Photosynthesis and Cell Respiration Feedback Loop
What gas bubbles are being produced in
the test tube?
What gas is inflating the
balloon?
In which jar will the candle burn the
longest? Why?
Describe what is occurring in set ups C,
D, and E--why?
C:
D:
E:
Factors Affecting Respiration Lab
Objective: To investigate factors affecting respiration in an organism.
Background: Living things depend on various nonliving components of their environments to
survive and grow. These abiotic factors include sunlight, oxygen, carbon dioxide, availability
of water, and temperature. In this experiment, we will be dealing with several abiotic factors:
temperature, pH, and availability of food (sugar). Organisms need cellular respiration to get
energy their cells can use from their food. This chemical reaction (cellular respiration) requires
sugar and (if aerobic respiration) oxygen. Cellular respiration is also controlled by enzymes,
which can be affected by the environment. Cellular respiration produces ATP, and two waste
products (carbon dioxide and water). We will measure the carbon dioxide production to
determine the effect of different factors on cellular respiration.
Pre-lab Questions:
1. What is the purpose of cellular respiration?
2. What form of energy, produced by cellular respiration, can cells easily use?
3. What does aerobic respiration need to occur?
4. What waste products are produced by cellular respiration?
Procedure:
Your group will be assigned ONE factor. ONLY do the procedure for THAT factor!
Hypothesis
Write a hypothesis predicting the effect of the factor your group was assigned on the rate of
cellular respiration:
If _________________________________, then______________________________.
Data
Effect of Various Factors on Yeast Respiration
Factor Affecting Respiration
Measurement of Respiration
Before
After
None – Control Group
High (Hot) Temperature
Low (Cold) Temperature
Acidic (Low) pH
Basic (High) pH
Different Food Source (Starch not Sugar)
No Food Source
Analysis:
1. True/False – Cellular respiration can be affected by many factors.
2. Write the equation for cellular respiration. Circle the reactants and draw a square
around the products:
_______________________________________________________________
3. If you add yeast, warm water, and sugar to a Zip-loc bag, the bag expands. What
waste product of cellular respiration caused the bag to become larger?
_________________________
4. Compare the factors the class completed to the control group. For each factor, write
whether respiration decreased, increased, or showed no difference:
a. High Temperature
_______________________
b. Low Temperature
_______________________
c. Acidic pH
_______________________
d. Basic pH
_______________________
e. Different Food Source _______________________
f. No Sugar
_______________________
5. Cellular respiration is a chemical reaction that requires enzymes. Using what you know
about enzymes, why would high temperatures, low temperatures, acidic and basic pH
levels change the rate of respiration?
_______________________________________________________________________
___________________________________________________________
6. Using what you know about starch (a complex carbohydrate made of many simple
sugars) and sugar (a simple carbohydrate), why might having starch instead of sugar
slow down respiration?
_______________________________________________________________________
___________________________________________________________
7. Why would having no sugar prevent respiration from occurring?
_______________________________________________________________________
___________________________________________________________
8. What were the optimum temperature and pH conditions for yeast’s cellular respiration,
based on the data from this lab? How do you know?
_______________________________________________________________________
___________________________________________________________
Conclusion
a. Write a conclusion that summarizes the lab, accepts or rejects your original hypothesis,
and answers the purpose question of the lab. Discuss any experimental error that may
have occurred.
b. Consider each of the factors that were shown to affect the rate of cellular respiration.
Which of these factors do you think will have the GREATEST effect? Develop an
argument outlining at least 3 points to support your answer.
Chloroplasts and Mitochondria
Plant cells and some Algae contain an organelle called the
chloroplast. The chloroplast allows plants to harvest energy from sunlight
to carry on a process known as Photosynthesis. Specialized pigments in the
chloroplast (including the common green pigment chlorophyll) absorb sunlight
and use this energy to combine carbon dioxide and water and make
GLUCOSE and OXYGEN. The complete the chemical reaction for
Photosynthesis is:
6 CO2 + 6 H2O + energy (from sunlight)
RAW MATERIALS
ENERGY
C6H12O6 + 6 O2
PRODUCTS
In this way, plant cells manufacture glucose and other carbohydrates
that they can store for later use. Photosynthetic cells found mainly in the
leaves may have thousands of chloroplasts.
