Lab 5 – Diffusion, Osmosis and Enzymes

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Lab 5 – Diffusion, Osmosis and Enzymes

Objective: The objective of this lab is to introduce you to the concepts of diffusion, osmosis and enzyme activity.

Reading Assignment: Read 4.9 and 5.4; Diffusion and Osmosis and How Enzymes Work from the textbook Essentials of the Living World.

 

For this lab you will need to supply the following materials:

Camera or cell phone (you will upload pictures of your experiment)

Kitchen scale (food scale, it can weigh in either ounces or grams)

Microwave

Liquid measuring cup

Teaspoon

Tablespoon (3 Tsp = 1 Tbs)

Several Drinking cups (1 needs to hold at least 2 cups of liquid)

1 Potato

Knife

Blender or Potato masher

Zip lock sandwich bag (not a freezer bag)

Pancake syrup

Salt

Sugar

Vinegar

Hydrogen Peroxide (H2O2)

 

Solutions to prepare

Sucrose solution – add one tablespoon of sugar to 1 cup of water

 

Exercise 1 – Diffusion

· In this exercise you will observe the diffusion of water through a semipermeable membrane (a plastic bag)

Step 1. Place ¼ of a cup of pancake syrup into a plastic zip lock bag and seal the bag.

Step 2. Weigh the bag using a small kitchen scale and record the weight on your worksheet.

Step 3. Fill larger cup (2 cup measuring or equivalent) with 1 cup of water. Record the time.

Step 4. Place the syrup bag in the larger cup and leave overnight (12+ hours).

Step 5. Remove the bag, dry it off and weigh it using a small kitchen scale. Record weight on your worksheet and the time you ended the experiment. (Hint: The bag should gain weight. If it loses weight you may have had a puncture. You must redo this exercise).

Step 6. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name and a photo ID.

Exercise 2 – Osmosis

· In this exercise you will determine the result of putting cells into solutions of various tonicity.

Step 1. Cut (2) potato slices: 3 inches long, 1 inch wide, 0.5 inches thick.

Step 2. Prepare two coffee cups with the following solutions:

Cup 1 = add one cup of water

Cup 2 = add one cup of water and 1 teaspoon of salt

Step 3. Add one potato slice to each cup and let stand for 1 hour.

Step 4. Remove potato slices and determine if the slice is crisp or limp. Record your observations of the slices on the data sheet.

Step 5. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name, and a photo ID.

Exercise 3 – Enzyme Activity

· In this exercise you will observe factors that affect the enzyme activity of catalase. Catalase is found in potato cells.

H2O2 (hydrogen peroxide) 2 H2O + O2 (oxygen gas) when catalase is present.

Step 1. Place the remaining amount of potato in a blender with two tablespoons of water. Blend to a paste. If you don’t have a blender use a potato masher to make the paste.

Experiment 3-1

Step 2. Transfer one tablespoon of the paste to a small cup and add 1 tablespoon of hydrogen peroxide.

Step 3. Mix together by gently rotating the cup clockwise and record your observations on the data sheet

Step 4. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name and photo/student ID.

 

Experiment 3-2

Step 5. Transfer one tablespoon of the paste to a small cup and add 1 tablespoon of sucrose solution.

Step 6. Mix together by gently rotating the cup clockwise and record your observations on the data sheet.

Step 7. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name and photo/student ID.

 

Experiment 3-3

Step 8. Transfer one tablespoon of the paste to a small cup and add 1 tablespoon of vinegar (an acid).

Step 9. Next add 1 tablespoon of hydrogen peroxide.

Step 10. Mix together by gently rotating the cup clockwise and record your observations on the data sheet.

Step 11. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name and photo/student ID.

 

Experiment 3-4

Step 12. Transfer one tablespoon of the paste to a small cup and add 1 tablespoon of water.

Step 13. Microwave on high for 1 minute.

Step 14. Remove from microwave (careful it’s hot) and allow 5 minutes to cool.

Step 15. Next add 1 tablespoon of hydrogen peroxide.

