Photosynthesis Overview
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Questions and Answers

Which chlorophyll pigment is primarily responsible for the direct conversion of light energy to chemical energy?

  • Accessory pigments
  • Chlorophyll b
  • Carotenoids
  • Chlorophyll a (correct)

    • Chlorophyll b has an absorption spectrum shifted toward violet wavelengths.

    False (B)

    What is the structure at the center of the porphyrin ring in chlorophyll?

    magnesium atom

    Chlorophyll b complements chlorophyll a by increasing the proportion of _____ in sunlight that plants can harvest.

    <p>photons</p> Signup and view all the answers

    What happens to the electrons in the porphyrin ring when photons are absorbed?

    <p>They are excited and become delocalized. (A)</p> Signup and view all the answers

    Carotenoids are highly efficient in transferring energy absorbed from photons.

    <p>False (B)</p> Signup and view all the answers

    Match the chlorophyll pigment with its characteristic:

    <p>Chlorophyll a = Directly converts light energy to chemical energy Chlorophyll b = Absorbs green wavelengths Carotenoids = Absorb a wide range of photon energies Porphyrin ring = Complex ring structure containing magnesium</p> Signup and view all the answers

    The process by which chlorophyll absorbs photons is analogous to the _____ effect.

    <p>photoelectric</p> Signup and view all the answers

    What role does chlorophyll play in photosynthesis?

    <p>It transfers energy to a membrane-bound protein. (A)</p> Signup and view all the answers

    Jospeh Priestly discovered that plants do not contribute anything to the air.

    <p>False (B)</p> Signup and view all the answers

    What two compounds are produced during the light-dependent reactions of photosynthesis?

    <p>ATP and NADPH</p> Signup and view all the answers

    Jan Baptista van Helmont incorrectly concluded that the water mainly accounted for the plant's increased ______.

    <p>biomass</p> Signup and view all the answers

    Match the scientists with their contributions to the understanding of photosynthesis:

    <p>Jan Baptista van Helmont = Incorrectly concluded water added to plant mass Joseph Priestly = Demonstrated that plants restore air quality Jan Ingenhousz = Solved the puzzle of photosynthesis Chlorophyll = Main pigment responsible for light absorption</p> Signup and view all the answers

    What does the photosystem primarily act as in photosynthesis?

    <p>An antenna for gathering light energy (C)</p> Signup and view all the answers

    Light-independent reactions are also known as the Calvin cycle.

    <p>True (A)</p> Signup and view all the answers

    What did Priestly's experiment with mint and a candle demonstrate?

    <p>Plants can restore air quality.</p> Signup and view all the answers

    What is the role of NADP+ in the light-dependent reactions of photosynthesis?

    <p>To accept electrons (D)</p> Signup and view all the answers

    Chloroplasts are responsible for photosynthesis in all plants.

    <p>True (A)</p> Signup and view all the answers

    What do the light-dependent reactions produce that is essential for synthesizing sugars?

    <p>ATP and NADPH</p> Signup and view all the answers

    Pigments absorb light energy in the __________ range to facilitate photosynthesis.

    <p>visible</p> Signup and view all the answers

    Match the following terms with their correct descriptions:

    <p>Photon = A discrete bundle of light energy Photoelectric effect = Creation of electrical current from light Electromagnetic spectrum = Range of all forms of light energy Wavelength = Distance between successive peaks of a wave</p> Signup and view all the answers

    Which of the following statements about the electromagnetic spectrum is correct?

    <p>X-rays have higher energy than ultraviolet light. (A)</p> Signup and view all the answers

    Chlorophyll is responsible for reflecting green light, which is why chlorophyll-rich plants appear green.

    <p>True (A)</p> Signup and view all the answers

    What factors affect the strength of the photoelectric effect?

    <p>The wavelength of light (D)</p> Signup and view all the answers

    Explain why shorter wavelengths of light contain higher energy photons.

    <p>Shorter wavelengths are closer together, resulting in more energy per photon due to the wave nature of light.</p> Signup and view all the answers

    Longer wavelengths of light are generally more effective at producing the photoelectric effect than shorter wavelengths.

    <p>False (B)</p> Signup and view all the answers

    What is the phenomenon called when photons transfer energy to electrons?

    <p>photoelectric effect</p> Signup and view all the answers

    Each pigment has a characteristic __________ spectrum.

