2100 Anthropology Exam.

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2100 Anthropology Exam.. ATH2100L LAB 5: READING

 

DIRECTIONS: Please read the materials that follow and then complete the Lab 5 Quiz on PILOT.

 

By the time you finish reading these materials, you should be able to answer the following questions about primates:

1. What ancestral traits do primates share with other mammals?

2. What derived traits characterize primates compared to other mammals?

3. What is the value of studying primates to understand human evolution?

 

Primates are mammals (and therefore, so are you!)

Taxonomic classification organizes organisms based on shared characteristics due to common ancestry. The Linnean classification system is a nested hierarchy that becomes more exclusive with each taxonomic level (for example, a phylum contains more groups than a class and so on). Below is the taxonomic classification for modern humans.

 

Linnean Classification of Human

 

GENERAL KINGDOM Animalia (we’re ANIMALS)

(inclusive)

PHYLUM Chordata (we’re animals with SPINAL CORDS)

 

CLASS Mammalia (we’re a kind of spined animal MAMMALS)

 

ORDER Primates (we’re a type of mammal called a PRIMATE)

 

FAMILY Hominidae (includes us and apes, aka HOMINIDS)

 

GENUS Homo (this is us and closely related enchephalized bipeds)

SPECIFIC

(exclusive) SPECIES Homo sapiens (we’re a special group called HUMANS)

 

From this classification, we see that modern humans are grouped within the order Primates which falls within the class Mammalia. This means that humans are primates, a special type of mammal that shares a common ancestry with OTHER mammals. As a result of this ancestry, primates and mammals share many ANCESTRAL TRAITS.

 

Mammals are diverse. On the surface, it may seem hard to find similarities between humans and a dog or cat, etc. However, we all share traits found in our common mammalian ancestor that indicate a closer evolutionary relationship among all animals grouped within the Class Mammalia than other animals.

 

 

Mammalian characteristics

 

1. Homeothermy/endothermy: Mammals have the ability to regulate body temperature. This means mammals can adapt to different climates.

 

2. Heterodonty: Mammals have different types of teeth. Mammals have four kinds of teeth with different shapes and characteristics: incisors, canines, premolars, and molars. Other animals, such as crocodiles and sharks are homodonts (the teeth are all the same).

 

http://inside.ucumberlands.edu/academics/biology/faculty/kuss//courses/Digestive%20system/HomodontHeterodont.jpg

 

3. Viviparity: Mammals have internal gestation and give birth to live young (there are a few exceptions). Young are then dependent upon the mother for milk produced by mammary glands.

 

4. Pentadactyly: Mammals have five fingers and toes. The basic structure of the mammalian “hand” and “foot” is similar, but many groups have modified this condition (i.e. ungulates have hooves, felids have paws with claws). Primates retain the primitive structure of pentadactyly.

http://www.evolutionnews.org/Panda%27s%20Thumb.jpg

5. Brain: The mammalian brain tends to be larger for body size compared to other vertebrates. Mammals also have a unique area of the brain known as the neocortex. The neocortex is involved in higher level functions such as spatial reasoning and sensory perception. This area reaches its greatest expansion among primates.

 

 

What makes primates different from other mammals?

 

Primates are defined by a group of features, known as DERIVED TRAITS. Derived traits are modified from the ancestral (in this case, mammalian) condition. The tricky thing about ancestral and derived traits is that their status (or polarity) depends on the context. For example, if we are comparing mammals and primates, the features below are considered DERIVED. However, if we are comparing different groups of primates, those same features are considered ANCESTRAL because all primates share them.

 

In the next lab, you will explore more in-depth what distinguishes primates from other mammals. Here are a few key features of primates:

 

1. Vision: Vision is the most important sense for most primates. They have forward-facing eyes and stereoscopic vision. This means that a primate’s eyes are located in the front of the skull. This allows the fields of vision to overlap, and provides depth perception (very important if you primarily live in the trees). Furthermore, the primate eye socket features post-orbital closure or a post-orbital bar. You will explore this characteristic more in Lab 6.

