UMUC Biology Lab 3: Cell Structure And Function

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Your Full Name:

UMUC Biology 102/103
Lab 3: Cell Structure and Function
INSTRUCTIONS:

• On your own and without assistance, complete this Lab 3 Answer Sheet electronically and submit it via the Assignments Folder by the date listed in the Course Schedule (under Syllabus).
• 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 3 Answer Sheet in the following format:  LastName_Lab3 (e.g., Smith_Lab3).
• You should submit your document as a Word (.doc or .docx) or Rich Text Format (.rtf) file for best compatibility.

Pre-Lab Questions

1. Identify three major similarities and differences between prokaryotic and eukaryotic cells.

 

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

 

3.  Identify three structures which provide support and protection in a eukaryotic cell.

Experiment 1: Cell Structure and Function
The structure of a cell dictates the majority of its function. You will view a selection of slides that exhibit unique structures that contribute to tissues function.

Materials:
Onion (allium) Root Digital Slide Images

Procedure
1. Examine the onion root tip digital slide images on the following pages. Then, respond to the Post-Lab Questions.

Onion Root Tip: 100X

Onion Root Tip: 1000X

Onion Root Tip: 1000X

 

Onion Root Tip: 100X. Each dark circle indicates a different nucleus.

Onion Root Tip: 1000X

Post-Lab Questions
1. Label each of the arrows in the following slide image: A=Chromosomes, B=Nucleus, C=Cytoplasm, D=Cell Wall
2. What is the difference between the rough and smooth endoplasmic reticulum?

 

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

 

 

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

 

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

Experiment 2: Osmosis – Direction and Concentration Gradients
In this experiment, we will investigate the effect of solute concentration on osmosis. A semi-permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. This selective permeability allows us to examine the net movement of water across the membrane. You will begin the experiment with a 30% sucrose solution, and perform a set of serial dilutions to create lower concentration solutions. Some of the sucrose concentrations will be membrane permeable; while others will not be permeable (can you determine why this is?).

Materials
(3) 250 mL Beakers
(1) 10 mL Graduated Cylinder
(1) 100 mL Graduated Cylinder
Permanent Marker
*8 Rubber Bands (2 blue, 2 green, 2 red, and 2 yellow)
60 g Sucrose (Sugar) Powder, C12H22O11
4 Waste Beakers (any volume)
*Paper Towels
*Scissors
*Stopwatch
*Water
*(4) 15 cm. Pieces of Dialysis Tubing
*Contains latex. Please handle wearing safety gloves if you have a latex allergy.

*You Must Provide

*Be sure to measure and cut only the length you need for this experiment. Reserve the remainder for later experiments.

Procedure
1. Use the permanent marker to label the three 250 mL beakers as 1, 2, and 3.
2. Cut four strips of dialysis tubing, each 15.0 cm long. Fill Beaker 3 with 100 mL of water and submerge the four pieces of dialysis tubing in the water for at least 10 minutes.
3. After 10 minutes, remove one piece of tubing from the beaker. Use your thumb and pointer finger to rub the tubing between your fingers; this will open the tubing. Close one end of the tubing by folding over 3.0 cm of one end (this will become the bottom). Fold it again and secure with a yellow rubber band (use
4. Tie a knot in the remaining dialysis tubing just above or just below the rubber band. This will create a seal and ensures that solution will not leak out of the tube later in the experiment.
5. To test that no solution can leak out, add a few drops of water to the tubing and look for water leakage. If any water leaks, tighten the rubber band and/or the knot in the tubing. Make sure you pour the water out of the tubing before continuing to the next step.
6. Repeat Steps 4 – 5 with the three remaining dialysis tubes, using each of the three remaining rubber band colors.
7. Reconstitute the sucrose powder according to the instructions provided on the bottle’s label (your kit contains 60 g of sucrose in a chemical bottle) . This will create 200 mL of a 30% stock sucrose solution.
8. Use Table 2 to create additional sucrose solutions that are 30%, 15% and 3% concentrated, respectively. Use the graduated cylinder and waste beakers to create these solutions. Set these solutions aside.
Table 2: Serial Dilution Instructions
Sucrose Solution mL of Stock Sucrose Solution Needed mL of Water Needed
30% 10  0
15% 5  5
3% 1  9
3% 1  9
9. Pour 150 mL of the remaining stock sucrose solution into Beaker 1.
10. Use some of the remaining stock sucrose solution to create an additional 200 mL of a 3% sucrose solution into Beaker 2.
Hint: Use your knowledge of serial dilutions to create this final, 3% sucrose solution.
11. Measure and pour 10 mL of the remaining 30% sucrose solution into the dialysis bag with the yellow rubber band. Seal the top of this tubing with the remaining yellow rubber band.
12. Measure and pour 10 mL of the 15% sucrose solution in the bag with the red rubber band, and seal the top of the dialysis tubing with the remaining red rubber band. 10 mL of the 3% sucrose solution in the bag with the blue rubber band, and seal the dialysis tubing with the remaining blue rubber band. The final 10 mL of 3% sucrose solution in the bag with the green rubber band. Seal the dialysis tubing with the remaining green rubber band.
13. Verify and record the initial volume of solution from each bag in Table 3.

