Podcast
Questions and Answers
In the photosynthesis equation, what is the role of chlorophyll and light energy?
In the photosynthesis equation, what is the role of chlorophyll and light energy?
- They are reactants that combine to form glucose and oxygen.
- They are products formed as a result of the reaction between carbon dioxide and water.
- They are inhibitory compounds that prevent excessive production of glucose.
- They act as catalysts, providing the energy needed for the reaction to occur. (correct)
If a plant is kept in complete darkness for an extended period before testing for starch, what result would you expect and why?
If a plant is kept in complete darkness for an extended period before testing for starch, what result would you expect and why?
- An intense blue color, showing that excess starch accumulated in the absence of photosynthesis.
- A pale orange color, indicating a small amount of starch production due to other metabolic processes.
- No color change, because the plant would have consumed any existing starch and cannot produce more without light. (correct)
- A blue-black color change, indicating the presence of starch produced during the dark period.
Why is it important to boil the leaf in alcohol (ethanol) during the starch test?
Why is it important to boil the leaf in alcohol (ethanol) during the starch test?
- To extract the chlorophyll, which would mask the color change caused by the iodine. (correct)
- To break down the cell walls, releasing the starch for easier detection.
- To kill the leaf and stop any further metabolic processes.
- To soften the leaf tissue, making it easier to observe the color change.
A student performs the starch test on a leaf, but skips the hot water bath step. What is the most likely outcome and why?
A student performs the starch test on a leaf, but skips the hot water bath step. What is the most likely outcome and why?
A plant with variegated leaves (patches of green and white) is tested for starch after exposure to sunlight. What result would you expect?
A plant with variegated leaves (patches of green and white) is tested for starch after exposure to sunlight. What result would you expect?
If a leaf tests negative for starch even after being exposed to sunlight, which factor could be a plausible explanation?
If a leaf tests negative for starch even after being exposed to sunlight, which factor could be a plausible explanation?
Which of the following is not a direct requirement for photosynthesis to occur in a green leaf?
Which of the following is not a direct requirement for photosynthesis to occur in a green leaf?
What would be the expected outcome of the starch test if you used a leaf from a plant that is not green, such as a red-colored leaf?
What would be the expected outcome of the starch test if you used a leaf from a plant that is not green, such as a red-colored leaf?
Why is a wire gauze used when heating the alcohol with the leaf in a Bunsen burner setup?
Why is a wire gauze used when heating the alcohol with the leaf in a Bunsen burner setup?
Flashcards
Photosynthesis
Photosynthesis
The process where plants use sunlight to synthesize foods from carbon dioxide and water.
Photosynthesis Equation
Photosynthesis Equation
Takes place when carbon dioxide and water are used together and transformed into glucose and oxygen, with the energy from light, using the Chlorophyll in the plant
Starch
Starch
A polysaccharide carbohydrate consisting of a large number of glucose units joined together.
Beaker (in starch test)
Beaker (in starch test)
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Test tube (starch test)
Test tube (starch test)
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Dropper (starch test)
Dropper (starch test)
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Forceps (starch test)
Forceps (starch test)
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Alcohol (in starch test)
Alcohol (in starch test)
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Iodine Test Results
Iodine Test Results
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Study Notes
- Photosynthesis is the process that produces glucose
Photosynthesis Equation
- CO2 + H2O -> C6H12O6 + O2
- Carbon dioxide and water are the reactants
- Glucose and oxygen are the products
- Light energy and chlorophyll drive the reaction
Test for Starch in Plants
- The aim is to determine if a plant contains starch and has undergone photosynthesis
Apparatus Required
- Beaker: Holds boiling water
- Test tube: Holds leaf and alcohol
- Dropper: Holds and drops iodine
- Forceps: Grips the leaf
- Bunsen burner: Provides heat
- Wire gauze: Acts as a mat for tripod when heating
- Alcohol (ethanol): Extracts chlorophyll
- Iodine solution: Turns blue-black in the presence of starch, indicating starch
- Green leaf: A leaf containing chlorophyll to be tested
Important Points
- A green leaf exposed to sunlight for hours is required to manufacture starch via photosynthesis
- Hot water kills and softens the leaf
- Alcohol with the leaf changes color when heated, breaking down chlorophyll and removing the green color
- Iodine is an indicator for the presence of starch and turns blue-black
Results
- Positive result: Iodine on the leaf turns it blue-black, indicating the presence of starch and photosynthesis
- Negative result: The leaf remains orange-brown, indicating no starch and no photosynthesis
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Description
Learn about photosynthesis, the process that produces glucose from carbon dioxide and water using light energy and chlorophyll. Understand the equation for photosynthesis, identifying reactants and products. Explore the test for starch in plants, including required apparatus and important steps.
