SCI 115 Quiz 9

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Version 1

1. Which of the following is a disadvantage of an exoskeleton?

2. Which of the following animals do NOT have tissues?

3. Which of the following organisms have an exoskeleton?

4. Tetrapods are the direct descendants of

5. In amphibians, what function does the cloaca serve?

6. This vertebrate is a fish, has a cartilaginous skeleton, no jaws, and a tooth-covered tongue. This animal is a

7. The number of individuals of the same species in some specified area or volume of habitat is the

8. The most common type of population distribution is

9. A change in a population that is NOT related strictly to the size of the population is best described as

10. Which of the following models of growth takes place when the amount of available resources is not limiting?

11. Jellyfish are as likely to die at one age as any other. Thus, a type ___ survivorship curve characterizes their life history.

12. What invention about 11,000 years ago led to a boom in the human population?

Version 2

1. This animal has radial symmetry, a gastrovascular cavity, and the same opening is for the entry of food and expulsion of waste. It is ___.

2. Which of the following are characterized by radially symmetrical members?

3. Sponges are

4. This animal is a tetrapod that has a cloaca, aquatic larvae, and is tailless as an adult. This animal is

5. Amniotes differ from amphibians by

6. This vertebrate is a fish, has a cartilaginous skeleton, no jaws, and a tooth-covered tongue. This animal is a

7. The most common type of population distribution is

8. The number of individuals that make up a population gene pool is the

9. Which of the following factors is NOT a density-independent factor?

10. A change in a population that is NOT related strictly to the size of the population is best described as

11. Most octopuses die early in life; those that survive can live up to 5 years. Octopuses are best characterized by a type __ survivorship curve.

12. What invention about 11,000 years ago led to a boom in the human population?

 
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Gogo

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If Only I Had a System …This will be your opportunity to be the teacher. Click on “View Full Description and attachments” below for the directions and questions. Be sure to open the file that says “MATH110 Read This First” before you jump in!View Full Description and Attachment(s)Start with the attached files. First read the one entitled “READ THIS FIRST” and then open the file called “Systems of Equations Problems with Answers”. It is difficult to learn how to do story problems because there are so many different types. If you want to do well on this week’s test, FOLLOW THESE INSTRUCTIONS! 1) Go through ALL the story problems provided and try to solve them. Pretend it’s a Practice Test. Check your answers with the key provided. 2) Pick ONE of the problems that you got right (that has not already been solved by a classmate), and demonstrate its solution for the rest of us. 3) Study how your classmates solved the problems that you missed. Remember that these may be on the test!

To demonstrate your problem, select Start a New Conversation and make BOTH the problem number and topic (#10 Jarod and the Bunnies) the subject of your post.

Begin your post with a statement of the problem so that we can understand what you are doing.
The answers are at the end of the file, so don’t just give an answer—we can already see what the answers are. Don’t post an explanation unless your answer matches the correct one!

Your goal should be to explain this problem so well that a classmate who “just doesn’t get it” will be able to understand it completely!
This is a moderated forum. Your posting will say PENDING and will not be visible to the rest of the class until I approve it. Occasionally, more than one person will tackle a problem before they can see the work of others. In that case, credit will be given to all posters. Once the solution to a problem has become visible, that problem is off limits and you will need to choose a different problem in order to get credit.
I will indicate in the grading comments if corrections need to be made. If you haven’t received credit, first double-check for my comments in the gradebook. If everything looks OK, then message me asking me to check on it.
You must make the necessary corrections and have your work posted in order to receive credit.
For this particular Forum, no responses are required – your initial post is worth the full 10 points. Should you choose to respond to a classmate, a request for clarification on the procedure used, a suggestion for an alternate method of solving the problem or a general comment about the technique would all be appropriate. I’m sure that a “thank you” for an exceptionally clear explanation would also be welcome!