Figure 8: The dialysis bags are filled with varying concentrations of sucrose solution and placed in one of two beakers.
14. Place the yellow, red, and blue banded tubing in Beaker 2. Place the green banded tubing in Beaker 1 (Figure 8).
15. Hypothesize whether water will flow in or out of each dialysis bag. Include your hypotheses, along with supporting scientific reasoning in the Hypotheses section at the end of this procedure.
16. Allow the bags to sit for one hour. While waiting, pour out the water in the 250 mL beaker that was used to soak the dialysis tubing in Step 1. You will use the beaker in Step 19.
17. After allowing the tubing to sit for one hour, remove them from the beakers.
18. Carefully open the tubing. The top of the tubing may need to be cut off/removed as they tend to dry out over the course of an hour. Measure the solution volumes of each dialysis bag using the 100 mL graduated cylinder. Make sure to empty and dry the cylinder completely between each sample.
19. Record your data in Table 3.
Table 3: Sucrose Concentration vs. Tubing Permeability
Band Color Sucrose % Initial Volume (mL) Final Volume (mL) Net Displacement (mL)
Yellow
Red
Blue
Green
Hypothesis:

Post-Lab Questions
1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

2. Which tubing increased the most in volume? Explain why this happened.

 

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?
4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

Your Full Name:

UMUC Biology 102/103

Lab 3: Cell Structure and Function

INSTRUCTIONS:

 

· On your own and without assistance, complete this Lab 3 Answer Sheet electronically and submit it via the Assignments Folder by the date listed in the Course Schedule (under Syllabus).

· 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 3 Answer Sheet in the following format: LastName_Lab3 (e.g., Smith_Lab3).

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

Pre-Lab Questions

 

 

1. Identify three major similarities and differences between prokaryotic and eukaryotic cells.

 

 

 

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

 

 

 

3. Identify three structures which provide support and protection in a eukaryotic cell.

 

Experiment 1: Cell Structure and Function

The structure of a cell dictates the majority of its function. You will view a selection of slides that exhibit unique structures that contribute to tissues function.

concept_tab_l

Materials:

Onion (allium) Root Digital Slide Images
 

 

Procedure

1. Examine the onion root tip digital slide images on the following pages. Then, respond to the Post-Lab Questions.

Onion Root Tip: 100X
Onion Root Tip: 100X

 

 

Onion Root Tip: 1000X
Onion Root Tip: 1000X

 

 

Onion Root Tip: 1000X
Onion Root Tip: 1000X

 

 

 

 

Onion Root Tip: 100X. Each dark circle indicates a different nucleus.
Onion Root Tip: 100X. Each dark circle indicates a different nucleus.

 

 

Onion Root Tip: 1000X
Onion Root Tip: 1000X

 

 

Post-Lab Questions

1. Label each of the arrows in the following slide image: A=Chromosomes, B=Nucleus, C=Cytoplasm, D=Cell Wall

Lab3_Experiment1_PostLabQuestion1

 

2. What is the difference between the rough and smooth endoplasmic reticulum?

 

 

 

 

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

 

 

 

 

 

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

 

 

 

 

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

 

 

Experiment 2: Osmosis – Direction and Concentration Gradients

In this experiment, we will investigate the effect of solute concentration on osmosis. A semi-permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. This selective permeability allows us to examine the net movement of water across the membrane. You will begin the experiment with a 30% sucrose solution, and perform a set of serial dilutions to create lower concentration solutions. Some of the sucrose concentrations will be membrane permeable; while others will not be permeable (can you determine why this is?).

concept_tab_2

Materials

(3) 250 mL Beakers (1) 10 mL Graduated Cylinder (1) 100 mL Graduated Cylinder Permanent Marker *8 Rubber Bands (2 blue, 2 green, 2 red, and 2 yellow) 60 g Sucrose (Sugar) Powder, C12H22O11 4 Waste Beakers (any volume) *Paper Towels *Scissors

  

*Stopwatch *Water *(4) 15 cm. Pieces of Dialysis Tubing *Contains latex. Please handle wearing safety gloves if you have a latex allergy. *You Must Provide *Be sure to measure and cut only the length you need for this experiment. Reserve the remainder for later experiments.

