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Photosynthesis Overview
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Photosynthesis Overview

Created by
@BrainyMars

Questions and Answers

What role do accessory pigments play in photosynthesis?

  • They are only present in prokaryotic photosynthesis.
  • They assist in absorbing light at different frequencies. (correct)
  • They produce glucose during photosynthesis.
  • They are the main pigments for light absorption.

    • Where do the light reactions of photosynthesis occur in eukaryotic cells?

  • In the stroma
  • In the outer membrane
  • In the thylakoid membrane (correct)
  • In the cytoplasm

    • What is produced as a result of the light reactions during photosynthesis?

  • Glucose
  • Oxygen gas and ATP (correct)
  • Carbon dioxide
  • NADH

    • What is the primary function of the stroma in chloroplasts?

    <p>To facilitate the dark reactions of photosynthesis</p> Signup and view all the answers

    Which of the following statements about chloroplasts is incorrect?

    <p>They are responsible for aerobic respiration.</p> Signup and view all the answers

    What is the primary purpose of the light reactions in photosynthesis?

    <p>To generate chemical energy compounds from light energy</p> Signup and view all the answers

    Which of the following is produced during the light reactions of photosynthesis?

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

    What role does Rubisco play in photosynthesis?

    <p>It catalyzes the first reactions of the Calvin Cycle</p> Signup and view all the answers

    Which molecule is considered the first product of the Calvin Cycle?

    <p>3-PGA</p> Signup and view all the answers

    What is the main function of ATP and NADPH produced in light reactions?

    <p>To reduce CO2 to sugars</p> Signup and view all the answers

    What type of reaction does the Calvin Cycle represent?

    <p>Light-independent reaction</p> Signup and view all the answers

    What is released as a byproduct when water is split during the light reactions?

    <p>Oxygen gas</p> Signup and view all the answers

    Which compound is NOT created during the light reactions of photosynthesis?

    <p>3-PGA</p> Signup and view all the answers

    What is the primary function of photosynthesis in plants and algae?

    <p>To synthesize organic compounds from inorganic compounds using sunlight.</p> Signup and view all the answers

    Which pigment is primarily responsible for absorbing light in photosynthesis?

    <p>Chlorophyll a</p> Signup and view all the answers

    What component of light is absorbed by pigments for photosynthesis?

    <p>Visible light</p> Signup and view all the answers

    Which of the following statements about chlorophyll a is true?

    <p>It absorbs red and blue light but reflects green.</p> Signup and view all the answers

    What is the general formula for photosynthesis?

    <p>6 CO2 + 12 H2O 🡪 C6H12O6 + 6 O2 + 6 H2O</p> Signup and view all the answers

    What role do accessory pigments play in photosynthesis?

    <p>They capture light energy and transfer it to chlorophyll a.</p> Signup and view all the answers

    Why is photosynthesis considered vital for life on Earth?

    <p>It generates oxygen and organic compounds essential for life.</p> Signup and view all the answers

    How do chloroplasts contribute to photosynthesis?

    <p>They convert sunlight into chemical energy stored in sugars.</p> Signup and view all the answers

    What is the primary purpose of G3P in the Calvin Cycle?

    <p>To regenerate RuBP and synthesize sugars</p> Signup and view all the answers

    What is a key factor that reduces the efficiency of photosynthesis in C-3 plants?

    <p>Photorespiration due to low CO2 concentration</p> Signup and view all the answers

    How many cycles of the Calvin Cycle are needed to produce one glucose molecule?

    <p>6</p> Signup and view all the answers

    What distinguishes C-4 plants from C-3 plants in terms of photosynthesis?

    <p>C-4 plants have a higher first product efficiency and different anatomy</p> Signup and view all the answers

    What is the overall equation for the carbon reactions of photosynthesis?

    <p>$6 CO_2 + 18 ATP + 12 NADPH \rightarrow C_6H_{12}O_6 + 6 H_2O + 6 O_2$</p> Signup and view all the answers

    What role does rubisco play in the Calvin Cycle?

    <p>It fixes carbon dioxide into organic molecules</p> Signup and view all the answers

    Which anatomical feature is characteristic of C-4 plants?

    <p>Parallel venation in leaves</p> Signup and view all the answers

    What is the photosynthetic efficiency range of C-3 plants?

    <p>1 - 4%</p> Signup and view all the answers

    Study Notes

    Introduction to Photosynthesis

    • Photosynthesis is derived from Greek words; "photo" means light, and "synthesis" means putting together.
    • It involves plants, algae, and some bacteria converting the sun's energy into organic compounds, specifically sugars, using carbon dioxide (CO2) and water.
    • Crucial for life on Earth, photosynthesis produces oxygen, consumes CO2, and contributes to food and energy sources.

    General Formula for Photosynthesis

    • The chemical equation is:
      • 6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O
    • Oxygen production supports aerobic respiration and evolution of complex life forms.

    Properties of Light and Pigments

    • All life forms rely on light, which travels in energy units known as photons.
    • The energy of a photon is inversely proportional to its wavelength, with visible light displayed as a spectrum of colors.
    • Chlorophyll a is the primary pigment in photosynthesis, absorbing blue and red light while reflecting green.

    Accessory Pigments

    • Accessory pigments, such as chlorophyll b and carotenoids, extend the range of light wavelengths absorbed and protect cells from harmful byproducts.
    • Light-harvesting complexes (LHCs) composed of chlorophyll and accessory pigments enhance light absorption efficiency.

    Chloroplast Structure and Function

    • Chloroplasts have a double membrane and contain thylakoids, stroma, and grana.
    • Light reactions occur in the thylakoid membranes, while dark reactions (Calvin Cycle) take place in the stroma.
    • Chloroplasts share evolutionary similarities with mitochondria, evolving from cyanobacteria.

    Light Reactions

    • Light-dependent reactions occur in thylakoid membranes, where water is split into oxygen and protons.
    • These reactions generate ATP and NADPH using light energy.
    • The chemical equations involved include:
      • ADP + Pi + Energy → ATP
      • NADP+ + 2e- + H+ → NADPH

    The Calvin Cycle (Dark Reactions)

    • The Calvin Cycle is light-independent and takes place in the stroma, utilizing ATP and NADPH generated from light reactions.
    • CO2 is reduced to sugar through a series of enzymatic reactions involving ribulose bisphosphate (RuBP) and the enzyme Rubisco.
    • Glyceraldehyde 3-phosphate (G3P) is produced, serving as a precursor for glucose and other carbohydrates.

    Photosynthetic Efficiency

    • Photosynthesis in C-3 plants is low, with efficiency ranging only between 1-4%, often hampered by photorespiration when internal CO2 levels fall.
    • C-4 plants (e.g., sugar cane, corn) are more efficient, achieving about 7% efficiency and thriving in hot climates.

    Comparative Leaf Anatomy

    • C-3 plants exhibit net venation, while C-4 plants show parallel venation in their leaves, which is an adaptation to enhance photosynthetic efficiency.

    Summary of Photosynthesis

    • Photosynthesis transforms light energy into chemical energy, producing organic compounds while releasing oxygen as a byproduct.
    • It is essential for establishing the foundation of food chains and supporting life on Earth.

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    Related Documents

    Photosynthesis.ppt.pdf

    Description

    This quiz delves into the fascinating process of photosynthesis, exploring its key components such as light properties, chloroplast functions, and the roles of light and dark reactions. Understanding photosynthesis is critical for comprehending energy flow in ecosystems and the carbon cycle.

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