The Human Digestive System

Section 1: Multiple Choice Questions (30 Questions)

1. What is the primary function of the digestive system?

a) To transport oxygen to the cells.
b) To break down food, absorb nutrients, and eliminate solid waste.
c) To exchange gases with the environment.
d) To send electrical signals throughout the body.
2. The process of breaking down food into smaller molecules is called:
a) Circulation
b) Respiration
c) Digestion
d) Excretion
3. Where does the process of digestion begin?
a) Stomach
b) Small intestine
c) Esophagus
d) Mouth
4. Which enzyme found in saliva begins the chemical digestion of carbohydrates?
a) Pepsin
b) Lipase
c) Amylase
d) Trypsin
5. The muscular tube that connects the pharynx to the stomach is the:
a) Trachea
b) Esophagus
c) Small intestine
d) Larynx
6. The wave-like muscular contractions that move food through the digestive tract
are called:
a) Peristalsis
b) Diffusion
c) Osmosis
d) Segmentation
7. In the stomach, which substance is primarily responsible for killing bacteria and
providing an acidic environment for pepsin to work?
a) Bile
b) Mucus
c) Hydrochloric acid
d) Bicarbonate
8. The main site for the absorption of digested nutrients into the bloodstream is the:
a) Stomach
b) Large intestine
c) Small intestine
d) Liver
9. Which organ produces bile, a substance that aids in the emulsification of fats?
a) Pancreas

1
 b) Gallbladder
c) Stomach
d) Liver
10.The role of bile in digestion is to:
a) Break down proteins into amino acids.
b) Break down large fat globules into smaller fat droplets.
c) Break down starch into simple sugars.
d) Neutralize stomach acid.
11.Which organ produces a variety of digestive enzymes, including trypsin, lipase,
and amylase, and also secretes bicarbonate to neutralize stomach acid?
a) Liver
b) Stomach
c) Pancreas
d) Gallbladder
12.The finger-like projections that line the small intestine and increase its surface
area for absorption are called:
a) Cilia
b) Villi
c) Alveoli
d) Flagella
13.What is the primary function of the large intestine?
a) To digest proteins and fats.
b) To absorb water from undigested food and form feces.
c) To produce bile.
d) To absorb most of the nutrients from food.
14.The enzyme pepsin, found in the stomach, begins the chemical digestion of:
a) Carbohydrates
b) Fats
c) Proteins
d) Fiber
15.Where is bile stored and concentrated before being released into the small
intestine?
a) Pancreas
b) Liver
c) Duodenum
d) Gallbladder
16.The final section of the large intestine, where feces are stored before elimination,
is the:
a) Appendix
b) Cecum
c) Rectum
d) Colon
17.Which of the following is NOT a part of the small intestine?
a) Duodenum
b) Jejunum
c) Ileum
d) Cecum

2
18.What is the purpose of mucus in the stomach?
a) To digest proteins.
b) To absorb nutrients.
c) To protect the stomach lining from acid and enzymes.
d) To kill bacteria.
19.The process of taking food into the body through the mouth is called:
a) Digestion
b) Absorption
c) Ingestion
d) Egestion
20.The removal of undigested and unabsorbed solid waste from the body is called:
a) Excretion
b) Egestion (or defecation)
c) Respiration
d) Circulation
21.What is the semi-liquid mixture of partially digested food and stomach juices
that leaves the stomach called?
a) Bile
b) Bolus
c) Feces
d) Chyme
22.Which nutrient class provides the most energy per gram?
a) Carbohydrates
b) Proteins
c) Fats (Lipids)
d) Vitamins
23.The flap of tissue that prevents food from entering the trachea (windpipe) during
swallowing is the:
a) Epiglottis
b) Uvula
c) Tonsil
d) Pharynx
24.What is the pH of the environment in the stomach?
a) Strongly alkaline (pH > 8)
b) Neutral (pH ≈ 7)
c) Strongly acidic (pH 1.5 - 3.5)
d) Slightly acidic (pH ≈ 6)
25.The end products of carbohydrate digestion are:
a) Amino acids
b) Fatty acids and glycerol
c) Monosaccharides (e.g., glucose)
d) Polypeptides
26.Which organ is considered an accessory organ of the digestive system, meaning
food does not pass through it?
a) Stomach
b) Esophagus
c) Small intestine
d) Pancreas
3
 27.The end products of protein digestion are:
a) Amino acids
b) Fatty acids and glycerol
c) Monosaccharides
d) Simple sugars
28.What is the main function of the bacteria residing in the large intestine?
a) To digest proteins.
b) To produce hydrochloric acid.
c) To synthesize certain vitamins (like vitamin K) and ferment undigested
carbohydrates.
d) To absorb water.
29.The enzyme lipase breaks down:
a) Proteins
b) Starch
c) Fats (Lipids)
d) Sucrose
30.Where in the digestive tract does the absorption of water primarily occur?
a) Stomach
b) Small intestine
c) Large intestine
d) Esophagus

