Molecules of Life Packet due March 12th
Name ______Hour ______
Lab 33 / Due:______Light and / Pre Lab / 0 / 1 / 2
Carbon / Questions / 0 / 1 / 2 / 3
Dioxide / Data Table / 0 / 1 / 2
Lab 34 / Due:______
I2 Leaf Stain / Illustration / 0 / 1 / 2
Questions / 0 / 1 / 2 / 3
Investigation / 0 / 1 / 2
Lab 35 / Due:______
Build / Pre Lab / 0 / 1 / 2
Glucose / Questions / 0 / 1 / 2 / 3
Model / 0 / 1 / 2 / 3
HW / Page 1 / 0 / 1 / 2 / 3
Page 2 / 0 / 1 / 2 / 3
investigation / 0 / 1 / 2
Your Points
Total Points Possible pts
INVESTIGATION: PHOTOSYNTHESIS
ROLE OF LIGHT AND CARBON DIOXIDE IN PHOTOSYNTHESIS
Introduction: Photosynthesis, the most important chemical process on Earth, occurs with the aid of colored pigments in the presence of light. During the process, carbon dioxide is combined with water to form glucose and oxygen is given off as a by-product. The process takes place in two steps – the light reaction and the dark reaction. These two reactions are able to convert light energy into chemical energy.
In this lab you will investigate the role of light and the production of carbon dioxide in a sprig of Elodea. You will use an indicator, bromthymol blue as an indicator of the presence of Carbon Dioxide. It turns blue when the pH is above 7.6 (alkaline) and yellow when the pH is less than 6 (acidic). Carbon dioxide dissolves in water and produces carbonic acid. Carbonic acid causes the bromothymol blue to turn yellow because it lowers the pH below 7 (not oxygen).
Pre-lab Questions:
1. Write the overall chemical equation for photosynthesis including the terms enzymes, chlorophyll, and sunlight.
2. The introduction states that photosynthesis “occurs with the aid of colored pigments in the presence of light”. What are the “colored pigments” that the introduction is referring to?
3. If carbon dioxide is added to a blue solution of bromthymol blue, what color will result?
Materials (per team of 4)
500 ml beaker straw
4 test tubes bromthymol blue solution
marker aluminum foil
Procedure:
1. Half-fill a 500 ml beaker with bromthymol blue solution. Using the straw, blow gently into the solution until it turns a pale yellow color. This demonstrates that the solution turns yellow when CO2 is added.
2. Place the 4 test tubes in a test tube rack. Label the tubes with the marker as follows: 1 , 2 , 3 , and 4. Also be sure to label the test tubes with your group name so you can find your tubes after 24 hours.
3. Add bromthymol blue solution to the 4 test tubes until about 2/3’s full.
4. Obtain two sprigs of Elodea of about equal size. Place a sprig in tube 1 and the other sprig in tube 3.
5. Record your observations about the starting color for each tube in the table below.
6. Follow your instructor’s directions to place the tubes in the following conditions:
Tubes 1 & 2 in total darkness
Tubes 3 & 4 in bright light
After 24 hours:
7. Obtain your test tubes for observation. Complete the following table:
Test Tube Number /Light or Dark
/ Starting Color / Final Color1 (Elodea)
2
3 (Elodea)
4
8. Remove the Elodea sprigs from tubes 1 & 3 and place the sprigs back into the container where you obtained them.
9. Place the tubes in the soap and water container at the front of the room.
Post Lab Questions:
1. What happens to the carbon dioxide that you blew into the bromthymol blue?
2. What was the purpose of tubes 2 & 4 without the Elodea? Explain carefully!
3. What substances were used by the Elodea for photosynthesis?
4. Photosynthesis is comprised of two reactions. What are they? Summarize what happens in each reaction.
A.
B.
5. How do you explain the color results in tubes 1 & 3 that did not contain Elodea?
6. What colors of light does chlorophyll absorb? What colors does chlorophyll reflect?
Conclusion: Explain what you learned in this investigation.
7. In the space below, use color pencils to draw the results of an experiment where tubes 1 and 2 are kept in red light and tubes 3 and 4 are kept in green light.
Lab: I2 Leaf staining or Plant photographs:
Background:
Sugars produced during photosynthesis are often stored as starch. Thus, starch production is another indirect measure of photosynthesis. To produce this starch, photosynthesis requires light as an energy source (in the absence of light, starch is not produced). Photosynthesis also requires chlorophyll to capture light energy (in the absence of chlorophyll, starch is not produced). In the following procedure you will detect the presence of starch by staining it with a solution of iodine and demonstrate the requirement of light and chlorophyll for photosynthesis.
Procedure A:
1. Remove one green leaf from a plant that has been in the light and cut the petiole off.
2. Remove one green leaf from a plant that has been in the darkness for a couple of days and leave the petiole on.
3. Remove a variegated leaf that has been kept in the light.
4. Immerse the leaves in boiling water for one minute into the pot that is labeled with Light for the leaf kept in the light, dark for the leaf kept in the dark and variegated for the variegated leaf.
5. Bleach the pigments by leaving the leaves in methanol overnight.
6. Remove the leaves from their containers and place the leaves in Petri dishes with a little water and 5-8 drops of iodine.
