ICE
Inquiry-based Curriculum Enhancement
Lesson Plan: Understanding Digestion
General Description
In this activity, students analyze data from the primary literature to explore multiple
aspects of digestion. The questions often ask students to generate alternative or multiple
explanations and apply their understanding to new situations.
Objectives
1. Students will learn about the relationships among various digestive characters and life
history traits.
2. Students will practice reading figures and tables.
3. Students will practice generating alternative explanations for observations.
4. Students will work in teams to create well-developed answers to questions.
Concepts
Digestion: function, regulation, importance, variation, connection to other systems;
analyzing data and generating alternatives
Time: about 50 minutes with questions leftover as homework or review.
Prerequisite Skills
general understanding of digestion
Materials
Student handouts
Overheads of figures
ICE
Inquiry-based Curriculum Enhancement
UTI Instructions: Understanding Digestion
Introduction:
In this activity, students will review fundamental characteristics of digestion by examining
data taken from the primary literature and answering questions designed to focus their
attention on alternative explanations or hypothesis. Students practice analyzing data and
learn general features of digestion.
Procedure:
Briefly introduce the activity by telling the class that they will be working on a worksheet
covering digestion. Have students do a short warm-up exercise to get them thinking about
digestion. Possible warm-ups are: list as many parts of the digestive system as you can
think of, then compare lists with a neighbor; list all the jobs of the digestive system that
you can think of, then compare lists with a neighbor; write down two or three body systems
that interact closely with the digestive system and describe the interaction; review their
pre-activity worksheet with a partner, etc. The idea is to transition students into thinking
about digestion.
Divide the class into groups of three or four and distribute the student handout (NOT the
pages containing the figures). Place the Peromyscus table on the overhead. Tell students
to work on questions 1 through 8. As they do so, circulate around the room, providing
direction or assistance as appropriate. After around 15 minutes or when it seems that most
groups are done with at least questions 1 through 5, turn off the overhead to collect there
attention. Choose a group to report their answer to question 1. Ask if the are other
relationships or explanations from different groups. Proceed to question 2 and do the same.
The key idea is that with four minds together, the students are covering just about every
aspect of the questions and everyone is coming to similar conclusions. Skip questions 3 and
4, but have one group report on question 5.
Move on to the pythons data. Again, show overhead and have students work on the
appropriate questions. When it seems that most groups have worked through the
questions, collect their attention. Have a group report on question 10. Other groups will
have chosen different data to explain, so have another group or two also report what they
determined. Skip to question 12 and collect from the students all of the reasons they
generated to explain increased metabolism in the python.
As time permits, continue in this same vein until the class time runs out. Focus the group
reporting on questions that could have multiple correct answers, and emphasize that
explanation of their answers is very important. If your professor has suggested it, have
students do the Individual Accountability item. As students leave, give them the copies of
the figures/tables so that they can work the rest of the questions. Collect handouts as
determined by the professor for the course. It might be appropriate to make extra copies of
the last two pages of the questions for students to take with them.
Table 1. Characteristics of Peromyscus (mice) species and
their habitats.
Approximate Productivity Average
Length of
body mass
of natural
BMR
intestine
(g)
habitat
P. eremicus
22
48
0.75
Short
P. melanophrys
45
67
0.85
Short
P. californicus
44
340
?
?
P. maniculatus
19
600
?
Long
P. leucopus
19
604
1.03
Long
Productivity is a measure of the amount of available carbon (g) per m2 per
year. Productivity also is an indication of available calories. BMR = basal
metabolic rate.
Data taken from Muller and Diamond for educational purposes. Proc. Natl. Acad.
Sci. 98(22):12550-12554.
Data taken from Secor and Diamond for educational purposes. Nature 395:659-662.
TABLE 6. Percentage of persons aged 55 years or
older who ate fruits and vegetables five or more
times daily, by region, age group, and race -United States, Behavioral Risk Factor Surveillance
System (BRFSS), 1994 and 1996§
Age
(yrs)/
Race
55-64
White
Black
Total
65-74
White
Black
Total
>=75
White
Black
Total
North
East
%
Mid
West
%
South
%
West
%
29
19
27
24
18
24
28
22
27
29
31
30
35
27
34
31
20
31
31
25
30
38
-37
35
21
34
37
27
36
33
21
32
39
-38
TABLE 8. Percentage of persons aged
55 years or older who ate fruits and
vegetables 5 or more times daily, by
race, age group, and sex -- United
States, Behavioral Risk Factor
Surveillance System (BRFSS), 1994
and 1996†
Age
(yrs)/Sex
55-64
Men
Women
Total
65-74
Men
Women
Total
>=75
Men
Women
Total
Race
White Black
%
%
22
33
28
18
24
21
28
37
33
17
29
24
30
39
35
21
24
23
Data taken from Kamimoto et al for
educational purposes. MMWR
48(SS08):89-130.