  

Procedure

1. Use the permanent marker to label the three 250 mL beakers as 1, 2, and 3.

2. Cut four strips of dialysis tubing, each 15.0 cm long. Fill Beaker 3 with 100 mL of water and submerge the four pieces of dialysis tubing in the water for at least 10 minutes.

3. After 10 minutes, remove one piece of tubing from the beaker. Use your thumb and pointer finger to rub the tubing between your fingers; this will open the tubing. Close one end of the tubing by folding over 3.0 cm of one end (this will become the bottom). Fold it again and secure with a yellow rubber band (use

4. Tie a knot in the remaining dialysis tubing just above or just below the rubber band. This will create a seal and ensures that solution will not leak out of the tube later in the experiment.

5. To test that no solution can leak out, add a few drops of water to the tubing and look for water leakage. If any water leaks, tighten the rubber band and/or the knot in the tubing. Make sure you pour the water out of the tubing before continuing to the next step.

6. Repeat Steps 4 – 5 with the three remaining dialysis tubes, using each of the three remaining rubber band colors.

7. Reconstitute the sucrose powder according to the instructions provided on the bottle’s label (your kit contains 60 g of sucrose in a chemical bottle) . This will create 200 mL of a 30% stock sucrose solution.

8. Use Table 2 to create additional sucrose solutions that are 30%, 15% and 3% concentrated, respectively. Use the graduated cylinder and waste beakers to create these solutions. Set these solutions aside.

Table 2: Serial Dilution Instructions
Sucrose Solution mL of Stock Sucrose Solution Needed mL of Water Needed
30% 10 0
15% 5 5
3% 1 9
3% 1 9

9. Pour 150 mL of the remaining stock sucrose solution into Beaker 1.

10. Use some of the remaining stock sucrose solution to create an additional 200 mL of a 3% sucrose solution into Beaker 2.

Hint: Use your knowledge of serial dilutions to create this final, 3% sucrose solution.

11. Measure and pour 10 mL of the remaining 30% sucrose solution into the dialysis bag with the yellow rubber band. Seal the top of this tubing with the remaining yellow rubber band.

12. Measure and pour 10 mL of the 15% sucrose solution in the bag with the red rubber band, and seal the top of the dialysis tubing with the remaining red rubber band. 10 mL of the 3% sucrose solution in the bag with the blue rubber band, and seal the dialysis tubing with the remaining blue rubber band. The final 10 mL of 3% sucrose solution in the bag with the green rubber band. Seal the dialysis tubing with the remaining green rubber band.

13. Verify and record the initial volume of solution from each bag in Table 3.

Figure 8: The dialysis bags are filled with varying concentrations of sucrose solution and placed in one of two beakers.
Figure 8: The dialysis bags are filled with varying concentrations of sucrose solution and placed in one of two beakers.

14. Place the yellow, red, and blue banded tubing in Beaker 2. Place the green banded tubing in Beaker 1 (Figure 8).

15. Hypothesize whether water will flow in or out of each dialysis bag. Include your hypotheses, along with supporting scientific reasoning in the Hypotheses section at the end of this procedure.

16. Allow the bags to sit for one hour. While waiting, pour out the water in the 250 mL beaker that was used to soak the dialysis tubing in Step 1. You will use the beaker in Step 19.

17. After allowing the tubing to sit for one hour, remove them from the beakers.

18. Carefully open the tubing. The top of the tubing may need to be cut off/removed as they tend to dry out over the course of an hour. Measure the solution volumes of each dialysis bag using the 100 mL graduated cylinder. Make sure to empty and dry the cylinder completely between each sample.

19. Record your data in Table 3.

Table 3: Sucrose Concentration vs. Tubing Permeability
Band Color Sucrose % Initial Volume (mL) Final Volume (mL) Net Displacement (mL)
Yellow        
Red        
Blue        
Green        

Hypothesis:

 

Post-Lab Questions

1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

 

 

2. Which tubing increased the most in volume? Explain why this happened.

 

 

 

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

 

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

 

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

 

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

 
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Bio Lab Classification And Evolution

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PAGE

UMUC Asia DE lab – Evolution © UMUC – all rights reserved.

