Questions and Answers
What is photosynthesis?
Plants use the sun's energy to convert water and carbon dioxide into sugars, and release oxygen as a by-product.
What are autotrophs?
Organisms that make their own food.
Define photoautotrophs.
An organism that harnesses light energy to drive the synthesis of organic compounds from carbon dioxide.
What are heterotrophs?
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The _____ in plant cells capture light energy that comes from the sun.
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What are chemoautotrophs?
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What do 'self-feeding' photoautotrophs require from the environment to make their own food?
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______ are the major sites of photosynthesis in most plants.
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What is chlorophyll?
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What is mesophyll?
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What are stomata?
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A typical mesophyll cell has about __ to __ chloroplasts.
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What is stroma?
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____ in the ____ form the framework within which many of the reactions of photosynthesis occur.
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Which of the following organelles can open or close? Thylakoids are found in the __________.
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What are thylakoids?
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Write the equation for photosynthesis.
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What happens when CO2 and water are converted to sugar and O2?
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Scientists used isotopes to identify the source of oxygen released during photosynthesis. What did they discover?
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What is the chemical formula for glucose?
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During photosynthesis CO2 is reduced to _____ as _____ and ________ _______ are added to it.
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During photosynthesis water molecules are ______.
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Which of the following statements regarding the reduction of CO2 to sugar during photosynthesis is correct? Electrons (with accompanying protons)
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What are the two stages of photosynthesis?
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What are light reactions?
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During light reactions _____ is split, providing _________ and giving off _____ as a by-product.
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________ _______ is used to drive the transfer of _______ and ___ from water to the electron acceptor ______, reducing it to _______.
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What does NADPH temporarily store?
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What are the inputs of the light reaction?
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What are the outputs of the light reaction?
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Describe the Calvin cycle.
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What is carbon fixation?
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______ provides the _______ for reducing _______ compounds in the Calvin cycle.
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What are the inputs of the Calvin cycle?
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What are the outputs of the Calvin cycle?
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The light reactions of photosynthesis yield __________. The Calvin cycle produces __________.
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The reduction of NADP+ to NADPH in the light reactions occurs with the assistance of __________.
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What is wavelength?
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What is the electromagnetic spectrum?
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What is chlorophyll A?
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What is chlorophyll B?
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What are carotenoids?
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What is the most important function of carotenoid pigments in plants?
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What is a photosystem?
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Describe the relationship between Photosystem 2 and Photosystem 1.
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During the light reactions, __________ and an __________ transform __________ energy into __________ energy of ATP and NADPH.
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What is the source of the electrons that are moving through the photosystems to NADPH?
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In the thylakoid space water is split into __ electrons, __ hydrogen ion (H+), and __ oxygen atom (1/2 O2).
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What is the final electron acceptor in the light reactions of photosynthesis?
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What is photophosphorylation?
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Two separate processes occur in the light reactions of photosynthesis. In one, __________ is generated as the result of an electric transport chain. In the other, the high concentration of __________ in the thylakoid space drives the synthesis of __________.
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List the steps of the Calvin cycle.
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To synthesize 1 glucose molecule, the Calvin cycle uses ___ CO2, ___ ATP, ___ NADPH.
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At which step of the 4-step Calvin cycle is G3P produced?
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How many molecules of ATP and NADPH are required to make one molecule of G3P in the Calvin cycle?
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What are C3 plants?
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What is photorespiration?
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What are C4 plants?
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What are CAM plants?
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Plants remove __________ from the atmosphere and return __________ to the atmosphere. The other product(s) of photosynthesis is (are) __________.
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About __________ % of the products of photosynthesis are used to power cellular respiration and to make organic molecules that the plant cells need. What happens to the rest of the products?
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What is the greenhouse effect?
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List the three most important greenhouse gases. What positive effect do these gases exert on Earth's atmosphere?
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Study Notes
Photosynthesis Overview
- Photosynthesis transforms sunlight, water, and carbon dioxide into glucose and oxygen.
- Autotrophs create their own food; photoautotrophs specifically use light for this process.
- Heterotrophs consume other organisms or organic by-products for energy.
Chloroplasts and Structure
- Chloroplasts are organelles in plant cells that capture light energy.
- Major sites of photosynthesis are primarily located in leaves, with most chloroplasts found in mesophyll tissue.
- Chlorophyll is the key pigment that absorbs light, critical for converting solar energy into chemical energy.
Photosynthesis Reactions
- The overall equation is 6 CO2 + 6 H2O → C6H12O6 + 6 O2.
- During photosynthesis, CO2 is reduced to glucose (C6H12O6), and water is oxidized to oxygen (O2).
Light Reactions
- Occur in the thylakoid membranes of chloroplasts, converting light energy to chemical energy (ATP and NADPH).
- Water is split during light reactions, providing electrons and releasing O2 as a by-product.
- The main inputs for light reactions include ADP + P, NADP+, H2O, and light energy; outputs are ATP, NADPH, and O2.
Calvin Cycle
- The Calvin cycle occurs in the chloroplast stroma and utilizes CO2 and products of light reactions to synthesize sugar.
- Key steps include carbon fixation, reduction of 3-carbon molecules to G3P, and regeneration of RuBP.
- Inputs consist of CO2, ATP, and NADPH; outputs include G3P, NADP+, and ADP + P.
Carotenoids and Pigments
- Chlorophyll A primarily absorbs blue-violet and red light, reflecting green light, while chlorophyll B broadens light absorption range.
- Carotenoids protect plants from excessive sunlight and broaden the light spectrum usable for photosynthesis.
C3, C4, and CAM Plants
- C3 plants use the Calvin cycle directly for CO2 incorporation, producing a three-carbon compound.
- C4 plants initially convert CO2 into four-carbon compounds for later use in the Calvin cycle.
- CAM plants absorb CO2 at night and store it for use during the day, minimizing water loss.
Importance of Photosynthesis
- Photosynthesis plays a crucial role in converting atmospheric CO2 into organic compounds and releasing oxygen.
- Approximately 50% of photosynthesis products are utilized for cellular respiration and organic molecule synthesis; excess is stored as cellulose.
Greenhouse Effect
- The greenhouse effect is the warming caused by gases like carbon dioxide, methane, and water vapor trapping solar radiation, which provides insulation for the planet.
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Description
Test your knowledge on photosynthesis with this quiz based on Chapter 7 of BIO 20. Learn about the processes and organisms involved in photosynthesis, including autotrophs and heterotrophs. Perfect for reinforcing your understanding of plant biology and energy conversion.