Lab 6-Bioenergetics as a cycle
Pre-Lab Questions
Part A: Cellular Respiration “How does the cell obtain energy from food?”
1. Explain the purpose for cellular respiration.
2. What is the formula for cellular respiration?
3. If there is no oxygen available, what process then would occur?
4. What is ATP and what is ATP used for?
5. Do mealworms perform cellular respiration? Plants? Humans? Justify your answer.
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Part A: Cellular Respiration: “How does the cell obtain energy from food?”
Cellular Respiration Formula:
C₆H₁₂O₆ + O₂
→
CO₂
+ H₂O + energy
glucose + oxygen → carbon dioxide + water + energy
Introduction: All eukaryotic organisms have mitochondria. (Fungi, plants, animals and protists). Mitochondria are
very efficient at breaking food down (fats, carbohydrates and proteins). The mitochondria can efficiently recharge
our “mini-batteries” called ATP. ATP is known as potential energy or stored energy. The ATP can donate a (P)
phosphate to a cell, organelle (tiny organ), chemicals, etc. This (P) phosphate will aid in providing energy to help a
cell perform various functions in maintaining homeostasis (an internal balance). If oxygen is not available, then
organisms can breakdown food through fermentation. The two types of fermentation are lactic acid fermentation
and alcohol fermentation. This process does not recharge as much (ATP) energy as cellular respiration, but it keeps
us going.
In this experiment, we will use KOH (potassium hydroxide). KOH will take carbon dioxide released from
cellular respiration and transform this gas form into a precipitate (solid). By making carbon dioxide into
a solid, you have now created a vacuum. (The dye will move into the chamber as cellular respiration
continues).
Overview: Students will investigate measure and compare the rate of cellular respiration in meal worms
at various stages of development.
Materials for the lab group of 2 students : As you inspect your kit, check off the materials found.
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Meal worms (one will be placed in your respirometer)
Size of
Size of
Forceps for absorbent cotton & non-absorbent cotton (rayon)
cotton
rayon
Spoon to collect meal worms
ball
ball
Absorbent cotton (small size)
Non-absorbent cotton (rayon) (small size)
Potassium hydroxide (KOH)
Weighted plastic syringe with glued capillary tube on tip and ruler taped to capillary tube (see
image on page _____)
Food coloring
Micropipette
1-mL pipette
Timer
Safety: (Wear goggles, gloves and apron)
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Chemical Caution: The KOH (potassium hydroxide) is
corrosive. Do not touch this with bare hands or your seeds.
Wear safety gear
Procedures: (Wear your safety equipment)
(All images to refer to will be found on page 6)
1. Record room temperature on page 3 (data table)
2. Take your respirometer and carefully remove the plunger.
3. Next, add one (small) piece of cotton using a pair of forceps and insert the absorbent cotton
into the respirometer chamber.
4. Using a 1-mL pipette, carefully add 1 mL of KOH (potassium hydroxide) to the absorbent
cotton. Do not let the KOH touch the sides of the chamber. If the KOH does, the KOH will harm
the mealworm.
5. Use your forceps once again, and add a small piece of dry non-absorbent cotton (no KOH on
this ball) on top of the cotton ball with KOH.
6. Carefully place the chamber in a horizontal position to add one mealworm into the
respirometer chamber. (Do not let the mealworm come in contact with the non-absorbent
cotton). If your mealworm does get caught in the non-absorbent cotton immediately
remove it and start over. (KOH will affect the mealworm and your results).
7. Insert the plunger into the plastic syringe (do not force the plunger into place).
8. Invert the chamber with the syringe to an upward position.
9. Using a micropipette, place one drop of food coloring onto the tip of the capillary tube. (Do not
force air or dye into the capillary tube. If you force air or dye into the tube, you will cause alter
your results). As soon as you place a drop of food coloring onto the capillary tube begin
recording your data for twenty minutes.
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10. When you have finished your first trial remember to open the chamber, mealworms need
oxygen too.
11. Repeat this experiment two more times
Date Table:
Temp ºC
Time
(minutes)
Start @ 0
1
2
3
Record the
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temperature
5
below
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7
_____ ºC
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9
10
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12
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Mealworms Trial Mealworms Trial Mealworms Trial
1
2
3
Dye in mm
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15
16
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18
19
20
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Post Lab Questions: Part A
questions
1. What caused the food coloring to enter your respirometer? Justify your response.
2. What was the purpose for using a non-absorbent cotton (rayon) in this experiment?
3. Would the rate of cellular respiration in mealworms change if the temperature was decreased by ten
degrees? Explain. (Hint cell respiration uses many enzymes)
4. If you had to perform another cellular respiration but this time on a rodent, draw and label what this
experiment would look like. (please research this question)
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Lab 6: Bioenergetics as a cycle: Part B
-Part B
Pre-Lab Questions
Part B: Chromatography “How to extract the pigments from a leaf”.
1. What does chromatography mean?
2. What major pigments are involved in photosynthesis?
3. Why is chlorophyll A is considered a primary pigment?
4. What practical purposes can chromatography be used for?
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Part B: Chromatography: How to extract the pigments from a leaf:
Introduction: Plants have the ability to make their own food though the process of photosynthesis.