Please sign ALL your Forum posts with the name that you like to be called – it makes it so much easier for the rest of us to address you by your preferred name when we respond.

Initial Post Due: Tuesday, by 11:55 p.m., ET

Systems+of+Equations+with+Answers.pdfMATH110 Read This First.pdf

Systems of Equations

1) A vendor sells hot dogs and bags of potato chips. A customer buys 4 hot dogs and 5 bags of potato chips for $12.00. Another customer buys 3 hot dogs and 4 bags of potato chips for $9.25. Find the cost of each item.

1)

2) University Theater sold 556 tickets for a play. Tickets cost $22 per adult and $12 per senior citizen. If total receipts were $8492, how many senior citizen tickets were sold?

2)

3) A tour group split into two groups when waiting in line for food at a fast food counter. The first group bought 8 slices of pizza and 4 soft drinks for $36.12. The second group bought 6 slices of pizza and 6 soft drinks for $31.74. How much does one slice of pizza cost?

3)

4) Tina Thompson scored 34 points in a recent basketball game without making any 3-point shots. She scored 23 times, making several free

throws worth 1 point each and several field goals worth two points each. How many free throws did she make? How many 2-point field goals did

she make?

4)

5) Julio has found that his new car gets 36 miles per gallon on the highway and 31 miles per gallon in the city. He recently drove 397 miles on 12 gallons of gasoline. How many miles did he drive on the highway? How many miles did he drive in the city?

5)

6) A textile company has specific dyeing and drying times for its different cloths. A roll of Cloth A requires 65 minutes of dyeing time and 50 minutes of drying time. A roll of Cloth B requires 55 minutes of dyeing time and 30 minutes of drying time. The production division allocates 2440 minutes of dyeing time and 1680 minutes of drying time for the week. How many rolls of each cloth can be dyed and dried?

6)

7) A bank teller has 54 $5 and $20 bills in her cash drawer. The value of the bills is $780. How many $5 bills are there?

7)

8) Jamil always throws loose change into a pencil holder on his desk and takes it out every two weeks. This time it is all nickels and dimes. There are 2 times as many dimes as nickels, and the value of the dimes is $1.65 more than the value of the nickels. How many nickels and dimes does Jamil have?

8)

9) A flat rectangular piece of aluminum has a perimeter of 60 inches. The length is 14 inches longer than the width. Find the width.

9)

1

 

 

10) Jarod is having a problem with rabbits getting into his vegetable garden, so he decides to fence it in. The length of the garden is 8 feet more than 3 times the width. He needs 64 feet of fencing to do the job. Find the length and width of the garden.

10)

11) Two angles are supplementary if the sum of their measures is 180°. The measure of the first angle is 18° less than two times the second angle. Find the measure of each angle.

11)

12) The three angles in a triangle always add up to 180°. If one angle in a triangle is 72° and the second is 2 times the third, what are the three angles?

12)

13) An isosceles triangle is one in which two of the sides are congruent. The perimeter of an isosceles triangle is 21 mm. If the length of the congruent sides is 3 times the length of the third side, find the dimensions of the triangle.

13)

14) A chemist needs 130 milliliters of a 57% solution but has only 33% and 85% solutions available. Find how many milliliters of each that should be mixed to get the desired solution.

14)

15) Two lines that are not parallel are shown. Suppose that the measure of angle 1 is (3x + 2y)°, the measure of angle 2 is 9y°, and the measure of

angle 3 is (x + y)°. Find x and y.

15)

16) The manager of a bulk foods establishment sells a trail mix for $8 per pound and premium cashews for $15 per pound. The manager wishes to make a 35-pound trail mix-cashew mixture that will sell for $14 per

pound. How many pounds of each should be used?

16)

17) A college student earned $7300 during summer vacation working as a waiter in a popular restaurant. The student invested part of the money at 7% and the rest at 6%. If the student received a total of $458 in interest at the end of the year, how much was invested at 7%?

