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Questions and Answers
What is the absorption wavelength of photosystem I's reaction center, P700?
What is the absorption wavelength of photosystem I's reaction center, P700?
In which part of the chloroplast does the light reaction occur?
In which part of the chloroplast does the light reaction occur?
Which photosystem is involved in the noncyclic light reaction?
Which photosystem is involved in the noncyclic light reaction?
What happens to the electron released by P680 in the noncyclic light reaction?
What happens to the electron released by P680 in the noncyclic light reaction?
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What is produced as a result of the cyclic light reaction?
What is produced as a result of the cyclic light reaction?
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During the noncyclic light reaction, what causes the splitting of water molecules?
During the noncyclic light reaction, what causes the splitting of water molecules?
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Which ion is formed when water molecules are split during photosynthesis?
Which ion is formed when water molecules are split during photosynthesis?
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What role does the primary electron acceptor play in the cyclic light reaction?
What role does the primary electron acceptor play in the cyclic light reaction?
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What part of the plant is primarily responsible for photosynthesis?
What part of the plant is primarily responsible for photosynthesis?
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Which tissue in dicot leaves is specifically involved in photosynthesis?
Which tissue in dicot leaves is specifically involved in photosynthesis?
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What is the role of guard cells in the leaf?
What is the role of guard cells in the leaf?
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Which of the following substances is a by-product of photosynthesis?
Which of the following substances is a by-product of photosynthesis?
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In photosynthesis, what is the primary function of water?
In photosynthesis, what is the primary function of water?
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What chemical process occurs when carbon dioxide and water combine in photosynthesis?
What chemical process occurs when carbon dioxide and water combine in photosynthesis?
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Which component of the vascular tissue is responsible for transporting water to the leaves?
Which component of the vascular tissue is responsible for transporting water to the leaves?
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What is the significance of light energy in photosynthesis?
What is the significance of light energy in photosynthesis?
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What is primarily responsible for the green appearance of leaves?
What is primarily responsible for the green appearance of leaves?
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Which pigments are considered accessory pigments in chloroplasts?
Which pigments are considered accessory pigments in chloroplasts?
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What is the main purpose of chloroplasts in photosynthesis?
What is the main purpose of chloroplasts in photosynthesis?
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What percentage of light energy that strikes a leaf is utilized in photosynthesis?
What percentage of light energy that strikes a leaf is utilized in photosynthesis?
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Which type of chlorophyll is present in all photosynthetic organisms?
Which type of chlorophyll is present in all photosynthetic organisms?
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What are photosystems primarily composed of?
What are photosystems primarily composed of?
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What role do electron carriers play in the chloroplast?
What role do electron carriers play in the chloroplast?
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Which enzyme found in the chloroplast is critical for photosynthesis?
Which enzyme found in the chloroplast is critical for photosynthesis?
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What stable compound is formed when a hydrogen ion and an electron bind with NADP*?
What stable compound is formed when a hydrogen ion and an electron bind with NADP*?
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Which process occurs during the dark reaction of photosynthesis?
Which process occurs during the dark reaction of photosynthesis?
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What is the role of the enzyme rubisco in the dark reaction?
What is the role of the enzyme rubisco in the dark reaction?
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How many PGAL molecules are formed if six CO2 molecules enter the dark reaction?
How many PGAL molecules are formed if six CO2 molecules enter the dark reaction?
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Which of the following is NOT a product of the noncyclic light reaction?
Which of the following is NOT a product of the noncyclic light reaction?
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What happens to 10 of the 12 PGAL molecules produced in the dark reaction?
What happens to 10 of the 12 PGAL molecules produced in the dark reaction?
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Which of the following components is a five-carbon sugar that acts as a carbon dioxide acceptor?
Which of the following components is a five-carbon sugar that acts as a carbon dioxide acceptor?
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How does photosynthesis primarily function in terms of energy transformation?
How does photosynthesis primarily function in terms of energy transformation?
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Study Notes
Photosynthesis Overview
- Photosynthesis takes place in the leaves of plants.
- Chloroplasts, organelles within plant cells, are where photosynthesis occurs.
- Leaves are the plant's food factories.