Name:

Lab 8. Evolution

Introduction

Evolution is often defined as change over time, usually in response to a change in the environment. What this means is that the gene pool of a population shifts as time passes.

What is a gene pool? It is simply the collection of all the available alleles of all the genes on all the chromosomes in the population. What’s a population? It is the group of individuals that have geographic and behavioral mating access to each other. Geographic access is obvious; the dandelions in a yard in Virginia are not in the same gene pool as those in a yard in Pennsylvania, even if they are the same species. They could mate if they were brought together, but dandelion pollen doesn’t blow that far, so they are geographically isolated. Behavioral mating access can be less obvious; one example would be a stag that keeps all other males out of his territory and mates with all the does. The other stags are not allowed to mate, so their genes are not in the pool.

A great deal of the time for most species, evolution is not occurring. The gene pool stays the same, because the environmental situation is not changing. In the early days of population genetics, people argued over whether dominant alleles could “take over” a gene pool without any selection. Two mathematicians, Hardy and Weinberg, showed that this would not happen.

The basis of their argument is that the gene pool will not change, and the frequency of the various alleles will stay the same if the following conditions are met:

· The population is large.

· The population is freely interbreeding at random (this excludes the stag and the does).

· No individuals are taking their alleles out of the population (emigrating) or adding their alleles to the population (immigrating), so the percentages of the alleles can’t change because of migration.

· There are no mutations, so no new alleles appear.

· None of the alleles has a selective advantage (in other words, there aren’t any combinations of alleles that give some individuals a better chance of surviving that anyone else).

Here is the mathematical basis of their argument:

Imagine a simple situation in which a gene has only two alleles, A and a, and A is dominant. Let the frequency of A, expressed as a decimal with a value less than one, be p, and let the frequency of a, expressed as a decimal with a value less than one, be q. Because there are only two alleles, every allele must be either A or a, so,

p + q = 1

By definition, p and q are also the frequencies of the alleles in the eggs and sperm produced by this species. These sperm and eggs can come together in four ways when random mating occurs.

1. The chance that a male p sperm will meet a female p egg is p x p, or p2. The children produced by this cross will be genetically AA and express the dominant allele; they will have the A phenotype.

2. The chance that a male p sperm will meet a female q egg is p x q, or pq. The children produced by this cross will be genetically Aa and express the dominant allele; they will also have the A phenotype.

3. The chance that a male q sperm will meet a female p egg is also p x q, or pq. The children produced by this cross will also be genetically Aa and express the dominant allele; they will also have the A phenotype.

4. The chance that a male q sperm will meet a female q egg is q x q, or q2. The children produced by this cross will be genetically aa and express the recessive allele; they will have the a phenotype.

These four situations are the only possibilities, so

p2 + pq + pq + q2 = 1 (1.0 represents 100% of all possible events in a mating)

When we combine the middle two terms, we get

p2 + 2pq + q2 = 1

These two formulas,

p + q = 1

p2 + 2pq + q2 = 1

summarize what is known as the Hardy-Weinberg Law.

However, usually we don’t know the frequency of the alleles in a population; in most cases, we can’t even see the gametes! If we want to know what the frequencies of the alleles are, we have to use these two formulas to figure it out.

The most important things to remember are the two formulas above. In these formulas,

· p = the frequency of the dominant allele

· q = the frequency of the recessive allele

· p2 = the frequency of individuals in the population who are homozygous dominant

· 2pq = the frequency of individuals in the population who are heterozygous

· q2 = the frequency of individuals in the population who are homozygous recessive

Materials

· Three colours of beans (chili, pinto and navy are good, but any three contrasting objects will do – M&Ms, coins, beads, etc).

· Two bowls

· A pocket calculator (MS Windows has one too)

Procedure

Two alleles which control hair texture are incompletely dominant to each other, and the phenotypic expression of hair texture is a function of which alleles are present. The genotypes and phenotypes are:

Genotype Phenotype
C1C1 curly
C1C2 wavy
C2C2 straight

This is where Hardy-Weinberg comes in. Recall:

p2 + 2pq + q2 = 1.0

Remember:

p2 = the frequency of the C1C1s

2pq = the frequency of the C1C2s

q2 = the frequency of the C2C2s

These percentages will remain stable through all subsequent rounds of mating of this population.

Please refer to the following table for calculation references. Also, please adjust the calculations for the rest of the tables.

Please submit this Lab Report Sheet in Webtycho in the Assignments folder.

