Category: Curriculum Map

Calorimetry lab

Calorimetry – Measuring the energy in Foods

Introduction:
There are two processes that organisms use to make usable energy. The process by which autotrophs convert sunlight to a usable form of energy is called photosynthesis. Photosynthesis supports all life on earth. Products from photosynthesis include food, textiles, fuel, wood, oils, and rubber. During photosynthesis, light energy is used to make organic compounds from inorganic water and carbon dioxide. Photosynthesis goes through light dependent reactions and the light independent reactions which include the Calvin cycle.
The process where heterotrophs break down food molecules to release energy for work is called cellular respiration. Cellular respiration is the reverse of photosynthesis; the reactants of one are the products of the other. The reactants of cellular respiration are glucose and oxygen, and the products are carbon dioxide, water, and energy.  Cellular respiration breaks down glucose to form carbon dioxide and water, while releasing energy usable by the cells. The first step, glycolysis is the process  that converts glucose to pyruvate and releases a small amount of cellular energy.  The second step may be aerobic or anaerobic depending on the amount of oxygen available.  Aerobic respiration is the breakdown of pyruvate in the presence of oxygen.  A larger amount of cellular energy or ATP is produced during the Kreb’s cycle and electron transport chain. Anaerobic respiration is the breakdown of food molecules in the absence of oxygen. Less ATP is produced by anaerobic respiration or fermentation.

Hypothesis:
If the heat given off by a burning pecan is measured by how much the temperature increases in a given amount of water, then the number of calories of energy stored in the nut during photosynthesis can be determined.

Materials:
Items needed for the lab included a large paper clip, a 100 ml graduated cylinder, thermometer, 2 soft drink cans, electronic balance, butane lighter, plastic tray, scissors, paper, and pencil.

Procedure:
Use a graduated cylinder to measure 100 ml of water and add this to an empty soft drink can. Cut holes on two sides of a second soft drink can so there is room to place a large bent paper clip.  Measure and record the mass of one pecan using the electronic balance. Bend a large paper clip to make a “nut stand” and measure and record  the mass of this clip. Place the pecan on the nut stand and put the stand inside the cut-out drink can.  Use a thermometer to measure and record the temperature of the water in the second can.  Place this can on top of the can with the nut. Use a butane lighter to ignite the nut. Record the temperature of the water when the nut is completely burned. Complete the data table by calculating the  the total calories in the pecan.

Data:    

Data Table 1
Before Burning After Burning Difference
Mass of Nut 1.7 g 0.1g 1.6g
Temperature of Water 20 40.1 20.1
Mass of Paper Clip 1.4g 1.4g 0g

 

Data Table 2
Mass of pecan 0.1 g
Temperature change of 100 ml of water 20.1
Calories required to produce temperature change in 100 ml water 2010
Calories per gram contained in the pecan 1182.4

Error Analysis:
Errors may have occurred in several ways during this experiment. One error that may have occurred is that some of the energy may have been lost during the burning. Some of the pecan’s energy was lost as light instead of heat energy. Also some of the heat measured in the water could have been due to the butane lighter used to ignite the pecan.

Conclusion:
The temperature of the 100 ml of water in the can above the burning pecan was changed by the energy given off by the pecan when it was burned.  The energy given off by the burning pecan was great enough to increase the water temperature by 20.1 degrees Celsius. The mass of the unburned pecan was 1.7g. It takes 100 calories to raise the temperature of 1 ml of water by 1 degree Celsius. The temperature of 100 ml of water was recorded to have increased by 20.1 degrees Celsius; therefore, the total number of calories in the pecan equals 20.1 x 100 or 2010 calories. Since the nut had a mass of 1.7g, the number of calories per gram equals 2010 divided by 1.7 or 1182.4 calories per gram.
The increase of temperature in the water showed that energy had been stored in the pecan. In this experiment, the amount of calories of heat energy stored in a pecan during photosynthesis was measured by a process known as calorimetry.

 

Campbell Problem 7

Molecular Genetics Problem 7
7. Using the information from problem 6, a further testcross was done using a heterozygote for height and nose morphology. The offspring were tall-upturned nose, 40; dwarf-upturned nose, 9; dwarf-downturned nose, 42; tall-downturned nose, 9. Calculate the recombination frequency from these data; then use your answer from problem 6 to determine the correct sequence of the three linked genes.

