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This is to certify that the

thesis entitled
THE ROLE OF DECOMPOSERS AS RECYCLERS IN THE BIOSPHERE
presented hy

Jill Banner Quinley

has been accepted towards fulfillment
of the requirements for

Master W degree inBiglogigal Science

/%Mt M95

Dr. Martin Hetherington

 

Major professor

Date July 22, 1994

 

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

 

 

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TO AVOID FINES Mum on or baton duo duo.

DATE DUE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

THE ROLE OF DECOMPOSEFIS AS RECYCLERS IN THE BIOSPHERE

By

Jill Banner Quinley

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree at

MASTERS IN BIOLOGICAL SCIENCE

College of Natural Science

1 994

Martin Hetherington

ABSTRACT

It has been observed in the teaching of biology that while most students are
familiar with the concept of recycling most haven't made the connection

that nature is the ultimate recycler and that the earth's resources are
finite and must be constantly recycled by decomposers. This observation was
the premise for the unit of study that focused on special interrelationships,
biodegradation, composting, decomposition and biogeochemical cycling.

It was hypothesized that the sequence of material, different laboratory
exercises, demonstrations, and projects would make a difference in the

student's understanding of the vital role of decomposers in the biosphere.

ACKNOWLEDGEMENTS

There are many people who have given support, inspiration, and guidance in the
development and writing of this thesis. i would foremost like to thank my family for
always being there and filling in during my forays to Michigan the past three summers.
i wish to thank Dr. Howard Hagerman, Dr. Martin Hetherington, Dr. Merle Heidemann
and the Center for Microbial Ecology at Michigan State University for providing the
instructional foundation that made this thesis possible. A special thanks to the
National Science Foundation and the Towsley Foundation for their funding and
special recognition of teachers.

TABLE OF CONTENTS

introduction

instruction

Evaluation

Discussion and Conclusions

Appendix A Timeline with Objectives

Appendix B Laboratories

Appendix C Survey, Personal and Exit interviews
Appendix D Data Analysis

Appendix E Test Materials

Bibliography

iv.

14

25

27

42

59

INTRODUCTION

in recent years, attention has been focused on the mounting garbage
crisis, toxic spills, and nutrient overload in rivers, lakes, and the Chesapeake
Bay. As these topics receive increased attention, the need for a basic yet
unifying understanding of the vital role of decomposers is evident.

it has been observed in the teaching of biology that while most students
are familiar with the concept of recycling most haven't made the connection that
nature is the ultimate recycier and that the earth’s resources are finite and must
be constantly recycled by decomposers. This observation was the premise for
this thesis and the foundation for the ensuing three week ecology unit that
encompassed interrelationships, biodegradation, composting, syntrophy and
biogeochernical cycling.

The principal groups of living organisms based on production and
utilization of food materials are:

1. producers which possess photosynthetic pigments that in the

presence of sunlight, catalyze the chemical reaction between water

and carbon dioxide to form sugars.

2. consumers which ingest producers or other consumers.

3. decomposers which reduce the producers and consumers and the

products of their metabolism to the original chemicals from which they

were formed.

Whenever an organism dies, its remains are attacked and broken down
by decomposers which include many microorganisms, fungi, and soil
invertebrates. it is this continual breakdown that produces nutrients and
minerals required by the photosynthesizers who constitute the broad base of
the energy pyramid.

Microorganisms encompass a vast, diverse group of organisms that
include producers and consumers but those microorganisms whose role is
decomposition were the focal point of this project. Additional decomposers
emphasized in this project include earthworms, termites and fungi.

Earthworms are extremely efficient decomposers and as
vermicomposters they are well equipped to feed on dead plant and animal
material encountered as they tunnel through the soil. The acceptance of the
great importance of earthworms as decomposers though is relatively recent.
Charles Darwin's last book, The Formation of Vegetable Mouig, published in
1881, was the first methodical study of earthworms. (Conniff 1992)

it has been estimated that an average acre contains 0.5 Ton of
earthworms whereas an acre of rich soil contains 12 T. Earthworms consume
50% of their body weight daily and their waste material, casts, are a rich source
of nutrients for producers. (Patent 1978)

One of the most interesting groups of decomposers are the bacteria
(spirilli, cocci, and bacilli) and protozoa that are mutuaiistic in the hindgut of the
termite, Reticuiitermes flgvipg. This type of symbiosis permits termites to live
by xyiophagy. Other xylophagus organisms include cockroaches and aquatic
cranefly larvae (Breznak, i982).

Fungi are heterotrophic, eukaryotic organisms that do not have the

3
capacity to produce their own food and are totally dependent on preformed

organic matter; they exist as either saprophytes or parasites. Fungi have the
ability to secrete exoenzymes into their surroundings; these exoenzymes
degrade organic matter that is then absorbed into their structures and
reorganized to produce new cellular materials.

The end products of decomposition are known both as humus and
compost. Since the dawn of cultivation, farmers have been covering their fields
with deteriorated food scraps and manure including human waste but the
making of compost as a science was not recognized until the late nineteenth
century with the work of Albert Howard, a British agricultural scientist. (Gillis,
1992) it has been found that compost forms in much the same way whether in
the woods in a home or in a municipal composting facility. in the presence of”
sufficient carbon, nitrogen, and water, microorganisms go into a feeding frenzy /
that generates carbon dioxide and heat and reduces the organic source into \
smaller and smaller bits and pieces which eventually becomes quite fine
textured.

The Environmental Protection Agency has estimated that approximately
65% of municipal solid waste is reusable organic material with paper and paper
board making up 40% of the total weight; yard wastes and food scraps together
constitute another 25%. Presently 80% of all municipal waste is iandfiiled with
only 10% being recycled (including composting) and 10% being incinerated
(Narayan, 1992) but a survey conducted within the two honors biology classes
who participated in this unit indicated that 66% of the control group said that
they did some type of recycling while 57% of the experimental group said that
they did some type of recycling. The rational for including a student recycling
survey is included in the discussion section.

4
INSTRUCTION:

The instruction of this unit incorporated two honor’s biology classes; the
textbook used was WW. it was hypothesized that
the sequence of material, diffferent laboratory excercises, demonstrations and
projects developed for this unit made a difference in the student’s
understanding of the vital role of decomposers in the biosphere. The control
group was taught in the same manner as in previous years using the sequence
of topics and chapters that were specified by 8808. Lesson plans for the
control and experimental groups are included in Appendix A

The first two days of the 1993-94 school year required the standard
completion of forms, issuing of textbooks, assigning lab and class supplies, and
safety contract review; this unit of study actually began the third day of school
for both groups but henceforth will be referred to as Day 1, Day 2, etc.

The experimental and control groups were composed of honors level
freshmen and sophomore students at Monacan High School in Richmond,
Virginia. The students were generally from middle class homes in suburban
Richmond.

No specific criterion was used in designating which class would serve as
the control or the experimental group. it was decided that first period would be
the control group and second period would be the experimental group; each
period met for forty-seven minutes.

Each group completed the Student Survey and the Personal interview
on Day 1. The Student Survey was designed to evaluate the student’s feelings
regarding science whereas the Personal interview gave the student the
opportumity to identify their interests both in and out of school. The pretest was

5
given to both groups on Day 2 and on Day 3 both groups wrote the “Rotten

Apple Essay” using the following scenario:

it is late August, the days are still hot and the first apples of the season
have ripened. You love juicy, crisp apples so you haw bought the first apples
that appeared in your favorite supermarket but when you take the first bite of
one of the apples, it is soft and has some brown spots. You try another with the
same disappointing results and another until, in disgust, you throw all of the
apples under a tree in your yard. For the next three weeks as you come and go
to school you notice the apples.

This essay is to be written about your observations of the discarded

apples.
You may be as creative as you wish and you may write as much as you

feel is necessary to describe what is happening to the apples.

Day 4 was the point of departure for instructional scheduling for the two
groups. The control group continued with Unit One: “The World of Life: The
Biosphere” and the experimental group began a three week period of
instruction that was composed of labs, projects, and a demonstration that
focused on the vital role of decomposers in the biosphere. The experimental
group laboratory excerclaes included:

Pop Bottle Landfill

Composting exercise

Winogradsky Columns

Termite observations on the termite hindgut
Garden of Microorganisms

The demonstration was:

Testing for carbon dioxide production in rotting fruit and vegetables

The projects included:

Trash and Garbage diary
Building and maintaining a school compost pile

Worm farm

Details for setting up individual labs used by the experimental group are
found in Appendix B.

