Questions on Digestion

1

Name:

Questions on Digestion

Directions: The following questions are taken from previous IB Final Papers on

Topic 6.1 (Digestion). Answer all questions. This will serve as a
study guide for the next quiz.

Due Date: Thursday March 15

2

1.

What is absorption?

A.

Food entering the mouth and being chewed

B.

Food entering the stomach for digestion

C.

Taking digested food into the blood stream

D.

Making complex organic molecules in cells using digested foods

(Total 1 mark)

2.

Ducts connect the liver, gall bladder and pancreas to the alimentary canal. Which diagram
shows the correct pattern of duct connections?

A.

gall bladder

liver

pancreas

intestine

B.

gall bladder

liver

pancreas

intestine

C.

liver

pancreas

gall bladder

intestine

D.

gall bladder

liver

pancreas

intestine

(Total 1 mark)

3.

What sequence of organs do substances pass through, as they move through the human digestive
system?

A. Mouth

→

stomach

→

pancreas

→

small intestine

→

liver

→

large intestine

→

anus

B. Mouth

→

stomach

→

small intestine

→

pancreas

→

liver

→

large intestine

→

anus

C. Mouth

→

esophagus

→

stomach

→

small intestine

→

large intestine

→

anus

D. Mouth

→

esophagus

→

stomach

→

large intestine

→

small intestine

→

anus

(Total 1 mark)

3

4.

Why is most food digested?

A.

Digestive enzymes require a variety of substrates.

B.

It ensures that the diet is balanced.

C.

Most ingested food molecules are large.

D.

To prevent disorders of the intestine.

(Total 1 mark)

5.

Two cellular activities that support human life are absorption and assimilation. What is needed
for assimilation but not for absorption?

A.

Enzymes to synthesize new molecules

B.

Blood capillaries

C.

Dissolved nutrients

D.

Microvilli

(Total 1 mark)

6.

Describe the role of enzymes in digestion with reference to two named examples.

(Total 5 marks)

7.

Draw a labelled diagram of the digestive system.

(Total 5 marks)

8.

State the sources, substrate, product, and optimum pH conditions for the enzyme amylase.

(Total 4 marks)

4

9.

Dietary factors are known to influence the incidence of colon cancer. The graphs below show
the correlation between meat consumption (eating meat) and colon cancer in sample countries
and the correlation between fat consumption and colon cancer.

Colon cancer incidence /

100 000 women

50

40

30

20

10

0

Sweden

Hungary

0

40 80 120 160 200 240 280 320

Meat consumption / grams day

–1

[Source: B Armstrong and R Doll, Environmental factors and cancer incidence and mortality in different countries, with special

reference to dietary practices, (1975), International J Cancer, 15, pp 617–631]

Colon cancer incidence /

100 000 men

30

25

20

15

10

5

0

0 20 40 60 80 100 120 140 160

Fat consumption / grams day

–1

[Source: http:members.aol.com/wantnomeat/page]

(a)

(i)

State the relationship between daily meat consumption and the incidence of colon
cancer in women.

..........................................................................................................................

(1)

5

(ii)

Using the data in the two graphs opposite, suggest reasons for the relationship
between daily meat consumption and the incidence of colon cancer in women.

..........................................................................................................................

(2)

(b)

(i)

Calculate the difference in colon cancer incidence between Hungarian women and
Swedish women.

..........................................................................................................................

(1)

(ii)

Discuss whether meat consumption causes colon cancer in Sweden and Hungary.

..........................................................................................................................

(3)

(Total 7 marks)

10.

Draw a diagram of a villus in vertical section.

(Total 5 marks)

11.

(a)

State two sources of disaccharides in the diet.

1.

.........................................................................................................................

2.

.........................................................................................................................

(1)

6

(b)

Outline the use of absorbed carbohydrates.

...................................................................................................................................

(3)

(c)

Discuss the relationship between high levels of saturated lipids in the diet and health of
the individual.

...................................................................................................................................

(4)

(Total 8 marks)

7

12.

(a)

Identify the parts of the human digestive system indicated below.

(2)

(b)

In the space below draw the structure of an amino acid.

(2)

(c)

The enzyme pepsin, involved in protein digestion in the stomach, requires an acid pH to
work properly. Explain the effect of pH on enzyme activity.