17)

2

 

 

18) A retired couple has $160,000 to invest to obtain annual income. They want some of it invested in safe Certificates of Deposit yielding 6%. The rest they want to invest in AA bonds yielding 11% per year. How much should they invest in each to realize exactly $15,600 per year?

18)

19) A certain aircraft can fly 1330 miles with the wind in 5 hours and travel the same distance against the wind in 7 hours. What is the speed of the wind?

19)

20) Julie and Eric row their boat (at a constant speed) 40 miles downstream for 4 hours, helped by the current. Rowing at the same rate, the trip back against the current takes 10 hours. Find the rate of the current.

20)

21) Khang and Hector live 88 miles apart in southeastern Missouri. They decide to bicycle towards each other and meet somewhere in between. Hector’s rate of speed is 60% of Khang’s. They start out at the same time and meet 5 hours later. Find Hector’s rate of speed.

21)

22) Devon purchased tickets to an air show for 9 adults and 2 children. The total cost was $252. The cost of a child’s ticket was $6 less than the cost of an adult’s ticket. Find the price of an adult’s ticket and a child’s ticket.

22)

23) On a buying trip in Los Angeles, Rosaria Perez ordered 120 pieces of jewelry: a number of bracelets at $8 each and a number of necklaces at $11 each. She wrote a check for $1140 to pay for the order. How many bracelets and how many necklaces did Rosaria purchase?

23)

24) Natasha rides her bike (at a constant speed) for 4 hours, helped by a wind of 3 miles per hour. Pedaling at the same rate, the trip back against the wind takes 10 hours. Find find the total round trip distance she traveled.

24)

25) A barge takes 4 hours to move (at a constant rate) downstream for 40 miles, helped by a current of 3 miles per hour. If the barge’s engines are set at the same pace, find the time of its return trip against the current.

25)

26) Doreen and Irena plan to leave their houses at the same time, roller blade towards each other, and meet for lunch after 2 hours on the road. Doreen can maintain a speed of 2 miles per hour, which is 40% of Irena’s speed. If they meet exactly as planned, what is the distance between their houses?

26)

3

 

 

27) Dmitri needs 7 liters of a 36% solution of sulfuric acid for a research project in molecular biology. He has two supplies of sulfuric acid solution: one is an unlimited supply of the 56% solution and the other an unlimited supply of the 21% solution. How many liters of each solution should Dmitri use?

27)

28) Chandra has 2 liters of a 30% solution of sodium hydroxide in a container. What is the amount and concentration of sodium hydroxide solution she must add to this in order to end up with 6 liters of 46% solution?

28)

29) Jimmy is a partner in an Internet-based coffee supplier. The company

offers gourmet coffee beans for $12 per pound and regular coffee beans for $6 per pound. Jimmy is creating a medium-price product that will

sell for $8 per pound. The first thing to go into the mixing bin was 10 pounds of the gourmet beans. How many pounds of the less expensive regular beans should be added?

29)

30) During the 1998-1999 Little League season, the Tigers played 57 games.

They lost 21 more games than they won. How many games did they win that season?

30)

31) The perimeter of a rectangle is 48 m. If the width were doubled and the length were increased by 24 m, the perimeter would be 112 m. What are the length and width of the rectangle?

31)

32) The perimeter of a triangle is 46 cm. The triangle is isosceles now, but if its base were lengthened by 4 cm and each leg were shortened by 7 cm, it would be equilateral. Find the length of the base of the original triangle.

32)

33) The side of an equilateral triangle is 8 inches shorter than the side of a square. The perimeter of the square is 46 inches more than the perimeter of the triangle. Find the length of a side of the square.

33)

34) The side of an equilateral triangle is 2 inches shorter than the side of a square. The perimeter of the square is 30 inches more than the perimeter of the triangle. Find the length of a side of the triangle.