Section 2: Fill in the Blanks (10 Questions)

1. Mechanical digestion in the mouth is carried out by the __________.

2. The __________ produces enzymes to digest carbohydrates, proteins, and fats,
and delivers them to the small intestine.
3. After nutrients are absorbed in the small intestine, they enter the __________ to
be transported to the rest of the body.
4. The process of breaking down large fat globules into smaller droplets by bile is
called __________.
5. The first part of the small intestine, where chyme from the stomach is mixed
with bile and pancreatic juices, is the __________.
6. The valve that controls the passage of chyme from the stomach to the small
intestine is the __________ sphincter.
7. Undigested solid waste material is known as __________.
8. The liver plays a crucial role in metabolism and detoxification, and it produces a
substance called __________ that aids in fat digestion.
9. The main acid present in stomach juice is __________ acid.
10.The small, finger-like projections on the surface of villi that further increase the
surface area are called __________.

Section 3: True or False (10 Questions)

(Indicate whether each statement is True (T) or False (F).)

1. ___ The esophagus is responsible for the chemical digestion of food.

2. ___ Bile is an enzyme that chemically digests fats.
3. ___ The stomach is protected from its own acidic contents by a layer of mucus.

4
 4. ___ The pancreas is both an endocrine gland (producing hormones like insulin)
and an exocrine gland (producing digestive enzymes).
4s. ___ Most of the water we consume is absorbed in the stomach.
5. ___ Villi and microvilli decrease the surface area of the small intestine.
6. ___ Peristalsis is a voluntary muscular contraction.
7. ___ The appendix is a vital organ for human digestion.
8. ___ Protein digestion begins in the mouth with the enzyme pepsin.
9. ___ The liver, gallbladder, and pancreas are all accessory organs of the digestive
system.

Section 4: Short Answer & Practical Application Questions (10 Questions)

1. A person eats a sandwich containing bread (carbohydrates), turkey (protein), and

butter (fat). Trace the journey of the carbohydrate component, describing where
and how it is chemically digested.
2. Why is it important to chew your food thoroughly before swallowing? (Give two
reasons).
3. What would be the consequence for fat digestion if a person's gallbladder was
surgically removed?
4. Describe two structural adaptations of the small intestine that make it highly
efficient at absorbing nutrients.
5. What is heartburn (acid reflux), and what muscular structure normally prevents it
from happening?
6. Celiac disease is a condition where the villi in the small intestine are damaged.
How would this damage affect a person's ability to gain nutrients from their
food?
7. Explain why the pancreas is sometimes called the "dual-function" gland,
referring to its roles in both digestion and blood sugar regulation.
8. A person is lactose intolerant, meaning they cannot digest lactose, the sugar in
milk. Which digestive enzyme are they likely lacking?
9. Describe the role of the large intestine in the digestive process. What is its main
function?
10.Imagine you eat a very large meal. Describe the role of peristalsis in moving this
food from your esophagus to your stomach, even if you were to hang upside
down.

Answer Key

Section 1: Multiple Choice

1. b) To break down food, absorb nutrients, and eliminate solid waste.