The trash/garbage diary was a project designed to enable the students to
appreciate their role in the garbage crisis. Recent surveys indicate that the
average person in the United States discards 1,930 pounds of garbage
annually and that the United States heads the list of annual discards with
200,000,000 tons. US. citizens discard enough trash to fill the Louisiana
Superdome every twelve hours. (Seymore and Girardet 1987)

The Trash Diary was kept for two weeks and included the student and
one adult family member. The trash diary assignment included cooperative
data from an adult member of the family for several reasons:

* team effort would improve family communications

* team effort would illucidate the need for individual recycling
* team effort would establish a school to family relationship

* determine if amount of discards varied with age

A record was kept of the type of throwaway, its potential for recycling, and
an approximate mass. A list of questions targeting the fate of throwaways
followed the two week data collection. Closure included discussion, comments,
and a question/answer session the day the diary was collected. It was pointed
out to the students during the discussion session that 57% of them had
indicated three weeks earlier that they were recycling but when their total mass
of throwaways was considered, the E.P.A.’s figures of only 10% of solid waste
currently being recycbd was close to correct for them.

The beginning of the year list of supplies for the experimental group

7
included three clean pop bottles and an. ample supply of vegetable and fruit

scraps from home which were used in setting up the pop bottle landfill and the
composting lab. Objectives for both labs included:

* developing an understanding of the meaning of biodegradation
nonbiodegradable.

* developing an understanding of why safety precautions and usage
of microbial technique must be used in these exercises.

Both exercises enabled the students to draw the parallel between
decomposition and composting and to understanding that death and
decomposition are only part of the cycle that redistributes earth matter and
makes it available again for living matter.

Teacher setup time was minimal for these two laboratory exercises but
sufficient time was needed for explaining microbial technique and its
importance. A review of pathogens and their transmissions was also included
as part of the introduction.

The composting exercise gave the students the opportunity to alter
abiotic factors that in turn influenced the rate of decomposition. Four different
composting situations were set up and included:

(1) a compost pile that was never turned

(2) a compost pile made of grass clippings only

(3) a compost pile made of leaves, grass clippings, and vegetable

scraps with just enough water to kwp it moist

(4) a very wet compost pile made of leaves, grass clippings, and

vegetable scraps.
Each station was assigned a composting situation; data were collected
every three days for two weeks and shared among the stations.

The association between stench and anaerobic decomposers in the wet

 

8
The association between stenchand anaerobic decomposers in the wet

compost pile was quickly made. The aerobic setups were left for the remainder
of the year and served as ecocolumns that the students could observe and refer
back to during different discussion sessions. Most of the students were
surprised at how quickly the leaves and vegetable matter changed in
appearance and were no longer recognizable.

The popbottie landfill laboratory exercise examined the abiotic conditions
that are found in an actual landfill with those found in a compost pile. The
students used deductive reasoning for making inferences about the two
different “landfills” and began the reasoning process that explained why
decomposition proceeds at different rates. in this exercise, each partner set up
one of the two landfills which were examined after one week; the data was
shared between the partners.

The Winogradsky columns were used as an inductive laboratory
experience by providing the students the opportunity to formulate concepts
through first hand experiences before those concepts were taught or discussed
in the classroom. The laboratory handout included a materials and procedure
section only. A student log was kept and the columns were examined on a
weekly basis.

The Winogradsky columns were used to initiate discussion regarding:

* biogeochemical cycling

* role photosynthetic bacteria play in providing carbon for
nonphotosynthetic bacteria

* ecological succession

* syntrophy

Rich, dark mud was obtained from a local horse farm. Calcium sulfate

9
was added as a soluble source of sulfate for the sUlfur transformation. Rice and

pieces of paper were added to supply the organic material needed for the
carbon transformation.

Some of the questions asked during the setup were:

Why is light needed?

Are we going to grow plants?
Will the rice grains germinate?
Why do we need special mud?

During the course of observation several different colored regions were
seen in the fourteen tubes setup by the experimental group. The bottom of
some of the tubes turned black as the fermenting bacteria produced organic
acids that were in turn used by the sulfate reducing bacteria. The sulfate
reducers further degraded organic acids to produce hydrogen sulfide which
reacted with iron forming the black precipitate. Purple areas indicated the
presence of the purple sulfur bacteria. The rust colored areas present in some
of the tubes were the result of the purple non-sulfur bacteria which preferred
lower concentrations of hydrogen sulfide. White deposits of sulfur and pockets
of gas were observed in many of the tubes. Throughout the observations, the
students could be heard asking each other reasons for the color changes.
Seldom were bacteria mentioned in either group and the follow-up questions
revealed the same lack of association.

Termites, Reticulitennes flavigs, were found and brought in by students
for the termite lab. ' Preparations were made using a 0.1 M potassium phosphate
buffer (pH 7) then examined microscopically in order to observe the diversity of
protozoa and bacteria that colonize the termite hind gut. The hindguts were

withdrawn from the termite using forceps then immediately placed on a slide

10
containing a drop of the buffer. The paunch region of the hindgut was pierced

with a needle to release the bacteria and protozoa. in Reticulitermes it was
relatively easy to see three different species of protozoa: Trichonymgha agilis
which looked like “rapid swimming fish”, flrsonymgha vertens which looked
like a “snake in a bag” and Dinenymgha gracilis which looked like a
“hairysnake” and was the smallest of the three protozoa.

This laboratory exercise was ideal for teaching mutualism, introducing
anaerobic bacteria, and beginning the nitrogen cycle. Studies have shown that
nitrogen fixation in termites is mediated by the bacteria living in the hindgut.
(Breznak, 1982).

The post lab discussion revealed that while most students are familiar
with the potential destructiveness of termites their ecological significance had
been largely overlooked. Termites with their intestinal microbiota are important
decomposers of plant litter in the biosphere and in temperate climates their
effectiveness rivals even the “large decomposer" groups such as earthworms.
(Breznak, 1982).

The ecological significance of earthworms was introduced to the
experimental group with the reading aloud of an article found in Mother Earth
News that recounted the solution to a frequently clogged toilet in a small
corporation in southern California. It was hypothesized by the owner that toilet
tissue was the culprit in stopping the drain therefore no more tissue would be
flushed; instead, it would be placed in a 10-gailon hamper along with a
generous supply of earthworms and garden soil. This procedure continued for
four years with huge success. (Nyerges 1991)

After a brief discussion and question/answer time, the experimental

group was introduced to their new worm bin which had been ordered from Mary

11
Appelhof in Kalamazoo, Michigan. NeWspaper was given to each student with

the instructions to shred it into narrow strips; this along with soil would be used
as bedding for the two pounds of redworms that would live in the bin. The bin
was filled half way with alternating two inch layers of newspaper and soil.
Enough water was added to moisten the mixture then the redworms were
placed in the bin. The students were asked to bring vegetable scraps from
home to feed to the worms. The bin was to be examined on a monthly basis.

This project introduced vermicomposting which is the process of using
earthworms and microorganisms to convert organic waste into black, earthy-
smelling nutrient humus. it provided hands-on experience that reinforced the
concept of decomposition and led to an unexpected and unplanned class
project.

The class was so enthusiastic about bringing in vegetable scraps for the
worm bin that it became evident after two weeks that there were more scraps
and materials than the worms could eat. During class discussion regarding the
overabundance of scraps, several students commented that they couldn't just
throw the scraps away. One voice said, “Why don’t we compost it?” and almost
in unison the class replied, “Yes." More discussion ensued and it was decided
that one of the students would seek permission from the school administration
to set up a comost pile outside the classroom for not only their vegetable scraps
but for the vegetable scraps from the school cafeteria. Permission was granted
from the principal and a student volunteer began picking up the cafeteria scraps
after the last lunch.

The compost pile was maintained for the duration of the school year and
was checked periodically. The students were able to compare the rates of

decomposition in the winter with the spring and were constantly commenting

1 2
about the absence of odor.

The garden of microorganisms lab was designed as an exploratory lab
that would enable the student to differentiate between fungal and bacterial
growth. Finger bowls of six different food specimens were covered with a glass
plate then observed for a week. included in the specimens were dog food, fruit,
home baked bread, and cream cheese. Observations made with the
stereoscope soon revealed growth of a slimey material unlike the cottony
appearing mold growth. The post lab questions were designed so that the
inferences and comparisons would help in identifying the slimey appearing
growth on the dog food.

The two day demonstration was done as closure for the decomposition
unit. A 500 mL Erlenmeyer flask was half filled with rotting apples and
stoppered with a one hole rubber stopper fitted with a U-shaped piece of glass
tubing. A beaker of clear saturated calcium oxide solution was positioned on a
ring stand so that the other end of the U-tube was submerged. A second beaker
containing the clear saturated calcium oxide solution was left open and
exposed to air and served as the control. The equipment, an explanation of a
closed system and the name of the calcium oxide solution were included for the
class and anticipatory questions such as “What might be the purpose of the
solution?” and “Why is a closed system needed?" were asked.

The second day, the class was shown the effects of bubbling into a
beaker of clear calcium oxide solution which produced a cloudy white
precipitate of calcium carbonate. The beaker was set aside until the latter part
of the period at which time it was examined and compared with the
experimental beaker and the control. The experimental beaker had a layer of
white precipitate on the bottom while the control had no layer of precipitate but

13
did have a few flakes of white scum floating on the top of the solution. The class

discussion immediately concluded that the white precipitate formed by bubbling
was the result of carbon dioxide and appeared the same as the precipitate in

the experimental beaker.