Step 16. Mix together by gently rotating the cup clockwise and record your observations on the data sheet.

Step 17. Take a picture of the completed exercise and upload to the worksheet. Make sure it includes the date, your name and photo/student ID.

 
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Biology Essay Help

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Complete 6 out of 8 questions in this Essay Section, required questions are: 1, 2, 3, 4, and 7. Alternate questions are 5a or 5b and 6a or 6b. Select one of each of these questions to answer

1. You scoop up a water sample from a local pond nearby, because you are curious about the possible microbes that might live there. After looking at several slides that held drops of the sample, you noticed two different kinds of cells: One kind was very small and had no separate internal structures; the other kind was much larger, and it contained several kinds of internal structures that were physically different from each other. Please name each cell and briefly describe their overall similarities and differences.

2. PKU (phenylketonuria) is an enzyme deficiency disease that only develops in individuals who are homozygous recessive for that gene. An individual with PKU has parents that do not have this disease. What is the parents’ genotype for the gene responsible for PKU? What is the probability that they may have another child with PKU? How many future children of the affected individual will be carriers? Explain your answers.

3. Humans share 99% of their genes with chimpanzees, 90% with mice, 50% with fruit flies, and 37% with celery. Please explain the evolutionary significance of these data.

4. Describe the major land biome where you live. How have human activities changed the landscape and how has this affected native species? Include specific examples.

5. The habitat of one species of tropical fish is red coral reefs. The large majority of the fish in this population are red. A few individual fish carry a mutation that prevents the production of the red pigment; as a result these individual fish are white. The temperature of the ocean where these fish live gets warmer and warmer over a 10 year period, and as a result the coral is bleached and turns white. Use what you have learned about natural selection to explain how this bleaching event may have affected the evolution this fish population (not including possible direct effects of warmer temperatures on the fish). Include the following terms in your explanation: differential reproduction, beneficial trait, allele frequency, selection pressure, evolution.

Alternative to question 5:

At the beginning of the spring, Dr. Betty Burner notices that there is an equal distribution of long and short stemmed the dandelions in her backyard. By the end of the summer she notices that the majority of the dandelions have short stems. This observation is an example of what biological principle? Develop a hypothesis as to why there was an increase in the proportion of the short stemmed dandelions within the population.

6. You have read that inorganic fertilizers contribute to water pollution and would like to make a switch from inorganic fertilizers to organic compost in your vegetable garden. A friend graciously gives you a truck load of his compost. As a good researcher and critical thinker you are not convinced that organic compost will yield the same results as the inorganic fertilizer you have used for years with good results. To draw your own conclusion based on scientific evidence you decide to conduct an experiment in your garden. State a good hypothesis, design an experiment (include test subjects, sample size, control(s), dependent and independent variables, type of data collected) and hypothetical results/conclusion. Does your conclusion support the hypothesis?

Alternative to question 6:

If researchers establish that Myrothecium verrucaria is an effective biological control agent against kudzu, they must then demonstrate that the pathogen will not harm desirable species such as soybeans (a close relative to kudzu). Describe an experiment that could fulfill this purpose, including all steps of the scientific method. Identify control(s), dependent and independent variables.

7. Use what you have learned about energy transfer in food chains and the second law of thermodynamics to explain why it is an environmentally good choice to eat a plant based diet. Include the following terms in your answer: producer, herbivore, omnivore, trophic level, resources and energy

 
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BIO – Chapter 9 Calculating Ecological Footprints

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Calculating Ecological Footprints- Chapter 9

 

 

 

Population (millions) Total paper consumed

(millions of metric tons)

 Per capita paper consumed

(pounds)
Africa 999 6 13
Asia 4,117 159
Europe 738 99
Latin America 580 27
North America 341 77
Oceania 36 4
World 6,810 127

 

 

 

 

 

1. How much paper would North Americans save each year if we consumed paper at the rate of Europeans?

 

2. How much paper would be consumed if everyone in the world used as much paper as the average European? As the average North American?