2. c) Digestion
3. d) Mouth
4. c) Amylase
5. b) Esophagus
6. a) Peristalsis
5
 7. c) Hydrochloric acid
8. c) Small intestine
9. d) Liver
10.b) Break down large fat globules into smaller fat droplets.
11.c) Pancreas
12.b) Villi
13.b) To absorb water from undigested food and form feces.
14.c) Proteins
15.d) Gallbladder
16.c) Rectum
17.d) Cecum (It is the beginning of the large intestine).
18.c) To protect the stomach lining from acid and enzymes.
19.c) Ingestion
20.b) Egestion (or defecation)
21.d) Chyme
22.c) Fats (Lipids)
23.a) Epiglottis
24.c) Strongly acidic (pH 1.5 - 3.5)
25.c) Monosaccharides (e.g., glucose)
26.d) Pancreas
27.a) Amino acids
28.c) To synthesize certain vitamins (like vitamin K) and ferment undigested
carbohydrates.
29.c) Fats (Lipids)
30.c) Large intestine

Section 2: Fill in the Blanks

31. teeth
32. pancreas
33. bloodstream (or circulatory system)
34. emulsification
35. duodenum
36. pyloric
37. feces
38. bile
39. hydrochloric
40. microvilli

Section 3: True or False

41. F (The esophagus only transports food via peristalsis; no digestion occurs there).
42. F (Bile emulsifies fats, which is a form of mechanical digestion; it is not an enzyme
and does not chemically digest them).
43. T
44. T
45. F (Most water is absorbed in the large intestine, with a significant amount also
absorbed in the small intestine).
46. F (They vastly increase the surface area).
47. F (Peristalsis is an involuntary muscular contraction).

6
48. F (The appendix is considered a vestigial organ with no vital role in digestion).
49. F (Protein digestion begins in the stomach with pepsin).
50. T

Section 4: Short Answer & Practical Application

51. The chemical digestion of carbohydrates (starch) begins in the mouth, where
salivary amylase breaks it down into smaller sugars. No carbohydrate digestion occurs
in the stomach. In the small intestine, pancreatic amylase continues to break down
starch, and other enzymes (like maltase, sucrase, lactase) on the intestinal wall break
down disaccharides into monosaccharides (like glucose), which are then absorbed.
52. 1. Mechanical Digestion: Chewing breaks down large pieces of food into smaller
ones, which increases the surface area for digestive enzymes to act upon, making
chemical digestion more efficient. 2. Mixing with Saliva: Thorough chewing allows
food to mix well with saliva, initiating the chemical digestion of carbohydrates by
salivary amylase.
53. If the gallbladder is removed, the liver still produces bile, but it can no longer be
stored and concentrated. Bile will drip continuously into the small intestine in smaller
amounts. This means the person will have difficulty digesting large amounts of fat at
once, as there isn't a large reserve of bile to release in response to a fatty meal. This can
lead to digestive discomfort.
54. 1. Huge Surface Area: The small intestine is very long and its inner wall is highly
folded and covered with villi and microvilli. This vastly increases the surface area
available for nutrient absorption. 2. Thin Walls: The walls of the villi are only one cell
thick, providing a very short distance for nutrients to pass from the intestine into the
blood capillaries or lacteals.
55. Heartburn is a burning sensation caused when acidic stomach contents (chyme)
flow back up into the esophagus. The muscular structure that normally prevents this is
the lower esophageal sphincter (or cardiac sphincter), a ring of muscle at the
junction of the esophagus and stomach that is meant to stay closed except when food is
passing through.
56. Damaged villi would severely reduce the surface area of the small intestine. This
would greatly impair the absorption of all digested nutrients (carbohydrates, fats,
proteins, vitamins, minerals). The person would suffer from malnutrition, weight loss,
and nutrient deficiencies, even if they eat a healthy diet.
5s. The pancreas has a "dual function" because it is both an exocrine gland and an
endocrine gland. Its exocrine function is to produce and secrete digestive enzymes
into the small intestine. Its endocrine function is to produce and secrete hormones (like
insulin and glucagon) directly into the bloodstream to regulate blood sugar levels.
58. They are likely lacking the enzyme lactase, which is specifically needed to break
down lactose (milk sugar) into glucose and galactose.
59. The main function of the large intestine is to absorb water from the remaining
indigestible food matter, electrolytes, and vitamins produced by gut bacteria. It then
compacts the leftover material into feces for storage in the rectum before elimination.
60. Peristalsis is the coordinated, wave-like contraction and relaxation of muscles in
the wall of the digestive tract. In the esophagus, circular muscles behind the food
contract, squeezing it forward, while longitudinal muscles ahead of the food contract to
widen the tube. This wave-like motion is involuntary and powerful enough to move
food against gravity, which is why you can still swallow even if you are upside down.

7
8