 

14

EVALUATION

Evaluation of this project was determined by using a pretest and posttest,
essays, attitude surveys, a personal interview and an exit survey.

The personal interview (Appendix C) gave the student the opportunity to
indicate in and out of school interests and the data found in Table 1 below

revealed some interesting differences in the two groups.

Table 1. RESULTS OF PERSONAL INTERVIEW

 

Groups
NT R L EXPERIMENT AL
Number of students 22 28
Science given as favorite academic subject 50% 60%
Read in spare time 13% 50%
Would like to visit a research laboratory 77% 91%

 

The Student Survey (Appendix C) was a science attitude survey given to
both groups at the beginning and the end of the school year. The survey used
bipolar adjectives that were used to develop a scale referred to as a semantic
differential instrument (Collette and Chiappetta 1989). Responses were ranked
on a numerical scale of 1 to 7 with 1 being never and 7 being always. The
mean score for the pre—control curvey was 4.4 and the pre-experimental mean

was 4.6 indicating a positive feel about science which did increase during the

15

year . This increase is reflected in the mean score of 5.4 for the post control
survey and the mean of 5.1 for the post experimental survey.

The pretest was given to both groups at the beginning of the school year;
the post test was given upon completion of the study of decomposers.
Completion for the experimental group was at end of the first month of the
school year and the control group completion was at the end of the first month of
the second semester. The pretest was used as a diagnostic tool to determine
the level of student knowledge and the means for both groups indicated that
they had essentially the same prior knowledge. The pretest and posttest
contained the same eighty-two questions pertaining to decomposers,
composting, and biogeochemical cycling. A multiple choice and true/false
format was used to test cognitive levels of knowledge, comprehension, and
application. The student’s t statistic was used to determine if the observed
differences between the means of the two groups were statistically significant.
The research hypothesis states that the sequence of material, different
laboratory exercises, demonstrations, and projects would make a difference in
the student's understanding of the vital role of decomposers in the biosphere.
The null hypothesis states that the sequence of material, different laboratory
exercises, demonstrations, and projects would not make a difference in the
student’s understanding of the vital role of decomposers in the biosphere. The t
indicated that there was no significant difference in the performance of the two
groups on either the pretest or the posttest. Data for the pretest results are
given in Table 2 and posttest results are found in Table 3:

16

Table 2: RESULTS OF PRETEST

 

Control

Number of students 21
Total number questions 82
Mean 43.71
Standard deviation 8.0
Variance 63.71

t obs =1 .16

tos, 44 = 2.021

Groups

Exgrimental

25

82
45.92

4.8
22.83

The calculated t of 1.16 < 2.021 and is not significant at the 0.05 level
therefore there is not a statistical difference in the pretest scores of the

control and experimental groups.

 

The results of the pretest indicated that there was not a significant

difference in the understanding of the two groups.

Table 3: RESULTS OF POSTTEST

 

QM
Number of students 24
Total number questions 82
Mean $3.56
Standard deviation 8.0

Variance 6467

Experimental
28
82

56.04
6.8
46.12

17
tabs =1.17

tbs, 50 =2.o

The calculated t of 1.17 < 2.0 and was not significant at the 0.05 level.
Because the calculated value of t was not significant, the null hypothesis

was let stand and the research hypothesis that the experimental group would
have higher scores was not supported.

 

Because there was no statistical difference in the posttest of the two
groups overall and it was felt by the researcher that class discussions had
indicated a difference in understanding within the groups, the pretest/post
questions were carefully scrutinized then divided into specific areas that
included composting, decomposition, methanogens and biogeochemical
recycling. A t test was applied to each of the specific areas and it was
determined that there was a significant difference in the perfomance within each
of the four areas (Appendix D). Results for the correct responses in these

specific areas are given below in Table 4:

Table 4 RESULTS OF SPECIFIC QUESTIONS RELATING TO COMPOSTING,
DECOMPOSITION, METHANOGENS, AND BIOGEOCHEMICAL RECYCLING

 

Questions 1, 54, 56, 2211f relating to composting:

Control Experimental
number of students 20 27
mean 13.5 21
standard deviation 6.2 4.5

variance 39 20.7

18

Questions 39,55, 58, and 20, 23 fit relating to decomposition:

Control Experimental
number of students 20 27
mean 7.8 18.4
standard deviation 6.4 6.3
variance 40.7 39.3

Questions 27, 29, 4th relating to methanogens:

Control Experimental
number of students 20 24
mean 13.5 21
variance 39 20.7
standard deviation 6.2 4.5

Questions 34, 42, 13, 16, and 21 relating to biogeochemical
recycflng:

Control Experimental
number of students 20 27
mean 12 17.8
variance 18.5 15.7
standard deviation 4.3 4.0

 

The student’s t statistic was used to determine if the observed differences
between the means of the two groups for each specific group of questions were

statistically significant (Appendix D.) and it was determined that there was a

19
statistical difference in the correct responses when broken down into the

specific areas of composting, decomposition, methanogens, and
biogeochemical recycling.

The Rotten Apple Essay was evaluated by counting the number of terms
used by the students that were indicative of an understanding of
decompositions. A complete listing of those terms used in the pre- and post
essays are given in Appendix D. The post results from the rotten apple essay
indicated a significant difference in the number of relevant terms used by the
experimental group. A comparison of the means, variances, and standard
deviations for the number of relevant terms used in the post essay are given
below in Table 5:

Table 5: NUMBER OF RELEVANT TERMS USED IN POST ESSAY
INDICATING UNDERSTANDING OF DECOMPOSITION

 

99m assuming
Mean 4.2 6.5
Standard deviation 1.7 2.1
Variance 2.9 5.8

tabs = 3.9

t .05, 49 = 2

 

The t indicated that there was a statistical difference in the performance
of the two groups.

Exit interviews were given to a select number of students in each group
to assess attitudes regarding the course of study. Answers were selected from

five different subject areas studied during the year. These areas included

20
animals, plants, decomposers, genetics, and cells.

An overview of results relating to decomposition are reported as per
centages and are found below in Table 6. A complete listing of the per centage
responses for each of the five areas can be found in Appendix D. The

individual comments are included in Table 7.

Table 6: EXIT SURVEY RESULTS

 

Control Experimental
Number of students 18 18
Learned most in area 11% 14%
of decomposition
Ranked decompostion 5% 20%
labs as most helpful
Experienced a postive 77% 85%
change in attitude regarding
decomposition

 

Table 7: STUDENT’S COMMENTS REGARDING DECOMPOSITION:

 

Control group:

i never knew how things decomposed until this year.

i understand now how helpful it is to our environment

There is more to decomposition than i once thought.

Now i recycle because i see how easy it is and understand that
decompositon doesn’t take very long if you do it right.

21

Experimental group:

i know now how bacteria do it--it is nature’s way

i know what’s actually happening and i can respect the bacteria more.
My attitude has definitely changed. Before i thought it was disgusting but
now i know its a natural recycling thing.

I understand more clearly the natural cycle of nutrients and materials plus
the need for decomposers.

I used to think all fungi and bacteria were gross and bad but I have
gained a respect for decomposers. i am trying to persuade my friend's
mom to have a compost pile in her flower bed.

I still think it looks gross but i do realize the importance and am amazed
at nature’s built in recycling program.

 

22

DISCUSSION AND CONCLUSION:

This unit on the role of decomposers in the biosphere was enjoyable to
teach and was openly accepted by the students in the experimental group. The
laboratory exercises were instrumental in conveying the key concepts regarding
decomposition.

The termite laboratory exercise was particularly effective for introducing
protozoa and teaching symbiosis. The prodigious number of protozoa
observed in this exercise impressed the experimental group much more than
the purchased paramecia, euglena, etc. used later in the protist chapter. The
post lab discussion tended to be more oriented in identifying the different
species but with redirection was effective in teaching interrelationships and
introducing the nitrogen cycle.

The carbon dioxide demonstration provided an opportunity for drawing
inferences regarding gases released during decomposition. The student
response to this demonstration was great enough that this instructor was
encouraged to use it in her chemistry classes as well. The Winogradsky
columns were also used in the chemistry classes to illustrate redox reactions.
These chemical connections are particularly important for both biology and
chemistry students and this project provided many opportunities to bridge the
gap that unfortunately has formed between those two disciplines.

The worm bin and the compost pile were particularly enjoyed by the
students but the worm bin presented an unexpected problem—fruit flies. initially,
the bin was kept in the class room but when the fruit flies became more

23
numerous than the students, it was moved outside. Going outside to check on

the worms or the compost pile were favorite activities of the experimental group
and provided numerous observations that led to some outstanding discussion
sessions.

Improvements need to be made in the composting laboratory exercise.
The pop bottles were insufficiently insulated and should be replaced with
styrofoam containers; the students also experienced difficulty in setting up a
data table for this exercise. in the pop bottle landfill lab, it was difficult to make
adequate observations by just looking through the plastic bottle and in the
future, the bottles will be opened and the contents examined using forceps and
probes. The pretest/posttest also needs to be reworked. The overall test should
be abbreviated, more conceptual questions should be added, and superfluous
terminology needs to be removed.