Note: L-MA=lactose malabsorbtion; F-MA=fructose malabsorbtion; FLMA=fructose and lactose malabsorbtion.
Data taken from Ledochowski et al. for educational purposes. Digestive Diseases &
Sciences 45(7):1255-1259.
ICE
Inquiry-based Curriculum Enhancement
Pre-Activity Worksheet: Understanding Digestion
General Description
In the activity you will do this week during your learning/discussion group, you will be
examining factors that influence digestion, different digestion strategies, and some dietary
trends in US populations. In order to be prepared for this activity, complete this worksheet.
Reading
Browse the “Animal Nutrition” chapter in your text. Pay particular attention to figures 41.1,
41.9, 41.13, 41.15 through 41.19, and 41.21, and tables 41.1 and 41.2. Read the section
on the Mammalian Digestive System beginning on pg. 859.
Definitions
Write a definition of the following words. Use your text, textbook glossary, and your
previous knowledge to create the best definition possible. Remember to connect your
definitions to digestion.
1) metabolic rate (basal metabolic rate)
2) digestive system
3) intestines (long & short)
4) kidneys
5) carbohydrates (absorption of carbohydrates)
Questions
Answer the following questions. You will explore your answers to these questions in-depth
during learning/discussion group.
1) Do you think there is a relationship between body mass and the productivity of a
habitat? Why do you think so?
2) What factors can influence metabolic rate?
3) What is the relationship between cellular respiration and metabolic rate? Do these
terms describe the same thing or different things?
4) Who eats more fruit and vegetables – 55 year olds or 80 year olds (both Americans)?
What makes you think this?
ICE
Inquiry-based Curriculum Enhancement
Understanding Digestion
In this activity, you will examine data that provide information about digestion in
a variety of animals. Each question asks you to apply and analyze this
information. For each question you should write your group’s answer and be
prepared to share it and associated reasoning with the class.
For Questions 1-8, use the data on the overhead labeled “Characteristics of Peromyscus
(mice) species and their habitats.”
1) Is there a relationship between average body mass and habitat? Summarize the
relationship in 15 words or less. How did you determine if a relationship exists between
these two factors?
2) Is there a relationship between productivity and BMR? Summarize the relationship in 15
words or less. How did you determine if a relationship exists between these two factors?
Predict the BMR of P. californicus and P. maniculatus.
3) There is a relationship between productivity and length of intestine. Describe it and
provide a rationale for this relationship. Estimate the length of the intestine of P.
californicus.
4) Is there a relationship between body mass and length of intestine? Describe the
relationship, if any, and prepare a 15 word or less suggestion as to why the relationship
does or does not exist. Based on the relationship between body mass and length of
intestine, estimate the length of the intestine of P. californicus.
5) Which factor do you think has a greater influence on intestine length of P. californicus –
body mass or habitat productivity? Describe your reasoning.
6) List three abiotic or biotic factors that could influence body mass, nt including the factors
listed in the table. Explain at least one of your factors.
7) Is the information you’ve gathered from above useful in studying plants? Explain.
8) Is the information you’ve gathered from above useful in studying humans? Explain.
Use the table labeled “Comparison of regulatory spans of pythons and mammals” on the
overhead to answer Questions 9-12.
9) In complete sentences, explain the information in the table regarding intestinal maltase
activity in pythons and mammals.
10) Choose any of the intestinal data listed above. Describe why there would be differences
between fasting periods and feeding periods for these data. Consider both pythons and
mammals
11) After a meal, python kidney mass increases 2.1 times its pre-food (fasting) level (mean
kidney mass 4.5g) and mammals increase by 1.1 times (mice mean kidney mass 0.35g).
Do you consider these to be small or substantial changes? Why? Give two possible reasons
why kidney mass might increase after eating a meal.
12) Burmese pythons usually eat once every 1-2 months, but can live for over a year
without a meal. When they do eat, their prey weigh between 25% - 150% of the snake’s
total mass. (This is analogous to you eating something the size of yourself in one gulp.)
After eating its prey, the snake curls up and stays motionless for 5-11 days to complete
digestion. According to the table above, python metabolic rate increases 44 times after
eating. If the snake is just lying there, how is this possible? Describe three ways in which
metabolic rate could increase in a non-moving digesting animal.
