Lab: Making Connections - Weebly
Name ____________________________ Date __________
Regents Biology Mr. Collea
Making Connections
Part I. The Effect of Temperature on Heart Rate in Daphnia
Background Information
Homeostasis is the maintenance of a stable internal environment. One way organisms maintain homeostasis is by controlling their body temperature. Thermoregulation is the maintenance of internal temperatures within a range that allows cells to function. It may involve both physical and behavioral adaptations. For example, humans thermoregulate by sweating or shivering (physiological) and snakes by basking on sunny rocks (behavioral).
Figure 1. Thermoregulation in Humans
In this activity, we will be using a tiny crustacean called a Daphnia (related to shrimp) that has a clear outside skeleton (carapace) and jointed legs. Like other arthropods (jointed appendages), its heart is on its back and clearly visible through its carapace which makes it an ideal organism to study heart rate. Check out the diagram below to see more of the Daphnia’s anatomy.
Anatomy of the Daphnia
Discovering and explaining connections is one of the basic methods by which our knowledge of the world advances. It is what science is all about! Sometimes the connections are not what we expect or would predict, and sometimes we may have a hard time explaining them. Nevertheless, that is how science makes progress.
As previously stated in the Gum Lab, when scientist make connections, they are really looking at what impact the independent variable has on the dependent variable of an experiment. Being able to identify these variables is a skill we have been working on throughout the year.
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QUESTION: What affect does temperature have on the heart rate of Daphnia?
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(1) Based upon your prior knowledge, make a hypothesis as to how you predict a decrease in temperature will affect the heart rate of a Daphnia.
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MATERIALS
Daphnia in culture liquid Transfer pipette cotton
A clean depression slide/coverslip Compound microscope
METHODS
1. Place a SMALL stand(s) of cotton in the center of your depression slide and using a clean pipette, carefully transfer a Daphnia and ONE drop of liquid onto a depression slide over the piece of cotton.
(Keep the drop small so that the Daphnia can’t swim out of your field of view.)
2. Place the slide under the microscope and focus on the Daphnia so that you can see the beating heart.
Keep the light for your microscope OFF as much as possible to avoid overheating your Daphnia!
3. Count the number of heart beats that occur in 10 seconds. Have your lab partner time 10 seconds for you as you count heartbeats. You want to make your measurements quickly, so that the Daphnia does not become stressed in the small volume of water.
4. Record the number of heart beats in the data table below. Multiply the number by 6 to get the number of beats per minute.
5. Take at least three separate heart rate measurements for each individual Daphnia and calculate the average of the three measurements.
6. When you have finished recording the heart rate in water at room temperature (the CONTROL), repeat the same procedure, however, this time you will place your Daphnia in the refrigerator for 1 minute to simulate a COLD environment.
7. Record the number of heart beats in the data table below. Multiply the number by 6 to get the number of beats per minute.
8. Take at least three separate heart rate measurements for each individual Daphnia in each environment and calculate the average of the three measurements.
Table 1.
| |Temperature |
| |Room Temp. (control) |Cold |
|Trial |10 sec. |BPM (x6) |10 sec. |BPM (x6) |
|1 | | | | |
|2 | | | | |
|3 | | | | |
|Average |----- | |----- | |
Making Connections
Part II. Calculating and Graphing your Resting Heart Rate
Background Information
Homeostasis is the maintenance of a stable internal environment. Another way organisms maintain homeostasis is by controlling their heart rate. Heart rate can be measured by taking your pulse. Your heart rate / pulse rate will vary depending on your cells demand to take oxygen/O2 into the body and remove carbon dioxide (CO2) from the body.
Figure 1. Equation for Cellular Respiration
Any activity that requires energy or ATP will most likely increase your heart rate because of the need for your circulatory system to bring glucose and oxygen TO BODY CELLS and remove carbon dioxide FROM BODY CELLS.