A few of the Students indicated on the exit survey that there were too
many overlapping observations being made with the composting lab, pop bottle
landfill, Winogradsky columns, and garden of microorganisms but the nature of
these labs required a prolonged observation time and overlap was inevitable.

One of the difficulties encountered was maintaining controlled classroom
conditions for the control group. Both groups met in the same classroom and all
of the laboratory exercises conducted by the experimental group required
several days of observation therefore the set-ups were always present when the
control group met. Both groups were highly motivated and many questions
were asked by the control group regarding the lab set-ups and discussion
frequently occurred between members of the two classes. There was
considerable indignation expressed by the control group because they did not

have a compost pile or a worm bin.

24
The Winogradsky columns were particularly effective for forming

hypotheses and interpreting data, however, comments from the exit interviews
indicated that a few of the students felt that the columns were not that effective
because there were not immediate observable results. it was pointed out to
these students that actual research often requires observations to be made over
a long period of time. These comments were interpreted as being the
result of a “cookbook” approach employed by many laboratory manuals.

Although there was not a significant difference in the overall performance
of the two groups on the posttest evaluation, those conceptual areas of
decompostion, methanogens, composting and biogeochemical cycling did
show a significant difference. All other areas of evaluation showed a significant
difference in performance between the control and experimental groups. It is
because of the success of this unit that future biology classes will be taught in
the same manner as the experimental group.

It is concluded that the research hypothesis stating that the sequence of
material, different labs, demos, and projects would make a difference in the
student’s understanding of the vital role of decomposers is statistically

supported by the data generated from this project.

TIMELINE WITH

GROUPS

DAY EXPERIMENTAL

10

11

GROUP

Survey l and Personal
interview

Pretest

Rotten Apple Essay

Trash Diary

Compost lab

Pop Bottle Landfill lab

Termite lab

Discuss difierent
microbial roles
observed in termite lab

Lab: WinogradSkY
Columns

Project: Worm bin

Garden Microorsianism
lab

 

25

APPENDIX A

CONTROL
GROUP

OBJECTIVES FOR EXPERIMENTAL AND CONTROL

OBJECTIVES

Survey l and Personal Evaluate feelings toward

interview

Pretest

Rotten Apple Essay

science
Assess prior knowledge

Evaluate prior knowledge of role
of decomposers

Control continued with Unit I and did not study

decomposers until second sem ‘
ester. Followm
schedule was used at that time 9

Water Diary

Video, “Leaf
Composting"

Video: 'Solid Waste
Disposal Alternatives”

Introduce
archaebacteria

Review
archaebactei'ia

Discuss mineral cycles

Read article, 'On the
Lowly Worm We
Earthlings Pin Our
Loftiest Dreams”

Distribution of
Microorganisms
lab

Calculate individual’s impact on
ecosystems

Draw parallel between
composting and
decomposrtion

Identify which types of garbage
are biodegradable and
nonbiodegradable

Hypothsize roles of
symbiotic organisms

Determine microbial
interrelationships

interpret biogeochemical cycling

Demonstrate vital role of
earthworms as deoom 9059's

Utilize and understand the need
for microbial technique

DAY EXPERIMENTAL

12

13

14

15

16

17

GROUP

Examine Popbottle
Landfill

Trash Diary due. Discussion
on results; tie in with Pop
Bottle lab

Observations: Garden
Microorganisms lab

Demo: Carbon Dioxide
production during
decomposition

Project: School compost

pile; conclude Garden
Microorganisms lab

Posttest

26

CONTROL
GROUP

Read article then write
essay on “To Rot or
Not'

Discuss landfill
construction

Observatons:
Distribution of

Microorganisms lab
Discuss carbon cycle

Review roles of
decomposers;
conclude Distribution
Microorganisms lab

POSIIest

OBJECTIVES

identify abiotic factors that
accelerate or retard
decomposition

Reinforce impact of abiotic
factors on decomposition

Distinguish between microbial
and fungal growth

Show that carbon dioxide is
released during decomposition

Compare and contrast myriad
roles of microbes

Evaluate effectiveness of
different approaches in teaching
same concepts

 

APPENDIX B:

27

EXPERIMENTAL GROUP EXERCISES
TERMITE LAB

WINOGRADSKY COLUMN

TRASH AND GARBAGE DIARY
COMPOSTING LAB

A GARDEN OF MICROORGANISMS LAB
POPBOTTLE LANDFILL LAB

28

TERMITE LAB

Microscopic examination of the hindgut microbiota of termites is a fascinating
experience. Motile microorganisms including numerous sizes and shapes of
both bacteria (bacilli, cocci, spirilla, and spirochetes) and flagellated protozoa
are readily discernible at 400x. The hindgut is an anaerobic environment
therefore most of the microorganisms found there are anaerobes. it is this
anaerobic environment that requires the use of a specially made phosphate
buffer.

MA IA

TBYMHWW
ice container

Light microscope

Forceps

Microscope slides

Coverslips

Anaerobic buffer

Distilled water

W R. flavims is a cold-blooded animal and the easiest
method of inactivating them without harming their microbiota is to place a small
container with these insects on ice. Within five minutes the insects will be
immobile. Once inactive, the intestinal tract of the insect can be removed by
using fine tip forceps, grasping the anterior and posterior end of the termite and
pulling. The dissected gut will remain intact until punctured or squashed.

WW Add a drop of buffer to a microscope slide then
immediately add the termite gut and coverslip. The coverslip should be

depressed slightly to burst the gut tract. Observe first with low power then with
high power. Drawings should be made on high power.

 

29

Analysis:

1. Are all of the microorganisms motile?

2. Give three ways you can distinguish between the different microorganisms.

3. Do you think that the termite could live without these microorganisms.

Substantiate your answer.

4. Using your understanding of symbiosis, which form is exhibited in the termite
gut?

Explain why.

5. Why was the buffer solution used?

6. in the space below draw at least four different types of microorganisms
observed.

Carefully analyze the data then write a conclusion on the back for this lab.

30

The Winogradsky Column

MATERiALS:

large test tube

black mud from an area rich in organic material

calcium sulfate

organic material to be decomposed (rice, newspaper, vegetable matter)
lamp with incandescent bulb but without shade

PROCEDURE:

1. Prepare a slurry consisting of four parts black mud, one part calcium
sulfate, and a small amount of dechlorinated water.

2. Add approximately one teaspoon rice and bits of other organic
material to the test tube. Avoid trapping air bubbles. Add water to
withini cm. oftopoftesttube.

3. Cap test tube loosely with aluminum foil and place about a foot from a
60W incandescent bulb.

4. incubate at room temperature, checking periodically to see that the
water has not evaporated. it usually takes 2-4 weeks for changes to
become obvious. Record weekly observations of changes that occur
on data sheet.

5. Wash hands and clean lab area.

Directions:

31

TRASH AND GARBAGE DIARY

You and one adult member of your family are to each keep a diary of all
your daily discards for two weeks. You are to list each item(s) and then
approximate the weight for these at the end of each day. Kitchen scales are
useful for small items and bathroom scales could be used for the larger items,
such as, grass clippings.

Some of the items that you must include are:

junk mail

daily newspapers

discarded notebook paper and pencil shavings

any type of tissue

any type of food container

all kitchen scraps

any meal leftovers

yard wastes such as grass trimmings, branches, or leaves
packaging materials

Obtaining and recording accurate data is a vital part of science. The
following sample data may be helpful as you set up your diary:

DAY1:

lTEMS APPROXIMATE WElGHT
4 tissues 6 pounds
small orange juice carton
2 small milk cartons
lunch bag
1 Snickers bar candy wrapper
1 newspaper
1 unwanted mail order catalogue
approximately 1 bushel grass clippings
2 cat food cans
3 sheets of notebook paper
food leftovers from lunch and dinner:
about 1/2 slice of bread
1 tablespoon of peas
fat trimmings from steak
several pieces lettuce and onion in salad

Since an adult member is helping you with this project, it would be

32
helpful for you to show them how you want the data collected and recorded.

At the end of the two week period, review both sets of data and answer
the following questions:

1. Which throwaway(s) produced the greatest weight (mass)?

2. Make a list of all the throwaways that could be recycled.

3. List the throwaways that will go to the landfill.

4. Explain what you think will happen to the throwaways once they are in
the landfill.

Both diaries and questions with answers will be turned in at the
end of two week

 

33
coupesrmc

iNTRODUCTlON: Composting is a natural biochemical process that converts
once living organic material to humus. Living microorganisms like bacteria and
fungi feed on material such as food scraps, leaves, grass and twigs thereby
breaking it down. This is the biochemical process that results in humus
formation. Humus is soil that is rich in soil nutrients and organic matter vital to
plants grown in the soil.