....................................................................................................................................

(2)

8

(d)

Explain how three structures of the villus are related to the role of the villus in
absorption.

....................................................................................................................................

(3)

(Total 9 marks)

13.

The electron micrograph below shows part of several pancreatic islet cells.

Capillary

I

Storage vesicles

II

III

9

(a)

Identify the structures labelled I, II and III in the micrograph above and give a role for
each one.

Structure

Role

A.

B.

C.

D.

(3)

(b)

(i)

Using the letter A, identify one location on the micrograph where transcription
takes place.

(1)

(ii)

Using the letter B, identify one location on the micrograph where chemiosmosis
occurs.

(1)

The large, black vesicles store products of the cells that are released into the capillaries of the
pancreas.

(c)

(i)

Suggest what product each cell is likely to be making.

..........................................................................................................................

(1)

(ii)

Explain how the products are transported from the site of production and released
from the islet cells.

..........................................................................................................................

(3)

(Total 9 marks)

10

14.

Enzymes are used by living organisms to catalyse reactions. Some of these reactions occur in
the cytoplasm of cells. Other reactions take place outside cells, for example the digestion of
foods in the human gut.

(a)

State the name used by biochemists for the chains and cycles of reactions that occur
inside cells.

.....................................................................................................................................

(1)

(b)

Enzymes of digestion in humans are secreted by glands. They have a pH optimum which
allows them to work efficiently in the part of the gut into which they are secreted.

(i)

In the table below, identify the missing enzyme, the two glands, and the pH
optimum

Name of

enzyme

Gland secreting

the enzyme

Substrate

Products

pH optimum

amylase

starch

maltose

triglycerides fatty acids and

glycerol

7

(4)

(ii)

Outline the effect of pH values above and below the optimum on enzyme structure.

.....................................................................................................................................

(2)

11

(c)

Enzymes that work inside cells are sometimes affected by non-competitive inhibitors.
Explain how a non-competitive inhibitor affects the activity of an enzyme.

.....................................................................................................................................

(3)

(Total 10 marks)

15.

(a)

Outline the role of the liver in the storage of nutrients.

.....................................................................................................................................

(2)

(b)

Explain how the body overcomes the problem of lipid digestion in the alimentary canal.

.....................................................................................................................................

(2)

(Total 4 marks)

12

16.

(a)

List two glands that secrete digestive juices into the alimentary canal.

.....................................................................................................................................

(1)

(b)

Describe the process of erythrocyte and hemoglobin breakdown in the liver.

.....................................................................................................................................

(4)

(Total 5 marks)

1.

C

[1]

2.

A

[1]

3.

C

[1]

4.

C

[1]

5.

A

[1]

6.

large food molecules must be broken down;
such as carbohydrates / proteins, etc;
by hydrolysis of bonds / to form monomers;
in preparation for absorption;
rate of reaction at body temperature too slow;
enzymes increase the rate of breakdown / act as catalysts;
first enzyme example – name, substrate and product;
second enzyme example – name, substrate and product;
Award [3 max] if no examples given.

[5]

7.

Award [1] for each two of the following structures clearly drawn and correctly labelled.
Connections between organs must be correct for full marks.

mouth / teeth / tongue;
esophagus;
stomach;
small intestine;
large intestine / colon;
anus;
pancreas;
liver;
gall bladder;
rectum;
salivary glands;
sphincters;

[5]

8.

source: salivary glands;

pancreas;

substrate: starch / glycogen; (do not accept carbohydrate)
product: maltose / disaccharide;
optimum pH: 7–8 / neutral–slightly alkaline;

[4]

9.

(a)

(i)

positive correlation / higher incidence with higher meat consumption

1

(ii)

fat consumption is correlated with / causes colon cancer;
meat contains (high levels of) fat;

2

(b)

(i)

12(

±

1) deaths per 100000 women

1

(ii)

same meat consumption but higher colon cancer rate in Sweden;

other factors cause colon cancer (in Sweden) / eg genetic factors,
lack of fibre;
only some types of meat may cause colon cancer;
meat may contain more fat in Sweden / other chemical differences;
other foods may protect against cancer (in Hungary);

3 max

[7]

10.

