Podcast
Questions and Answers
What is the primary role of pigments in plants?
What is the primary role of pigments in plants?
- To absorb light energy for photosynthesis (correct)
- To store starches for energy
- To reflect sunlight and prevent overheating
- To provide structural integrity to cells
Which type of pigments is masked by chlorophyll in leaves until fall?
Which type of pigments is masked by chlorophyll in leaves until fall?
- Anthocyanins
- Carotenoids (correct)
- Xanthophylls
- Chlorophyll b
What color reflects green light in plants?
What color reflects green light in plants?
- Blue
- Red
- Yellow
- Green (correct)
Which accessory pigments are known for their yellow and orange colors?
Which accessory pigments are known for their yellow and orange colors?
In the Coleus plant, what pigment is primarily responsible for the dark red and violet colors?
In the Coleus plant, what pigment is primarily responsible for the dark red and violet colors?
What is the function of I2KI in the starch test during the experiment?
What is the function of I2KI in the starch test during the experiment?
Which of the following areas of the Coleus leaf will contain no pigments?
Which of the following areas of the Coleus leaf will contain no pigments?
How do carotenoids contribute to photosynthesis despite being accessory pigments?
How do carotenoids contribute to photosynthesis despite being accessory pigments?
What is the purpose of placing pigment bands into the beaker with acetone?
What is the purpose of placing pigment bands into the beaker with acetone?
At what range of wavelengths do Chlorophyll pigments show peak absorption?
At what range of wavelengths do Chlorophyll pigments show peak absorption?
Which cuvette contains the pigment sample during the spectrophotometric analysis?
Which cuvette contains the pigment sample during the spectrophotometric analysis?
Which of the following pigments is expected to have a peak absorption in the 400-500 nm range?
Which of the following pigments is expected to have a peak absorption in the 400-500 nm range?
What is the first step to ensure accurate readings in spectrophotometric analysis?
What is the first step to ensure accurate readings in spectrophotometric analysis?
In which light condition did the leaf show the highest presence of starch?
In which light condition did the leaf show the highest presence of starch?
What happens to excess glucose produced during photosynthesis in plants?
What happens to excess glucose produced during photosynthesis in plants?
Which filter condition resulted in no starch presence according to the starch test?
Which filter condition resulted in no starch presence according to the starch test?
Which statement accurately describes paper chromatography?
Which statement accurately describes paper chromatography?
Which color wavelengths were absorbed by the green leaf when using a blue filter?
Which color wavelengths were absorbed by the green leaf when using a blue filter?
Where in a leaf should starch be present to support the hypothesis?
Where in a leaf should starch be present to support the hypothesis?
What is the role of non-polar molecules in paper chromatography?
What is the role of non-polar molecules in paper chromatography?
Which of the following best describes the transmission of green light through leaves under a green filter?
Which of the following best describes the transmission of green light through leaves under a green filter?
What are the products of the photosynthesis equation?
What are the products of the photosynthesis equation?
Which stage of photosynthesis involves capturing energy from sunlight?
Which stage of photosynthesis involves capturing energy from sunlight?
What role do pigments play in photosynthesis?
What role do pigments play in photosynthesis?
In the process of photosynthesis, what is produced during the use of ATP and NADPH?
In the process of photosynthesis, what is produced during the use of ATP and NADPH?
What is the primary safety precaution when handling ethanol in the lab?
What is the primary safety precaution when handling ethanol in the lab?
How does polarity play a role in the chromatography process during this lab?
How does polarity play a role in the chromatography process during this lab?
What is the reason for using gloves and forceps when handling flammable materials in the lab?
What is the reason for using gloves and forceps when handling flammable materials in the lab?
What type of light do human eyes perceive from the electromagnetic spectrum?
What type of light do human eyes perceive from the electromagnetic spectrum?
What is the primary reason most plants appear green?
What is the primary reason most plants appear green?
Which filter would best allow for the presence of starch in leaves?
Which filter would best allow for the presence of starch in leaves?
What can be concluded about leaves under black construction paper?
What can be concluded about leaves under black construction paper?
How does a blue filter affect the pigments in a leaf?
How does a blue filter affect the pigments in a leaf?
What should be done to test the predictions made about leaf color and starch production?
What should be done to test the predictions made about leaf color and starch production?
What is the expected outcome for leaves with red filter paper?
