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Ecosystems of the BodyHASPI Medical Biology Lab 10 Background/IntroductionBiodiversityEcosystems have carrying capacities, which are limits to the numbers of organisms and populations they can support. These limits result from such factors as the availability of living and nonliving resources and from such challenges as predation, competition, and disease. Organisms would have the capacity to produce populations of great size were it not for the fact that environments and resources are finite. This fundamental tension affects the abundance (number of individuals) of species in any given ecosystem. The amount of variation in living organisms is called biodiversity. It encompasses species, genetic, and ecosystem variation in a specific location or biome. A complex set of interactions within an ecosystem can keep its numbers and types of organisms relatively constant over long periods of time under stable conditions. If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e. the ecosystem is resilient), as opposed to becoming a very different ecosystem. Extreme fluctuations in conditions or the size of any population, however, can challenge the functioning of ecosystems in terms of resources and habitat availability. Factors That Affect BiodiversityBiodiversity in an area is different depending on the type of biome. For example, tropical biomes near the equator tend to have very high biodiversity. Within the body, biodiversity of microorganisms is highest in the intestinal tract. Throughout the Earth, biodiversity tends to accumulate in small areas called hot spots. The map below identifies those hot spots, and how much of the original habitat is remaining.

Ecosystems of the Body, HASPI Medical Biology Lab 10

www.cspeirs.blogspot.com

http://www.takepart.com/article/2010/05/21/infographic-international-biodiversity

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Name(s): Period: Date:Normal ecosystem interactions, such as competition and predation, can affect the amount of biodiversity in an area. Natural disasters such as wild fires, floods, or volcanic eruptions can also impact biodiversity. In a healthy ecosystem, there would be a healthy rise and fall of species and organisms. Unfortunately, human activity has a large impact on biodiversity worldwide. Human activities that affect biodiversity include:

Introduction of invasive species – a new species in an environment can change the dynamics of an ecosystem

Habitat loss or alteration – an ecosystem is changed to accommodate human habitats or industrialization

Overexploitation – humans harvest resources faster than the resources can be produced

Pest control – overuse of pesticides, herbicides, and overhunting of species that threaten humans

Pollution – human activities can produce pollution to air, water, and soil Climate change – while climate change is a natural occurrence, human activity

is increasing the rate of climate change; climate change results in new ecosystems

These human activities have already altered biodiversity, particularly in areas of high urbanization. The following graph depicts specific activities and how they impact species, and therefore biodiversity.

Ecosystems of the BodyAs discussed in Lab 09, there is an entire microscopic world living in and on the human body. There are even separate ecosystems depending on the location. For example, the microorganisms that live in the intestines are very different than the microorganisms that live on the skin, or in the mouth. The large majority of these microorganisms are bacteria that live peacefully in symbiosis with their human host. There is greater biodiversity in the human microbiome than any other biome on the entire planet.

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http://www.biodiversitybc.org/assets/Taking~Natures~Pulse/figure-

36.png

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Name(s): Period: Date:Normal Flora of the Skin & MouthThe skin is our body’s first line of defense against pathogens. The surface of the skin is covered with millions of bacteria and other one-celled organisms. Certain bacteria like to live on certain parts of the body. For example, the bacterial species that live under the arms are similar among most people on Earth. Many disorders that affect the skin have been linked to an improper balance of normal flora. [Flora are all forms of plant life including fungus and bacteria.] Some of these skin disorders include eczema, psoriasis, and acne. The Human Microbiome Project has identified over 50,000 different species of bacteria that live on the skin, but not every human has the exact same species. Characteristics of the environment of an individual’s skin—such as whether it is oily, moist, or dry—attract different types of bacterial species that prefer to live there. Oily skin has the most biodiversity. The area of the entire body having the most biodiversity is the forearm, while the least biodiversity is located behind the ears.Over 1,000 species of bacteria make their home in the mouth alone. An imbalance or introduction of foreign bacteria in the mouth can cause oral diseases such as infections, dental caries (tooth decay), and bad breath. The diagram below provides examples of a few common microorganisms found in different environments of the human body.

http://www.advisoranalyst.com/glablog/2013/11/25/the-human-microbiome.html

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Name(s): Period: Date:Changing Conditions Within the BodyThe human microbiome changes drastically throughout an individual’s lifetime. There is a natural succession of biodiversity and populations as an individual ages. The womb is a sterile environment, and newborns have no microbiome when they are born. At birth, microorganisms from the mother and other individuals who interact with the newborn begin to colonize the baby. The microbiome changes most drastically from birth until about 2 years of age. It will generally remain fairly stable from that point, but life events, such as pregnancy or disease, can impact biodiversity. In addition, the microbiome can also be changed by the human host’s choices. For example, the microbiome could be changed by the host’s environment, diet, lifestyle, disease, or even antibiotic use.

