Lab 7: Ecology of Organisms 85 Introduc on Organisms have adapted and evolved anatomical, physiological, and behavioral characteris cs that compensate for varia on within the environment. Organisms have the ability to compensate for mini mal temporal and spa al varia on within their environment by regula ng their body temperature or controlling the rate at which water is transpired however, there are limits to an organism’s ability to compensate for environmental factors. No single species can tolerate all of earth’s environments. The geographic distribu on of a species is thus limited by the physical environment. Species distribu on is said to be limited by abio c factors or the non living components of our environment. All species have a de ned habitat tolerance which is the range of condi ons in which a species can live. For example, some plant species can tolerate a broad range of soil varia on while others are con ned to a single soil type. If a species has a narrow habitat tolerance because of one or more abio c factors then they are limited in their distribu on range. Organisms with a broad range of tolerance are usually distributed widely whereas those with a narrow range have a Figure 2 Dandelion (Taraxicum o cionale) species like the dande lion are very common and show no aspects of rarity making them very common handling a broad range of tolerances . Figure 1 Mountain Gorilla (Gorilla gorilla beringei) mountain gorillas have a restricted geographic range, a narrow habitat tolerance, and a small local popula on classifying them in the “rarest” category, this species is one of many that is highly vulnerable to ex nc on. Concepts to explore: Ecology of organisms Range of tolerance Concepts to explore: Lab 7: Ecology of Organisms 86 more restricted distribu on. Habitat tolerance along with a species geographic range (limited vs. wide spread) and the species local popula on size (large vs. small) determine a species commonness or rari ty. Understanding a species range of tolerance helps to determine whether a species is common or rare which can be a huge determinate in areas such as agricultural produc on and wildlife manage ment. Experiment 1: E ects of pH on radish seed germina on Natural soil pH depends on the parent rock material from which it was formed and processes like cli mate. Soil pH is a measure of the acidity or alkalinity of the soil. Acidic soils are considered to have a 5.0 or lower pH value whereas 10.0 or above is considered a strong basic or alkaline soil. The pH of soil a ects the solubility of nutrients in soil water and thus it a ects the amount of nutrients available for plant uptake. Di erent nutrients are available under di ering pH condi ons. In this lab we will look at the e ect of pH on the germina on and growth rate of radish seeds in order to determine the range of pH tolerance for the seed. Acidic or basic water will be used in order to s mulate acidity or alkalinity in soil. Procedure ...

1. Lab 7: Ecology of Organisms
85
Introduc on
Organisms have adapted and evolved anatomical, physiological,
and behavioral characteris cs that
compensate for varia on within the environment. Organisms
have the ability to compensate for mini
mal temporal and spa al varia on within their environment by
regula ng their body temperature or
controlling the rate at which water is transpired however, there
are limits to an organism’s ability to
compensate for environmental factors. No single species can
tolerate all of earth’s environments. The
geographic distribu on of a species is thus limited by the
physical environment. Species distribu on is
said to be limited by abio c factors or the non living
components of our environment.
All species have a de ned habitat tolerance which is the range of
condi ons in which a species can live.
For example, some plant species can tolerate a broad range of
soil varia on while others are con ned
to a single soil type. If a species has a narrow habitat tolerance
because of one or more abio c factors
then they are limited in their distribu on range. Organisms with
a broad range of tolerance are usually
distributed widely whereas those with a narrow range have a
Figure 2 Dandelion (Taraxicum o cionale) species like the

2. dande
lion are very common and show no aspects of rarity making
them
very common handling a broad range of tolerances .
Figure 1 Mountain Gorilla (Gorilla gorilla beringei) mountain
gorillas
have a restricted geographic range, a narrow habitat tolerance,
and a
small local popula on classifying them in the “rarest” category,
this
species is one of many that is highly vulnerable to ex nc on.
Concepts to explore:
Ecology of organisms
Range of tolerance
Concepts to explore:
Lab 7: Ecology of Organisms
86
more restricted distribu on. Habitat tolerance along with a
species geographic range (limited vs. wide
spread) and the species local popula on size (large vs. small)
determine a species commonness or rari
ty. Understanding a species range of tolerance helps to
determine whether a species is common or
rare which can be a huge determinate in areas such as
agricultural produc on and wildlife manage

3. ment.
Experiment 1: E ects of pH on radish seed germina on
Natural soil pH depends on the parent rock material from which
it was formed and processes like cli
mate. Soil pH is a measure of the acidity or alkalinity of the
soil. Acidic soils are considered to have a
5.0 or lower pH value whereas 10.0 or above is considered a
strong basic or alkaline soil. The pH of soil
a ects the solubility of nutrients in soil water and thus it a ects
the amount of nutrients available for
plant uptake. Di erent nutrients are available under di ering pH
condi ons.
In this lab we will look at the e ect of pH on the germina on and
growth rate of radish seeds in order
to determine the range of pH tolerance for the seed. Acidic or
basic water will be used in order to
s mulate acidity or alkalinity in soil.
Procedure
1. Obtain your petri dishes and label them, one for each solu on
2. Cut out the paper towel to t inside the petri dish. Wet each
individual towel with its determined
solu on.
Materials
50% Vinegar solu on
Radish seeds
Saturated baking soda solu on
Paper towel sheets (cut to t into
petri dish)*