Figure 2. Transport of Gases O2 and CO2 in Humans
METHODS
(1) Looking at the diagram to the right, practice taking and calculating your resting pulse rate.
Table 1. Resting Pulse Rate
| |Resting Pulse Rate. (control) |
|Trial |10 sec. |BPM (x6) |
|1 | | |
|2 | | |
|3 | | |
|Average |----- | |
(2) Using the average resting pulse rate for each student in the class, complete the data table below.
Table 2. Class Results - Average Resting Pulse Rate
|Average Resting Pulse Rate |< 51 |51-60 |61-70 |71-80 |81-90 |> 90 |
(3) Using the information in the data table above, to construct a histogram of the class results on your Summary Sheet.
Making Connections
Part III. The Effect of Exercise on Clothespin Squeezing Rate
Background Information
You hear many claims made every day. Advertisers make claims about the usefulness or
effectiveness of their products. Your friend may claim to be able to do something that you
do not think he or she can really do. Do you believe all the claims that people make? Have
you ever bought a product based on a claim made in an advertisement, only to find that the
product did not work as you expected it to?
When does a claim become a fact? Scientists look for evidence to support or refute a claim.
Evidence can help you determine which claims are facts and which are opinions or even
misrepresentations. For example, if one of your classmates claims to be the fastest runner
in the class, you could gather evidence by holding a series of races. If your classmate’s claim
is true, that person should win all of the races. If another individual wins the races, your
classmate’s claim was simply an opinion not supported by the evidence.
In this part of the laboratory activity, you will conduct an investigation to determine which
of two opposing claims can supported with evidence. First read the section below. It
describes two opposing claims. Then investigate using to see which claim (if either) is supported.
Conflicting Claims About the Effect of Exercise on the Rate of Clothespin Squeezing
Student A claims that a person will be able to squeeze a clothes pin more times in a minute if
the person exercises first.
Student B claims that a person will be able to squeeze a clothespin more times in a minute if
the person does not exercise first.
Which of the two students do you agree with? ______
Use your knowledge of biology to come up reasons that support each student.
|Reason(s) to Support Student A |Reason(s) to Support Student B |
| | |
State your hypothesis (prediction) in the space below:
HYPOTHESIS:
____________________ before activity will increase the number of squeezes per minute. (exercising/resting)
Let us test your hypothesis by conducting a simple experiment to see if it is correct.
Record your data in Table 3.
| |Number of Squeezes/Minute |
|Trial |Resting |Exercise |
|1 | | |
|2 | | |
|3 | | |
|Avg. | | |
Table 3.
Name ____________________________ Date __________
Regents Biology Mr. Collea
Making Connections
Part I. The Effect of Temperature on Heart Rate in Daphnia
Summary Sheet
1. Define homeostasis.
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2. Restate your hypothesis for this experiment.
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3. Identify the independent and dependent variable for this experiment.
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| |Temperature |
| |Room Temp. (control) |Cold |
|Trial |10 sec. |BPM (x6) |10 sec. |BPM (x6) |
|Average |----- | |----- | |
|Heart Rate | | | | |
4. Transfer the information from Table 1 to the data table to the right.
5. Using the information above, construct a bar graph in the grid below.
Effects of Cold Temperatures on the Heart Rate of Daphnia
| | | | | | | |
1. Histogram Title: _________________________________________________________
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
|< 51 |51-60 |61-70 |71-80 |81-90 |> 90 |
1. State TWO observations from the histogram.
(a) ____________________________________________________________________
____________________________________________________________________
(b) ____________________________________________________________________
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2. State TWO inferences from the histogram.
(a) ____________________________________________________________________
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(b) ____________________________________________________________________
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3. Briefly describe the transport of gases in humans.
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Making Connections
Part III. The Effect of Exercise on Clothespin Squeezing Rate
Summary Sheet
1. Construct a bar graph on the grid below using the information from Table 3.
| |Number of Squeezes/Minute |
|Trial |Resting |Exercise |
|1 | | |
|2 | | |
|3 | | |
|Avg. | | |
Table 3.