http://www.actionbioscience.org/images/microbes_over_time_sized.jpg

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Review Questions – answer questions on a separate sheet of paper1. What are carrying capacities? Give an example of a factor that limits carrying capacity.2. What is biodiversity? What part of the Earth has the most biodiversity? Why?3. What percentage of the world's plant and vertebrate species are located in hot spots?4. Which biodiversity hot spot has lost the most habitat? How much has it lost?5. Which biodiversity hot spot has lost the least habitat? How much has it lost?6. How can human activity impact biodiversity? Give an example.7. What is the greatest impact on biodiversity caused by agriculture? Climate change? 8. How many different species of bacteria live on the skin? In the mouth?9. Why do you think the biodiversity of microorganisms living on the human body changes depending

on the environment? For example, why is there more biodiversity on oily skin, rather than dry skin?10. How does the human microbiome change throughout an individual's lifetime?11. Is the microbiome of a baby different if he or she is breast-fed, formula-fed, or eating solid food? 12. How is the microbiome of a toddler different than that of an elderly individual?

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Name(s): Period: Date:Ecosystems of the BodyHASPI Medical Biology Lab 10 ScenarioThe goal of this lab will be to collect, culture, and observe some of the normal flora in the mouth and skin of the human body. Your lab team will also decide on an “environmental change” to test on the normal flora, and observe how this change impacts the populations and species that grow on the nutrient agar plate.MaterialsPetri plate w/ nutrient agar (2) Cotton swabs Permanent markerSkin “environmental change” Mouth “environmental change”

ProcedureYour lab team will be given tasks, or directions, to perform on the left. Record your questions, observations, or required response to each task on the right.Part A. Preparing the Plates

Task Response1 Obtain 2 petri plates. Your instructor has already poured nutrient agar into the petri

plates, or if not will provide instruction. DO NOT OPEN YOUR PLATE UNTIL DIRECTED!2 Using the permanent marker, label the top of one plate

“Skin” and include your group name (see upper image).

3

Notice the plate is split into two sides. On the bottom of the plate, in very small writing, write “A” on one side and “B” on the other as close to the edge as possible. You do not want to have to look through your labeling to see what grows on the plate.

4 Using the permanent marker, label the top of the other plate “Mouth” and write your group name.

5Notice this plate is also split into two sides. On the bottom of this plate, in very small writing, write “A” on one side and “B” on the other as close to the edge as possible.

6 Choose one individual in your group to be the test subject.

7 Have the test subject swirl a cotton swab in his or her mouth for at least 5 seconds.

8Whenever removing the lid from the plate, it is important to not remove the lid completely! Hold the lid over the plate. Contaminants in the air can easily settle and grow in the dish if the lid is completely removed.

9 The nutrient agar in the plate is similar in consistency to Jello. Try not to break the surface of the agar.

10

On side A of the “Mouth” plate, starting at the middle, very gently brush the cotton swab back and forth in a zig-zag motion (see lower image).

1 Remove and discard the cotton swab. Place the lid back on the plate.

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SkinGroup E

A

B

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12

Choose an “environmental change” for the mouth. Suggestions include: mouthwash, soda, food, or anything else that could be placed and moved around in the mouth.

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Have the test subject put the choice in his or her mouth, and swish around the “environmental change” for 30 seconds. For example, a soda can be swished just like a mouthwash. After 30 seconds, spit the choice into the sink or trash.

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Immediately have the test subject swirl a cotton swab in his or her mouth for at least 5 seconds.

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On side B of the “Mouth” plate, starting at the middle, very gently brush the cotton swab back and forth in a zig-zag motion (see image). Remember not to break the agar.

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Remove and discard the cotton swab. Place the lid back on the plate, and set the plate aside.

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Choose one individual in your group to be the test subject for the “Skin” activity.

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Whenever removing the lid from the plate, it is important to not remove the lid completely! Hold the lid over the plate. Contaminants in the air can easily settle and grow in the dish if the lid is completely removed.

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Remember, the nutrient agar in the plate is similar in consistency to Jello, so you are trying to avoid breaking the surface of the agar here as well.

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On side A of the “Skin” plate and starting at the middle, have the test subject very gently brush an index finger back and forth in a zig-zag motion. Place the lid back on the plate.

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Choose an “environmental change” for the skin. Suggestions include: lotion, soap, disinfectant, or anything else that could be used on the skin.

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Have the test subject put the choice on both hands, and wait for 3 minutes. For example, if the choice is lotion, have the test subject apply lotion to the hands in the usual way.

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On side B, starting at the middle, have the test subject very gently brush the index finger back and forth in a zig-zag motion. Place the lid back on the plate.