(Award [1] for each of the following structures clearly drawn
and labelled correctly.)
lymph vessel;
arteriole;
venule;
(central) lacteal;
capillary network;
epithelial layer / lining / epithelium;
microvilli;
goblet cells;

[5]

11.

(a)

Award [1 max] for any two of the following.
cane sugar / honey / onion / milk / maple syrup / fruit / soft drinks

/ other answers

1

(b)

provide energy / cell respiration;
excess carbohydrate (glucose) can be converted into fat / glycogen for storage;
synthesis of glycoproteins / combine with proteins to form glycoproteins;
components of nucleic acids eg ribose in mRNA / deoxyribose in DNA;
required for the synthesis of some amino acids;
constituent of connective tissue;

3 max

(c)

diets high in saturated lipids increase risk of heart disease / atherosclerosis;
diets high in saturated lipids increase risk of obesity;
obesity linked to a variety of health problems eg diabetes;
atherosclerosis is narrowing of artery lumen;

atherosclerosis leads to high blood pressure / increased risk of coronary thrombosis /
stroke;

smoking / lack of exercise in combination with diet high in saturated lipids
compounds risk of heart disease;
relationship may be affected by genetic factors;

4 max

[8]

12.

(a)

I:

liver;

II:

stomach;

III:

pancreas;

IV:

large intestine / (descending) colon;

2 max

Award [1] for every two correct, up to [2 max].

(b)

amino group properly drawn;
acid group properly drawn;
C with H and R group attached; (no labels are required)

eg

2

H

N

H

C

O

OH

R

H

;

Award [2] if three are correct, [1 max] if two are correct and
[0] if one is correct.

N.B . A condensed formula is acceptable which shows H

2

N-

and -COOH instead of the expanded amino group and
carboxyl group attached to the central carbon atom; N atom of
amino group must be joined to central C atom.

(c)

each enzyme has an optimum pH where enzyme functions best / drawing of
bell curve with optimal pH labelled;
changes in pH (from optimum pH) decrease activity / effectiveness;
pH slightly changes the shape of the active site / tertiary structure of protein

changed / enzyme denatured;

more difficult to form enzyme-substrate complex;

2 max

N.B . Accept above marking points if given through a specific
example such a s pepsinogen conversion to pepsin when
pH is lowered.

(d)

microvilli increase surface area of absorption;
epithelium / one layer of cells provides a thin layer to enhance absorption /
small distance for diffusion;
protein channels (in membrane of microvilli) allow facilitated diffusion;
mitochondria (for energy) present for active transport;

blood capillaries close to epithelium / surface membrane reduce distance /
increase speed for diffusion;
blood capillaries carry away glucose / amino acids / nutrients;
lacteal carry away fats / fatty acids / glycerol;

3 max

Accept any of the above points in a clearly drawn annotated
diagram.

[9]

13.

(a)

Award [1] for each correct structure and its role.

Structure

Role

I:

mitochondria

produce ATP / site of (aerobic)
respiration;

II:

nucleus

contains genetic information / produces
RNA /
site of replication;

III:

(rough) endoplasmic
reticulum

(site of) translation / protein production /
protein
transport;

3

(b)

(i)

A in nucleus / A in mitochondria

1

(ii)

B in a mitochondrion

1

(c)

(i)

insulin / glucagon

1

Do not accept proteins.

(ii)

vesicles formed at / bud off from RER;
product carried to Golgi apparatus (and modified there);
vesicles carry product to plasma membrane;
fuse with membrane;
release product (to lumen) / exocytosis;
ATP used / energy required;

3 max

[9]

14.

(a)

metabolic pathways / metabolic
reactions / metabolism / anabolism and catabolism

1

(b)

(i)

salivary gland / pancreas;
pH 7.5 (

±

0.5);

lipase; (accept lipidase)
pancreas;

4

(ii)

ionic bonds / polar bonds broken / disrupted /
charge distribution altered;
ionization of amino / carboxyl groups altered;
conformation / shape of enzyme / active site altered /
tertiary structure altered;
enzyme denatured;

2 max

Digestive System Practice Quiz

Circle the correct answer choice or fill in the blank.

1. Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

A. small intestine B. esophagus C. stomach D. large intestine E. rectum

2. Chemical digestion of carbohydrates begins in the

A. esophagus B. stomach C. duodenum D. oral cavity E. jejunum

3. The enzyme which begins carbohydrate digestion is named ___________ ___________.

4. ________ is produced by the _________ and released from the __________ into the

___________ , aiding the digestion of fats through emulsification, which increases the surface

area for the enzyme __________ ___________ to attack the triglyceride molecules.

5. Most of the nutrient absorption along the alimentary canal occurs in the

A. ascending colon B. stomach C. jejunum D. ileum E. cecum

6. The taeniae coli of the large intestine is formed by the ______________ layer of the

muscularis externa.

7. The small intestine possesses permanent folds along its length known as

A. plicae circulares B. haustra C. rugae D. villi E. intestinal crypts

8. The G cells of the stomach secrete the hormone __________, which stimulates the

__________ and ___________ cells.

Practice Quiz by
Andrey Michel

9. The _________ cells secrete _________, the enzyme precursor which begins the chemical

digestion of protein.

10. Protein digestion in the stomach requires the activation of __________ by ____________

_______, which is secreted by the ________ cells.

11. The _________ cells also secrete __________ _________ which facilitates the absorption

of vitamin B

12

in the ileum.

12. The specific tissue type of the submucosa is

A. areolar CT B. dense irregular CT C. reticular CT D. smooth muscle E. adipose

13. The muscularis externa of the upper third of the esophagus has primarily

A. skeletal muscle B. smooth muscle C. both skeletal and smooth muscle

14. The three major enzymes secreted by the pancreas into the duodenum are

____________________, __________________, and _________________(inactive form).

15. Which of the following structures secures the small intestine to the posterior abdominal wall?

A. greater omentum B. lesser omentum C. mesocolon D. serosa E. mesentery proper

16. The hormone _____________ stimulates the release of pancreatic enzymes, buffers, and bile.

17. Nutrient-rich, oxygen-poor blood arrives at the liver through the _______________________

while oxygen-rich blood arrives via the _______________________.

18. In which region of the gastrointestinal tract are Peyer’s patches most common?

A. stomach B. duodenum C. jejunum D. ileum E. sigmoid colon

(c)

inhibitor binds (to the enzyme) away from the active site /
at allosteric site;
shape / (intramolecular) bonding / conformation of the protein /
enzyme is altered;
shape / properties of active site altered;
substrate no longer fits the   active site /
no enzyme-substrate / ES complex formed;
no enzyme activity /
works more slowly (until the inhibitor dissociates);

3 max

Award [1 max] if competitive inhibition is described.

[10]

15.

(a)

liver stores excess glucose as glycogen / releases glucose from glycogen
(as levels drop);
liver breaks down red blood cells / hemoglobin and stores iron;
liver stores fat soluble vitamins / vitamin A / vitamin D / vitamin B12 /
folic acid;

2 max

(b)

lipids are hydrophobic / not water soluble;
bile helps to break up lipid droplets / bile emulsifies fats / increases
surface area of lipid droplets for lipase attack;
lipids more accessible to lipase / lipase breaks down lipids;
pancreatic juices brings up pH as optimal pH for lipase is alkaline / pH8;

2 max

[4]

(c)

inhibitor binds (to the enzyme) away from the active site /
at allosteric site;
shape / (intramolecular) bonding / conformation of the protein /
enzyme is altered;
shape / properties of active site altered;
substrate no longer fits the   active site /
no enzyme-substrate / ES complex formed;
no enzyme activity /
works more slowly (until the inhibitor dissociates);

3 max

Award [1 max] if competitive inhibition is described.

[10]

16.

(a)

Two of the following needed for [1].
pancreatic;
salivary;
gastric pits / gastric glands;
glands in intestinal wall / krypts / Brunner’s gland;
liver

1 max

Questions on Digestion

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1.

7.

10.

(b)

13.

Digestive System Practice Quiz

9. The _ cells secrete _...

(c)

Questions on Digestion

Description

Study Set Content:

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Item 4

Item 5

Item 6

Item 7

Item 8

Item 9

Item 10

Item 11

Item 12

1.

7.

10.

(b)

13.

Digestive System Practice Quiz

9. The _________ cells secrete _________...

(c)

9. The _ cells secrete _...