7. Observe color changes and draw and color each leaf below. Label each drawing.
Kept in Light Variegated Kept in DARK Kept in LIGHT
Questions:
1. Which leaves showed stored starch?
2. Explain how and why your drawings differed.
3. Would you expect leaves to be the primary area for starch storage? Why or why not?
4. How would starch get to other parts of a plant?
5. Can photosynthesis take place in any plant structures beside the leaf? Explain your answer.
6. Design a step-by-step procedure to determine if there is starch in the root of a potato. List all needed steps here:
Investigation:
Investigate the various variegated plants that are around us and their green counterparts. List your findings here.
Lab: Building Glucose, cellular respiration and photosynthesis
Photosynthesis and Respiration Formula Lab
Directions: Cut up 6 CO2’s and 6 H20’s into separate pieces. Then build a glucose molecule using the pieces you cut up from both CO2 and H20. Remember that Carbons are located at five of the six edges of the hexagon with one Carbon attaching outside of the hexagonal shape. Use your chemistry of fats, proteins, lips activity to help you along.
Pre-Lab:
Use your notes to write the equation for photosynthesis below:
Use your notes to write the equation for cellular respiration below:
Color all the H2O’s on the following sheet blue, the CO2’s red.
How many bonds can an oxygen form? A carbon atom? A hydrogen atom?
Procedure:
Part A – Photosynthesis:
Cut out the C,H, and O from the table and using the linkers build a glucose molecule. Be careful to use the right number of bonds for each atom.
1. How many hydrogen atoms are used from the waters?
2. How many carbons are used from the carbon dioxide?
3. How many oxygen atoms are used?
4. What happens to the extra oxygen atoms?
5. What is one use for glucose in the cell?
6. What is the cell part in a plant where this glucose is used?
7. What time of day is the most glucose made in the leaves of a plant?
8. When glucose is used in a cell what is the name of the reaction that utilizes the glucose?
Part B – Cellular Respiration
Using your glucose burn this sugar for energy in the mitochondria, releasing water, carbon dioxide and forming ATP from the energy of the bonds.
1. Write the equation for cellular respiration here:
2. What is one use of ATP?
3. What does the body do with the CO2 that is produced in the cells during cellular respiration?
4. If you are in the desert and drink only sugar-filled soda will you be hydrating or dehydrating and explain why or why not?
5. How many hydrogen atoms are present in glucose? How many hydrogen atoms are present in the water formed by cellular respiration?
Lab Analysis:
1. Based on these lab activities, what does a plant need in order for photosynthesis to take place (reactants)?
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2. One more item is needed by plants during photosynthesis. Based on your prior experience, what do plants need every few days or so or they will wilt and die?
3. Based on these activities, what does a plant produce as a result of photosynthesis (products)?
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4. What is the overall equation for photosynthesis?
5. Light travels in the form of waves. Different wavelengths appear as different colors and are measured in nanometers.
Looking in your notes packet, what color of light has a wavelength of around 450 nanometers?
6. Where does the oxygen come from that plants produce? In which reaction are these molecules produced?
HW Biology Plants
1. What is the overall equation for photosynthesis?
2. (A) Name a gas released as by-product of the light dependent reactions of photosynthesis.
(B) Name the molecule that is the source of this gas.
(C) Why is oxygen removed from this molecule?
3. Light travels in the form of waves. Different wavelengths appear as different colors and measured in nanometers.
A. Which wavelength color attracts the most energy?
B. Which wavelength color attracts the least energy?
4. During photosynthesis, the energy from the sun is stored within ______compounds. What color(s) do they absorb? What color(s) do they reflect?
5. Draw a chloroplast in the space below. Be sure to clearly label thylakoids, grana and stroma. Neatness counts.
6. What gas is used by autotrophs and what gas is produced?
7. Where does the oxygen come from that plants produce? In which reaction is oxygen produced?
8. a. What molecules do plants use to produce sugar?
b. Where do those molecules come from?
c. In which reaction are these molecules produced?
9. Summarize, in one sentence, what happens during the light dependent reactions of photosynthesis.
Cellular Respiration
1. Where does the process of cellular respiration take place?
2. Do plants undergo cellular respiration? If so, why?
Photosynthesis Investigation
History:
Jan Baptiste Van Helmont was the first to understand that there were gases in the atmosphere. He conducted an experiment to discover how trees get their mass. He grew a willow tree in 1647 and measured the amount of soil, the weight of the tree and the water he added. After five years the plant had gained about 164 pounds. Since the amount of soil was basically the same as it had been when he started his experiment, he deduced that the tree's weight gain had come from water.
From there, an English scientist named John Priestly studied photosynthesis in 1771. What he did was placed a candle in a bell jar (pictured below) until it went out. Using up all of the oxygen in the jar. Then he placed a plant in the jar. After several days, he noticed that the candle would begin to burn again.
The following year, Priestley did an experiment with plants and mice. He placed a plant in the bottom of the bell jar and a mouse on a platform above. The other jar he placed the mouse but did not put a plant in there (see the pictures below). What he discovered was that the mouse placed in the jar without the plant passed out. However, the mouse with the plant would never pass out.
Jan Igenhousz was a Dutch physiologist who discovered that plants would give off oxygen only when exposed to light by taking plants and placing them in light. He discovered that these plants gave off bubbles from their green parts while plants kept in the shade, the bubbles eventually stopped.
1. Why did the candle burning in the jar go out?
2. What gas did the plant put into the air when placed inside the bell jar?
3. What else must the plant have made beside this gas?
4. How did Priestley test to see if the plant had made oxygen?
5. As a result of these experiments, what was Priestley able to discover about Photosynthesis?