Photosynthesis

Questions and Answers

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

Zero

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

It decreases

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

Turgor pressure

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

Transpiration Signup and view all the answers

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

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

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

Hydrogen bonding of water molecules 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?

Transpiration 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?

Evaporation of the water film Signup and view all the answers

What type of work does ATP perform?

Chemical Work Signup and view all the answers

Why are plants green?

Chlorophyll reflects green wavelength of light Signup and view all the answers

What is the primary function of cellular respiration?

Extracting energy stored in sugars Signup and view all the answers

What happens with free energy in a closed system?

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

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

Critical for transferring electrons Signup and view all the answers

Why doesn’t equilibrium happen in living systems?

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

What is the primary function of photosynthesis?

Harvesting solar energy Signup and view all the answers

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

Plants release oxygen during photosynthesis Signup and view all the answers

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

Translocation Signup and view all the answers

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

Stomata Signup and view all the answers

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

Pressure flow Signup and view all the answers

What mechanism opens and closes stomata?

Changes in turgor pressure Signup and view all the answers

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

Bulk flow 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?

Relative humidity Signup and view all the answers

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

Sugar loading Signup and view all the answers

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

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

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

Sugar unloading Signup and view all the answers

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

Cavitation Signup and view all the answers

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

Cohesion-tension mechanism 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?

Cohesion and adhesion in the ascent of xylem sap Signup and view all the answers

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

They use H2S instead of H2O for photosynthesis Signup and view all the answers

Why does chlorophyll appear green?

It mainly absorbs red and blue light Signup and view all the answers

What is the function of carotenoids in photosynthesis?

Protect chlorophyll from damage by excess light Signup and view all the answers

What is the primary role of photosystems I and II?

Convert light energy to chemical energy Signup and view all the answers

What is the main purpose of blocking photosynthetic reactions?

Prevent weed growth Signup and view all the answers

What did Melvin Calvin identify in the Calvin cycle?

The carbon pathways Signup and view all the answers

How many stages does the Calvin cycle have?

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

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

Exposed filamentous algae to different light wavelengths Signup and view all the answers

What is the nature of sunlight crucial for photosynthesis?

Electromagnetic energy with visible light wavelengths Signup and view all the answers

Where does the synthesis through the Calvin cycle occur?

In the stroma Signup and view all the answers

What is the main product of the Calvin cycle?

Sugars for energy storage Signup and view all the answers

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

Splitting water Signup and view all the answers

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

Rubisco 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?

C4 Photosynthesis Signup and view all the answers

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

High water use efficiency rates Signup and view all the answers

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

Water; it helps support the plant and regulate temperature Signup and view all the answers

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

Apoplastic Route Signup and view all the answers

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

Surface Tension Signup and view all the answers

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

Proton pump Signup and view all the answers

What is the role of ion channels in plants?

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

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

Help plants get nutrients from soil Signup and view all the answers

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

Water Potential Signup and view all the answers

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

Reduce photodamage to plants Signup and view all the answers

What is the main function of chloroplasts in plants?

Facilitate photosynthesis Signup and view all the answers

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

Rubisco Signup and view all the answers

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

Photorespiration Signup and view all the answers

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

Stomata closing due to water stress Signup and view all the answers

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

Mutant Arabidopsis plants Signup and view all the answers

What reduces losses to photorespiration in plants?

C4 and CAM mechanisms Signup and view all the answers

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

C4 plants Signup and view all the answers

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

CAM plants Signup and view all the answers

Which plants exhibit CAM idling under severe water stress?

Incomplete/Facultative CAM plants Signup and view all the answers

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

CAM plants Signup and view all the answers

What movements reduce photodamage to plants under high light conditions?

Chloroplast avoidance movements Signup and view all the answers

What does plant resource acquisition include?

Shoot and root adaptations Signup and view all the answers

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

PEP carboxylase and Rubisco 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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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.

Photosynthesis

Questions and Answers

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

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

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

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

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

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

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

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

What type of work does ATP perform?

Why are plants green?

What is the primary function of cellular respiration?

What happens with free energy in a closed system?

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

Why doesn’t equilibrium happen in living systems?

What is the primary function of photosynthesis?

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

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

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

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

What mechanism opens and closes stomata?

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

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?

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

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

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

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

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

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

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

Why does chlorophyll appear green?

What is the function of carotenoids in photosynthesis?

What is the primary role of photosystems I and II?

What is the main purpose of blocking photosynthetic reactions?

What did Melvin Calvin identify in the Calvin cycle?

How many stages does the Calvin cycle have?

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

What is the nature of sunlight crucial for photosynthesis?

Where does the synthesis through the Calvin cycle occur?

What is the main product of the Calvin cycle?

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

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

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

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

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

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

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

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

What is the role of ion channels in plants?

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

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

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

What is the main function of chloroplasts in plants?

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

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

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

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

What reduces losses to photorespiration in plants?

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

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

Which plants exhibit CAM idling under severe water stress?

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

What movements reduce photodamage to plants under high light conditions?

What does plant resource acquisition include?

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

Study Notes

Studying That Suits You

Description

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