4. pH paper
Water*
3 Petri dishes
Ruler
* You must provide
Lab 7: Ecology of Organisms
87
3. Test pH of three solu ons and the paper towels containing the
solu on, record your values.
4. Arrange 10 radish seeds on each paper towel in each petri
dish. Make sure the seeds have space
and are not touching.
5. Place the petri dishes in a sunny or well lit warm place. You
must be sure to keep the paper towels
moist for the length of the lab with the appropriate solu on and
make sure that the solu ons re
main at the same rela ve pH.
6. Observe seeds daily for 7 days and record the number of
seeds that germinate (note when the
seed cracks and roots or shoots emerge from the seed).
Note: During this observa on period, take pictures to document
the radish seed growth. This
can be done in a number of ways (example, mobile phone,
camera, webcam, etc.). Images can
then be scanned , uploaded via USB/cable connec on, etc. onto a

5. computer and be integrated
into your nal document.
7. On the 7th day record the lengths of radish seed sprouts.
Compare and graph sprout lengths below.
Don’t forget to tle your graph and label the axes.
Table 1: Radish Seed Observa on and Germina on
*You will need to expand on the table below to record your
observa ons and results for all 7 days.
Solu on pH
Days 1 2 Day 3 Day 4
Observa on
Seeds
Germinated
% Observa on
Seeds
Germinated
% Observa on
Seeds
Germinated
%
Water
Vinegar

6. Baking
soda
Lab 7: Ecology of Organisms
88
Ques ons
1. Was there any no ceable e ect on the germina on rate of the
radish seeds as a result of the pH?
Compare and contrast the growth rate for the control with the
alkaline and acidic solu ons.
2. According to your results would you say that the radish has a
broad pH tolerance? Why or why
not? Use your data to support your answer.
3. Knowing that acid rain has a pH of 2 3 would you conclude
that crop species with a narrow soil pH
range are in trouble? Is acid rain a problem for plant species
and crops?
Figure 3: Sample set up for sprout lengths graph.
Se
ed
Le
ng
th
(m
m

7. )
Seed Length vs. Environment Category
his coming week, you will do your very last lab exercise – Lab
7. This particular lab deals with the Ecology of Organisms. In
your BIOL 101 classes, you will by now have begun to discuss
environmental issues. I have also introduced the topic this week
– it is if utmost importance! Incidentally, you will also do a
Final Analysis for this class, instead of a final Exam. I am
urging you to do Option 2 for your final analysis. As we have
already learned, physiological/chemical activities within any
organisms may only properly happen between restricted ranges
of temperature and pH levels. If they are wrong, cellular
activities will slow down, or stop altogether. Organisms have
adapted to a great variety of environmental conditions; but this
means that they are limited to those areas. For example, many
wildflowers of northern areas require that their seeds freeze for
a while, before they can germinate. Such specializations are
called ‘habitat tolerance’.
For Lab 7, you will grow radish seeds in regular water, a baking
powder solution (alkaline) and a vinegar solution (acid) for
seven days. All the materials are in your lab kit! You must keep
a very careful record for 7 days. Therefore it is best to begin
right away.
However, before you begin you exercise, please read the
instructions carefully. Then set up your three petri dishes with
the seeds, and extend your recording table to seven days. Then
do your graph and answer the questions.
UMUC Biology 102/103Lab 7: Ecology of
OrganismsINSTRUCTIONS:
· On your own and without assistance, complete this Lab 7

8. Answer Form electronically and submit it via the Assignments
Folder by the date listed on your Course Schedule (under
Syllabus).· To conduct your laboratory exercises, use the
Laboratory Manual that is available in the WebTycho classroom
(Reserved Reading or provided by your instructor) or at the
eScience Labs Student Portal. Laboratory exercises on your CD
may not be updated.
· Save your Lab7AnswerForm in the following format:
LastName_Lab7 (e.g., Smith_Lab7).· You should submit your
document in a Word (.doc or .docx) or Rich Text Format (.rtf)
for best compatibility.
Experiment 1: Effects of pH on Radish Seed Germination
Table 1: Radish Seed Observation and Germination
Solution
pH
Days 1-2
Day 3
Day 4

9. Observation
Seeds Germinated
%
Observation
Seeds Germinated
%
Observation
Seeds Germinated
%
Water
Vinegar

10. Baking soda
Complete the graph. Use the graph provided as your template.
You will need to impose figures and shapes over the graph.
00.20.40.60.811.2Category 1Category 2Category 3
00.20.40.60.811.2Category 1Category 2Category 3

11. Questions
1. Was there any noticeable effect on the germination rate of the
radish seeds as a result of the pH? Compare and contrast the
growth rate for the control with the alkaline and acidic
solutions.
2. According to your results would you say that the radish has a
broad pH tolerance? Why or why not? Use your data to support
your answer.
3. Knowing that acid rain has a pH of 2-3 would you conclude
that crop species with a narrow soil pH range are in trouble? Is
acid rain a problem for plant species and crops?
TYPE YOUR FULL NAME:
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Figure 3: Sprout lengths after 7 days of growth for radish seeds
exposed to different pH values.

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