 

2. Hands, feet, and limbs: Primates retain the ancestral condition of pentadactyly. They also have prehensile (gripping) fingers and toes, nails instead of claws (with some exceptions), tactile pads, and an opposable thumb. Primates also have very flexible and generalized limbs that allow us to locomote (move) in many different ways.

 

3. Brains and speed of growth: As mentioned above, primate brains are more complex than other mammals, and our brains tend to be larger than expected for body size (this is seen to the extreme among hominins). Primates also feature longer gestation periods and slower postnatal growth than most other mammals.

 

The utility of non-primates for understanding evolution

 

Non-human primates (NHP) are fascinating because they are so like us in both appearance and behavior (and many are very cute!) NHP studies help us to understand:

a) the relationship between dental and skeletal form and their behavioral functions (to reconstruct things like locomotion, group structure, and diet in fossil species),

b) the evolutionary underpinnings of some of our behaviors (tool use, group living, social politics, etc.)

c) evolutionary processes, adaptation, and speciation.

 

HOWEVER, we have to remember that extant NHP are not “living fossils,” and they were evolving and changing long before hominins (our ancestors) ever came on the scene. Therefore, we must be cautious in our use of NHP as analogies for hominin evolution.

 

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2100 Anthropology Exam.

 
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Annotated Bibliography

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Annotated Bibliography. Assess sources for your research for your final presentation (for credibility, reliability, and relevance) and list references in proper APA format. That means the sources you use for this assignment should be directly related to the species that you chose in Forum 1 of the class

Assignment Instructions:  The Research Project/Presentation for this class is divided into three major Assignments, 1) annotated bibliography, 2) outline and 3) final presentation. The first part is the annotated bibliography. An annotation is a summary and evaluation, and your annotated bibliography will include a summary and evaluation of some of the sources (or references) you will use for your presentation.

To prepare for this assignment, I recommend that you do the following:

  • Read these directions carefully.
  • Review the sample annotated bibliography provided to you below.
  • Read the grading criteria below. The grading criteria is a detailed evaluation that I will use to assess your performance. It will also help you understand what is expected of you as you prepare your assignment.
  • Message me with any questions!

The reason the annotated bibliography is included as part of the research project is that writing an annotated bibliography is important in that it provides excellent preparation for the final presentation. One of the issues regarding any type of research, especially in biology, is the credibility of the sources used, particularly those obtained from various websites. By forcing you to evaluate each of your potential sources carefully, the annotated bibliography helps you determine if in fact the source you chose is credible and helps you determine how relevant it is to your topic and understand the topic better which will help you develop your presentation.

For this project, you will assess three sources to include:

1) a complete citation for each source,

2) a summary of each source, and

3) an evaluation of each source.

Three sources are required for this assignment (i.e., you are to write an annotation for each source).  However, you must use five or more sources in your final presentation. 

Use this TEMPLATE to summarize and evaluate each of your three sources.

  1. Citation:

Written in APA reference list format. For more help with formatting, see APA handout.

  1. Summary:

What is the purpose of the source, review article, original research? What topics are covered? This section is generally 4-6 sentences that summarize the author’s main point. For more help, see this link on paraphrasing sources.

  1. Evaluation:

After summarizing the article (or research paper or book), it is necessary to evaluate it and state where you found it – its source (e.g., journal, website, etc.).  Briefly answer the following questions in 4-6 sentences:

What is the format or type of source (e.g., peer-reviewed journal paper, website, book)? How reliable is the information in the article, and how credible is the source (e.g., website’s sponsoring organization, journal or book publisher) and the author(s)?