An ideal soil contains 45-50% minerals, 25% air, 25% water, and 25%
organic matter. The production of humus helps to assure that these
percentages of materials are maintained in the soil. Furthermore, humus helps
control weeds, prevent erosion, prevent rain runoff and decrease evaporation
of water from soil thus leaving more water available for plants.

The lab will demonstrate how relatively easy it is to compost as long as a
few proper conditions are maintained. Turning the compost every few days
provides oxygen for the aerobic conditions needed by most bacteria. Some
bacteria, however, prefer no oxygen and are called anaerobes. These are the
bacteria responsible for producing the unpleasant smelly odors of hydrogen
sulfide and ammonia.

in addition to aerobic or anaerobic conditions, all organisms need a
certain amount of moisture. if you have too much water you will have more of
the bacteria that produce odors because the water takes the same little spaces
that hold oxygen in your compost. if your composting material feels like a damp
sponge, you have added the correct amount of water.

Also needed is a proper pH range. pH is an expression of how acidic or
alkaline your material is and ranges numerically from 0-14. A pH of 7 is neutral,
a pH less than 7 is acidic, and a pH greater than 7 is alkaline. Fresh leaves
usually have a pH of 7 but as your materials decompose, more acids are
produced and the pH will become lower. if too little oxygen is present, more
acids will be present, therefore a low pH may indicate lack of oxygen.

in this lab you will be composting leaves, grass, twigs, soil and vegetable
scraps and observing changes in temperature, pH, moisture content, and
appearance under different environmental conditions.

HYPOTHESIS: From the information above, form a hypothesis for each
situation:

1. A compost pile that is never turned.

2. A compost pile composed of grass clippings only.

3. A very wet compost-pile.

MATERIALS: insulated coolers or very large styrofoam cups

PH paper
thermometers

 

34
leaves, grass clippings, twigs, rich garden soil, vegetable scraps
distilled water
tweezers
50 ml. graduated cylinder
troweis

CAUTION: Adding just the right amount of water to groups 1, 2, and 3 is very
important. The composting material should feel like a damp sponge with no
water standing in the bottom of the container. Should the composting material
dry out during the course of the lab, additional distilled water can be added. Do
not handle compost with hands.

PROCEDURE:
Group 1: 1. in large insulated container, place leaves, grass clippings,
twigs, soil, and vegetable scraps. Mix.
2. Add enough distilled water to make it feel moist.
3. On third day, insert thermometer into middle compost pile and
leave approximately five minutes. Take reading then
thoroughly mix.

Group 2: 1. in second insulated container, place grass clippings only.
2. Add enough distilled water to make it feel moist
3. On third day, insert thermometer into middle of compost pile
and leave approximately five minutes. Take reading then
thoroughly mix.

-L

Group 3: . in an insulated container, place leaves, grass clippings, twigs,
soil, and vegetable scraps. Mix.

2. Add enough water to make it feel moist.

3. On thrid day, insert thermometer into middle compost pile and

leave approximately five minutes. Take reading but do not turn
compost.

Group 4: 1. in an insulated container, place leaves, grass clippings, twigs,
soil, and vegetable scraps. Mix.
2. Add an excess of water to compost pile so that water fills half of
container.
3. On third day, insert thermometer into middle of compost pile
and leave approximately five minutes. Take reading then
thoroughly mix.

All Groups: 1. Observe the initial volume of contents then note carefully to see
if any volume change has occurred each time you examine
contents.

35
2. Record initial temperature of contents, as well as the
temperature each time observed.
3. Using pH paper, measure the pH each time the contents are
examined.

DATA

Construct a data table for each of the four groups with heading for pH,
temperature, appearance, and other observations. Data is to be collected every
three days and shared among the groups.

QUESTIONS

Note: Data from all four groups will be needed before answering the
questions.

i. Did each compost pile increase or decrease in size? Give an
explanation.

2. Did the temperature increase or decrease in each compost pile during
the course of the lab? Give an explanation.

3. identify the pH range as alkaline or acid for each compost pile and
describe any changes that occur.

What were the effects of limiting the material to grass clippings?
What were the effects of NOT turning the compost over?
What were the effects of adding too much water?

Where do the bacteria and fungi observed in this lab come from?

9.“???

What conditions are necessary for successful aerobic composting?

CONCLUSION

Carefully analyze the data collected. Accept or reject your chosen
hypothesis on the basis of the class date. Be sure to explain acceptance or
rejection of the hypotheses on the basis of observable and tabulated data.

36

A Garden of Microorganisms

The purpose of this lab is to observe different types of microorganisms
growing on different media. Each of the culture dishes are covered and are to
remain so during the course of the observations. Each station has a culture
dish and stereoscope and can be observed in any order.

Five observations will be made on every other day. Be specific with your
observations.

General Appearance Color Size Appearance Additional
with stereoscope comments

$3.“?le

QUESTIONS:
1. Do all of the organisms have the same general appearance?

2. Which type of growth, according to general appearnace, was most often
observed?

Did all of the organisms appear the same color?
Which color was most often recorded?

Do all the bowls have only one type of growth?

93939.“

if not, identify the bowls and the different types of growth.

37

7. Which bowl had the greatest variety of growth?

8. Was the general appearance always the same when described
macroscopically as when described with the use of the stereomicroscope?

9. Support your answer in #8 with specific examples.

10. Did you record any characteristics other than general appearance, color,
and size?

11. List those additional characteristics.
12. What was the food source for the organisms in this lab?
13. What effect did the growing organisms have on the media?

14. in review of this lab, list five ways in which microorganisms observed may
differ from one another.

15. Name two substance released through decomposition.

16. How did the growth on the dog food differ from the growth on the orange?

CONCLUSION:

 

38

POPBOTTLE LANDFILL

TO THE STUDENT One of the purposes of this laboratory excercise is to
develop an understanding of the scientific method and an appreciation of its
practical applications to everyday problem solving.

iNTRODUCTlON Solid waste disposal is reaching crisis proportions in many
communities. Our throw away mentality, as well as our increased use of
nonbiodegradable plastics and other synthetics, has substantially increased our
solid waste output. It has been estimated that the average American produces
four to six pounds of garbage per day. This volume, coupled with the increasing
toxicity of the garbage, makes iandfilling more technically challenging than ever
before.

Siting of landfills has become a volatile issue and the acronym NlMBY (not in
my backyard) reflects the feelings of most US. citizens. Public concern is
focused on esthetics, odors, ground water contamination and pestilence. New
methods of disposal are needed to address our current and future waste
streams which are composed by biodegradable and nonbiodegradable
materials.

Biodegradable materials can be broken down into simpler substances by
bacteria and other decomposers but in modern landfills this can take decades.
Nonbiodegradable materials are not broken down by by biological organisms
and include plastics, aluminum, and may chemicals used in industry and
agriculture.

Scientists must address the effects on the environment, as well as, the
economic impact of handling our wastes. in this investigation, the student will
study some of the characteristics of their waste stream and the problems
associated with its disposal.

Two simulated landfills will be constructed: one using garden soil and the other
using sand. Both landfills will contain discarded food samples and discarded
food packaging samples and they both will be left at room temperature.

39

HYPOTHESIS Write three hypotheses for this lab.

MATERIALS

2 - 2 liter pop bottles

garden soil

scissors

tweezers

distilled water

graduated cylinder

wax-pencil or permanent marker
metric ruler

trowel

discarded food samples, i.e., vegetables and fruits but ABSOLUTELY NO
MEATli

discarded food packaging samples
shallow pan

sand

CAUTIONS

7.

Hands should be washed before and after this lab with soap and water.

ABSOLUTELY NO FOOD OR DRINK IN THE LAB AT ANY TIME DURING
THE COURSE OF THIS LAB.

Lab area should be wiped with a l0% bleach solution before and after
setting up the lab and before and after examining contents.

Use a wafting technique for detecting odors.
Lab area should be uncluttered with NO books, pens, etc.

Special care should be used when cutting the pop bottles. Plastic, as well
as scissors can cause cuts.

At the completion of the lab, dispose of all materials as directed by your
teacher.

4O

PROCEDURE

1. Obtain two 2-L plastic pop bottles and remove the labels leaving only a
clear bottle. Using a marker, label the bottles with your name, date,

and iorll.

2. Using scissors, cut the discarded food samples into small pieces,
approximately 3 square centimeters in size, keeping all samples
uniform in size. Repeat this procedure for the pieces of discarded

packaging.
3. With scissors, cut each pop bottle in half.

4. Using a trowel, fill the base of bottle’s i and ii with approximately 6 cm.
of garden soil or sand. Add garden soil to Bottle i and sand to Bottle ll.

5. Record the size, color, texture, odor and any other important
characteristic features of each sample in your data table. include a
prediction as to how each sample will look after a weeks time.

6. Using a pair of tweezers, place an assortment of food and packaging
samples on the soil in Bottles l and ii. Cover the samples completely
with approximately 3 cm garden soil if setting up Bottle i and 3 cm. sand
if setting up Bottle ll

7. Add enough water to the soil to moisten it. Contents should not be
soggy but should feel like a damp sponge. Add no water to the sand
in Bottle ll.

