Author: Biology Junction Team

Scientific Method & Blood Flow

 

Scientific Method & Blood

 

INTRODUCTION:

In this lab you will learn to form a hypothesis, conduct experiments around that hypothesis, and collect and analyze data. One of the most important characteristics of modern science is its quantitative approach to solving problems. One of the first scientists to use quantitative methods was William Harvey, who discovered that blood circulated through the body. At the time Harvey began his work, anatomists believed that the liver produced blood from the food that the body consumed. The blood was then carried by veins to the heart, purified in the lungs, and then pumped to the various organs of the body, where it was consumed. Harvey measured that the left ventricle of the heart held roughly 100 ml of blood. He also measured that the heart beats an average of 64 times per minute.

QUESTION 1:

From the information above, and assuming that 1 ml of blood weighs 1 g, how much blood would the body need to produce per hour in ( g/hr.) to replace the blood consumed by the organs? _______g/hr.

Harvey hypothesized that the same blood must circulate continuously throughout the body.

MATERIALS:

Watch with second hand, or clock

PROCEDURE:

  1. While sitting quietly at your desk, find the pulse in your wrist and count the beats for one minute. You and your lab partner can do this on yourselves, or each other. Record the names of both subjects and their beats per minute heart rate on DATA TABLE 1 as sample 1.
  2. Repeat step 1 two more times for each subject. Record the data in the appropriate place on DATA TABLE 1.
  3. Calculate the average pulse rate for each subject and record the results on DATA TABLE 1.

How do you think standing or holding your breath will affect your pulse rate? ______________________________________________________

QUESTION 2:

Choose one of these activities and formulate a hypothesis about its effect on pulse rate. What is the independent variable? What is the dependent variable?

Hypothesis _______________________________________________

Independent Variable _______________________________________

Dependent Variable ________________________________________

  1. Repeat steps 1, 2, and 3 for each subject, this time with the subjects standing or holding their breath. Record your data and calculations in the appropriate DATA TABLE

 

 

DATA TABLE 1: Resting heart rate
NUMBER OF BEATS PER MINUTE AVERAGE NUMBER OF
BEATS PER MINUTE
SUBJECT sample 1 sample 2 sample 3

 

 

 

DATA TABLE 2: Heart rate standing
NUMBER OF BEATS PER MINUTE AVERAGE NUMBER OF
BEATS PER MINUTE
SUBJECT sample 1 sample 2 sample 3

 

 

 

DATA TABLE 3: Heart rate holding breath
NUMBER OF BEATS PER MINUTE AVERAGE NUMBER OF
BEATS PER MINUTE
SUBJECT sample 1 sample 2 sample 3

 

Conclusion:  Compare your data from step 4 with your data from step 3.

1. How do your results in step 4 compare with the hypothesis you made?

 

2. What measurement did you use as a control in this investigation?

 

3. What are some possible sources of error in this experiment?

Scientific Method puzzle

Scientific Method

Find each term and then define it on the back of the paper.

 

 

Y N B E L F U N I J M H T N M
H O E N B G W N C G W N Q S Y
A I R X H Y P O T H E S I S C
C T E A P L K J V D V L Y R O
H A A L U E Q G N I O F E C N
A V X D B P R E X R S P G F C
R R C E B A P I T O E H S F L
T E G T R E I N M A H T I K U
I S E S D R O R T E A Y S A S
E B K N V C O A A B N Q Y V I
I O I Q T V B R L V K T L P O
S X Q R F L L E S H J S A P N
B I T N E D N E P E D X N V B
Q O N I Y K Z H E L Q Z A J P
T E S T I N G H P A R G N R O

 

 

 

ANALYSIS CHART CONCLUSION
CONTROL DATA DEPENDENT
ERRORS EXPERIMENT GRAPH
HYPOTHESIS INDEPENDENT OBSERVATION
REPEATABLE TABLE TESTING
VARIABLE

 

 

 

 

Solution

 

 

Scientific Method activity

Scientific Method “I’m All Thumbs”
Introduction:
What makes a “Class Champion” thumb wrestler? Does thumb diameter, length, or wrist diameter have an effect on the overall chances of winning a thumb wrestling match? In this investigation we will develop a hypothesis based on physical data collected from our classmates. We will then test this hypothesis by conducting a thumb wrestling tournament to determine an overall “Class Champion”.

Materials:
Metric ruler, metric tape measure (see bottom of lab), scissors, string, calculator

Objectives:

  • Students will take and record accurate measurements of their wrist, and their thumb’s circumference and length.
  • Students will analyze the data collected and determine if their hypothesis is correct.
  • Correctly line graph the collected data.
  • Learn the rules of thumb wrestling.
  • Conduct a thumb wrestling tournament.