SCIN130 – Introduction to Biology with Lab

 

Annotated Bibliography

 

 

Name:
Course Number:
Presentation Topic:

 

 

 

Source #1

 

Citation

(in APA format)

  

 

 
 

Summary

 

 

 

 

 

 

 

  

 
 

Evaluation

 

 

 

 

 

 

 

  

 

 

 

Source #2

 
 

Citation

(in APA format)

  

 

 
 

Summary

 

 

 

 

 

 

 

  
 

Evaluation

 

 

 

 

 

 

 

  

 

 

 

Source #3

 
 

Citation

(in APA format)

  

 

 
 

Summary

 

 

 

 

 

 

 

  
 

Evaluation

 

 

 

 

 

 

 

  

 

 

American Public University System May 2018

Annotated Bibliography

 
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Bio Statistics Quiz

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Bio Statistics Quiz. This quiz consists of 20 questions most appear to be similar but now really. I ned someone who is familiar with bio-statistics and math. The due date is tomorrow 4 pm PST. or (16:00). Please if you accept handshake you must do the work not get from previous papers or tell me you had emergency an hour before its due. This is important to me.

attached is the file just in case you need it in word format. Thank you in advance.

1.      The standard deviation of the diameter at breast height, or DBH, of the slash pine tree is less than one inch. Identify the Type I error. (Points : 1)

[removed] Fail to support the claim σ < 1 when σ < 1 is true.
[removed] Support the claim  μ < 1 when μ = 1 is true.
[removed] Support the claim σ < 1 when σ = 1 is true.
      [removed] Fail to support the claim μ < 1 when μ < 1 is true.

1a.  The EPA claims that fluoride in children’s drinking water should be at a mean level of less than 1.2 ppm, or parts per million, to reduce the number of dental cavities. Identify the Type I error. (Points : 1)

[removed] Fail to support the claim σ < 1.2 when σ < 1.2 is true.
[removed] Support the claim μ < 1.2 when μ = 1.2 is true.
[removed] Support the claim σ < 1.2 when σ = 1.2 is true.
[removed] Fail to support the claim μ < 1.2 when μ < 1.2 is true.

2.      Biologists are investigating if their efforts to prevent erosion on the bank of a stream have been statistically significant. For this stream, a narrow channel width is a good indicator that erosion is not occurring. Test the claim that the mean width of ten locations within the stream is greater than 3.7 meters. Assume that a simple random sample has been taken, the population standard deviation is not known, and the population is normally distributed. Use the following sample data:

3.3 3.3 3.5 4.9 3.5 4.1 4.1 5 7.3 6.2

What is the P-value associated with your test statistic? Report your answer with three decimals, e.g., .987 (Points : 1)

2a. Medical researchers studying two therapies for treating patients infected with Hepatitis C found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions np ≥ 5 and nq ≥ 5 are satisfied.

  Therapy 1 Therapy 2
Number of patients 39 47
Eliminated Hepatitis 20 13
C infection    

Construct a 95% confidence interval estimate of the odds ratio of the odds for having Hepatitis C after Therapy 1 to the odds for having Hepatitis C after Therapy 2. Give your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)

[removed]

3. Researchers studying sleep loss followed the length of sleep, in hours, of 10 individuals with insomnia before and after cognitive behavioral therapy (CBT). Assume a .05 significance level to test the claim that there is a difference between the length of sleep of individuals before and after CBT. Also, assume the data consist of matched pairs, the samples are simple random samples, and the pairs of values are from a population having a distribution that is approximately normal.

Individual 1 2 3 4 5 6 7 8 9 10
Before 6 5 4 5 3 4 5 3 4 2
CBT                    
After 8 8 7 6 7 6 6 5 7 5
CBT                    

Construct a 95% confidence interval estimate of the mean difference between the lengths of sleep. Give your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)

[removed]

3a. Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations, but do not assume that the population standard deviations are equal.

Construct a 90% confidence interval for the difference between the two means. Give your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)

4.      The paired data consist of the cost of regionally advertising (in thousands of dollars) a certain pharmaceutical drug and the number of new prescriptions written (in thousands).

Cost 9 2 3 4 2 5 9 10
Number 85 52 55 68 67 86 83 73

Find the value of the linear correlation coefficient r. Give your answer to three decimals, e.g., .987. (Points : 0.5)

4a. The paired data consist of the cost of regionally advertising (in thousands of dollars) a certain pharmaceutical drug and the number of new prescriptions written (in thousands).