8. Place the top half of the bottle over the bottom half. Patience and
repeated attempts are needed at this point, making sure that top half is
pushed down far enough for a tight fit.

9. After one week, examine Bottles i and ii by carefully removing the top
layer of soil or sand into a shallow pan then remove food and packaging
material with tweezers. Measurements can be made but be very careful

not to touch the specimens.

10. Replace samples and soil in respective bottle and reseal. Observe the
bottles at weekly intervals for the next three weeks but DO NOT
REOPEN THE BOTTLES. Observations can be made by rotating the
bottle on its side and viewing through the plastic. Record observations

in data table.

41

11. Follow your teacher’s instructions for proper disposal of all materials.
12. Answer questions 16

DATA
Make a data table for all observations and measurements made for each of

the samples at one week intervals. include changes in size, appearance
and other observations; use an 'X” if no change occurs.

QUESTIONS
1. Rank samples in order of fastest to slowest rates of degradation. Give
an explanations for different rates of degradation or decomposition.

2. Based on your data, classify each specimen used in this lab as
biodegradable or nonbiodegradable.

3. What conditions proved to be most favorable for decomposition?

4. Devise a plan for lowering the amount of garbage going into the
landfills in your community.

5. Are there any specimens or materials in this landfill simulation that
could be recycled or re-used?

6. Account for the condensation that collected on the inside of the bottle.

CONCLUSION

Carefully analyze the data collected. Accept or reject your chosen
hypothesis on the basis of the class data. Be sure to explain acceptance or
rejection of the hypotheses on the basis of observable and tabulated data.

Using prior knowledge suggest possible reasons for the changes or lack of
changes observed.

42

APPENDIX C:

STUDENT SURVEY
PERSONAL INTERVIEW
EXIT INTERVIEW QUESTIONS

43

STUDENT SURVEY

Rank the following questions:
1. Never
2. Almost never
3. Seldom
4. Occasionally
5. Frequently
6. Almost all the time
7. Always

H

. I use science to help explain how things work.
. Only smart people understand science.

. I am reminded of science daily.

. Understanding science is rewarding.

I use science to solve problems.

I understand science labs.

Science means learning useful facts.

I am thinking of pursuing science as a career.

smseneww

Science is too complex for me.

10. Science classes are challenging.

11. Realizing that I understand a new science concept makes me feel good about myself.
12. Science classes are a struggle and not meaningful to me.

13. Science is fun.

 

44
PERSDNRL .INTEBUIEIII

ANSWER EACH OF THE FOLLOWING QUESTIONS AS HONESTLY AS
POSSIBLE.

1. What subjects do you like most?

What do you do in your spare time?

What hobbies do you have?

Do you like to visit museums?

Would you like to visit a research laboratory?
Have you made a career choice?

if you have a career choice, identify it.

9899.595)

if you have not made a career choice, identify career areas that are of
most interest to you now.

9. Would you like to meet a scientist?
IO. What do you they he/she will be like?
i i. What do like about science?

12. Whai do you dislike about science?

13. Has anything in your science class(es) been useful in your everyday
living?

i4. identify those things that you did find useful.

45

EXIT INTERVIEW QUESTIONS:

THE FOLLOWING QUESTIONS PERTAIN TO THE DIFFERENT SUBJECT
AREAS WE HAVE STUDIED IN BIOLOGY THIS YEAR. THOSE AREAS
lNCLUDE:

ANIMALS PLANTS DECOMPOSERS GENETICS CELLS

1. Which subject area do you feel you learned the most?

2. Think back to the labs for each area and in which area were the labs
particularly helpful? (Choose only one.)

3. Which area do you feel the labs were least helpful?

4. We did not follow the sequence of topics in the book. Did this bother
you??
Circle your response from:

a. Not at all

b. Somewhat but it did not affect my academic performance

c. Yes, it bothered me but did not affect my academic performance
d. Yes, it bothered me and affected my academic performance

5. Has your attitude regarding decomposition changed?

6. Briefly state how.

 

48

APPENDIX D: DATA ANALYSIS

47

PRET EST SCORES

Total number of questions in pretest - 82

Control Group of 21 students Experimental Group of 25 students

total correct responses total correct responses

49 41
47 S4
52 42
45 47
33 52
45 42
41 41
36 52
41 Si
59 47
52 56
42 43
46 37
49 41
38 41
39 49
43 46
46 45
24 Si
55 45
36 46
mean 43.71 46
stdev 8.00 41
variance 63.71 45
47
mean 45.92
stdev 4.80
variance 22.83

t caic 1.16

tit 44

alpha 0.05

t 2.021

Calculated t of 1.1 6<2.021 and is not significant at the 0.05 level.
Because the calculated value of t Is not significant, the null hypothesis is
not rejected and the research hypothesis that the experimental group
would have higher scores is not supported.

48
POSTTEST

Total number of questions in posttest-82

Control group of 25 students Experimental group of 26 students
total number of correct responses total number of correct responses
54 59
52 51
50 46
58 41
52 S4
S4 S4
61 61
53 SO
61 57
61 52
S9 50
38 62
54 62
57 46
59 60
51 60
61 70
51 52
26 65
58 65
49 63
52 58
57 52
47 52
64 59
mean 53.56 56
stdev 8.00 mean 56.04
variance 64.67 stdev 6.80

variance 46.12

t calc 1.17
df 50
alpha 0.05
t 2

Calculated t of 1.17 < 2.0 is not significant at 0.05 level. Because the calculated value of t
is not significant, the null hypothesis is not rejected and the research hypothesis
that the experimental group would have higher scores is not supported.

 

49

PRE- ROTTEN APPLE ESSAY

WORDS mushrooms methane life cycle decay

USED: fermenting fungi evaporation biodegrade
nutrients decompose mold chemical structure
deteriorate bacteria gas disintegrate
worm larva fertilize pH change
rotting evaporation maggots microorganisms

small insects fertilizer

Control group of 22 students Experimental group of 24 students
total number relévant terms used total number relevant terms used

.nl

#M-JON-INNN-ImwNN—IA-lN-INN
o—lmd-d-JL—D-INwoo—JNNAdN—Jde—lfi)

mean- 2.16
stdev- 1.42
variance- 2.03
mean- 1.64
stdev - 1.44

variance - 2.07

WORDS
FROM
PRETEST

NEW WORDS

FOUND IN
POSTTEST

50

POST ROTTEN APPLE ESSAY

mushrooms
fermenting
nutrients
deteriorate
worm

methanogens
anaerobic
rhizoids
hyphae

food chain

Relevant terms chosen by
control group of 24 students

mean
stdev
vaflance

4.2
1.7
2.9

t calc
df
alpha
t

"unhane
fungi
deconwxmn
bactefia
larva

recycle
denitrifying
nitrifying
nitrate

carbon dioxide

life cycle
evaporation
mold

gas
fertilize

temperature
methane
ammonia
enriched soil
evaporation

decay fertilizer
biodegrade small insects
microorganism maggots

disintegrate rotting

pH dwange

food web humus
ammonia spores
nitrogen cycle surface area
organic

protist

Relevant terms chosen by
experimental group of 25 students

3.9
49
0.05
2

wean
stdev
vafiance

6.5
2.1
5.8

Calculated t of 3.9 > 2.0 and'is significant at the 0.05 level therefore
the null hypothesis is rejected and the research hypothesis that the experimental
group would have higher scores is supported

SI

SELECTED PRETEST QUESTIONS
qsts. 1, S4, 56, 22t/f regarding composting

CONTROL GROUP EXPERIMENTAL GROUP
#Correct/Zi students # Correct/Z7 students
3 3
1 2 20
1 9 24
. 16 21
mean 12.5 mean 17
variance 48.3 variance 48.3
stddev 6.9 stddev 9.8

SELECTED PRETEST QUESTIONS
qsts. 39, 55, 58 and 20, 23 t/f regarding decomposition

CONTROL GROUP EXPERIMENTAL GROUP
#Correct/ZI students #Comect/Z? students

1 5 8

1 9 22

1O 1 3

8 14

1 S 1 9

mean 13.4 mean 15.2

variance 1 9.3 - variance 29.7

stddev 4.4 Stddev 5.4

mean
vanance
std dev

mean
vafiance
stddev

52-

SELECT ED PRETEST QUESTIONS
qsts.27,29, 4tf regarding methanogens

CONTROL GROUP EXPERIMENTAL GROUP
# Correct/Z1 students # Correct/27students
16 18
9 14
8 16
1 1 mean 16
19 variance 4
4.4 stddev 2
SELECTED PRETEST QUESTIONS

qsts.34,42,13, 16 and 21
regarding biogeochemical recycling

CONTROL GROUP

# correct/Z1 students
1 1
15
13
15
5
12
17.2
4.1

EXPERIMENTAL GROUP
#correct/27 Students

1 7
2 5
1 5
23
8
mean 17.6
variance 45.8
stddev 6.8

53

SELECTED POSTTEST QUESTIONS
qsts.27,29, 4tf regarding methanogens

CONTROL GROUP EXPERIMENTAL GROUP
# Correct/20 students # Correct/27students
20 24
13 25
14 20
mean 15.6 mean 23
variance 14.3 variance 14.3
std dev 3.8 std dev 2.6
t cal - 3.9
df - 47
alpha - 0.05
t- 2

Calculated t of 3.9 > 2.0 is significant at the 0.05 level therefore the null
hypothesis is rejected and the research hypothesis that the experimental group
would have higher scores is supported.