- Upper and Lower Epidermis of leaves are transparent and allow light to pass through.
- Palisade and Spongy Tissue collectively called mesophyll tissue are the primary photosynthetic tissue containing chloroplasts.
- Stomata (singular: stoma) are small openings in the leaf that allow gas exchange (carbon dioxide and oxygen).
- Guard cells regulate the size of stomata.
- Veins contain xylem and phloem tissues.
- Xylem transports water and minerals from the roots.
- Phloem transports food (glucose) to other plant parts.
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Photosynthesis equation:
This equation means that carbon dioxide from the atmosphere and water from the roots combine in the presence of light and chlorophyll to produce glucose (sugar) and oxygen.6CO2 + 6H2O → C6H12O6 + 6O2
Raw Materials of Photosynthesis
- Carbon dioxide: comes from the atmosphere and is dissolved in water, stored as carbonic acid in the leaf.
- Water: absorbed from the soil and transported to the leaves. Photolysis (splitting water) provides electrons and ions (H+ and OH-) for energy production.
Factors Involved in Photosynthesis
- Light energy: comes from the sun in packets called photons.
- Red, blue, and violet wavelengths are most useful for photosynthesis.
- Green wavelengths are reflected, making leaves appear green.
- Chlorophyll is a light-trapping pigment found in chloroplasts.
- Chlorophyll a is present in all plants and absorbs energy from violet, blue, red, and orange wavelengths.
- Accessory pigments like chlorophyll b, c, d, and e, xanthophylls, and carotenoids help capture energy that chlorophyll a cannot absorb.
- Electron carriers (ferredoxin, plastocyanin, cytochrome complexes) transport electrons and release energy.
- Enzymes (like rubisco) catalyze specific chemical reactions.
Photosystems
- Photosystems are aggregates of pigments and proteins organized in the thylakoid membranes of chloroplasts.
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Two types of photosystems:
- Photosystem I (PSI): reaction center is P700 (absorbs light at 700 nm)
- Photosystem II (PSII): reaction center is P680 (absorbs light at 680 nm)
Photosynthetic Reactions
- Light dependent reactions (photoreaction): occur in the grana (stacks of thylakoid membranes)
- Dark reactions (synthesis reaction): occur in the stroma (fluid surrounding the grana)
Light Reactions (Two Sub-stages)
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Cyclic Light Reaction:
- Involves PSI with P700.
- Light excites P700, releasing an electron.
- Excited electron passes through an electron transport chain, generating ATP (adenosine triphosphate).
- Electron returns to P700, completing the cycle.
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Noncyclic Light Reaction:
- Involves PSI and PSII
- Light excites P680, releasing an electron, which also produces ATP.
- Electron is donated to PSI (P700).
- Water molecules are split (photolysis) to replace the electron lost by P680, producing hydrogen ions (H+), hydroxide ions (OH-), electrons, and oxygen.
- Hydrogen ions and electrons combine with NADP+ to form NADPH (another energy carrier).
- Overall products of noncyclic light reactions: ATP, NADPH, oxygen, and water.
Dark Reactions
- Calvin Cycle: converts carbon dioxide to sugar.
- RuBP5 (ribulose bisphosphate), a five-carbon sugar, is the carbon dioxide acceptor.
- CO2 combines with RuBP5 to form RuBP6 (unstable six-carbon sugar).
- Rubisco catalyzes this reaction.
- RuBP6 splits into two molecules of PGA (phosphoglycerate).
- PGA, ATP, and NADPH produce PGAL (phosphoglyceraldehyde), the key molecule in glucose synthesis.
- Two PGAL molecules combine to form a glucose molecule.
Photosynthesis Summary
- Photosynthesis is an anabolic pathway that captures light energy and converts it into chemical energy in the form of ATP and NADPH.
- These energy carriers are used to synthesize glucose (sugar), a high-energy carbon-based compound that powers plant growth.
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Description
This quiz covers the essential aspects of photosynthesis, including the structures involved, such as chloroplasts and stomata, and the process itself. Understand how plants convert light energy into chemical energy, the function of different tissues, and the photosynthesis equation. Perfect for students studying plant biology.