Cost 9 2 3 4 2 5 9 10
Number 85 52 55 68 67 86 83 73

Find the predicted value of the number of new prescriptions written if $6000 is spent in regional advertising. Give your answer as an integer. (Points : 0.5)

[removed]

5.      Use a .05 significance level and the observed frequencies of 70 Neonatal deaths to test the claim that number of neonatal deaths on each day of the week is equally likely.

Mon Tues Wed Thurs Fri Sat Sun
10 9 5 8 15 12 11

Determine the value of the χ2 test statistic. Give your answer to two decimals, e.g., 12.34 (Points : 0.5)

5a. Use a .05 significance level and the observed frequencies of 144 drowning at the beaches of a randomly selected coastal state to test the claim that the number of drowning for each month is equally likely.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
1 3 2 7 14 20 37 33 16 6 2 3

Determine the value of the χ2 test statistic. Give your answer to two decimals, e.g., 12.34 . (Points : 0.5)

[removed]

6.      Using a .01 significance level, test the claim that the proportions of fear/do not fear responses are the same for male and female dental patients.

Gender

  Male Female
Fear Dentistry 48 70
Do Not Fear Dentistry 21 32

Do you reject the null hypothesis, at the .01 significance level? Enter Y for yes (reject), N for no (fail to reject). (Points : 0.5)

6a. Using a .01 significance level, test the claim that the proportions of fear/do not fear responses are the same for male and female dental patients.

Gender

 

  Male Female
Fear Dentistry 48 70
Do Not Fear Dentistry 21 32

Determine the value of the χ2 test statistic. Give your answer to three decimals, e.g., 12.345 . (Points : 0.5)

[removed]

 

7. The table represents results from an experiment with patients afflicted in both eyes with glaucoma. Each patient was treated in one eye with laser surgery and in the other eye was treated with eye drops. Using a .05 significance level, apply McNemar’s test to test the following claim: The proportion of patients with no improvement on the laser treated eye and an improvement on the drops treated eye is the same as the proportion of patients with an improvement on the laser treated eye and no improvement on the drops treated eye.

    Eye Drop Treatment

 

    Improvement No Improvement
       
Laser Surgery Improvement 15 10
Treatment No Improvement 50 25

Determine the value of the χ2 test statistic. Give your answer to two decimals, e.g., 12.34 . (Points : 0.5)

7a. The table represents results from an experiment with patients afflicted with eczema on both arms. Each patient was treated with an immune modulator cream on one arm and a topical steroid cream on the other arm. Using a .05 significance level, apply McNemar’s test to test the following claim: The proportion of patients with no cure on the immune modulator treated arm and a cure on the topical steroid treated arm is the same as the proportion of patients with a cure on the immune modulator treated arm and no cure on the topical steroid treated arm.

    Immune Modulator Cream

 

    Cure No Cure
Topical Steroid Cure 25 11
Cream No Cure 42 22

Do you reject the null hypothesis, at the .05 significance level? Enter Y for yes (reject), N for no (fail to reject). (Points : 0.5)

[removed]

8.For a study on Type 1 diabetes, medical graduate students subdivided the United States into four study regions (Northeast, Southeast, Southwest, and Northwest). The students randomly selected seven patients per region and recorded the number of times during a randomly selected month that each patient used insulin shots to regulate blood sugar levels. Use One-Way ANOVA at a .05 significance level to test the claim that the means from the different regions are not the same.

Mean number of times patients used insulin shots to regulate blood sugar levels

 Northeast Southeast Southwest Northwest
4 6 4 4
3 5 5 4
3 6 6 5
4 8 6 6
3 6 7 3
2 6 5 5
5 8 4 3
   
   
   

Do you reject the null hypothesis, at the .05 significance level? Enter Y for yes (reject), N for no (fail to reject). (Points : 0.5

8a. Geneticists studying carriers of genetic diseases followed subjects subdivided by race. Researchers randomly selected seven patients per race who had been identified as carrying a certain gene for a genetic disease; these patients were followed to determine the number of their siblings who also carried the gene for the genetic disease. Use a One-Way ANOVA at a .05 significance level to test the claim that the means from the different races are not all the same.