SELECTED POSTTEST QUESTIONS
qsts. 34, 42,13, 16, and 21

regarding biogeochemical recycling

CONTROL GROUP EXPERIMENTAL GROUP
# correct/ 20 students #correct/Z7 students

8 15
17 23
11 14
16 21
8 16
mean 12 mean 17.8
variance 18.5 variance 1 5.7
std dev 4.3 std dev 4

t cal - 5.2

df - 49

alpha - 0.05

t - 5.2

Calculated t of 5.2 > 2.0 is significant at the 0.05 level therefore the null hypothesis
research hypotl is rejected and the research hypothesis that the experimental group
would have higher scores is supported.

54

SELECTED POSTTEST QUESTIONS
qsts. 1, 54, 56, 22t/f regarding composting

CONTROL GROUP
#Correct/ 20 students
5
20
14
15
mean 1 3.5
vaflance 39
std dev 6.2
t calc -
df .-
alpha -
t ..

6.1
47
0.05
2

EXPERIMENTAL GROUP
# Con'ect/Z7 students
15
26
22
21
mean 21
variance 20.7
std dev 4.5

Calculated t of 6.1 > 2.0 and is significant at the 0.05 level therefore
the null hypothesis is rejectd and the research hypothesis that the experimental
group would have higher scores is supported.

SELECTED POSTT EST QUESTIONS
qsts. 39, 55, 58 and 20, 23 t/f regarding decomposition

CONTROL GROUP

variance 7.8
std dev 40.7
6.4

5.9
47
0.05
2

EXPERIMENTAL GROUP
#Correct/27 students
22
1 8
27
12
13
mean 18.4
variance 39.3
std dev 6.3

Calculated t of 5.9 > 2.0 and is significant at the 0.05 level therefore the
null hypothesis is rejected and the research hypothesis that the
experimental group would have higher scores is supported.

55

EXIT SURVEY

CONTROL GROUP
18 students surveyed and results reported as per centages

Animals Plants Decomposers Genetics Cells
1. Which area feel you learned the most
0.33 0.11 0.11 0.33 0.12
2. Areas in which labs were helpful

0.39 0.17 0.05 0.1 1 0.28

3. Labs that were least helpful
0.17 0.17 0.17 0.44 0.05

4. How you were affected by not following sequence of book

a. Not at all 0.61
b. somewhat but it did not affect

my academic performance 0.17
c. yes, it bothered me but it
did not affect my academic 0.17
performance
d. yes, it bothered me and 0.05

it affected my academic performance

5. Has attitude regarding

decomposition changed?
a. yes 0.77
b. no 0.23

Some comments regarding the student's attitude change.
I understand how helpful it is to our environment.
There is more to decomposition than I once thought.
Decomposition happened before, it happens now, and it will always happen.
I never knew how things decomposed until this year.
I didn’t know much about decomposition before this class but now I know more about it.
Now I recycle because i see how easy it is and understand that decomposition doesn't
take long if you do it right.

 

S 6
EXIT SURVEY

EXPERIMENTAL GROUP
18 students surveyed and results reported as per centages

Animals Plants Decomposers Genetics Cells

1. Which area you feel that you leamed the most
0.18 0.07 0.14 0.39 0.22

2. Areas in which labs were helpful
0.44 0.1 1 0.2 0 0.25

3. Labs that were least helpful
0.03 0.26 0.18 0.26 0.07

4. How you were affected by not following sequence of book
a. not at all 0.61

b. somewhat but it did not
affect my academic
performance 0.1 7

c. yes, it bothered me but
it did not affect my academic
performance 0.1 7

d. yes, it bothered me and
it affected my academic
performance 0.05

5. Has your attitude regarding decomposition changed?
a. yes 0.77
b. no 0.23

Some comments regarding the student's attitude change:

I know now how bacteria do it—it is nature's way.

i understand now how it plays an extremely important role in the environment.

I know what's actually happening and I can respect the bacteria more.

My attitude has definitly changed. Before i thought it was disgusting but now I know

it's a natural recycling thing.

I understand more clearly the natural cycle of nutrients and materials plus the need for
decomposers

I still think it looks gross but I do realize the importance and am amazed at nature's built in

recycling program.
I used to think compost piles would smell and but now I know differently.

57

STUDENT SURVEY

Ranking of questions:

1. never

6. almost all

the time

2. almost never 3. seldom 4. occasionally 5. frequently
7. always

Pre-Control Experimental Post Control Experimental
Average Pre Average Average Post Average

1. I use science to explain how things work

3.7 3.7 5.4 4.5
2. Only smart people understand science
3 3.1 3.6 2.7
3. i am reminded of science daily
4.7 4.2 6.4 6.6

4. Understanding science is rewarding
4.6 5.3 6.1 5.9

5. I use science to solve problems.
3.3 3.8 4.3 4.6

6. I understand science labs
5.8 5.6 6.5 5.8

7. Science means learning useful facts.
5.4 4.8 6.1 4.9

8. I am thinking of pursuing science as a career
3.6 3.9 4.6 4.9

9. Science classes are challenging
4.7 4.6 5.6 5.5

10. Realizing that I understand a new science
concept makes me feel good about myself
4.4 5.6 5.7 5.8

11. Science is fun.
5.5 5.9 5.5 5.3

 

58,

APPENDIX E
TEST MATERIALS

59
APPENDIX E

FRET EST:

Choose the BEST answer for the following questions:
1. Everything the organisms of an ecosystem use is recycled except:
a. air
b. energy
0. food wastes
(I. water

2. Obligate anaerobes:
a. require oxygen for their life processes
b. require an absence of oxygen for their life processes
0. can live in oxygen or an absence of oxygen
d. under special conditions all of the above are true statements

3. Facultative anaerobes:
a. require oxygen for their life processes
b. require an absence of oxygen for their life processes
c. can live in oxygen or an absence of oxygen
d. under special conditions all of the above are true statements

4. A fungus such as Fihizopus gets its food by:
a. secreting enzymes to digest starch into soluble compounds
b. absorbing food from cells of its host
c. producing it from raw materials of the soil
d. chemical reactions similar to photosynthesis

5. Why are fungi important to us?
a. all of the follwing
b. many are decomposers
c. many cause diseases, especially in plants
a. some are used to make chemical and food products

6. Fungi are classified mainly on differences in:
composition of cell walls

pigments in their cells

sexual reproductive structures

size and shape of vegetative structures

9.0.0.”

‘IO.

11.

60

The threadlike stmctures of fungi that anchor them and absorb
food products are called:

a. hyphae

b. rhizoids

c. shoots

d. stalks

In the carbon cycle, carbon dioxide is released to the atmosphere by:
a. all organisms

b. consumers lonly

c. consumers and decomposers only

d. producers and decomposers only

Spores are:

a. pollen grains produced by plant like structures

b. small openings in many fungi that permit circulation of air

c. asexual reproductive cell capable of developing into an adult
organism

d. thread-like structures found in many fungi that enhance absorption

Why is it advantageous for fungi to produce large numbers of spores?
a. spores live a very short time

b. very few spores have a chance for fertilization

c. very few spores find a suitable environment for growth

d. mutation rates of fungi are low

Autotrophic means:

a. an organism that is unable to make its own food therefore must rely on
other organisms for its food source

b. an organism that makes its own food by photosynthesis

c. an organism that produces spores

d. a type of bacterial that survives at extremely high temperatures

61

12. Which of the following groups of organisms includes producers,
consumers, decomposers, parasites, predators, and prey?
a. animals
b. bacteria
c. fungi
d. protisis

13. The nitrogen cycle is vital because animals and most green plants
cannot use:
a. gaseous nitrogen
b. nitrates
c. nitrogen in any form
d. organic nitrogen compounds

14. Animals get their nitrogen from:
a. animal and plant foods
b. atmospheric ammonia
c. atmospheric nitrogen gas
d. nitrates in water or soil

The next 5 items refer to the nitrogen cycle. Select the letter of the term from
the key that best matches each numbered item.
KEY: a. ammonia (NH3) or ammonium (NH4)

b. atmospheric nitrogen (N2)
c. soil nitrates (N03)

