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Questions and Answers
What is the primary function of leaves in plants?
What is the primary function of leaves in plants?
- Pollination
- Storage of nutrients
- Support for the stem
- Photosynthesis (correct)
What component of a leaf is primarily responsible for photosynthesis?
What component of a leaf is primarily responsible for photosynthesis?
- Blade (correct)
- Midrib
- Leaf margin
- Petiole
Where are leaves typically found on a plant?
Where are leaves typically found on a plant?
- On the fruit
- Along the trunk
- At the root tip
- At a node on the stem (correct)
Which characteristic best describes the leaf structure?
Which characteristic best describes the leaf structure?
Which part of the leaf connects to the stem's vascular tissue?
Which part of the leaf connects to the stem's vascular tissue?
What is the role of the petiole in a leaf's structure?
What is the role of the petiole in a leaf's structure?
What might be a reason for leaves to be modified in some plants?
What might be a reason for leaves to be modified in some plants?
Which of the following parts of a leaf is NOT present at its edges?
Which of the following parts of a leaf is NOT present at its edges?
Which of the following statements about leaves is false?
Which of the following statements about leaves is false?
Which feature distinguishes the veins of a leaf?
Which feature distinguishes the veins of a leaf?
What is the primary role of leaves in photosynthesis?
What is the primary role of leaves in photosynthesis?
Which process allows leaves to lose water vapor?
Which process allows leaves to lose water vapor?
During which process do leaves take in carbon dioxide and release oxygen?
During which process do leaves take in carbon dioxide and release oxygen?
What gas is primarily taken in by leaves during respiration?
What gas is primarily taken in by leaves during respiration?
Which statement accurately describes the gaseous exchange in leaves?
Which statement accurately describes the gaseous exchange in leaves?
Which part of the leaf is primarily responsible for attaching the leaf to the stem?
Which part of the leaf is primarily responsible for attaching the leaf to the stem?
What is the function of the veins in a leaf structure?
What is the function of the veins in a leaf structure?
What distinguishes small netted veins from other vein structures in leaves?
What distinguishes small netted veins from other vein structures in leaves?
In a leaf, what part runs down the center of the leaf blade and provides structural integrity?
In a leaf, what part runs down the center of the leaf blade and provides structural integrity?
Which structure is typically found at the base of the petiole in a leaf?
Which structure is typically found at the base of the petiole in a leaf?
Which of the following is NOT a source of genetic variation in plants?
Which of the following is NOT a source of genetic variation in plants?
What are the primary mechanisms through which genetic variation occurs in plants?
What are the primary mechanisms through which genetic variation occurs in plants?
In the context of genetic variation, which term describes the process of exchange of genetic material between populations?
In the context of genetic variation, which term describes the process of exchange of genetic material between populations?
Which of the following statements about mutation in genetic variation is true?
Which of the following statements about mutation in genetic variation is true?
Which process allows for the rearrangement of genetic material leading to genetic diversity?
Which process allows for the rearrangement of genetic material leading to genetic diversity?
What is an example of phenoplasticity as demonstrated by Ranunculus aquatilis?
What is an example of phenoplasticity as demonstrated by Ranunculus aquatilis?
Which of the following statements about the leaf morphology of Ranunculus aquatilis is correct?
Which of the following statements about the leaf morphology of Ranunculus aquatilis is correct?
Which factors are known to influence environmental variation in plant phenoplasticity?
Which factors are known to influence environmental variation in plant phenoplasticity?
What type of leaves does Ranunculus aquatilis produce above the water surface?
What type of leaves does Ranunculus aquatilis produce above the water surface?
How does temperature contribute to environmental variation in plants like Ranunculus aquatilis?
How does temperature contribute to environmental variation in plants like Ranunculus aquatilis?
What is a significant factor that can cause confusion in identifying plants?
What is a significant factor that can cause confusion in identifying plants?
In which circumstance do the leaflets of Sclerocarya caffra appear serrated?
In which circumstance do the leaflets of Sclerocarya caffra appear serrated?
Which statement regarding the leaf structure of Sclerocarya caffra is true?
Which statement regarding the leaf structure of Sclerocarya caffra is true?
What does the term 'morphological evolution' imply in the context of plant development?
What does the term 'morphological evolution' imply in the context of plant development?
How does developmental variation relate to species identification?
How does developmental variation relate to species identification?
What is the state of P680 after it gains an electron during photosynthesis?
What is the state of P680 after it gains an electron during photosynthesis?
What role does P680+ serve after P680 loses an electron?