Caucasian African-American Other
2 0 0
3 0 1
3 1 2
3 2 2
4 2 2
5 2 3
5 4 4

Determine the value of the F test statistic. Give your answer to two decimals, e.g., 12.34 . (Points : 0.5)

[removed]

                            

9.      The reason we cannot use multiple t-tests to claim that four populations have the same mean is that we increase the likelihood of a type I error. (Points : 1)

[removed] True
[removed] False

9a.

If there is only one observation per cell in a Two-Way ANOVA, and it can be assumed there is not an interaction between factors, then we can proceed to interpret the results of the row and column effects. (Points : 1)

[removed] True
[removed] False

 

10.Use the following technology display from a Two-Way ANOVA to answer this question. Biologists studying habitat use in Lepidopteran moths measured the number of savannah moths found at three randomly selected prairie sites with two potential habitat interferences (expansion of row crops and grazing). Use a .05 significance level.

Source Df SS MS F P
Site 2 .1905 .0952 .0381 .9627
Habitat 1 304.0238 304.0238 121.6095 .0000
Site*Habitat 2 .1905 .0952 .0381 .9627

What is the value of the F test statistic for the site effect? (Points : 0.5)

10a. Use the following technology display from a Two-Way ANOVA to answer this question. Biologists studying habitat use in Lepidopteran moths measured the number of savannah moths found at three randomly selected prairie sites with two potential habitat interferences (expansion of row crops and grazing). Use a .05 significance level.

Bio Statistics Quiz

 
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Lab Enzymes

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Lab Enzymes. Full Name:

 

UMUC Biology 102/103

Lab 4: Enzymes

INSTRUCTIONS:

 

        On your own and without assistance, complete this Lab 4Answer Sheet electronically and submit it via the Assignments Folder by the date listed intheCourse Schedule (underSyllabus).

        To conduct your laboratory exercises, use the Laboratory Manual located under Course Content. Read the introduction and the directions for each exercise/experiment carefully before completing the exercises/experiments and answering the questions.

        Save your Lab 4Answer Sheet in the following format:  LastName_Lab4 (e.g., Smith_Lab4).

        You should submit your document as a Word (.doc or .docx) or Rich Text Format (.rtf) file for best compatibility.

 

Pre-Lab Questions

 

1.      How could you test to see if an enzyme was completely saturated during an experiment?

 

2.      List three conditions that would alter the activity of an enzyme. Be specific with your explanation.

 

3.      Take a look around your house and identify household products that work by means of an enzyme. Name the products, and indicate how you know they work with an enzyme.

 

 

Experiment 1: Enzymes in Food

This experiment tests for the presence of amylase in food by using Iodine-Potassium Iodide, IKI. IKI is a color indicator used to detect starch. This indicator turns dark purple or black in color when in the presence of starch. Therefore, if the IKI solution turns to a dark purple or black color during the experiment, one can determine that amylase is not present (because presence of amylase would break down the starch molecules, and the IKI would not change color).

 

Materials

(1) 2 oz. Bottle (Empty)

(1) 100 mL Graduated Cylinder

30 mL Iodine-Potassium Iodide, IKI

Permanent Marker

Ruler

2 Spray Lids

30 mL Starch (liquid)

*Cutting Board

  

*2 Food Products (e.g., ginger root, apple, potato, etc.)

*Kitchen Knife

*Paper Towel

*Saliva Sample

*Tap Water

*You Must Provide

 

Procedure:

1.      Remove the cap from the starch solution. Attach the spray lid to the starch solution.

2.      Rinse out the empty two ounce bottle with tap water. Use the 100 mL graduated cylinder to measure and pour 30 mL of IKI into the empty two ounce bottle. Attach the remaining spray lid to the bottle.

3.      Set up a positive control for this experiment by spraying a paper towel with the starch solution. Allow the starch to dry for approximately one hour (this time interval may vary by location).

