Evidence of Photosynthesis
1. Testing for the presence of carbon dioxide Materials:
4 Test tubes Drinking straw
4 Rubber stoppers lime water 2 500 mL empty mineral water bottles with cap 1 Graduated cylinder
Procedure:
a) Label the test tubes A and B.
b) Measure 5 mL of lime water using a graduated cylinder and pour into test tube A and test tube B.
c) Use a straw to blow air into test tube A, as shown in Figure 6.
d) Cover it immediately with a rubber stopper. (Note that exhaled air contains 3-4% carbon dioxide.)
e) Cover test tube B with rubber stopper f) Shake both test tubes very well.
Q12. What happened to the contents of the two test tubes?
Write your observations in the table below.
Table1.
Setup Observation Possible Explanation
Test tube A (exhaled
DRAFT
March 31, 2014
Learner’s Module
12 2. Photosynthesis and carbon dioxide
Materials:
Small fresh leaves drinking straw
Water 2 Test tubes
Limewater 2 Rubber stoppers Test tube rack compress the leaves because they won’t be able to absorb adequate carbon dioxide.
d) Cover both test tubes with a rubber stopper. See Figure 7b.
e) Place the two test tubes on a test tube rack. And put them under sunlight for 20 minutes.
f) After 20 minutes, get back the two test tubes and bring them back to your working area.
g) Add 5 mL of lime water to each test tube and cover with rubber stopper.
h) Shake well. Observe what happens to the contents of the two test tubes.
Write your observation on Table 2.
Table 2.
SetUp Observation Possible Explanation
Setup C Setup D
Carbon dioxide is one of the important materials to enable plants to produce food.
Figure 7b. Sample Set-up Photo Credit: Maricel Peña-SJDMNHS
Figure 7a. Test tubes C and D
Photo Credit: Maricel Peña-SJDMNHS
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Learner’s Module
13
After investigating the evidences that plants are photosynthetic organisms, the next thing that you will do is to conduct another experiment that will show the factors affecting the rate of photosynthesis. This will tell you how you can speed up the process of food making and how it can affect the quantity and quality of harvests.
3E. To show the effect of the varying amount of chlorophyll in the rate of photosynthesis.
Materials:
1 fresh coleus leaf (mayana) Alcohol lamp
Denatured alcohol Beaker
Petri dish Wire gauze
Tripod Test tube
Medicine dropper Tincture of iodine Procedure:
a) Get a variegated fresh coleus leaf (mayana) as shown in Figure 8.
b) Draw the leaf. Shade the green parts. Label it Leaf A.
c) Remove the chlorophyll from the leaf by boiling it in alcohol. To do this, follow the steps below.
1. Fill the beaker with (3/4 of its capacity) with water. Let it boil.
2. While waiting for the water to boil, get the leaf sample, then place it in a test tube.
3. Pour alcohol in the test tube until the leaf has been completely soaked as shown in Figure 9.
4. When the water in the beaker boils, place the test tube in it. Let the water boil for another three minutes or until all the colors of the leaf
have been extracted as shown in Figure 10.
Q19. What changes did you observe?
____________________________________________________
Q20. What do you think caused the changes?
____________________________________________________
Keep the alcohol away from the fire!
Caution
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d) Using a test tube holder, remove the test tube from the beaker using. Then get the leaf out of the test tube.
e) Rinse the leaf with water and place it on a petri dish.
Q21. What happened to the leaf after boiling?
__________________________________________________________
Q22. What can you infer from your observation?______________________
_____________________________________________________________
f) To test for the presence of starch, put drops of iodine until the leaf has been soaked.
g) Observe the leaf. Draw the leaf and shade the bluish black area. Label it Leaf h) Compare your drawings of leaf A and leaf B. B.
Q23. Which part of the leaf is shaded?___________________
Q24. Which part of the leaf produced more starch?____________
Q25. How does the presence of green pigment affect the production of starch? ____________________________________________________
KEY CONCEPTS:
Cellular Respiration
All heterotrophic organisms including man, depend directly or indirectly on plants and other photosynthetic organisms for food. Why do we need food? Organisms need food as the main source of energy. All organisms need energy to perform essential life processes.
The food must be digested to simple forms such as glucose, amino acids, and triglycerides. These are then transported to the cells. The immediate energy source of the cells is glucose. Glucose inside the cell is broken down to release the stored energy.
This stored energy is harvested in the form of adenosine triphosphate (ATP). ATP is a high-energy molecule needed by working cells.
Glycolysis
In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules.
The factors that affect the rate of photosynthesis are temperature, carbon dioxide, water, and light. Providing the plant with the right amount of these materials will ensure good quality and quantity of the harvest.
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Learner’s Module
15
Source:
http://www.hartnell.edu/tutorials/biology/cellularrespiration.html
Krebs Cycle
The Krebs Cycle occurs in the mitochondrial matrix and generates a pool of chemical energy (ATP, NADH, and FADH2) from the
oxidation of pyruvate, the end product of glycolysis.
Pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA, a 2-carbon molecule.
When acetyl-CoA is oxidized to carbon dioxide in the Krebs cycle, chemical energy is released and captured in the form of NADH, FADH2, and ATP.
Electron Transport Chain
The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD+ (NADH) and reduced FAD (FADH2). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH2).
The electron transport chain (ETC) consists of a series of molecules, mostly proteins, embedded in the inner mitochondrial membrane. This phase of cellular respiration produces the greatest number of chemical energy in the form of ATP.
In the following activities, you will learn how the chemical energy of "food"
molecules is released and partially captured in the form of ATP (Adenosine Triphosphate). You should learn first the part of the cell where ATP is produced.
Source:
http://www.hartnell.edu/tutorial s/biology/cellularrespiration.html
DRAFT
Mitochondria are membrane-enclosed organelles distributed through the cytoplasm of most eukaryotic cells. Their main function is the conversion of the potential energy of food molecules into ATP. This organelle has important parts. An outer membrane encloses the entire structure that contains many complexes of integral membrane proteins that form openings. A variety of molecules and ions move in and out of the mitochondrion through the openings. An inner membrane encloses a fluid-filled matrix. This membrane contains five complexes of integral proteins such as:
NADH dehydrogenase
succinate dehydrogenase
cytochrome c reductase (the cytochrome b-c1complex)
cytochrome c oxidase
ATP synthase
KEY CONCEPTS:
Task: Describe each part of the mitochondrion.
Eg. Cristae are the inner folded membrane of the mitochondrion.
Mitochondrion is considered as the power house of the cell. It plays an important role in the breakdown of food molecules to release the stored energy in the form of ATP (Adenosine Triphosphate).
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