    <p>absorption</p> Signup and view all the answers

    Match the following types of chlorophyll with their preferred light absorption:

    <p>Chlorophyll a = Violet-blue light Chlorophyll b = Red light</p> Signup and view all the answers

    Which types of pigments are primarily used in green plant photosynthesis?

    <p>Chlorophylls and carotenoids (D)</p> Signup and view all the answers

    Chloroplasts act as photoelectric devices by absorbing sunlight and transferring excited electrons to a carrier.

    <p>True (A)</p> Signup and view all the answers

    When a photon strikes a molecule with sufficient energy, it raises an electron to a higher __________ level.

    <p>energy</p> Signup and view all the answers

    What is the main role of carotenoids in photosynthesis?

    <p>To capture energy from wavelengths not absorbed by chlorophyll (C)</p> Signup and view all the answers

    Phycobiliproteins are accessory pigments found only in plants.

    <p>False (B)</p> Signup and view all the answers

    What happens when photosynthetic saturation is reached?

    <p>Further increases in light intensity cause no increase in output.</p> Signup and view all the answers

    A generalized photosystem contains an antenna complex and a ________ center.

    <p>reaction</p> Signup and view all the answers

    Match the following components of photosystems with their respective functions:

    <p>Chlorophyll a = Main pigment that absorbs light Accessory pigments = Capture energy from other light wavelengths Reaction center = Transfers excitation energy to drive ATP synthesis Antenna complex = Channels light energy to the reaction center</p> Signup and view all the answers

    Which statement best describes the function of the reaction center in a photosystem?

    <p>It channels energy to a specific molecule for ATP synthesis. (D)</p> Signup and view all the answers

    Chlorophyll molecules operate independently in absorbing light for photosynthesis.

    <p>False (B)</p> Signup and view all the answers

    Carotenoids and accessory pigments are important for survival in ________ light situations.

    <p>low</p> Signup and view all the answers

    Study Notes

    Photosynthetic Pigments

    • Chlorophyll a is the main photosynthetic pigment in plants and cyanobacteria.
    • Chlorophyll b acts as an accessory pigment and complements chlorophyll a by expanding its light absorption range.
    • Chlorophylls contain a porphyrin ring containing a central magnesium atom.
    • Pigments absorb photons by transferring energy to electrons, similar to the photoelectric effect.
    • Variations in side groups and associations with proteins alter the absorption properties of different types of chlorophylls.
    • Carotenoids are pigments that absorb photons across a wide range of energies, efficiently transferring the energy to a key chlorophyll molecule in contact with a protein.
    • Phycobiliproteins are accessory pigments found in cyanobacteria and some algae.
    • These pigments are crucial for survival in low-light conditions in oceans.

    Photosystem Organization

    • Photosystems are clusters of chlorophyll and accessory pigment molecules that absorb light energy.
    • Photosystems channel excitation energy gathered by multiple pigment molecules to a single reaction center chlorophyll molecule.
    • The reaction center chlorophyll molecule then passes the energy out of the photosystem as excited electrons, driving the synthesis of ATP and organic molecules.
    • Photosystems consist of an antenna complex and a reaction center.
    • The antenna complex collects light energy and transfers it to the reaction center.
    • The reaction center converts light energy into chemical energy by transferring excited electrons to molecules involved in ATP and NADPH production.

    Light-Dependent Reactions

    • Light energy is used to reduce NADP+ and synthesize ATP, which are then used to reduce carbon dioxide and form organic molecules.
    • The electrons released from water molecules are transferred to NADP+ during the light-dependent reactions.

    Light-Independent Reactions

    • ATP and NADPH produced in the light-dependent reactions are used to reduce carbon dioxide into sugars in the light-independent reactions.
    • The process occurs within chloroplasts and is crucial for plant growth and carbon fixation.

    Discovery of Photosynthetic Processes

    • Jan Baptista van Helmont performed an experiment to test the source of plant growth incorrectly concluding that it was water.
    • Joseph Priestly discovered that plants add something to the air by observing that mint revived air unsuitable for burning a candle.
    • Jan Ingenhousz found that plants only release oxygen in the presence of light.
    • These experiments show that photosynthesis occurs within chloroplasts and that the light-dependent reactions are essential for the production of ATP and NADPH, which are then used in light-independent reactions to reduce carbon dioxide.

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    Photosynthesis Unit 5 PDF

    Description

    This quiz covers the essential pigments involved in photosynthesis, including chlorophyll a, b, carotenoids, and phycobiliproteins. Understand their roles and absorption properties in different light conditions. Test your knowledge on the organization of photosystems in plants and cyanobacteria.

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