4.      In the mean time, set up a negative control for this experiment. Use your knowledge of the scientific method and experimental controls to establish this component (hint: what should happen when IKI solution contacts something that does not contain starch?) Identify your negative control in Table 1.

Note: Be sure to space the positive and negative controls apart from each other to prevent cross-contamination.

5.      When the starch solution has dried, test your positive and negative controls. This step establishes a baseline color scale for you to evaluate the starch concentration of the food products you will test in Steps 7 – 11. Record your results in Table 1.

6.      Select two food items from your kitchen cabinet or refrigerator.

7.      Obtain a kitchen knife and a cutting board. Carefully cut your selected food items to create a fresh surface.

Figure 3: Sample set-up.

8.      Gently rub the fresh/exposed area of the food items on the dry, starch-sprayed paper towel back and forth 10 – 15 times. Label where each specimen was rubbed on the paper towel with a permanent marker (Figure 3).

9.      Wash your hands with soap and water.

10.  Take your finger and place it on your tongue to transfer some saliva to your finger. Then, rub your moistened finger saliva into the paper towel. Repeat this step until you are able to adequately moisten the paper towel.

Note: You should always wash your hands before touching your tongue! Alternatively, if you do not wish to put your hands in your mouth, you may also provide a saliva sample by spitting in a separate bowl and rubbing the paper towel in the saliva. Be sure not to spit on the paper towel directly as you may unintentionally cross-contaminate your samples.

11.  Wait five minutes.

12.  Hold the IKI spray bottle 25 – 30 cm away from the paper towel, and mist with the IKI solution.

13.  The reaction will be complete after approximately 60 seconds. Observe where color develops, and consider what these results indicate. Record your results in Table 1.

Table 1: Substance vs. Starch Presence
Substance Resulting Color Presence of Starch?
Positive Control: Starch    
Negative Control: Student Must Select    
Food Product:    
Food Product:    
Saliva:    

 

Post-Lab Questions

1.      What were your controls for this experiment? What did they demonstrate? Why was saliva included in this experiment?

 

2.      What is the function of amylase? What does amylase do to starch?

 

3.      Which of the foods that you tested contained amylase? Which did not? What experimental evidence supports your claim?

 

4.      Saliva does not contain amylase until babies are two months old. How could this affect an infant’s digestive requirements?

 

5.     There is another digestive enzyme (other than salivary amylase) that is secreted by the salivary glands. Research to determine what this enzyme is called. What substrate does it act on? Where in the body does it become activated, and why?

 

6.       Digestive enzymes in the gut include proteases, which digest proteins. Why don’t these enzymes digest the stomach and small intestine, which are partially composed of protein?

 

 

Experiment 2: Effect of Temperature on Enzyme Activity

Yeast cells contain catalase, an enzyme which helps convert hydrogen peroxide to water

Figure 4: Catalase catalyzes the decomposition of hydrogen peroxide to water and oxygen.

and oxygen. This enzyme is very significant as hydrogen peroxide can be toxic to cells if allowed to accumulate. The effect of catalase can be seen when yeast is combined with hydrogen peroxide (Catalase: 2 H2O2 → 2 H2O + O2).

In this lab you will examine the effects of temperature on enzyme (catalase) activity based on the amount of oxygen produced. Note, be sure to remain observant for effervescence when analyzing your results.

 

Materials

(2) 250 mL Beakers

3 Balloons

30 mL 3% Hydrogen Peroxide, H2O2

Measuring Spoon

Permanent Marker

Ruler

20 cm String

  

3 Test Tubes (Glass)

Test Tube Rack

Thermometer

Yeast Packet

*Hot Water Bath

*Stopwatch

*You Must Provide

 

Procedure

1.      Use a permanent marker to label test tubes 1, 2, and 3. Place them in the test tube rack.

2.      Fill each tube with 10 mL hydrogen peroxide. Then, keep one of the test tubes in the test tube rack, but transfer the two additional test tubes to two separate 250 mL beakers.