 

3. Why do you think people in other regions consume less paper, per capita, than North Americans? Name three things you could do to reduce your paper consumption.

 

4. Describe three ways in which consuming FSC-certified paper rather than conventional paper can reduce the environmental impacts of paper consumption

 
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Skeletal System

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  Experiment 11: Skeletal System of the Fetal Pig

In this exercise you will become familiar with the skeletal system of the fetal pig. Because the fetal pig had not reached its full gestation, many of the bones have not fully developed, but are instead still cartilaginous. Still, we can look at this structures to gain a better understanding of the axial and appendicular skeletons, along with the joints.

 
  Materials

Fetal Pig Dissection Tray

 Dissection Tools Kit String (should still be tied onto pig’s hooves)  
       

Procedure

1. To begin, lay your underpad down and place your dissecting tray on top of it. Lay out your dissecting tools. Be sure you have all of your safety equipment on before beginning the experiment.

2. Once prepared, gently open the bag your pig is in. Note: DO NOT destroy this bag or empty out the preserving solution within the bag, you will need it for the whole semester.

3. Lay your pig into the dissecting tray, dorsal side facing up. Slide the strings over the dissection tray to hold the pig in place.

4. Look at Figure 21 displaying the skeletal system of a grown pig. Notice the similarities and differences between that of your human skeleton and that of the pig.

5.
Figure 21:  The pig skeleton

6. Due to the rigidity of your pig, it typically will not stay in this position on its own so you will need to hold it while you examine the skeletal system.

7. Begin by examining, through the skin, the axial skeleton as shown in Figure 21. Feel the bones of the skull, then continue down the vertebral column feeling the vertebrae along the way. Notice that the tail of the pig is composed of caudal vertebrae. Note your observations in Table 34.

8. Slide the strings off of the dissection tray and gently turn your pig ventral side up. Slide the strings back under the dissection tray after the pig is correctly positioned.

9. Feel the thoracic cage of the pig. Though you will not cut into the pig today, feel the similarities that occur between the fetal pig and the human skeleton model. Note your observations in Table 34.

10. Turn your attention to the appendicular skeleton. The pig’s four appendages correlate to the human arms and legs. Use Figure 21 as a guide to try and feel the different bones of the arms and legs (humerus, femur, tibia, etc.). Note your observations in Table 34.

11. In Figure 21, look at the pelvic girdle of the pig. This structure appears noticeably different than that of a human. However, the innominate bones of the pig are created by the ilium, ischium and pubis.

12. Focus your attention on the joints of the pig. The pig should be fairly rigid due to the preservation fluids. However, you should still attempt to produce the movements created by synovial joints on the pig (e.g., flexion, rotation, etc.). Notice the joints at which these movements are possible. Do they correlate to human movement? Note your observations in Table 34.

13. Take a photograph of your pig in the dissection tray for the upload document. Make sure that your name is written on a piece of paper that is clearly visible in the background of the photograph.

14. You are now finished with the external observations of the skeletal system. Remember that as you dissect into your pig, you will be able to touch and feel the bones of the skeletal system. As the dissection progresses, always take note of the bones present within the fetal pig.

15. To finish, locate the bag the pig came in. Gently place the pig back into the bag and tightly secure the bag with a rubber band, or place in the zip-seal bag provided in the dissection box.

16. Place the pig back into the cool environment you had previously stored it in. Remember, the best place to keep the pig is in a cool, dark place.

17. After your pig has been put away, clean off your dissecting tray and dissection tools with soap and water. There should not be any biological scraps because you did not cut into the pig. However, biological scraps should not be thrown into the garbage.

18. Clean the area in which you worked with soap and water as well. As long as the underpad has not been damaged, keep it for future experiments.

 
Figure 22:  Palpate the skeleton of the fetal pig using gloved hands.

 

Table 34: Skeletal Region Observations
Skeletal Region Observations
Axial Skeleton  
Appendicular Skeleton  
Joints  

 

 

 

 

 

 

    

 

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