34)

4

 

 

Answer Key Testname: SYSTEMS_OF_EQUATIONS

1) $1.75 for a hot dog; $1.00 for a bag of potato chips 2) 374 senior citizen tickets 3) $3.74 per slice of pizza 4) 12 free throws, 11 field goals 5) 180 miles on the highway, 217 miles in the city 6) 24 rolls of Cloth A, 16 rolls of Cloth B 7) 20 $5 bills 8) 11 nickels and 22 dimes 9) 8 inches

10) length: 26 feet; width: 6 feet 11) first angle = 114°

second angle = 66°

12) 72°, 72°, 36° 13) 3 mm, 9 mm, 9 mm 14) 70 mL of 33%; 60 mL of 85%

15) x = 288 7

, y = 36 7

16) 5 pounds of trail mix 30 pounds of cashews

17) $2000 18) $120,000 at 11% and $40,000 at 6% 19) 38 mph 20) 3 mph 21) 6.6 mph 22) adult’s ticket: $24; child’s ticket: $18 23) 60 bracelets and 60 necklaces 24) 80 mi 25) 10 hr 26) 14 mi 27) 56% solution: 3 L; 21% solution: 4 L 28) 4 L of 54% solution 29) 20 lb 30) 18 games 31) Length: 16 m; width: 8 m 32) 8 cm 33) 22 inches 34) 22 inches

5

 
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Effect of human impacts on the living world.

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Objectives

· Investigate the process of Natural Selection using the Peppered Moth as the example

· Analyze population trends

· Understand the effect of human impacts on the living world.

NGSS: 3-LS4-2. Use evidence to construct an explanation for how the variations in characteristics among individuals of the same species may provide advantages in surviving, finding mates, and reproducing

· LS4.B: Natural Selection Sometimes the differences in characteristics between individuals of the same species provide advantages in surviving, finding mates, and reproducing. (3-LS4-2)

Introduction

Between 1831 and 1836 Charles Darwin, a naturalist, sailed around the world as a member of a British scientific expedition. During the trip he made observations about the natural world and collected numerous species of plants and animals. These observations led to a book called The Origin of the Species, where he proposed The Theory of Natural Section.  Darwin suggests that “those individuals who possess superior physical, behavioral, or other attributes are more likely to survive than those which are not so well endowed” (a.k.a. survival of the fittest).

One example of an advantage that leads to survival of the fittest is camouflage. The term camouflage means to conceal by disguise. There are many examples in nature of animals that hide from predators. Chameleons are known for their ability to alter their skin color to blend in with the leaves and plants they are hiding in. This enables them to “sneak attack” their prey. Insects often use camouflage to hide from birds or other predators.

The case of the peppered moth in Manchester, England is a well documented scientific study of the value of camouflage in Natural Selection. This case involves two forms of a moth, an insect which relies on camouflage to survive. One form of the moth was white colored and the other form a black color. During the end of the 19th century, with the beginning of the Industrial Revolution, smoke particles from the factories gradually blackened the trees on which the moths rested. What was the result of this change in the environment? How were the moth populations affected? How did the moth populations change?

Instructions 
               Go to:                   http://peppermoths.weebly.com
               Click on:               A bird’s eye view of natural selection (far right circle with bird)
               Read:                    The Instructions
               Play:                     5 minutes in the Lichen Forest; hit pause and write down your 
                                              percentages in the table below.  Stop and goto the Sooty Forest.
               Play:                     5 minutes in the Sooty Forest; hit pause and write down your 
                                              percentages in the table below.  Stop and answer the questions.
Alternatives:       http://www.techapps.net/interactives/pepperMoths.swf
                               http://www6.district125.k12.il.us/~nfischer/Moth/default.htm
Name:  _____________________
Peppered Moth Analysis

 