What is the expected outcome for leaves with red filter paper?
What type of pigments are primarily involved in the deep purple color of some leaves?
What type of pigments are primarily involved in the deep purple color of some leaves?
What is the role of chlorophyll in photosynthesis?
What is the role of chlorophyll in photosynthesis?
What can be used to estimate the polarity of a pigment?
What can be used to estimate the polarity of a pigment?
Which pigment is considered the most polar?
Which pigment is considered the most polar?
In a paper chromatography experiment, what happens when the solvent moves up the paper?
In a paper chromatography experiment, what happens when the solvent moves up the paper?
Which of the following pigments would move the slowest in paper chromatography?
Which of the following pigments would move the slowest in paper chromatography?
Which pigment would be expected to dissolve in a non-polar solvent first?
Which pigment would be expected to dissolve in a non-polar solvent first?
What is the order of pigments from most to least polar in the chromatography experiment?
What is the order of pigments from most to least polar in the chromatography experiment?
What is the role of the pencil line in the chromatography procedure?
What is the role of the pencil line in the chromatography procedure?
How should the chromatography paper be prepared before placing it in the solvent?
How should the chromatography paper be prepared before placing it in the solvent?
Flashcards
Photosynthesis
Photosynthesis
The process plants use to create glucose and other organic molecules from sunlight, water, and carbon dioxide.
Photosynthetic Equation
Photosynthetic Equation
6H₂O + 6CO₂ → 6O₂ + C₆H₁₂O₆ + H₂O
Pigments
Pigments
Molecules that absorb light of specific wavelengths.
Electromagnetic Spectrum
Electromagnetic Spectrum
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Photons
Photons
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Visible Light
Visible Light
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Starch Test
Starch Test
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Paper Chromatography
Paper Chromatography
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Chlorophyll
Chlorophyll
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Accessory Pigment
Accessory Pigment
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Carotenoids
Carotenoids
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Anthocyanins
Anthocyanins
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Coleus leaf
Coleus leaf
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Chloroplasts
Chloroplasts
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Stationary Phase
Stationary Phase
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Mobile Phase
Mobile Phase
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Polarity
Polarity
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More Polar Components
More Polar Components
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Non-Polar Components
Non-Polar Components
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Why are most plants green?
Why are most plants green?
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Chlorophyll a and b
Chlorophyll a and b
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Light filters and photosynthesis
Light filters and photosynthesis
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What happens to leaves with green light?
What happens to leaves with green light?
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What happens to leaves with blue light?
What happens to leaves with blue light?
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What happens to leaves with red light?
What happens to leaves with red light?
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What happens to leaves with no light?
What happens to leaves with no light?
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Absorption Spectrum
Absorption Spectrum
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Peak Absorption
Peak Absorption
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Spectrophotometer
Spectrophotometer
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Why is the absorption spectrum important?
Why is the absorption spectrum important?
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Non-polar molecule
Non-polar molecule
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Why does chlorophyll a move faster in chromatography?
Why does chlorophyll a move faster in chromatography?
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What is the relationship between polarity and solvent?
What is the relationship between polarity and solvent?
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Why does carotene move the furthest?
Why does carotene move the furthest?
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What is the relationship between polarity and oxygen groups?
What is the relationship between polarity and oxygen groups?
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How does polarity affect pigment separation?
How does polarity affect pigment separation?
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Study Notes
Lab 1: Photosynthesis
- The lab investigates photosynthetic activity, pigment role, and polarity.
- Students will separate pigments using paper chromatography.
- A starch test evaluates photosynthetic activity.
- An absorption spectrum is generated for photosynthetic pigments.
Lab Safety
- Work with flammable and toxic substances.
- Always wear gloves and use forceps for handling flammable materials (leaves, chromatography paper).
- Beakers with ethanol should never be directly on a heat plate, but should be nested in a larger beaker with water.
- Do not inhale solvents used for certain lab exercises, close the jar as quickly as possible to minimize inhalation.
- Report any spills to the instructor immediately and do not attempt to clean yourself.
- Dispose of all chemical waste in designated glass waste containers, not the sink.
Photosynthesis
- Plants absorb sunlight to generate glucose, starch, and other organic molecules.