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Turn both plates in to the instructor. If an incubator is available, the bacteria and fungus will have grown by the following day. If not, it will be 2-3 days before the plates will be ready for observation.

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Part B. Observing the PlatesTask Response

1 Collect your plates. DO NOT REMOVE THE LIDS FROM YOUR PLATES!!!

Draw the growths that appear on each plate below.Mouth

Table 1. Normal Flora Growth: MouthSide A, B, or both?

Description Abundance

(how many)

Skin

Table 2. Normal Flora Growth: SkinSide A, B, or both?

Description Abundance

(how many)

2

Observe the bacterial and fungal growths on the plates. Bacterial growth will be evidenced by small round colonies, while fungal growths normally have a more complex structure, variety of colors, and can even look like mold. Record your observations on the right; use color if needed.

3

Record in Table 1 and Table 2 how many different types of organisms appeared, with a description of each on sides A and B of the respective plate. If there are more than 5 organisms, continue Tables 1 and 2 in the space below.

Once finished, return the plates to your teacher for disposal.

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Analysis & Interpretation

Connections & ApplicationsYour instructor may assign or allow you to choose any of the following activities. As per NGSS/CCSS, these extensions allow students to explore outside activities recommended by the standards.

1. RESEARCH MICROBIOTA INTERACTIONS: Species within ecosystems interact with one another, even on the microscopic level. Specific interactions, such as predation, competition, and symbiosis occur between microbiota. Corynebacterium and Staphylococcus are two families of bacteria that commonly colonize the human body. Use the Internet to research and answer the following questions. Cite ALL of your references.

a. Provide two specific species of Corynebacterium and Staphylococcus that colonize the human body.

b. What part of the human body does each family colonize?c. How does each family live in symbiosis with the human body? Provide a

specific example.d. How do these two families interact with one another? Provide a specific

example.e. Can species from either of these families cause disease? How?

2. HUMAN MICROBIOME PROJECT: The Human Microbiome Project (HMP) is a large-scale research project aimed at discovering and sequencing all of the microorganisms that make up the human microbiome. Using the Internet, research and answer the following questions related to the HMP. Cite your references.

a. What is the Human Microbiome Project, and why is it important to health and medicine? Give at least three examples.

Ecosystems of the Body, HASPI Medical Biology Lab 10

Analysis Questions – answer questions on a separate sheet of paper1. What environmental change was chosen for the skin plate? Be specific

(brand/variety).2. How did the environmental change impact the population and/or types of

growths that appeared on the skin plate?3. If the environmental change were to be consistently used (i.e. daily or hourly

use), do you think it could change the environment and biodiversity of the skin? Explain your answer.

4. What specific environmental change was chosen for the mouth plate? (Brand/flavor)

5. How did the environmental change impact the population and/or types of growths that appeared on the mouth plate?

6. If the environmental change were to be consistently used, do you think it could change the environment and biodiversity of the mouth? Explain your answer.

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Name(s): Period: Date:b. How many microorganisms that are part of the human microbiota have

currently been identified?c. Summarize at least two articles that outline how the HMP has provided

insight or implications on human health.3. GRAPHICAL COMPARISONS OF MICROBIOTA: Graphical comparisons of

biodiversity and populations in ecosystems can assist researchers in predicting interactions between species. Two species of bacteria, Bacillus subtilis and Staphyloccus aureus have been found in the nasal passageways of humans. In an experiment to determine how these two bacteria interact with one another, B. subtilis and S. aureus were grown in petri plates both independently and also together. The numbers of organisms in the populations were counted at 12-hour intervals for a week. The data collected can be found in Table A below. Create a single graph to represent the data in Table A, and then answer the questions below. (Title/label your graph!)Table A. Bacterial Species Growth Rate

Time Grown Separately Grown TogetherB. subtilis S. aureus B. subtilis S. aureus

0 hour 0 0 0 012 hours 5 3 4 224 hours 10 5 18 836 hours 22 16 47 1248 hours 45 32 112 2060 hours 94 68 282 4472 hours 184 156 296 12484 hours 348 254 260 21096 hours 542 415 210 342

108 hours 786 563 154 410120 hours 891 708 113 424132 hours 935 800 81 429144 hours 968 852 62 425156 hours 975 868 49 428168 hours 970 870 36 430

a. Compare the growths of B. subtilis and S. aureus when grown separately and grown together.

b. Hypothesize how B. subtilis and S. aureus interact with each other based on the graph. Explain your reasoning.

Resources & References NHGRI. 2009. Study Finds Unexpected Bacterial Diversity on Human Skin. National Institutes of

Health, National Human Genome Research Institute. http://www.genome.gov/27532034.

Reed, A. and Green, S. 2013. Human Microbiome FAQ. American Academy of Microbiology. http://microbio.me/americangut/img/FAQ_Human_Microbiome.pdf.

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