Graph Title: _________________________________________________________
| | | | | |
| | | | | |
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| | | | | |
| | | | | |
| | | | | |
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| | | | | |
Number
of
Squeezes
(minute)
Resting Exercise
2. Did you prove your hypothesis right or wrong? (Use data to support your answer.)
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3. Identify the independent variable in this experiment.
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4. Identify the dependent variable in this experiment.
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5. Identify THREE controlled variables in this experiment.
(a) ________________________________________________________________________________
(b) ________________________________________________________________________________
(c) ________________________________________________________________________________
6. What effect does exercise have on heart rate? Explain.
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Making Connections
Post Lab Questions
1. In designing any experiment, which step should you perform first?
(1) collect and organize the data (3) design the data tables
(2) determine the question you are trying to answer (4) decide how many subjects to test
2. Which activity was performed in lab to demonstrate muscle fatigue?
(1) repeatedly taking your pulse (3) repeatedly squeezing a clothespin
(2) jogging around the school (4) constructing a histogram
3. Which best describes the proper technique for taking your own pulse as described in the lab directions?
(1) Press your thumb lightly against your wrist.
(2) Press two fingers firmly against the side of your neck.
(3) Press two fingers firmly against your wrist.
(4) Press two fingers lightly around your wrist.
4. What was graphed in the histogram you created?
(1) The number of students in each average pulse range.
(2) How pulse rate affected muscle fatigue.
(3) How muscle fatigue affected pulse rate.
(4) The number of clothespins squeezed per minute.
5. If a scientist suspects that two activities have a connection, what is one reliable way the scientist can
find out if he or she is correct?
(1) He/she should ask many people if they have noticed the same connection.
(2) He/she should publish the idea in a scientific journal for peer review.
(3) He/she should look for other connections that might be related.
(4) He/she should design and perform a controlled experiment to test his suspicion.
6. A student squeezes a clothespin 115 times in one minute. She then repeats the activity and squeezes the
clothespin 96 times in one minute. Which would be the most likely biological explanation for this? (1) Her muscle cells became fatigued as waste product built up inside of them.
(2) Her pulse rate became too fast to deliver oxygen to the cells.
(3) The clothespin hinge became harder to squeeze as it heated up.
(4) The experiment as not designed properly, causing human error.
7. What is the best reason a person's pulse rate usually increases after exercise?
(1) As the blood moves faster, it makes the heart pump faster.
(2) Exercise raises blood sugar levels, causing more insulin in the heart.
(3) When the lungs breathe faster, the heart has to work harder to keep up.
(4) Muscles need extra oxygen and food to replace what was used up.
8. In this experiment, you measured the number of times that a clothespin was squeezed in a minute.
What purpose in the experiment did the clothespin squeeze data serve?
(1) control (3) hypothesis
(2) dependent variable (4) independent variable
9. A student formulated a hypothesis that cotton will grow larger bolls (pods) if magnesium is added to the soil. The student has two experimental fields of cotton, one with magnesium and one without. Which
data should be collected to support this hypothesis?
(1) height of the cotton plants in both fields (3) diameter of the cotton bolls in both fields
(2) color of the cotton bolls in both fields (4) length of the growing season in both fields
10. In an investigation to determine the change in heart rate with increased activity, a biology teacher asked students to take their pulses immediately before and immediately after exercising for 2 minutes.
The data showed an average heart rate of 72 beats per minute before exercising and 90 beats per minute
after exercising. If a valid conclusion is to be made from the results of this experiment, which assumption must be made?
(1) In most students, the average heart rate is not affected by exercise.
(2) Each student exercised with approximately the same intensity.
(3) Exercise causes the heart rate to slow down.
