Podcast
Questions and Answers
What is the primary source of carbon for autotrophs?
What is the primary source of carbon for autotrophs?
Heterotrophs are able to produce their own food through photosynthesis.
Heterotrophs are able to produce their own food through photosynthesis.
False (B)
What is the name of the process by which autotrophs convert light energy into chemical energy?
What is the name of the process by which autotrophs convert light energy into chemical energy?
Photosynthesis
The two stages of photosynthesis are the ______ reaction and the ______ reaction.
The two stages of photosynthesis are the ______ reaction and the ______ reaction.
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Match the following terms with their corresponding definitions:
Match the following terms with their corresponding definitions:
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Which of the following is NOT a characteristic of photons?
Which of the following is NOT a characteristic of photons?
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Pigments absorb all wavelengths of light equally.
Pigments absorb all wavelengths of light equally.
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What is the primary photosynthetic pigment in plants, cyanobacteria, and photosynthetic protists?
What is the primary photosynthetic pigment in plants, cyanobacteria, and photosynthetic protists?
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The accessory pigment, ______, gives carrots their orange color.
The accessory pigment, ______, gives carrots their orange color.
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Match the accessory pigments with their corresponding reflected colors:
Match the accessory pigments with their corresponding reflected colors:
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What is the primary reason that leaves turn yellow or orange in the fall?
What is the primary reason that leaves turn yellow or orange in the fall?
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The noncyclic pathway of photosynthesis produces ATP, NADPH, and carbon dioxide.
The noncyclic pathway of photosynthesis produces ATP, NADPH, and carbon dioxide.
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What is the process called where light energy breaks down water molecules during photosynthesis?
What is the process called where light energy breaks down water molecules during photosynthesis?
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The electron transfer chain in the thylakoid membrane is responsible for generating a ______ gradient.
The electron transfer chain in the thylakoid membrane is responsible for generating a ______ gradient.
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Which of the following statements is TRUE about the cyclic pathway of photosynthesis?
Which of the following statements is TRUE about the cyclic pathway of photosynthesis?
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The Calvin-Benson cycle is also known as the light-dependent reactions of photosynthesis.
The Calvin-Benson cycle is also known as the light-dependent reactions of photosynthesis.
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What is the name of the enzyme that fixes carbon dioxide to RuBP in the Calvin-Benson cycle?
What is the name of the enzyme that fixes carbon dioxide to RuBP in the Calvin-Benson cycle?
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The first stable intermediate formed in the Calvin-Benson cycle is a ______ -carbon compound.
The first stable intermediate formed in the Calvin-Benson cycle is a ______ -carbon compound.
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Which of the following is NOT a consequence of photorespiration?
Which of the following is NOT a consequence of photorespiration?
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C3 plants are adapted to minimize photorespiration.
C3 plants are adapted to minimize photorespiration.
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What is the name of the tiny gaps on the surfaces of leaves and stems that allow for gas exchange?
What is the name of the tiny gaps on the surfaces of leaves and stems that allow for gas exchange?
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Study Notes
Autotrophs and Heterotrophs
- Autotrophs produce their own food through photosynthesis, obtaining energy and carbon from inorganic sources like carbon dioxide.
- Photosynthesis converts light energy into chemical energy, using carbon dioxide and water to create glucose and releasing oxygen.
- Heterotrophs are consumers, obtaining carbon from other organisms (autotrophs).
Two Stages of Photosynthesis
- Photosynthesis equation: CO2 + H2O → sugars + O2
- Light-dependent reactions convert light energy to chemical energy (ATP), creating ATP and NADPH.
- Light-independent reactions (Calvin cycle) use ATP and NADPH to synthesize sugars.
Photosynthesis Location
- Thylakoid membrane: Inner membrane of chloroplast, site of light-dependent reactions.
- Stroma: Fluid surrounding thylakoid membrane, site of light-independent reactions.
Visible Light and Photosynthesis
- Theodor Engelmann's experiments demonstrated that different wavelengths of light affect photosynthesis rates, with red and blue light being most effective.
- Visible light wavelengths range from 380 to 750 nm.
- Photon: Packets of light energy (energy is inversely proportional to wavelength).
- Pigment: Molecules that absorb specific wavelengths of light.
Photosynthetic Pigments
- Chlorophyll a: Primary pigment, absorbs red and blue light, reflects green.
- Accessory pigments (e.g., chlorophyll b, carotenoids, xanthophylls, anthocyanins) broaden the range of absorbed light wavelengths.
- Accessory pigments provide color to plants and act as antioxidants.
- Plants conserve resources in winter, causing leaves to change color as chlorophyll is recycled and other pigments become more visible.
Light-Dependent Reactions (Noncyclic and Cyclic Pathways)
- Photosystem (PS): Protein complexes containing pigments that convert light energy to chemical energy.
- Noncyclic pathway: Primary pathway in plants, producing ATP, NADPH, and oxygen (O2).
- Photolysis: Water is split to provide electrons to PS2.
- Electron transfer chain creates a hydrogen ion gradient.
- ATP synthase uses the gradient to produce ATP.
- NADP+ is reduced to NADPH.
- Cyclic pathway: Uses PS1 to produce additional ATP when needed.
- Does not produce NADPH or O2.
- Important for generating extra ATP when light-dependent reactions are overtaxed.
Calvin-Benson Cycle
- Light-independent reactions.
- Rubisco fixes CO2 to RuBP, creating a 6-carbon molecule which splits to form 3PGA.
- ATP and NADPH provide energy and electrons to convert 3PGA to PGAL.
- PGAL is used to synthesize sugars (sucrose, starch) and regenerate RuBP.
Photorespiration in C3 plants
- Stomata close to conserve water, reducing CO2 intake and increasing O2 concentration.
- Rubisco binds O2 instead of CO2, leading to photorespiration (ATP/energy loss).
- C3 plants compensate for photorespiration by producing large amounts of Rubisco.
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Description
Test your knowledge on autotrophs and heterotrophs, their roles in ecosystems, and the process of photosynthesis. This quiz covers the stages of photosynthesis, the locations where it occurs, and the significance of visible light in the process.
