chap 9 photosynthesis
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Questions and Answers

Which molecule is directly converted into NADPH during photosynthesis?

  • O2
  • ATP
  • NADP+ (correct)
  • ADP

    • Where in the chloroplast do the light-dependent reactions occur?

  • Stroma
  • Thylakoid membranes (correct)
  • Outer membrane
  • Inner membrane

    • What is the main product of the light-independent reactions?

  • Oxygen
  • High energy sugars (correct)
  • NADPH
  • ATP

    • Which process in photosynthesis involves the electron transport chain?

    <p>Photosystem II</p> Signup and view all the answers

    What is the role of chlorophyll in photosystem II?

    <p>Absorb light and raise electron energy</p> Signup and view all the answers

    Which by-product is produced during the light-dependent reactions?

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

    What is the name of the fluid portion found outside the thylakoids in the chloroplast?

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

    Which structure within the chloroplast contains chlorophyll?

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

    How are thylakoids arranged within the chloroplast?

    <p>Interconnected in stacks called grana</p> Signup and view all the answers

    What surrounds the chloroplast, distinguishing it from other organelles?

    <p>Two envelope membranes</p> Signup and view all the answers

    In the process of photosynthesis, what role does chlorophyll play?

    <p>Absorbs and transfers light very efficiently</p> Signup and view all the answers

    Why is ATP not ideal for storing large amounts of energy over long periods?

    <p>Its energy storage capacity is lower than that of other molecules.</p> Signup and view all the answers

    Which part of the visible spectrum does chlorophyll reflect?

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

    What role do autotrophs play in the energy transfer on Earth?

    <p>They capture and convert sunlight into high-energy carbohydrates.</p> Signup and view all the answers

    In which part of the chloroplast does photosynthesis take place?

    <p>Thylakoid membrane</p> Signup and view all the answers

    How do heterotrophs obtain their energy?

    <p>By consuming other living things.</p> Signup and view all the answers

    What is glucose's role in cellular energy storage?

    <p>It stores energy to produce ATP as needed.</p> Signup and view all the answers

    What is the primary structural difference between ATP and ADP?

    <p>The number of phosphate groups</p> Signup and view all the answers

    What role does ATP play in cellular processes?

    <p>Providing energy for active transport and other cellular functions</p> Signup and view all the answers

    How do cells release energy stored in ATP?

    <p>By breaking bonds between the 2nd and 3rd phosphate groups</p> Signup and view all the answers

    What is the role of the sodium-potassium pump in cells?

    <p>Pumping sodium ions out of the cell and potassium ions into the cell</p> Signup and view all the answers

    Why is ATP referred to as a rechargeable battery?

    <p>Because it stores and releases energy by breaking and reforming bonds between phosphate groups</p> Signup and view all the answers

    In what way does ATP function as a basic energy source for cells?

    <p>By being able to release and store energy quickly through bond-breaking and forming</p> Signup and view all the answers

    What is one way that cells utilize the energy stored in ATP?

    <p>To power protein synthesis</p> Signup and view all the answers

    Which of the following is a component of ATP?

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

    What is the role of ATP synthase in the light-dependent reactions?

    <p>It produces ATP by combining ADP with a phosphate group.</p> Signup and view all the answers

    Which molecule is regenerated in the Calvin Cycle to allow the cycle to continue?

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

    How many molecules of 3-phosphoglycerate are produced from each molecule of CO2 entering the Calvin Cycle?

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

    What provides the energy for ATP synthesis in the light-dependent reactions?

    <p>The concentration gradient of hydrogen ions.</p> Signup and view all the answers

    What is the primary role of NADPH in the process of photosynthesis?

    <p>To provide reducing power for the Calvin Cycle.</p> Signup and view all the answers

    Which of the following statements about the Calvin Cycle is incorrect?

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

    Which specialized chemical pathway allows C4 plants to capture low levels of CO2?

    <p>C4 pathway</p> Signup and view all the answers

    What is the primary benefit of plants closing their leaf openings under hot conditions?

    <p>Conserving water</p> Signup and view all the answers

    What type of plants utilize Crassulacean acid metabolism (CAM) for photosynthesis?

    <p>Plants adapting to bright and hot conditions</p> Signup and view all the answers

    How do C4 plants differ from other plants in the way they process CO2?

    <p>They form a four-carbon compound as their first product</p> Signup and view all the answers

    What happens when the light intensity reaches a certain level in photosynthesis?

    <p>The plant reaches its maximum rate of photosynthesis</p> Signup and view all the answers

    How do CAM plants trap carbon during photosynthesis?

    <p>By combining CO2 with existing molecules to form organic acids at night</p> Signup and view all the answers

    Which factor is not directly mentioned as affecting photosynthesis?

    <p>Nutrient concentration in soil</p> Signup and view all the answers

    Why do high light intensity levels affect photosynthesis in plants?

    <p>They speed up the reactions of photosynthesis until a certain level</p> Signup and view all the answers

    Study Notes

    Energy and Life

    • All living things store energy in chemical bonds of certain compounds.
    • ATP (Adenosine Triphosphate) consists of adenine, a 5-carbon sugar called ribose, and three phosphate groups.
    • The phosphate groups are key to ATP's ability to store and release energy.
    • ATP functions like a rechargeable battery, releasing energy when a phosphate group is split off and released.

    How Cells Use ATP

    • Cells use ATP for carrying out active transport, moving molecules against their concentration gradient.
    • ATP provides energy for sodium-potassium pumps in cell membranes to pump sodium ions out and potassium ions into the cell.
    • Energy stored in ATP enables cells to move and transfer energy to other molecules for processes like protein synthesis and responses to chemical signals.

    Energy Transfer

    • ATP is not suitable for storing large amounts of energy over long periods.
    • Glucose molecules can store more than 90 times the energy required to produce ATP.
    • Heterotrophs obtain energy by consuming other living things, while autotrophs obtain energy from the sun.
    • Photosynthesis is the process by which plants convert energy from sunlight into chemical energy stored in carbohydrates.

    Photosynthesis

    • Chlorophyll, a pigment that absorbs light, is involved in photosynthesis.
    • Chlorophyll absorbs light in the blue-violet and red regions of the visible spectrum and reflects green light, making leaves appear green.
    • Photosynthesis takes place inside the chloroplast, which is surrounded by two envelope membranes and contains saclike chlorophyll-containing membranes called thylakoids.
    • Thylakoids are interconnected and arranged in stacks known as grana.

    Process of Photosynthesis

    • Light-dependent reactions require direct involvement of light and light-absorbing pigments.
    • Light-dependent reactions take place in thylakoid membranes and use energy from sunlight to produce ATP and NADPH.
    • Light-independent reactions take place outside thylakoids in the stroma and use ATP and NADPH to build high-energy sugars from carbon dioxide.
    • Photosynthesis produces oxygen as a by-product.

    Light-Dependent Reactions

    • Hydrogen ion movement and ATP formation occur during light-dependent reactions.
    • Hydrogen ions build up inside the thylakoid membrane, creating a concentration difference that provides energy for ATP synthase to produce ATP.
    • ATP synthase binds ADP and a phosphate group to produce ATP.

    Light-Independent Reactions: The Calvin Cycle

    • Carbon dioxide enters the Calvin Cycle from the atmosphere.
    • An enzyme within the stroma combines CO2 with a 5-carbon sugar called RuBP, producing two molecules of 3-phosphoglycerate.
    • Sugar production occurs during the Calvin Cycle, where 3-phosphoglycerate molecules are converted back into RuBP, which combines with new CO2 molecules to begin the next cycle.

    Photosynthesis

    • Light-dependent reactions trap the energy of sunlight in chemical form, while light-independent reactions use that chemical energy to synthesize stable, high-energy sugars from carbon dioxide and water.
    • Factors affecting photosynthesis include temperature, light, and water.
    • High light intensity increases the rate of photosynthesis, but after a certain level, the plant reaches its maximum rate.

    Photosynthesis under Extreme Conditions

    • C4 plants have adapted to extremely bright, hot conditions by using a specialized chemical pathway that allows them to capture very low levels of CO2 and pass it to the Calvin cycle.
    • C4 plants, including crops like corn, sugar cane, and sorghum, require extra energy in the form of ATP to function.
    • CAM plants, like those in the Crassulaceae family, have a similar adaptation, where CO2 is incorporated into organic acids during photosynthesis.
    • CAM plants admit air into leaves only at night, combining CO2 with existing molecules to produce organic acids, which release carbon dioxide inside the leaf during the daytime, enabling carbohydrate production.

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