Data Sheet – Sample table and calculations:

image1.png

Student answers to questions

1. In the absence of selection, what happens to gene frequencies in a population?

Type your answer here. This textbox expands as you type.

2. What have you learned about population genetics so far? i.e., what do these results tell you about how genes in a gene pool behave under tightly controlled (i.e., artificial/hypothetical) circumstances?

Type your answer here. This textbox expands as you type.

<more below>

image2.wmf

You’ll use your three colours of beans (or any 3 objects of your choice), from this point on, to represent the individuals in your population.  The red (chili) beans represent the homozygous dominants (C1C1 – curlies), the mottled (pinto) beans the heterozygotes (C1C2 – wavies), and the white (navy) beans the homozygous recessives (C2C2 – straights). 

Pick the beans (objects) two at a time and record your results here. Use the example above (page 6) to help you in your calculations).

Experiment 1

In this first exercise, you are going to determine what happens when you allow your population of 80 to interbreed freely.

In a bowl, place the correct numbers of the three colours of beans to represent the population of 80 people.  For 20 C1C1s, 40 C1C2‘s, and 20 C2C2’s, you would choose 20 red beans, 40 pinto beans, and 20 white beans (or any three different objects you chose).  Mix them thoroughly and then, without peeking (i.e., at random), withdraw two beans (or two objects).  Record the genotypes represented by the two beans.

Example :  if you withdraw a white bean and a pinto bean the first time, then you will record one (1) C2C2 x C1C2; you have mated one pair.

Put your first two beans in the second bowl and continue to draw pairs of beans from the first bowl until you have withdrawn all 40 pairs.  Your records will now show a series of 80 random matings from this population.

There are six possible combinations:

1. C1C1 x C1C1 (two chili beans),

2. C1C1 x C1C2 (one chili, one pinto),

3. C1C1 x C2C2 (one chili, one navy),

4. C1C2 x C1C2 (two pintos),

5. C1C2 x C2C2 (one pinto, one navy), and

6. C2C2 x C2C2 (two navies).

Record the total number for each of the six matings.

Data sheet (fill in the BLUE and YELLOW areas).

(see page 6 for detailed calculation help).

      MATINGS OFFSPRING = Matings x 4 C1S C2S  
C1C1 X C1C1          
C1C1 X C1C2          
C1C1 X C2C2          
C1C2 X C1C2          
C1C2 X C2C2          
C2C2 X C2C2          
              total
P= Frequency of C1 =  
Q= Frequency of C2 =  

3.    How do these compare with the parental generation?

Type your answer here. This textbox expands as you type.

4.    What principle have you demonstrated with this exercise?

Type your answer here. This textbox expands as you type.

<scroll down for more>

Experiment 2

Put your beans back in the bowl.  This time, withdraw only 20 pairs (= 20 random matings), and record the results as you did in Task 1.

Next, calculate the offspring of this generation:  again, assume 4 offspring per mating.  Total the numbers of C1C1s, C1C2s and C2C2s. and then calculate the allele frequencies.  Finally, determine the genotypic frequencies.

 

Data sheet (fill in the BLUE and YELLOW areas).

(see page 6 for detailed calculation help).

      MATINGS OFFSPRING = Matings x 4 C1S C2S  
C1C1 X C1C1          
C1C1 X C1C2          
C1C1 X C2C2          
C1C2 X C1C2          
C1C2 X C2C2          
C2C2 X C2C2          
              total
P= Frequency of C1 =  
Q= Frequency of C2 =  

5.    How do these last P and Q (frequencies) compare with the P (parental) generation (Experiment 1)?

Type your answer here. This textbox expands as you type.

6.    If you repeated this experiment (i.e., you selected another 20 pairs from the bowl) would you expect to get the same result?  Why or why not?

Type your answer here. This textbox expands as you type.

7. What principle have you illustrated this time?

Type your answer here. This textbox expands as you type.

<scroll down for more>

Experiment 3

Now you are going to assume that your population has been invaded by an ET which is a human predator.  It particularly fancies people with curly hair – eats them preferentially – and when it moves on (looking for more of its favourite lunch), your population has been denuded of curlies (C1C1).

Set up your new population in the bowl, and go through the mating (bean picking/ withdrawal) procedure again, recording your results.  Again, assume that each mating produces four offspring.

(see page 6 for detailed calculation help).

      MATINGS OFFSPRING = Matings x 4 C1S C2S  
C1C2 X C1C2          
C1C2 X C2C2          
C2C2 X C2C2          
              total
P= Frequency of C1 =  
Q= Frequency of C2 =  

8.    What is going on?

Type your answer here. This textbox expands as you type.