Experiment 3. (Frequency/Distance between T and S)

Determine the recombination frequency for the genes controlling Tallness and Snout:

40 tall-upturned snout = 40% expected
42 dwarf-downturned snout = 42% expected
9 dwarf-upturned snout = 9% recombinant
9 tall-downturned snout = 9% recombinant

Total = 100%

Therefore this recombination frequency between genes T and S is 18%

One can determine the relative frequency between genes using the percent frequencies as distances.

The Recombinant relationships from experiments 1-3 are:

Exp. 1 T-A = 12 map units Exp. 2 A-S = 5 map units Exp. 3 T-S = 18 map units

An arrangement that fits the data would be:

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Carbon Dioxide Use in Plants

 

 

Do Plants Consume or Release CO2?

 

Introduction

The rate of photosynthesis can be determined by measuring the rate of production of sugar or oxygen or by measuring the rate of decrease in carbon dioxide concentration. A common aquarium plant called, Elodea,  can be used to show fast carbon dioxide is being removed from the water in which the Elodea is submerged.

6CO2 + 12H2O + light energy —> C6H12O6 + 6O2 + 6H2O

 

In this lab, you will use phenol red as an indicator to show whether CO2 is being consumed or produced in a reaction. It is well known that in the presence of light, plants perform photosynthesis. At the same time, plants are also performing cell respiration. To demonstrate this, we will determine whether CO2 is consumed or produced as Elodea is placed in either a light or dark environment. The change in CO2 will be detected by the pH indicator phenol red. Phenol red is yellow under acidic conditions (high H+ ion concentration), pink to magenta under basic or alkaline conditions (low H+ ion concentration), and orange under neutral conditions. A change in the amount of CO2 will cause a directly proportional change in H+ ion.

If the CO2 concentration decreases, the H+ ion concentration will also decrease, and the solution will change to pink, becoming basic.

If the CO2 concentration increases, the H+ ion concentration will also increase, and the solution will change to yellow, becoming acidic.

Neutral solutions of phenol red will be orange.

Materials:

phenol red solution,  4 sprigs of Elodea, soda straw, 4 test tubes, labeling marker, 100 ml graduated cylinder, beaker, aluminum foil

Procedure:

  1. Create a solution of phenol red by adding concentrated phenol red to about 100 ml of water in a beaker. The phenol red may change color as a result of adding water (depending on how acidic your tap water is). Your goal is to make your solution a neutral orange color. You can do this by gently blowing into the solution with a straw.
  2. Label 4 test tubes 1, 2, 3, and 4.
  3. Once you have the solution at an orange color, transfer it to 4 test tubes (they should be filled about 2/3 full with your orange solution).
  4. Place a cut piece of Elodea (cut end up) into tubes 2 and 4 and tightly cap.
  5. Test tubes 3 and 4 will not have Elodea. Cap and then cover these tubes with aluminum foil so no light can enter.
  6. Place tubes 1 and 2 in bright light.
  7. Place tubes 2 and 4 in the dark.
  8. After 24 hours, uncover and examine all 4 test tubes and record the results.

Data:

 

Test Tube # Contents of Tube Initial Color Final Color
1
2
3
4

 

Conclusion:

1. What test tubes served as the controls in this experiment. Why?

 

 

2. What was the dependent variable?

 

3. Do you think there would have been any change in any of the test tubes if they were left for 48 or 72 hours? Explain.

 

 

4. Describe and explain what happened in the test tubes.

 

 

 

5. Why did the color change occur?

 

6. Where does the carbon dioxide that is removed from the solution go?

 

7. What other process goes on in plant cells that requires oxygen and produces carbon dioxide?

 

8. What was the purpose in tightly capping all four test tubes?

 

 

Campbell Problem 10

Molecular Genetics Problem 10
10. An aneuploid person is obviously female, but her cells have two Barr bodies. What is the probable complement of sex chromosomes in this individual?

This individual probably is XXX.

The individual is a female. Nondisjunction of sex chromosomes produces a variety of aneuploid conditions in humans. Most of these conditions appear to upset genetic balance less than aneuploid conditions involving autosomes. Extra copies of the X chromosome are deactivated as Barr bodies in the somatic cells. Females with trisomy of the X chromosome (XXX), which occurs about once in approximately 1000 live births, are healthy and cannot be distinguished from XX females except by karyotype.

An Example of nondisjunction:

Klinefelter’s syndrome

49 ,XXXXY

This karyotype shows a variant of Klinefelter’s syndrome.