(4) The heart rate of each student goes up by 18 beats after jogging for 2 minutes
11. A student hypothesized that lettuce seeds would not germinate (begin to grow) unless they were covered with a layer of soil. The student planted 10 lettuce seeds under a layer of soil and scattered 10 lettuce seeds on top of the soil. To improve the reliability of these results, the student should -
(1) conclude that darkness is necessary for seed germination.
(2) conclude that light is necessary for seed germination.
(3) revise the hypothesis.
(4) repeat the experiment using a larger sample size.
12. Diagrams, tables, and graphs are used by scientists mainly to -
(1) design a research plan for an experiment. (3) predict the independent variable.
(2) test a hypothesis. (4) organize data.
13. In an experiment to determine the effect of exercise on pulse rate, a student checks his pulse rate before and after exercising for several minutes. The purpose of checking his pulse rate before exercising is that it -
(1) serves as the conclusion for the experiment. (3) is needed to justify the sample size.
(2) serves as a control for the experiment. (4) is needed to formulate a hypothesis.
14. An increase in heart rate will most likely result in -
(1) a decrease in metabolic rate. (3) an increase in pulse rate.
(2) an increase in cell division. (4) a decrease in body temperature.
15. The students want to improve the validity of their conclusion. The best way to accomplish this is to -
(1) change the hypothesis. (3) repeat the investigation several times.
(2) increase the number of variables. (4) increase the height of participants in each group.
16. When people exercise, their body cells build up more waste quickly. Which two body systems work together to remove these wastes from their cells?
(1) immune and endocrine (3) digestive and skeletal
(2) respiratory and circulatory (4) circulatory and digestive
17. What is an advantage of a change in pulse rate after exercising?
(1) The heart needs to produce more energy to supply the active muscle cells and maintain homeostasis.
(2) An increased blood flow carries excess waste products away from the active muscle cells.
(3) The blood is removing oxygen from muscle cells that were not active and carrying it to muscle cells that are active.
(4) The blood is supplying the active muscle cells with carbon dioxide to neutralize wastes in those cells.
18. A student measures his pulse rate while he is watching television and records it. Next, he walks to a friend’s house nearby and when he arrives, measures and records his pulse rate again. He and his friend then decide to run to the mall a few blocks away. On arriving at the mall, the student measures and records his pulse rate once again. Finally, after sitting and talking for a half hour, the student measures and records his pulse rate for the last time.
Which graph to the right best illustrates the expected changes in his pulse rate according to the activities described above?
19. Students noticed that some of their classmates have a hard time concentrating during class. They thought it may have some connection with the fact that these students consume energy drinks just before class. An experiment was proposed to find out if there is a connection between energy drinks and the lack of ability to concentrate in class. A properly designed experiment to determine this would include having -
(1) the whole class drink energy drinks and no water at all, for the entire time of the experiment.
(2) the whole class drink water and no energy drinks at all, for the entire time of the experiment.
(3) the students drink both water and an energy drink just before class.
(4) half the students drink water and the other half drink an energy drink just before class.
20. Complete the “Pulse/Min” column in the data table below for all three trials as well as the average pulse rate per minute.
21. Explain how the validity of the clothespin experiment could be improved.
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22. When a person exercises, changes occur in muscle cells as they release more energy.
Explain how increased blood flow helps these muscle cells release more energy.
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Directions (23–24): Using the information given in the data table below, construct a line graph on the grid
provided following the directions below.
23. Label the axis and mark an appropriate scale for each.
24. Plot the data for each moth population on the grid. Surround each point for the light colored with a small circle and surround each point for the dark colored with a small square and then connect the points.
A group of students obtained the following data:
14. The activity of which body system was measured to obtain these data?
15. The activity of which other body system would be altered as a direct result of the exercise?
16. What effect would exercise have on the system you identified in question 15?
17. Explain how this change in pulse rate helps maintain homeostasis in muscle cells.
20. What additional data should the student have collected in order to determine the effect of squeezing a clothespin on his pulse rate?
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Heart Rate
(BPM)
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