QUESTIONS:
1. What type of cells contains chloroplasts?
2. What is the energy autotrophs use to make their own food?
3. The food making process is called ___________________.
4. What are the raw materials for photosynthesis?
5. What simple sugar is produced?
6. What gas is USED? ________________ RELEASED? ________
7. Where are most photosynthetic cells in plants found?
8. About how many chloroplasts can be found in photosynthetic cells?
Chloroplasts are double membrane organelles with a smooth outer
membrane and an inner membrane folded into disc-shaped sacs called
thylakoids. Color and label the outer membrane light green. Thylakoids,
containing chlorophyll and other accessory pigments (red, orange, yellow,
brown), are in stacks called granum (grana, plural). Color and label the grana
(STACK) dark green in Figure 1. They are surrounded by a gel-like material
called stroma. Color and label the stroma light blue in Figure 1.
FIGURE 1-CHLOROPLAST
9. How many membranes surround a chloroplast?
10. The INDIVIDUAL SACS formed by the inner membrane are called
_________________ and are arranged in ___________ like
pancakes.
11. What pigment is found inside a thylakoid? What color will it be?
12. Other pigments that trap sunlight are called A_____________
pigments. What colors are these pigments?
13. STACKS of thylakoids are called G___________ (plural) or GRANUM
(singular).
Mitochondria are the powerhouses of the cell because they “burn” or
break the chemical bonds of glucose to release energy to do work in a cell.
Remember that this energy originally came from the sun and was stored in
chemical bonds by plants during photosynthesis. Glucose and other
carbohydrates made by plants during photosynthesis are broken down by
the process of aerobic cellular respiration (requires oxygen) in the
mitochondria of the cell. This releases energy (ATP) for the cell. The
more active a cell (such as a muscle cell), the more mitochondria it will
have. The mitochondria are bout the size of a bacterial cell and are often
peanut-shaped. Mitochondria have their own DNA and a double
membrane like the nucleus and chloroplast. The outer membrane is
smooth, while the inner membrane is convoluted into folds called cristae
in order to increase the surface area.
14. Why are mitochondria called the powerhouse of the cell?
15. What cell process occurs in the mitochondria?
16. Why do some cells have MORE mitochondria? Give an example.
17. What simple sugar is broken down in the mitochondria?
18. Where does the energy in glucose come from ORIGINALLY?
19. Where is this energy stored in glucose?
20. Why is cellular respiration an aerobic process?
21. What energy is released when the chemical bonds of glucose are
broken?
22. Name two other organelles besides the mitochondria that contain
DNA and have a double membrane.
23. Describe the outer membrane of the mitochondria.
24. Why is the inner mitochondrial membrane folded?
25. What are the folds called?
Color and label the outer membrane pink and the cristae red on figure
3. This greatly increases the surface area of the membrane so that
carbohydrates (simple sugars) can combine with oxygen to produce ATP,
adenosine triphosphate (the energy molecule of the cell). The electron
transport chain takes place across the membranes of the cristae (crista,
singular). Inside the folds or cristae is a space called the matrix that
contains enzymes needed for the Kreb's Cycle. Color and label the
matrix yellow on figure 3.
FIGURE 3 - MITOCHONDRIA
Mitochondria
Cellular Energy—ATP (the $.25 from the $10.00 bill glucose)
Adenosine triphosphate (ATP) is the energy molecule used by all cells
to do work. It is a nucleotide consisting of a nitrogen-containing base
(adenine, thymine, cytosine, or guanine), a 5-carbon sugar, and 3 phosphate
groups. ATP is able to store and transport chemical energy within cells. The
LAST TWO phosphate groups (PO4), are joined by HIGH-ENERGY bonds.
When these bonds are broken, energy is released for cells to use and ADP
forms. Enzymes help to break and reform these high-energy bonds.
1. What does ATP stand for?
2. What three main things make up an ATP molecule?
3. How many high-energy bonds does ATP contain?
4. Where are these high-energy bonds found in ATP?
5. What helps weaken these bonds so energy can be released and then
later help reform them?
6. When ATP loses a phosphate group __________ is released for cells
and a molecule of _________ forms.
In Figure 4, COLOR the 5-carbon sugar RED and LABEL it RIBOSE.
COLOR and LABEL the double-ring nitrogen-base DARK BLUE. COLOR and
LABEL the 3 phosphate groups YELLOW, and COLOR & LABEL the 2 highenergy bonds GREEN.
FIGURE 4 – ATP MOLECULE
Questions:
7. What is the energy molecule of the cell called?
8. What macromolecule made by plants is "burned" in the mitochondria?
9. Where is chlorophyll found in the chloroplast?
10. In which part of a plant would you expect to find the most chloroplasts and why?
11. How would the number of mitochondria in an insect's wing compare to the amount found in
other cells in an insect's body? Explain your answer.
12. What are the raw materials for photosynthesis?
13. What product of photosynthesis is used in cellular respiration?
14. What is the advantage of having a folded inner membrane in the mitochondria?
15. What is the energy for photosynthesis?
16. Besides chlorophyll, what other pigments are found in the chloroplasts?