary amylase
D Trypsin
5
What triggers hunger contractions in the stomach?
A High blood glucose
B Low blood glucose levels
C Excess stomach acid levels
D Food in the small intestine
6
Which sphincter controls food entry from the esophagus to the stomach?
A Pyloric sphincter
B Cardiac sphincter
C Ileocecal sphincter
D Anal sphincter
7
Which cells in the stomach secrete hydrochloric acid (HCl)?
A Chief cells
B Parietal cells
C Goblet cells
D Mucous cells
8
What is the semi-liquid acidic mass formed in the stomach after digestion called?
A Bolus
B Chyme
C Bile
D Feces
9
Which layer of the stomach contains gastric glands?
A Serosa
B Submucosa
C Muscularis externa
D Mucosa
10
What causes the painful burning sensation known as heartburn (pyrosis)?
A Excess mucus
B Backflow of acidic chyme into the esophagus
C Insufficient HCl secretion
D Rapid digestion of proteins

Short Answer Questions (15×2=30)

Detailed Answer Questions (Answer any 2) (2×5=10)

1. Describe the structure and function of the stomach in digestion.

Stomach Structure & Function:
Structure:
• Four main layers: Mucosa, Submucosa, Muscularis, Serosa
• Three regions: Cardia, Fundus, Body, Pylorus
• Gastric glands with different cell types
• Rugae (folds) for expansion

Functions:
• Temporary food storage
• Mechanical digestion (churning)
• Chemical digestion (HCl, pepsin)
• Limited absorption (water, alcohol, drugs)
• Production of intrinsic factor for B12 absorption

2. Describe in detail the complete swallowing process (deglutition) from the oral cavity to the esophagus, including all protective mechanisms that prevent aspiration.

Swallowing Process (Deglutition):
Three Stages:
1. Oral Stage (Voluntary):
• Tongue pushes bolus against hard palate
• Bolus moves to oropharynx

2. Pharyngeal Stage (Involuntary):
• Soft palate rises to close nasopharynx
• Epiglottis covers larynx
• Vocal cords close
• Breathing temporarily stops

3. Esophageal Stage (Involuntary):
• Peristalsis moves bolus to stomach
• Cardiac sphincter relaxes for entry

3. Describe in detail the digestive processes that occur in the small intestine.

Small Intestine Digestion:
Three Sections:
Duodenum – Receives chyme, bile, pancreatic juice
Jejunum – Major absorption site
Ileum – Completes absorption

Digestive Processes:
• Carbohydrate digestion: Pancreatic amylase, disaccharidases
• Protein digestion: Trypsin, chymotrypsin, peptidases
• Fat digestion: Bile emulsification, lipase action
• Nucleic acid digestion: Nucleases
Key Digestive Enzymes:
Salivary amylase: Starch → Maltose Pepsin: Proteins → Peptides Trypsin: Proteins → Peptides Lipase: Fats → Fatty acids + Glycerol