9.    How have the relative proportions of C1s and C2s changed?

Type your answer here. This textbox expands as you type.

10.    What principle have you demonstrated here?

Type your answer here. This textbox expands as you type.

<scroll down for more>

Experiment 4

Go back to your population in Experiment 3.  This time, assume that through some further natural disaster which has discriminated against people with wavy hair, half the wavies have also been lost.  Allow this population to breed at random and determine the outcome of the next generation.

(see page 6 for detailed calculation help).

      MATINGS OFFSPRING = Matings x 4 C1S C2S  
C1C2 X C1C2          
C1C2 X C2C2          
C2C2 X C2C2          
              total
P= Frequency of C1 =  
Q= Frequency of C2 =  

13.    What is going on this time?

Type your answer here. This textbox expands as you type.

14.    What if this trend continues?

Type your answer here. This textbox expands as you type.

SUMMARY

15.   Summarize what you have learned from this lab about the principles of evolution.

Type your answer here. This textbox expands as you type.

Define (one short sentence each):

1) Evolution

2) Microevolution

3) Macroevolution

4) Genetic Drift

5) Natural selection

What did you learn about or in each of the following?

a) The Hardy-Weinberg Equilibrium

b) Experiment 1

c) Experiment 2

d) Experiment 3

e) Experiment 4

PAGE

Page 2 of 15

 
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SCIN Packet

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Complete all the activities in this lab instruction packet: SCIN 130 Lab 1: The Scientific Method.  Work through the instruction packet step by step. Record your results in the worksheet as you progress through this instruction packet.

  • SCIN 130 Lab 1: Scientific Method

     

    General Instructions

     

    Be sure to read the general instructions from the Lessons portion of the class prior to completing this packet.

     

    Remember, you are to upload this packet with your quiz for the week!

     

    Background

    In this lab, we are going to explore elephants, their current status, and discuss why it is so important to survey them. This ties in to the scientific method:

    · Ask A Question

    · Do Background Research

    · Construct A Hypothesis

    · Test with an Experiment

    · Analyze Data and Draw Conclusions

    · Communicate Results

     

    Specific Lab Instructions

     

    Name:

    Date:

     

    Go to: Survey Methods for African Elephants

     

     

    Read the “Why Study Elephants” page and answer the following questions:

     

    1. What is the question that scientists are trying to address with this study?

     

     

     

    2. What is a potential hypothesis for an experiment involving these elephants?

     

    3. Elephants are considered to be a keystone species. What does that mean?

     

     

    4. Name three elephant activities or functions that justify the term “keystone species” and describe how the activity changes African ecosystems.

    Elephant Activity Change in Ecosystem
       
       
       

    5. Why have elephant populations been declining for the past several decades?

     

     

     

    Click on the Species Range

     

    6. Click on the Forest Elephant Range, then the Savanna Elephant Range. Which is larger?

    ☐Forest Elephant Range

    ☐Savanna Elephant Range

     

    7. Review the Methods, Advantages and Disadvantages of the Species Range data collection; add your thoughts in the table on the last page of this packet.

     

    Click on Individual Range.

     

    8. Take the time to watch the video! In general, why to elephants move across the land?

     

     

    9. Why do we only have to collar one mature female to get a lot of data of movement of a group and not all individuals?

     

     

    10. Review the Methods, Advantages and Disadvantages of the Individual Range; add your thoughts in the table on the last page of this packet.

     

    Review the methods in the How Many section.

     

     

    11. Discuss the methods, sample type, advantages and disadvantages of each in the table at the end of this packet.

     

    Click on the Population Change. Review the video, and read the introductory material.

     

     

    12. Turn on both the 1979 and 2007 range for the elephants on the map. How did the range change? Did it increase, decrease or stay the same?

     

    13. Turn off the 1979 and 2007 range layers, and turn on the 2016 trends layer. What types of changes do you notice? Are there specific areas where the population is decreasing or increasing? Why do you think this is?

     

     

     

     

    Adapted from: Click and Learn “Survey Methods.” (2016). HHMI Biointeractive Teaching Materials.

     

     

    SCIN130 Lab 1: Scientific Method

     

    V1 01.2018 Felicetti

    Page of 7

     

      Information Gathered Methods Used Type of Count (Total or Sample/Direct or Indirect) Advantages Disadvantages
    Species Range     N/A    
    Individual Range     N/A    
    Aerial Survey          
    Individual Registration          
    Acoustic Surveys          
    Dung Transects          
 
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HSA 535HSA 535 FINAL EXAM PART 2 FINAL EXAM PART 2

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Question 1 

In the Yearly Mortality Bill for 1632, consumption referred to:

 

dysentery

 

tuberculosis

 

smallpox

 

edema

Question 2 

Cyclic variations in the occurrence of pneumonia and influenza mortality may reflect:

 

seasonal variations in cases of influenza.