3.      Find one of the balloons, and the piece of string. Wrap the string around the uninflated balloon and measure the length of the string with the ruler. Record the measurement in Table 2.

4.      Create a hot water bath by performing the following steps:

1.      Determine if you will use a stovetop or microwave to heat the water. Use the 100 mL graduated cylinder to measure and pour approximately 200 mL of water into a small pot or microwave-safe bowl (you will have to measure this volume in two separate allocations).

2.      If using a stovetop, obtain a small pot and proceed to Step 4c. If using a microwave, obtain a microwave-safe bowl and proceed to Step 4e.

3.      If using a stove, place a small pot on the stove and turn the stove on to a medium heat setting.

4.      Carefully monitor the water in the pot until it comes to a soft boil (approximately 100 °C). Use the thermometer provided in your lab kit to verify the water temperature. Turn the stove off when the water begins to boil. Immediately proceed to Step 5.

CAUTION: Be sure to turn the stove off after creating the hot water bath. Monitor the heating water at all times, and never handle a hot pan without appropriate pot holders.

5.      If using a microwave, place the microwave-safe bowl in the microwave and heat the water in 30 second increments until the temperature of the water is approximately 100 °C. Use the thermometer provided in your lab kit to verify the water temperature. Wait approximately one minute before proceeding to Step 5.

5.      Place Tube 1 in the refrigerator. Leave Tube 2 at room temperature, and place Tube 3 in the hot water bath.

Important Note: The water should be at approximately 85 °C when you place Tube 3 in it. Verify the temperature with the thermometer to ensure the water is not too hot! Temperatures which exceed approximately 85  °C may denature the hydrogen peroxide.

6.      Record the temperatures of each condition in Table 2. Be sure to provide the thermometer with sufficient time in between each environment to avoid obscuring the temperature readings.

7.      Let the tubes sit for 15 minutes.

8.      During the 15 minutes prepare the balloons with yeast by adding ¼ tsp. of yeast each balloon. Make sure all the yeast gets settled to the bulb of the balloon and not caught in the neck. Be sure not spill yeast while handling the balloons.

9.      Carefully stretch the neck of the balloon to help ensure it does not rip when stretched over the opening of the test tube.

10.  Attach the neck of a balloon you prepared in step 8 to the top of Tube 2 (the room temperature test tube) making sure to not let the yeast spill into the test tube yet. Once the balloon is securely attached to the test tube lift the balloon and allow the yeast to enter the test tube. Tap the bulb of the balloon to ensure all the yeast falls into the tube.

11.  As quickly and carefully as possible remove the Tube 1 (cold) from the refrigerator and repeat steps 9 – 10 with Tube 1 using a balloon you prepared in step 8.

12.  As quickly and carefully as possible remove Tube 3 (hot) from the hot water bath and repeat steps 9 – 10 with Tube 3 using a balloon you prepared in step 8.

13.  Swirl each tube to mix, and wait 30 seconds.

14.  Wrap the string around the center of each balloon to measure the circumference. Measure the length of string with a ruler. Record your measurements in Table 2.

Table 2: Balloon Circumference vs. Temperature
Tube Temperature (°C) Balloon Circumference (Uninflated; cm) Balloon Circumference (Final; cm)
1 – (Cold)      
2 – (RT)    
3 – (Hot)    

 

 

Post-Lab Questions

1.      What reaction is being catalyzed in this experiment?

2.      What is the enzyme in this experiment? What is the substrate?

3.      What is the independent variable in this experiment? What is the dependent variable?

4.      How does the temperature affect enzyme function? Use evidence from your data to support your answer.

 

5.      Draw a graph of balloon diameter vs. temperature. What is the correlation?

 

6.      Is there a negative control in this experiment? If yes, identify the control. If no, suggest how you could revise the experiment to include a negative control.

 

7.      In general, how would an increase in substrate alter enzyme activity? Draw a graph to illustrate this relationship.

 

8.      Design an experiment to determine the optimal temperature for enzyme function, complete with controls. Where would you find the enzymes for this experiment? What substrate would you use?

Lab Enzymes

 
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