Individuals with this syndrome are male, typically with the karyotype 47,XXY.

Individuals with Klinefelter’s syndrome exhibit a characteristic phenotype including tall stature, infertility, gynecomastia and hypogonadism.

Aneuploidy above one extra chromosome is usually fatal but because of X-inactivation, which “turns off” all but one X chromosome per cell, the effects of 3 extra chromosomes are reduced.

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Caught Red-Handed

 

Caught Red-Handed  

 

Introduction:

Bacteria are everywhere. They have evolved the ability to inhabit almost every surface on the planet; however, they are invisible to the naked eye due to their small size. Bacteria have been found living in the deepest part of the ocean, in volcanic vents, in boiling hot springs, and even deep in polar ice caps. Many species of bacteria live inside of other organisms in a harmless commensalistic way such as the intestinal bacteria, Escherichia coli. Bacteria can reproduce at very rapid rates whenever conditions are favorable, as often as every 20 minutes doubling in number. The bacterial population is kept in check by the natural defenses of the host, such as the immune system and proper washing habits. When these natural defenses fail, bacteria can quickly become a problem. Some bacteria produce poisons or toxins that can be life-threatening if the bacterial population isn’t controlled by our natural defenses.

The United States Centers for Disease Control (CDC) states that the best way to prevent bacterial spread and infection is through the use of proper sanitary techniques. Perhaps the most critical step in this prevention is the use of proper hand washing. When improperly washed, your hands are one of the most easily colonized areas of your body and many of our behaviors involve the use of our hands.  Proper hand washing requires the use of water as hot as you can stand, soap, and lots of rubbing. The soap and water serve to destroy bacteria, and the rubbing helps slough off dead skin cells along with lots of bacteria.

Objective:

Students will examine:

  1. The spread of bacteria through surface contact
  2. Surface washing techniques to reduce the spread of bacteria

Materials (Part A):

Black light, Glo-Germ powder, lotion or Glo-Germ oil, hand soap, water, paper towels, pencil, lab sheet

Procedure (Part A):

  1. Choose one student in the lab group and have them spread a SMALL AMOUNT of Glo-Germ powder or lotion evenly over the entire surface of their hands. Be sure to include hard to clean areas such as around & under the fingernail.
  2. Have another student use the Black light to check your hands for the fluorescent “germs”.
  3. Estimate the percentage of your hand that you have covered with Glo-Germ powder and record this percentage in your data table 1 under time “0”.
  4. Wash your hands for 10 seconds and then recheck your hands with Black light and record the percentage of “germs” remaining.
  5. Repeat step 5 for washing times of 30 seconds, 60 seconds, and 120 seconds.
  6. Return Glo-Germ powder, lotion, or oil to lab cart. 

Data Table 1

 

Time of Wash in Seconds Percent of Hand Covered with “germs”
0 (initial observation)
10
30
60
120

 

Materials (Part B):

Tennis ball, “play” money, stuffed toy, pencil, lab sheet

Procedure (Part B):

  1. Choose a different member of your lab group and use the Black light to check their hands for the presence of germs.  IF they are “infected”, have them thoroughly wash their hands to remove the “germs”.
  2. Record the percentage of their hand that is covered with “germs”.
  3. Pick up the basket from the lab cart with your materials for part B.
  4. Handle the tennis ball for at least 20 to 30 seconds.
  5. After handling the tennis ball, have your hands rechecked with the Black light for “germs”.
  6. Record this percentage in data table 2.
  7. Return to your lab table and handle each of the other items ONE AT A TIME, checking for “germs after EACH item and recording this percentage in table 2.
  8. Return the black light and basket with handled items to the lab cart.

Data Table 2

 

Name of Item Percent Coverage
Initial Hand Coverage
Tennis Ball
“Play” money
Toy

 

Questions:

  1. If almost every surface we touch is inhabited by bacteria, why don’t bacterial infections occur more often?
  2. Name 3 ways you  might prevent the spread of bacteria each day.
  3. Name several bacterial diseases.
  4. Name and describe the 3 shapes of bacteria.
  5. Are all bacteria harmful? Explain your answer.
  6. What effect, if any, did increased washing time have on the percentage of “germ” coverage on your hands?
  7. Name 3 areas of your home that are most susceptible to bacterial contamination. Explain steps you could take in each of these areas to prevent the spread of bacteria to other places in your home.

Optional:

Create a graph based on the data from table 1.

Title _____________________________