- The equation for photosynthesis is 6H₂O + 6CO₂ → 6O₂ + C₆H₁₂O₆ + H₂O
- Photosynthesis occurs in three stages: capturing energy from sunlight, producing ATP and NADPH, using ATP and NADPH to make carbohydrates.
Electromagnetic Spectrum
- Light is comprised of packets of energy called photons.
- Sunlight contains photons with varying energy levels, represented by the electromagnetic spectrum.
- Human eyes perceive photons of intermediate energy levels, which are visible light.
Pigments
- Pigments absorb light energy.
- Chlorophyll a and b are main plant pigments.
- Chlorophyll absorbs blue and red light, reflecting green light.
- Pigments used in photosynthesis are located within thylakoid membranes of chloroplasts.
- Accessory pigments include carotenoids (yellow, orange, and red) and xanthophylls (yellow and brown). Also anthocyanins (dark red and violet) are found in the vacuole.
Coleus Leaves
- Coleus leaves contain multiple pigments.
- Green areas contain chlorophyll.
- Pink areas contain anthocyanins.
- Dark purple areas contain both chlorophyll and anthocyanin pigments.
- White and light yellow areas contain no pigments.
Experiment: Pigments in Photosynthesis
- The experiment determines the pigments used in photosynthesis.
- Students detach multicolored leaves, map color regions, use ethanol and boiling water to extract pigments.
- I₂KI is used to test for starch presence in different leaf regions.
- Students identify regions with high, medium, and low starch content.
Predictions and Results: Starch Test
- The table summarizes predictions and results of the starch test for different leaf colors.
- For example, green areas are predicted to have starch.
6.1: Wavelengths of Light
- Only specific wavelengths of light reach the leaf.
- The color seen is from the wavelengths not absorbed but reflected or transmitted.
- Plants primarily appear green because they reflect green wavelengths of light.
- The hypothesis predicts different photosynthetic products under different light conditions.
6.1 Predictions
- Leaves under green filters have no starch.
- Leaves under blue filters have some starch.
- Leaves under red filters have some starch.
- Leaves under no light (black) have no starch.
Demo Procedure
- Students remove leaves with filters from a geranium plant
- Draw/photograph the leaf, noting filter locations
- Place leaves in ethanol, w/ boiling water
- Add iodine solution and observe results.
Demo Procedure and Predictions
- Record predictions on light wavelengths that will be absorbed or transmitted.
- Observe and record starch amounts in different leaf areas.
Iodine Test for Starch
- Results support the hypothesis that photosynthesis occurs only where chloroplasts are present.
- Glucose from photosynthesis is stored as starch in plants
- Starch is present in chlorophyll-containing areas
- No starch in areas containing only anthocyanins (or lack of pigments).
Demo Results
- Images demonstrating the results of the experiment.
Paper Chromatography (LM 6.3)
- Used to separate components in mixtures.
- Involves a stationary (polar) phase (paper) and a mobile (less polar) phase (solvent).
- Solvent moves up the paper, carrying different components.
- Components move differently based on their interaction with the paper and solvent.
Polarity
- Polar molecules bind to the paper (stationary phase), and less polar molecules dissolve in the solvent (mobile phase).
- More polar components move slower.
- Non-polar components move faster.
Estimating Polarity
- Pigments and their relative polarities are identified.
- Hypotheses about pigment behavior in paper chromatography can be made based on these relative polarities.
Experiment: Absorption Spectrum of Leaf Pigments (LM 6.4)
- Cut pigment bands from chromatography paper to separate them by their polarity.
- Place bands into a beaker with 20 ml of acetone and swirl to extract the pigments.
- Label two cuvettes, “P” for pigments and “B” for blank (acetone).
- Fill the cuvettes with the prepared samples and run the spectrophotometer.
- Record %T for each wavelength from 400 nm to 720 nm, 20nm intervals, and convert to absorbance.
Predictions and Results: Absorption Spectrum
- Absorption spectrum show the absorption pattern based on wavelength.
- Hypothesize and predict absorption peaks for different pigments.
Results: Absorption Spectrum
- Graph of absorption spectrum for different pigments.
To Do List
- List of remaining lab exercises.
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Description
This lab quiz focuses on the investigation of photosynthetic activity, the role of pigments, and related safety procedures. Students will learn about paper chromatography, starch testing, and the absorption spectrum of pigments involved in photosynthesis. Be mindful of safety practices when handling chemicals and materials during the experiment.