15.The most abundant nitrogen supply

16. The kind of nitrogen compound produced by nitrogen-fixing bacteria

17. The nitrogen supply used by most producers

18. The source of nitrogen in nitrogen-fixation by bacteria

19. The kind of nitrogen compound produced by nitrifying bacteria

20. in the nitrogen cycle, the organisms that take nitrogen from the air and fix
it in compounds plants can use are:
a. algae
b. bacteria

c. fungi
d. legumes

62

The next four items use the following groups of bacteria as responses. Any one
group may be used more than once or not at all. There is only one response
for each item.
KEY: a. decomposing bacteria

b. denitrifying bacteria

c. nitrifying bacteria

d. nitrogen-fixing bacteria

21. Convert atmospheric nitrogen to ammonia
22. Change ammonium ion to nitrates

23. Break down nitrogen containing compounds and release ammonium
ions.

24. Change nitrates to nitrogen gas

25. Which of these plants are hosts to organisms that put nitrogen
compounds into the soil?
a. carrots and corn
b. onions and potatoes

c. peas and soybeans
d. weeds and wild flowers

26. Which best describes archaebacteria?
a. appeared on earth only recently
b. are fundamentally different from all other organisms
c. are very similar to algae
d. have DNA and FINA similar to all other organisms

27. Which is true of methanogens?
a. all of the following
b. they are found in sewage treatment plants
c. they are killed by oxygen
(1. they produce methane

28. Which of the following groups of prokaryotes are considered to be
archaebacteria?
a. all of the following
b. the extreme halophiles
c. the methanogens
d. the therrnoacidophiles

 

 

30.

31.

32.

34.

63

Which group of microorganisms could play an important role in solving
our garbage, sewage and agricultural waste problem?

a. cyanobacteria

b. halophiles

c. methanogens

d. thermoacidophiles

How do prokaryotes differ from eukaryotes? Eukaryotes:

a. have DNA, prokaryotes do not

b. have membrane-bounded nuclei, prokaryotes do not

0. lack mitochondria and lysosomes which prokaryotes have
d. lack mitotic nuclear divisions which prokaryotes have

In the 5-kingdom classification system, prokaryotes are grouped in the
kingdom(s):

a. Monera

b. Plantae

c. Protista

d. Animalia

In the 5-kingdom classification system, fungi are separated from other
eukaryotes mainly by:

a. cell wall structure and development from spores

b. ability to make their own food

c. Sized

(1. color

Which best describes prokaryotes?

a. most are beneficial

b. most are harmful

0. they are complex structurally and functionally

(1. they are evolutionarily recent and quite delicate

Which organisms are essential to the carbon cycle?
a. consumers and decomposers

b. first-and second-order consumers

c. producers and consumers

d. producers and decomposers

35.

37.

38.

39.

41.

64

Which organisms are decomposers or include many species that are
decomposers?

a. amoebas, centipedes, nematodes

b. bacteria, earthworms, fungi

c. centipedes, earthworms, insects

d. insects, nematodes, plants

Which organisms include species that have mutualistic relationships with
plant roots?

a. bacteria and fungi

b. centipedes

c. earthworms and nematodes

d. insects

The death of a organism is advantageous to a:
a. decomposer

b. herbivore

c. parasite

d. producer

The relationship between an alfalfa plant and the nitrogen-fixing bacteria
in nodules on its roots is one of:
a. commensalism

b. competition

0. mutualism

d. parasitism

Some of the things bacteria can breakdown are:

a. metal ores c. dead material

b. oil d. all of these

For each 1 gram of compost material, the microorganism population is
approximately:

a. 10 0. 100,000

b. 1,000 d. 10,000,000

Nematodes are vital to composting they are:
a. bacteria c. microscopic roundworms

b. fungi d. algae

 

42.

47.

65

Which of the following are examples of carbon cycling made possible by

microorganisms?

a. fermentation c. methane or smelly “swamp gas” formation
b. photosynthesis d. all of these

Nitrogen is vital to the production of which of the following biomolecules:
a. carbohydrates b. nucleic acids c. proteins

d. fats a. both b + c

Prokaryotes are organisms that

a. have no organized nucleus

b. always are anaerobic

c. always photosynthesize

d. have recently evolved but are vital to carbon cycling

The weight of leaves formed in a single season by a hardwood tree such
as an oak or aim is:

 

a. 40 pounds c. 40tons

b. 400 pounds d. 400 tons

The average American throws away of garbage a year:
a. 150 lbs. 0. 1510ns

b. 1500 lbs. d. 5000 lbs.

Earthworms are moist because:

a. they can slip easily through soil

b. moisture is needed for oxygen and carbon dioxide exchange.

c. they contain a glass-like material similar to sand which makes them
slippery

d. all of the above.

The next six questions refer to the information given below:

Four glass covered bowls were set up as follows:
Bowl A: stale moistened bread
Bowl 8: warm, 10-day old beef soup
Bowl C: pond water
Bowl D: crushed grapes in water

 

 

49.

51 .
52.

55.

57

66
In which bowl would you find the fewest decomposers?

In which bowl would you find the most bacteria?

In which bowl would you find the most algae?

In which bowl would you find the most mold?

In which bowl would you find the most yeast?

In which bowl would you find the most producers and consumers

Composting is:

a. recycling by nature

c. important because it saves landfill space
c. a natural way to make enriched soil

d. all of the above

Decomposition proceeds best in:
a. dry conditions

b. moist conditions

c. sunlight

d. cold temperatures

Humus is:

a. a funny story

b. a bone in your upper arm

c. decomposed organic matter

d. a radioactive material produced in nuclear power plants

. Bioremediation is:

a. study of very slow growing organisms
b. breaking down of hazardous waste by microorganisms

c. studyoflife
d. noneoftheabove

. Gases are released when decomposition occurs. Identify those gases:

carbon dioxide
methane
oxygen

all of the above
only a + b

9.9.0.5!”

59.

60.

67
Identify the gas needed by aerobic organisms.
a. carbon dioxide
b. methane
c. oxygen
d. nitrogen
a. hydrogen
1. all of the above

Which of the following is nonbiodegradable?
a. grass clippings

b. lettuce leavews

c. plastic

d. dead animals

TRUE OR FALSE:

Plants aren't the only producers. Some bacteria contain chlorophyll and
can photosynthesize.

Methanogens are methane producing bacteria and are responsible for
releasing most of the methane found in the atmosphere.

Bacteria are the most numerous living organisms on earth.

Methanogens are anaerobic bacteria that chemically convert carbon
dioxide and hydrogen into methane and water.

The cell walls of fungi are made up of cellulose.

Earthworms remove their nitrogenous wastes with specialized structures
called nephridia.

Our atmosphere consists of about 70% nitrogen but we are unable to
use nitrogen and must rely on other organisms, e.g., bacteria to put it in a
usable form for us.

Methane and carbon dioxide are both greenhouse gases responsible for
global warming.

We depend on microorganisms, e.g., bacteria for fermentation to produce
alcohol and many organic acids, e.g., acetic acid.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.
20.
21.

68
Large particles that can be broken into smaller particles greatly increase
surface area which enables decomposition to prowed at a much faster
rate.

Some bacteria can cause oxidation of copper ores therefore making
recovery of copper from low—grade ore easier.

Bioremediation is the process of using bacteria and fungi to biodegrade
waste material.

Decomposition is complete when organic compounds are returned to the
environment in their inorganic form as carbon dioxide.

Decomposition returns nitrogen containing compounds to the
environment in the form of ammonia.

Worms can eat one half their weight daily.

There is a finite amount of materials available for the construction of all
living organisms and life would cease if these materials were not
released by decomposition.

Antibiotics are “warfare chemicals” made by fungi and bacteria for the
purpose of eliminating their competitors.

Fast food packaging, styrofoam and disposable diapers are main
constituents of American garbage.

America is running out of places to build landfills
A lot of biodegradation takes place in modern landfills.
Paper takes up much more landfill space than plastic.

A compost pile produces almost no odor.

 

BIBLIOGRAPHY

i i l 'n: E I 1 IA r .Dubuque,lowa:KendallHunt
Publishing Company, 1987.

Breznak, John A. “Intestinal Microbiota of Termites and Other Xylophagous
Insects." A n I R ' w Mi i I 362323-43 (1982)

Collette. Alfred T. and Eugene L Chlappetta. SW
WWW" Publishing Company. 1989.

Coniff, Tom. “0n the Lowly Worm We Earthlings Pin Our Loftiest Dreams.”
Smithsonian July, 1993: 86-94.

Gillis. Anna Maria. “Shrinking the Trash Heap." WWI 42 (1992):
90-93.

W. Videocassette. Flowerfield Enterprises. 1986. 28+ minutes

Narayan, Ramani. “Biodegradation of Polymeric Material During Composting.”
International Composting Research Symposium. Columbus, Ohio (1992)

Nyerges, Christopher. ”Its Not for Everyone.” MW September,
1991: 96.

Videocassette. Keep America

 

Patent, Dorothy Henshaw. W New York: Holiday House,
1978.

Seymore, John, and Herbert Giradet. l ri f r n Fl New York:
Prentice Hall Press, 1987

     

  

   

         

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