Procedures:

  • Choose a partner and perform the following measurements using the metric tape measure found at the bottom of this lab. Then have your partner perform them on you.
  • Measure the circumference of the thumb, in centimeters, at its widest point. Record this data on the following line ___________cm. and on the table on the chalk board.
  • Measure the length of the thumb, using the metric ruler in centimeters, from its tip to the end of its second joint. Record this data on the following line ___________cm. and on the table on the chalk board.
  • Measure the circumference of the wrist over the ulnar knob, in centimeters, and record this data on the following line ____________ and on the table on the chalk board.
  • Copy the data, on the board, on to the table in the results section of the lab.
  • The class will form and record a hypothesis based on the collected data.
  • The Hypothesis:
    ______________________________________________________________

        ______________________________________________________________

  • Rules of thumb wrestling: Two players grasp hands shown in the illustration; they touch thumbs to the opposite sides of the other person’s hand three times, then come out wrestling. The object, of course, is to hold the other person’s thumb down, for a count of three, using only your thumb.

 

  • Boys will wrestle boys and girls will wrestle girls.
  • A tournament schedule will be set up to match opponents.
  • After the completion, a champion will be declared in both categories, (male and female).

Results:
Complete the following data table:

 

Student Name
Gender (M / F)
Thumb Circumference in cm
Thumb Length in cm
Wrist circumference in cm
Record
( won/ lost)
Optional
1.aaaaaaaaaaaaaaaaa
M / F
2.aaaaaaaaaaaaaaaa
M / F
3.aaaaaaaaaaaaaaaa
M / F
4.aaaaaaaaaaaaaaaa
M / F
5.aaaaaaaaaaaaaaaa
M / F
6.aaaaaaaaaaaaaaaa
M / F
7.aaaaaaaaaaaaaaaa
M / F
8.aaaaaaaaaaaaaaaa
M / F
9.aaaaaaaaaaaaaaaa
M / F
10.aaaaaaaaaaaaaaaa
M / F
11.aaaaaaaaaaaaaaaa
M / F
12.aaaaaaaaaaaaaaaa
M / F
13.aaaaaaaaaaaaaaaa
M / F
14.aaaaaaaaaaaaaaaa
M / F
15.aaaaaaaaaaaaaaaa
M / F
16.aaaaaaaaaaaaaaaa
M / F
17.aaaaaaaaaaaaaaaa
M / F
18.aaaaaaaaaaaaaaaa
M / F
19.aaaaaaaaaaaaaaaa
M / F
20.aaaaaaaaaaaaaaaa
M / F
21.aaaaaaaaaaaaaaaa
M / F
22.aaaaaaaaaaaaaaaa
M / F
23.aaaaaaaaaaaaaaaa
M / F
24.aaaaaaaaaaaaaaaa
M / F

 

Graph Title: ____________________________________________________________


Analysis and Conclusion :

1. Restate your hypothesis: __________________________________________________

2. Which students won? (male) __________________________ and (female)_____________________

3. What were their measurements:

male: thumb circumference: ____________, thumb length ______________, and wrist circumference ______________;

female: thumb circumference:__________, thumb length _________, and wrist circumference ______________.

4. What was the mean thumb circumference of the class? _____________cm

5. What was the mean wrist circumference of the class? ______________cm

6. Did all those with larger measurements win their matches? ____________.

7. Was you hypothesis correct? ______________.

8. If not, explain what was different. 

_____________________________________________________

_____________________________________________________

_____________________________________________________

9. What is the independent variable? _____________________________________

10. What is the dependent variable? ______________________________________

11. List the controlled variables in this experiment. 

         __________________________________________________

__________________________________________________       

11. Would this be considered a controlled experiment? ____________.

12. Explain your answer.

_____________________________________________________

_____________________________________________________

_____________________________________________________

Here is a sample tournament grid : Cut and turn sideways.

_______________________________________________________________________

_______________________________________________________________________

 

Cut and use.

________________________________________________________________________

BACK

Scientific Laws

 

Scientific Laws, Hypotheses, and Theories

 

 

Scientific Theory versus “Just a theory” Layman’s term:

In layman’s terms, if something is said to be “just a theory,” it usually means that it is a mere guess, or is unproved. It might even lack credibility. But in scientific terms, a theory implies that something has been proven and is generally accepted as being true.

Scientific Meanings:

SCIENTIFIC LAW: This is a statement of fact meant to describe, in concise terms, an action or set of actions. It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true. Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.  Some scientific laws, or laws of nature, include the law of gravity, Newton’s laws of motion, the laws of thermodynamics, Boyle’s law of gases, the law of conservation of mass and energy, and Hook’s law of elasticity.

HYPOTHESIS: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation.

THEORY: A theory is more like a scientific law than a hypothesis. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. One scientist cannot create a theory; he can only create a hypothesis. Theories may be expanded or modified with further scientific evidence.