Percent Dark Moths
Percent Light Moths
Lichen Forest
Sooty Forest
1.    Explain how the color of moths increases or decreases their chances of survival depending on the environment. 
2.    Application:  500 light colored moths and 500 dark colored moths are released into a polluted forest.  After 2 days the moths were recaptured, make a prediction about the number of each type of moth that would be captured. 
3.    How has the striking change in coloration come about? (Include an explanation of how the dark moth appeared and how the proportion of dark moths changed from 0.0005% to more than 90% in polluted forests.)
4.    Using the four words we discussed in Lecture, explain how the Peppered Moth population is an example of Natural Selection.
5.    Is Evolution a directed or purposeful event?  Is it random?  Or is a populatio

Name: _____________/Sect___

 

Natural Selection and

MCj04380260000[1]

 

The Peppered Moth

(On-Line Simulation)

 

Objectives

1. Investigate the process of Natural Selection using the Peppered Moth as the example

1. Analyze population trends

1. Understand the effect of human impacts on the living world.

 

NGSS: 3-LS4-2. Use evidence to construct an explanation for how the variations in characteristics among individuals of the same species may provide advantages in surviving, finding mates, and reproducing

· LS4.B: Natural Selection Sometimes the differences in characteristics between individuals of the same species provide advantages in surviving, finding mates, and reproducing. (3-LS4-2)

 

Introduction

Between 1831 and 1836 Charles Darwin, a naturalist, sailed around the world as a member of a British scientific expedition. During the trip he made observations about the natural world and collected numerous species of plants and animals. These observations led to a book called The Origin of the Species, where he proposed The Theory of Natural Section. Darwin suggests that “those individuals who possess superior physical, behavioral, or other attributes are more likely to survive than those which are not so well endowed” (a.k.a. survival of the fittest).

One example of an advantage that leads to survival of the fittest is camouflage. The term camouflage means to conceal by disguise. There are many examples in nature of animals that hide from predators. Chameleons are known for their ability to alter their skin color to blend in with the leaves and plants they are hiding in. This enables them to “sneak attack” their prey. Insects often use camouflage to hide from birds or other predators.

The case of the peppered moth in Manchester, England is a well documented scientific study of the value of camouflage in Natural Selection. This case involves two forms of a moth, an insect which relies on camouflage to survive. One form of the moth was white colored and the other form a black color. During the end of the 19th century, with the beginning of the Industrial Revolution, smoke particles from the factories gradually blackened the trees on which the moths rested. What was the result of this change in the environment? How were the moth populations affected? How did the moth populations change?

Instructions 
(ask your instructor which site should be used)

	Go to:  		http://peppermoths.weebly.com

	Click on:	A bird’s eye view of natural selection (far right circle with bird)

	Read:  		The Instructions
	Play:  		5 minutes in the 
Lichen Forest
; hit pause and write down your
			percentages in the table below.  Stop and goto the Sooty Forest.
		Play:  		5 minutes in the 
Sooty Forest
; hit pause and write down your
				percentages in the table below.  Stop and answer the questions.
Alternatives:	

http://www.techapps.net/interactives/pepperMoths.swf


		

http://www6.district125.k12.il.us/~nfischer/Moth/default.htm


Name:  _____________________
Peppered Moth Analysis





Percent Dark Moths




Percent Light Moths








Lichen Forest
















Sooty Forest
















1. Explain how the color of moths increases or decreases their chances of survival depending on the environment.


2. Application:  500 light colored moths and 500 dark colored moths are released into a polluted forest.  After 2 days the moths were recaptured, make a prediction about the number of each type of moth that would be captured.


3. How has the striking change in coloration come about? (Include an explanation of how the dark moth appeared and how the proportion of dark moths changed from 0.0005% to more than 90% in polluted forests.)


4. Using the four words we discussed in Lecture, explain how the Peppered Moth population is an example of Natural Selection.



5. Is Evolution a directed or purposeful event?  Is it random?  Or is a population evolving “toward something”?  Explain your answer.



 

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	Lab Enzymes				
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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?

 

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