Use the figure labeled “Beck’s depression score in fructose and lactose malabsorbtion in
females” on the overhead to answer Questions 13-17. In this case, depression refers to
mental depression.
13) Summarize the results shown in this figure using complete sentences.
14) The boxes and lines surrounding the mean value (small square) indicate the variation or
variability in the results. Suggest two reasons to explain why the authors found more
variability in the FL-MA group than in the other groups.
15) Describe the effects that carbohydrate malabsorbtion may have on the physiology of an
individual. In other words, if one cannot absorb carbohydrates, what happens?
16) Suggest an explanation for how depression and carbohydrate malabsorbtion are
connected. Your explanation should reflect your understanding of respiration, digestion,
and neurobiology.
17) The data represented here were collected from females. Describe the results you would
expect if data representing the same variables were collected from males. Defend your
suggested results.
Use the tables on the overhead labeled Table 6 and Table 8 from the US CDC to answer
Questions 18-21.
18) Summarize the major results presented in these tables in complete sentences. Your
summary should not include numbers (percentages) or ages. Write two sentences of
summary for each table.
19) In the northeast, 29% of white individuals and 19% of black individuals aged 55-64
reported eating fruits and vegetables five or more times per day. Why is the total (27%)
not equal to the sum of these two percents? Be sure each member of your group can
explain why.
20) Suggest two explanations for the regional differences in fruit and vegetable
consumption. Could your suggestions reasonably explain the differences between age
groups as well?
21) Give two possible reasons for increasing fruit and vegetable consumption with
increasing age that are different than your answer for #20. Explain one of your reasons.
22) How is Table 8 different from Table 6? What is the value presenting this data two
different ways? What do you think the author (i.e. the CDC) was trying to demonstrate by
providing two tables?
Table 1. Characteristics of Peromyscus (mice) species and their habitats.
Approximate
Productivity of
Average
Length of
body mass (g)
natural habitat
BMR
intestine
P. eremicus
22
48
0.75
Short
P. melanophrys
45
67
0.85
Short
P. californicus
44
340
?
?
P. maniculatus
19
600
?
Long
P. leucopus
19
604
1.03
Long
2
Productivity is a measure of the amount of available carbon (g) per m per year.
Productivity also is an indication of available calories. BMR = basal metabolic rate.
Data taken from Muller and Diamond for educational purposes. Proc. Natl. Acad. Sci.
98(22):12550-12554.
Data taken from Secor and Diamond for educational purposes. Nature
395:659-662.
Note: L-MA=lactose malabsorbtion; F-MA=fructose malabsorbtion; FLMA=fructose and lactose malabsorbtion.
Data taken from Ledochowski et al. for educational purposes. Digestive
Diseases & Sciences 45(7):1255-1259.
TABLE 6. Percentage of persons aged 55 years or older who ate fruits and vegetables
five or more times daily, by region, age group, and race -- United States, Behavioral
Risk Factor Surveillance System (BRFSS), 1994 and 1996
Age (yrs)/
Race
55-64
!!White
!!Black
!!Total
65-74
!!White
!!Black
!!Total
>=75
!!White
!!Black
!!Total
North
East
Mid
West
South
%
%
%
West
%
29
19
27
24
18
24
28
22
27
29
31
30
35
27
34
31
20
31
31
25
30
38
-37
35
21
34
37
27
36
33
21
32
39
-38
TABLE 8. Percentage of persons aged 55 years or older who ate fruits and
vegetables 5 or more times daily, by race, age group, and sex -- United States,
Behavioral Risk Factor Surveillance System (BRFSS), 1994 and 1996
!
Race
White
!Age (yrs)/Sex
55-64
!!Men
!!Women
!!Total
65-74
!!Men
!!Women
!!Total
>=75
!!Men
!!Women
Total
%
Black
%
22
33
28
18
24
21
28
37
33
17
29
24
30
39
35
21
24
23
Data taken from Kamimoto et al for educational purposes. MMWR 48(SS08):89130.
ICE
Inquiry-based Curriculum Enhancement
Individual Accountability: Understanding Digestion
Demonstrate your new understanding of digestion by answering the following question:
Lizards, like pythons, are ectotherms – organisms that regulate their body temperature by
environment and behavior (mammals are endotherms – body temperature is regulated by
metabolic processes). However, lizards do not fast like pythons do. Will the regulatory
spans of lizards be more similar to pythons or to mammals? Defend your answer in four or
five sentences..