Development of a Simple Theory by the Scientific Method:

  • Start with an observation that evokes a question: Broth spoils when I leave it out for a couple of days. Why?
  • Using logic and previous knowledge, state a possible answer, called a Hypothesis: Tiny organisms floating in the air must fall into the broth and start reproducing.
  • Perform an experiment or Test: After boiling some broth, I divide it into two containers, one covered and one not covered. I place them on the table for two days and see if one spoils. Only the uncovered broth spoiled.
  • Then publish your findings in a peer-reviewed journal. Publication: “Only broth that is exposed to the air after two days tended to spoil. The covered specimen did not.”
  • Other scientists read about your experiment and try to duplicate it. Verification: Every scientist who tries your experiment comes up with the same results. So they try other methods to make sure your experiment was measuring what it was supposed to. Again, they get the same results every time.
  • In time, and if experiments continue to support your hypothesis, it becomes a Theory: Microorganisms from the air cause broth to spoil.

BACK

 

Scientific Method & Genetics

 

 

Using the Scientific Method With Genetics

 

Introduction:

Humans are classified as a separate species because of all the special characteristics that they possess. These characteristics are controlled by strands of DNA located deep inside their cells. This DNA contains the code for every protein that an organism has the ability to produce. These proteins combine with other chemicals, within the body, to produce the cells, tissues, organs, organ systems, and finally the organism itself. The appearance of these organs, such as the shape of ones nose, length of the fingers, or the color of the eyes is called the phenotype.

Even though humans contain hands with five fingers, two ears, or one nose, there are subtle differences that separate these organs from another. There are subtle differences in a person’s genes that allows for these different phenotypes. In this lab, we are going to observe some of these differences in phenotype. All human hands look pretty much alike, but there are genes on your chromosomes that code for the characteristics making up your hand. We are going to examine two of these characteristics (hand width and hand length) and try to determine why these phenotypic differences occurred.

Materials:

  • metric ruler (see end of lab)
  • pencil
  • calculator

Procedures:

Day 1

  1. Choose a partner and have them measure the length of your right hand in centimeters. (Measure from the tip of your middle finger to the beginning of your wrist as shown in figure 1.)  Record your measurements in Table 1.
  2. Now measure and record the length in centimeters of your partners hand.
  3. Have your partner measure the width of your right hand, straight across the palm, and record the data in Table 1. (see figure 1.)
  4. Now measure & record the width of your partner’s hand.

Figure 1.

 

Table 1

 

Group Data on Right Hand Width and Length
Student Name Length of Hand (cm) Width of Palm (cm)

 

  1. After the entire class has completed Table 1, record your group data on the Class Data Table at the front of the room
  2. Record the Class Data Table information on your lab sheet’s Table 2.

Table 2

Class Data on Right hand Width and Length (cm)

Class Period:
Student Gender
(M / F)		 Hand Length (cm) Hand Width (cm)
1. M / F
2. M / F
3. M / F
4. M / F
5. M / F
6. M / F
7. M / F
8. M / F
9. M / F
10. M / F
11. M / F
12. M / F
13. M / F
14. M / F
15. M / F
16. M / F
17. M / F
18. M / F
19. M / F
20. M / F
21. M / F
22. M / F
23. M / F
24. M / F

Click for Class Data Table

Day 2

  1. In order to form a more accurate conclusion, the collection of additional data from several classes is necessary. Using the Class Data Tables for each period at the front of the room, record the # of males and # of females having the same length hand in Table 3.
  2. Only record a hand length (e.g. 18.1 cm) once on table 3.

Table 3:

Hand Length (cm) of All Class Periods
Measurement of Hand length (cm) # of Males # of Females Total #
(Male + Female)
  1. Using the Class Data Tables for each period at the front of the room, record the # of males and # of females having the palm width in Table 4.
  2. Only record a palm width (e.g. 15.3 cm) once on table 4.

Table 4:

 Hand Width (cm) of All Class Periods
Measurement of palm width (cm) # of Males # of Females Total #
(Male + Female)
  1. Line graph data from table 3 using hand length as your independent variable and the number of times (total males & females) that measurement appeared as the dependent variable.
  2. Make a second line graph using data from table 4 using palm length as your independent variable and the number of times (total males & females) that measurement appeared as the dependent variable.
  3. Be sure to include a title for each graph and label the x and y axis and include their unit of measurement.

Graph Title: ___________________________________________________________

 

 

Graph Title: ___________________________________________________________

 

Analysis:

1. Examine the above graphs. What is the shape of the line for hand length?  for the palm width?

 

2. What is the most abundant measurement (mode) for hand length?

 

3. What was the average hand length (mean) for males?   for females?   for total students?

 

4.  What is (are) the least abundant measurement(s) for hand length?

 

5. What is the most abundant measurement (mode) for palm width?

 

6.  What is the least abundant measurement  for palm width?

 

7. What was the average palm width (mean) for males?   for females?   for total students?

 

8. Are there any similarities in the graph of the above two characteristics and if so, what are they?

 

9. Are there any differences in the graph of the above two characteristics and if so, what are they?

 

10. Is there a difference in the length of the male and female hand?

11. Is there a difference in the width of the male and female hand?

12. Does gender have an effect on the phenotype of a trait? Explain.

 

Cut and use: