Photosynthesis
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Questions and Answers

What is the water potential of pure water in an open beaker at room temperature?

  • Zero (correct)
  • Negative
  • Positive
  • Dependent on the volume of water

    • What happens to water potential when solutes are added to a solution?

  • It increases
  • It decreases (correct)
  • It becomes zero
  • It remains unchanged

    • What supports plant cells and tissues and can be lowered by water limitations causing tissues to wilt?

  • Solute potential
  • Pressure potential
  • Transpiration pull
  • Turgor pressure (correct)

    • What drives the transport of water and minerals from roots to shoots via the xylem?

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

    What is the function of the Casparian strip in the endodermis of plant roots?

    <p>Blocks apoplastic transfer of minerals from cortex to the vascular cylinder</p> Signup and view all the answers

    What allows water to withstand transpiration and is important for the transport of xylem sap?

    <p>Hydrogen bonding of water molecules</p> Signup and view all the answers

    What is responsible for the diffusion of water vapor from moist air spaces on the leaf to the drier air outside via stomata?

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

    What causes the air-water interface to retreat farther into the cell wall and become more curved during transpiration?

    <p>Evaporation of the water film</p> Signup and view all the answers

    What type of work does ATP perform?

    <p>Chemical Work</p> Signup and view all the answers

    Why are plants green?

    <p>Chlorophyll reflects green wavelength of light</p> Signup and view all the answers

    What is the primary function of cellular respiration?

    <p>Extracting energy stored in sugars</p> Signup and view all the answers

    What happens with free energy in a closed system?

    <p>Matter can’t flow in or out, but energy can</p> Signup and view all the answers

    What is the role of Redox Reactions in respiration and photosynthesis?

    <p>Critical for transferring electrons</p> Signup and view all the answers

    Why doesn’t equilibrium happen in living systems?

    <p>Energy still comes in, matter can’t enter or exit</p> Signup and view all the answers

    What is the primary function of photosynthesis?

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

    What is the reason for plants appearing to restore something to the air that is needed by animals?

    <p>Plants release oxygen during photosynthesis</p> Signup and view all the answers

    What is the process by which sugars are moved throughout the plant?

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

    What is the major pathway for water loss in a plant?

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

    What causes positive pressure to drive phloem sap from source to sink?

    <p>Pressure flow</p> Signup and view all the answers

    What mechanism opens and closes stomata?

    <p>Changes in turgor pressure</p> Signup and view all the answers

    What is the process by which water is moved quickly through the xylem?

    <p>Bulk flow</p> Signup and view all the answers

    What is the ratio, in percent, of the amount of moisture in a volume of air to the total amount which that volume can hold at the given temperature and atmospheric pressure?

    <p>Relative humidity</p> Signup and view all the answers

    What is the process by which sugars are loaded into sieve-tube elements before being exported to sinks?

    <p>Sugar loading</p> Signup and view all the answers

    What is the main reason for the movement of water into roots?

    <p>Water moves from areas where solute is lower to areas where solute concentration is higher (osmosis) exerting positive pressure</p> Signup and view all the answers

    What is the process by which sugars are unloaded at the sink?

    <p>Sugar unloading</p> Signup and view all the answers

    What is the process by which a gas bubble is introduced to the water column in xylem?

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

    What is the mechanism that explains the movement of water through xylem?

    <p>Cohesion-tension mechanism</p> Signup and view all the answers

    What is the process by which water is pulled into the surrounding cells and air spaces to replace the lost water?

    <p>Cohesion and adhesion in the ascent of xylem sap</p> Signup and view all the answers

    What did C.B. van Neil discover about purple sulfur bacteria?

    <p>They use H2S instead of H2O for photosynthesis</p> Signup and view all the answers

    Why does chlorophyll appear green?

    <p>It mainly absorbs red and blue light</p> Signup and view all the answers

    What is the function of carotenoids in photosynthesis?

    <p>Protect chlorophyll from damage by excess light</p> Signup and view all the answers

    What is the primary role of photosystems I and II?

    <p>Convert light energy to chemical energy</p> Signup and view all the answers

    What is the main purpose of blocking photosynthetic reactions?

    <p>Prevent weed growth</p> Signup and view all the answers

    What did Melvin Calvin identify in the Calvin cycle?

    <p>The carbon pathways</p> Signup and view all the answers

    How many stages does the Calvin cycle have?

    <p>Three: fixation/carboxylation, reduction, and regeneration</p> Signup and view all the answers

    What did W. Engelmann do in 1883 related to photosynthesis?

    <p>Exposed filamentous algae to different light wavelengths</p> Signup and view all the answers

    What is the nature of sunlight crucial for photosynthesis?

    <p>Electromagnetic energy with visible light wavelengths</p> Signup and view all the answers

    Where does the synthesis through the Calvin cycle occur?

    <p>In the stroma</p> Signup and view all the answers

    What is the main product of the Calvin cycle?

    <p>Sugars for energy storage</p> Signup and view all the answers

    What is the key process in which plants gain electrons from hydrogen atoms?

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

    What is the enzyme responsible for catalyzing the reaction between RUBP and CO2?

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

    In which type of photosynthesis do mesophyll cells pump CO2 into bundle-sheath cells, avoiding the use of RUBISCO?

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

    What is the main benefit of CAM photosynthesis in arid environments?

    <p>High water use efficiency rates</p> Signup and view all the answers

    What is the major factor in plant distribution and why is it important on a smaller scale?

    <p>Water; it helps support the plant and regulate temperature</p> Signup and view all the answers

    What is the route through which water and solutes cross cell walls and extracellular spaces?

    <p>Apoplastic Route</p> Signup and view all the answers

    What is the force exerted by water molecules at the air-water interface called?

    <p>Surface Tension</p> Signup and view all the answers

    What establishes the voltage across a membrane and is used to move solutes in plants?

    <p>Proton pump</p> Signup and view all the answers

    What is the role of ion channels in plants?

    <p>Open and close in response to voltage across a membrane and other factors</p> Signup and view all the answers

    What is the main function of rhizobia in association with legumes?

    <p>Help plants get nutrients from soil</p> Signup and view all the answers

    What is the chemical potential of water or its capacity to do work called?

    <p>Water Potential</p> Signup and view all the answers

    What is the main benefit of chloroplast avoidance movements in plants under high light conditions?

    <p>Reduce photodamage to plants</p> Signup and view all the answers

    What is the main function of chloroplasts in plants?

    <p>Facilitate photosynthesis</p> Signup and view all the answers

    Which enzyme catalyzes the reaction between RUBP and CO2, fixing CO2 80x faster than O2?

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

    What occurs when rubisco adds O to RuBP instead of C, consuming O2 and producing CO2?

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

    What leads to O2 buildup and CO2 depletion, favoring photorespiration?

    <p>Stomata closing due to water stress</p> Signup and view all the answers

    Which plants can only survive under high CO2 levels due to a lack of photorespiration?

    <p>Mutant Arabidopsis plants</p> Signup and view all the answers

    What reduces losses to photorespiration in plants?

    <p>C4 and CAM mechanisms</p> Signup and view all the answers

    Which plants involve spatial segregation of CO2 capture and concentration in mesophyll and bundle sheath cells?

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

    Which plants fix CO2 at night and conserve water by closing stomata during the day?

    <p>CAM plants</p> Signup and view all the answers

    Which plants exhibit CAM idling under severe water stress?

    <p>Incomplete/Facultative CAM plants</p> Signup and view all the answers

    Which plants have high water use efficiency rates, 5 to 10 times more than C3 or C4 plants?

    <p>CAM plants</p> Signup and view all the answers

    What movements reduce photodamage to plants under high light conditions?

    <p>Chloroplast avoidance movements</p> Signup and view all the answers

    What does plant resource acquisition include?

    <p>Shoot and root adaptations</p> Signup and view all the answers

    What is responsible for the spatial segregation of CO2 capture and concentration in C4 plants?

    <p>PEP carboxylase and Rubisco</p> Signup and view all the answers

    Study Notes

    Photosynthesis: Key Concepts and Processes

    • W. Engelmann (1883) exposed filamentous algae to different light wavelengths
    • C.B. van Neil (1930) discovered purple sulfur bacteria using H2S instead of H2O
    • Plants split water to gain electrons from hydrogen atoms
    • Photosynthesis occurs in two stages: light reactions in thylakoids and synthesis through the Calvin cycle in stroma
    • Nature of sunlight: electromagnetic energy with visible light wavelengths crucial for photosynthesis
    • Chlorophyll appears green because it mainly absorbs red and blue light
    • Photosynthetic pigments include reaction center chlorophyll a, chlorophyll b, and carotenoids
    • Light energy is converted to chemical energy through photosystems I and II
    • Practical applications include blocking photosynthetic reactions to prevent weed growth
    • The Calvin cycle fixes carbon from CO2 and produces sugars for energy storage
    • Melvin Calvin identified the carbon pathways in the Calvin cycle
    • The Calvin cycle has three stages: fixation/carboxylation, reduction, and regeneration

    Photosynthesis and Resource Acquisition in Plants

    • Rubisco enzyme catalyzes the reaction between RUBP and CO2, fixing CO2 80x faster than O2.
    • Photorespiration occurs when rubisco adds O to RuBP instead of C, consuming O2 and producing CO2.
    • Stomata closing due to water stress leads to O2 buildup and CO2 depletion, favoring photorespiration.
    • Mutant Arabidopsis plants without photorespiration can only survive under high CO2 levels.
    • Carbon dioxide concentrating mechanisms like C4 and CAM reduce losses to photorespiration.
    • C4 photosynthesis involves spatial segregation of CO2 capture and concentration in mesophyll and bundle sheath cells.
    • CAM plants fix CO2 at night and conserve water by closing stomata during the day.
    • CAM plants have morphological features that minimize water loss and thick cuticles.
    • Incomplete/Facultative CAM plants exhibit CAM idling under severe water stress.
    • CAM plants have high water use efficiency rates, 5 to 10 times more than C3 or C4 plants.
    • Chloroplast avoidance movements reduce photodamage to plants under high light conditions.
    • Plant resource acquisition includes shoot and root adaptations, microbial mutualists, and water and mineral acquisition.

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    Description

    Test your knowledge of photosynthesis with this quiz on key concepts and processes. From the discovery of photosynthetic pigments to the stages of the Calvin cycle, this quiz covers the fundamental aspects of photosynthesis, including key experiments and practical applications.

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