 

the fact that influenza is a disappearing disorder.

 

long-term changes in mortality trends.

 

both A and B

Question 3 

Which of the following is not usually an aim of epidemiology?

 

To describe
the health status of the population

 

To fund new public health programs

 

To explain
the etiology of disease

 

To predict
the occurrence of disease

 

To control
the distribution of disease

Question 4 

Indicate the level of prevention that is represented by screening for breast cancer

 

Primary Prevention Active

 

Primary Prevention Passive

 

Secondary Prevention

 

Tertiary Prevention

Question 5 

The difference between primary and secondary prevention of disease is:

 

primary prevention means control of causal factors, while   secondary prevention means control of symptoms.

 

primary prevention means control of acute disease, while   secondary prevention means control of chronic disease.

 

primary prevention means control of causal factors, while   secondary prevention means early detection and treatment of disease.

 

primary prevention means increasing resistance to disease,   while secondary prevention means decreasing exposure to disease.

Question 6 

Indicate the level of prevention that is represented by pasteurization of milk

 

Primary Prevention Active

 

Primary Prevention Passive

 

Secondary Prevention

 

Tertiary Prevention

Question 7 

Determining workload and planning the scope of facilities and manpower needs, particularly for chronic disease. Is this a use for incidence or prevalence data?

 

This is a use primarily for incidence data.

 

This is a use primarily for prevalence data.

 

This application could apply equally for both incidence and   prevalence data.

 

This is a use for neither incidence data nor prevalence data.

Question 8 

An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year:
 

Number of skaters in   Metroville during any given month

12,000

 

Roller-skating   injuries in Metroville

600

 

Total number of   residents injured from roller-skating

1,800

 

Total number of   deaths from roller-skating

90

 

Total number of   deaths from all causes

900

 

The cause-specific mortality rate from roller-skating was:

 

90/600 × 100,000

 

90/100,000 × 100,000

 

90/1,800 × 100,000

 

90/900 × 100,000

Question 9 

To provide a direct estimate of the risk of developing a disease. Is this a use for incidence or prevalence data?

 

This is a use primarily for incidence data.

 

This is a use primarily for prevalence data.

 

This application could apply equally for both incidence and   prevalence data.

 

This is a use for neither incidence data nor prevalence data.

Question 10 

Which of the following statements most accurately expresses the breeder hypothesis for schizophrenia?

 

The conditions of life in lower-class society favor its   development.

 

The conditions of life in upper-class society favor its   development.

 

The illness leads to the clustering of psychosis in the impoverished   areas of a city.

 

The illness is associated with increases in creative talents,   which contribute to wealth-enhancing achievements.

Question 11 

Descriptive epidemiology has the following characteristics (Choose the incorrect
option):

 

provides the basis for planning and evaluation of health   services.

 

allows causal inference from descriptive data.

 

allows comparisons by age, sex, and race.

 

uses case reports, case series, and cross-sectional studies.

 

identifies problems to be studied by analytic methods.

Question 12 

A null hypothesis is most similar to which of the following?

 

Positive declaration

 

Negative declaration

 

Implicit question

 

Explicit question

Question 13 

Which of the following data sources is most likely to provide a representative sample of the general health status of a population?

 

hospital outpatient statistics

 

absenteeism data

 

data from public health clinics

 

a morbidity survey of the general population

Question 14 

Cautious use of information from death certificates is warranted because:

 

certificates are not available for everyone who dies

 

certificates are often erroneous for date of death and sex

 

cause of death information may not be correct

 

autopsy results are not included

Question 15 

Ecologic studies:

 

are expensive and require a great deal of time to conduct

 

are a good approach for generating hypotheses

 

provide accurate measurements of exposure

 

yield results that can be applied directly to individuals

Question 16 

A large medical center’s oncology program reported an increased number of cases of pancreatic cancer during a certain month. The hospital’s epidemiologist decided to research the problem. Tumor registry records were searched to identify all cases of pancreatic cancer during a five-year period; cancer patients were matched with patients treated for other diseases during the same five-year period. All subjects in the study were questioned about lifestyle factors including alcohol, tea, and coffee consumption. The resulting data are as follows:

 

DATA

 

Cancer Patients

Other Patients

 

Men

Women

Men

Women

 

LIFESTYLE VARIABLE

 

Alcohol

185

120

270

260

 

Tea Drinking

140

110

230

225

 

Coffee Drinking

190

140

270

240

 

Note:   Total number of male cancer patients = 200.
Total number of female cancer patients = 150.
Total number of male patients (other diseases) = 300.
Total number of female patients (other diseases) = 300.
Does this study have an exposure status variable?