What role does P680+ serve after P680 loses an electron?
In the electron transport chain initiated by PSII, which molecule does the electron pass to immediately after plastoquinone?
In the electron transport chain initiated by PSII, which molecule does the electron pass to immediately after plastoquinone?
Which of the following correctly describes the arrangement of molecules involved with PSII?
Which of the following correctly describes the arrangement of molecules involved with PSII?
What is the initial reaction triggered by light energy in the photosynthetic process?
What is the initial reaction triggered by light energy in the photosynthetic process?
What occurs during photolysis in the photosynthesis process?
What occurs during photolysis in the photosynthesis process?
What role do H+ ions play as they pass through ATP synthase?
What role do H+ ions play as they pass through ATP synthase?
What happens to electron flow in cyclic phosphorylation under strenuous conditions?
What happens to electron flow in cyclic phosphorylation under strenuous conditions?
In cyclic phosphorylation, why is water not required?
In cyclic phosphorylation, why is water not required?
What is a consequence of reduced NADP+ production in cyclic phosphorylation?
What is a consequence of reduced NADP+ production in cyclic phosphorylation?
What is the primary consequence of the electron losing energy by the time it reaches Photosystem I (PSI)?
What is the primary consequence of the electron losing energy by the time it reaches Photosystem I (PSI)?
Which process is essential for replenishing the electrons lost by P680+ in Photosystem II?
Which process is essential for replenishing the electrons lost by P680+ in Photosystem II?
NADPH is produced at which stage of the electron transport chain?
NADPH is produced at which stage of the electron transport chain?
How does the flow of hydrogen ions (H+) influence ATP generation in photosynthesis?
How does the flow of hydrogen ions (H+) influence ATP generation in photosynthesis?
What ultimately happens to the electrons as they travel through the electron transport chain post-PSI?
What ultimately happens to the electrons as they travel through the electron transport chain post-PSI?
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Study Notes
Leaf Structure
- A leaf is typically a flattened organ.
- Attached to the stem at a node.
- Some leaves are modified for functions other than photosynthesis.
Leaf Functions
- Photosynthesis: the process of converting light energy into chemical energy.
- Gaseous Exchange:
- Takes in oxygen (O2) and releases carbon dioxide (CO2) during respiration.
- Takes in carbon dioxide (CO2) and releases oxygen (O2) during photosynthesis.
- Transpiration: the process of water vapor loss from the leaf surface.
External Leaf Structure
- Petiole: the stalk that attaches the leaf to the stem; some leaves may have a very short or no petiole.
- Blade: the expanded part of the leaf responsible for photosynthesis.
- Midrib: the main vein that connects to the stem's vascular tissue.
- Veins: may be either netted or parallel.
- Leaf Base: the point where the petiole attaches to the stem.
- Leaf Tip: the pointed or rounded end of the leaf.
- Leaf Margin: the edge of the leaf blade.
Plant Variation
- Genetic Variation: heritable differences in traits. Two sources include mutation and gene flow/recombination.
- Environmental Variation: non-heritable differences caused by factors such as light, water, nutrients, temperature, and soil.
- This is known as phenoplasticity.
- Developmental Variation: differences in morphology between immature seedlings and adult plants.
Light Dependent Reactions
- Non-cyclic Phosphorylation:
- Light energy captured by Photosystem II (PSII) in the thylakoid membrane.
- Excited electrons move through the electron transport chain (ETS).
- The energy released from electron movement is used to pump hydrogen ions (H+) into the thylakoid lumen.
- Electrons reach Photosystem I (PSI) and are re-excited.
- Electrons are used to reduce NADP+ to NADPH.
- P680+ (in PSII) takes electrons from water (H2O) through photolysis, splitting water into oxygen (O2) and hydrogen ions (H+).
Electron Transport Chain
- ATP production: H+ ions move through ATP synthase, providing energy for ADP phosphorylation to produce ATP.
- Electron Movement: Electrons move from water (H2O) through PSII and PSI, leading to the production of both NADPH and ATP.
Cyclic Phosphorylation
- Strenuous Conditions: In conditions of high light irradiance and heat, the plant may limit NADPH production.
- Electron Flow: The electron does not reach NADP+ and is recycled back to PSII to continue H+ pumping.
- No Photolysis: Water is not needed for cyclic phosphorylation.
Photosynthesis
- Water is broken down (photolysis) into oxygen (O2) and hydrogen ions (H+).
- H+ ions move through ATP synthase, providing energy for ATP production.
- ATP is stored for use in the light-independent reactions.
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