Plants are organisms that use sunlight to make their own energy (AKA producers). Each type of plant
contains various accessory pigments that allow the plant to absorb different wavelengths of visible light
(white light). Some of the accessory pigments are as followed: (chlorophyll b, chlorophyll c, chlorophyll d,
xanthophyll, carotenoids…). Each of the accessory pigments will channel their energy that they gained
from the sunlight and transferred it to a primary pigment known as chlorophyll a.
In this lab you will be able to separate these pigments and observe four of the six pigments mentioned
above. The stored energy (sugar) is use to support daily functions (homeostasis), growth (mitosis) and
reproduction (meiosis). Chromatography is a technique that is used to separate chemicals. In this lab, we
use a solvent that will help separate pigments in the plant. Separating pigments are based on density. The
lighter the pigment, the higher the pigments will travel. Chromatography is used for many purposes: in a
crime scene the scientists can test cologne found on a shirt to determine the brand of cologne, in a
hospital the doctors can test the patients’ blood to determine what chemicals the patience that have
consumed and made them ill, in a hit and run you can determine the make and model of a vehicle from a
paint chip left at the accident.
Overview: Students will investigate and extract pigment and calculate the Rf value of pigments
found in green plants leaves.
Materials for the lab group of 2 students : As you inspect your kit, check off the materials found.
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1 Pair of forceps
1 Chromatography vial, with hook & cap
1 Ruler (metric- read in mm)
1 Chromatography paper strip with pre-punched hole
1 Coin (dime or quarter) The ridges on the coin aid in removing the pigments
1 Piece of fresh kale or spinach
1 Wax pencil (mark your chromatography vial)
1 – 1 mL Pipet
1 mL Chromatography solvent (acetone / petroleum ether)
 Safety: (Wear goggles, gloves and apron)
Chemical Caution: The chromatography solution is very flammable, a serious health hazard and
moderately reactive. Chromatography solvent will only be used under a fume hood. Wear safety
gear and remember that the petroleum ether and acetone mixture is an irritant to your eyes.
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SAFETY REMINDER!!!
Wear your safety equipment: Gloves, goggles, and apron
The chromatography solvent must be used under the fume hood.
Once the chromatography vial contains the chromatography solvent,
it cannot leave the fume hood.
Procedures:
1. While wearing your gloves, hold your chromatography paper strip by the edge. (any skin lotion or oils
on your hands can ruin the chromotography experiment).
2. Measure 2-cm from one end of the chromatography strip. Using a pencil supplied in your kit, draw a
light line across the 2-cm mark. (See image #1 below).
3. Cut the end of the chromatography paper of scissors to cut off two small pieces below the pencil line to
form a pointed end (See image #2 below).
4. Take your kale or spinach leaf and place it on top of your line that drew on your chromatography strip.
5. Using a dime or quarter roll the edge of the coin over the spinach and the chromatography paper pencil
line. By rolling the coin over the leaf and chromatography strip, it will transfer the pigments in the leaf
onto the chromatography strip. (This process must be done several times over the pencil mark line
to create a dark green line) (See image #3 below).
Pencil Mark (2 cm)
Figure #1
Keep the pigment
only on the line
Figure #2
Figure #3
5. Next grab your chromatography vial, place your group name on it with your wax pencil.
SAFETY REMINDER!!!
The chromatography solvent must be used under the fume hood.
Once the chromatography vial contains the chromatography solvent,
it cannot leave the fume hood.
Walk over to the fume hood. The fume hood should be on and fume hood should be open enough to
complete the next few steps. Any questions, ask your instructor.
6. Using a 1 mL pipette, add 1 to 2 mL of chromatography solvent into the vial. (The solvent cannot touch
the edge of the vial)
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7. Insert the chromatography strip into the vial with the pointed tip downward. (The tip is the only part
that should come in contact with the chromatography solvent)
8. Lightly place the cap onto the vial and let the chromatography paper absorb the chromatography
solvent. Do not shake or quickly move the vial. (Keep an eye on the solvent front and the pigments that
move up the chromatography strip).
9. When the solvent front is about 1-2 cm from the top of the chromatography paper, use your forceps
and remove the chromatography paper from the vial. Mark your solvent front with a pencil. (Allow the
chromatography paper to completely before removing from the fume hood.)
10. When the chromatography paper has completely dried, take your chromatography paper to your
workspace and record the pigment colors and measure in mm the distance each pigment has traveled
starting from the pencil / leaf line.
11. Lastly, calculate the Rf value for each pigment. (Use the formula below)
Rf = Distance traveled by component from point of application
Distance traveled by solvent from point of application
Data
Pigment
Distance Traveled
(mm)
Rf Value
Top
Bottom
(Starting Point)
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Post Lab Chromatography Part B Questions
1. Which of the four pigments traveled the furthest? Why did this pigment travel the furthest?
2. How is chromatography useful in the medical field and forensic science?
3. If you used chromatography paper that was 1 foot in length, would your Rf values still be the same or
different? Justify your response.
4. Why are leaves often green in color? Is there any connection to the color you see and the wavelengths
of light a plant absorbs? (research this question)
5. What causes leaves to change from green to various colors in the fall? (research this question)
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