 

No

 

Yes, lifestyle

 

Yes, disease type

 

Yes, sex of patient

Question 17 

In case-control studies, the odds ratio is used as an estimate of the relative risk. In order for this approximation to be reasonable, some conditions must be met. Which of the following conditions is not necessary in order to use the odds ratio to estimate the relative risk?

 

With respect to exposure, controls are representative of the   population to which you want to generalize your results.

 

The event (disease) under study is rare in the population.

 

The exposure in question is rare in the population.

 

Cases are representative of all cases.

Question 18 

As an epidemiologist you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. [N.B.: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have delivered malformed infants. In addition, 10 other infants are born with malfunctions.
The number of individuals who both did not take the drug and did not give birth to infants who were malformed was:

 

140

 

150

 

155

 

160

 

170

Question 20 

Which of the following individuals helped draw people’s attention to the method of cohort analysis?

 

Snow

 

Frost

 

Graunt

 

Hill

Question 21 

A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of Lyme disease among clinic attendees is 10%.
Calculate the following values:
The predictive value of a positive test is:

 

33.0%

 

18.2%

 

94.0%

 

22.2%

 

6.0%

Question 22 

Drs. Poke and Jab (2014) conducted an employee health program that used 5 screening tests at the same time to detect diseases among workers. Which type of program is this?

 

Selective screening

 

Mass screening

 

Ad hoc screening

 

Multiphasic screening

Question 23 

Sensitivity and specificity of a screening test refer to its:

 

reliability

 

validity

 

yield

 

repeatability

Question 24 

You have just finished administering a food/drink questionnaire to ill and non-ill participants in a Minnesota summer picnic party. The ill individuals developed moderate to severe diarrhea 16 to 46 hours after the picnic. Six persons experienced vomiting. The following data were collected:

 

ATE

DID NOT EAT

 

Number of people

Number of people

 

Food item

Ill

Not ill

Total

Ill

Not ill

Total

 

Hot dogs

40

30

70

10

20

30

 

Hamburgers

32

8

40

20

40

60

 

Potato salad

45

25

70

15

25

40

 

Ice cream

48

12

60

2

38

40

 

Lemonade

20

40

60

20

20

40

 

Which food item appears to be the most probable vehicle for the salmonella (agent) infection associated with the illness?

 

Hot dogs

 

Hamburgers

 

Potato salad

 

Ice cream

 

Lemonade

Question 25 

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea, five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases.
Foods served at the luncheon included home-canned olives, chicken salad, homemade flavored drink mix, freshly baked rolls, and raw vegetables. Based on your understanding of foods that potentially are capable of transmitting salmonella, the most likely source of the outbreak was:

 

home-canned olives

 

chicken salad

 

drink mix

 

freshly baked rolls

 

raw vegetables

Question 26 

The site where a disease agent enters the body is the:

 

reservoir

 

portal of entry

 

vehicle

 

portal of exit

Question 27 

A situation in which the combined effect of several exposures is greater than the sum of the individual effects:

 

threshold

 

latency

 

synergism

 

square

Question 28 

It has been suggested that occupational exposure to benzene in the petroleum industry increases the risk of developing leukemia. The levels of benzene to which workers in this industry have been exposed were high from 1940 to 1970, but since 1970 have been significantly reduced. What kind of study design, using petroleum workers, would provide the most useful information on whether benzene affects incidence rates of leukemia in this industry? You may assume that records of individual worker assignments to jobs involving benzene exposure have been maintained by the industry.

 

Experimental

 

Retrospective cohort

 

Prospective cohort

 

Case-control

 

Cross-sectional

Question 29 

The type A behavior pattern is hypothesized to be a risk factor for:

 

chronic obstructive pulmonary disease

 

coronary heart disease

 

rheumatoid arthritis

 

retirement

Question 30 

Which of the following statements describes a stressful life event?

 

discrepancy between husband and wife in social and educational   status

 

goodness of fit between the characteristics of the person and   environment

 

an occurrence that might cause readjustments in people’s   activities

 

sleeping

 
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