Multiple Choice
Which factor makes enzymes well-suited to the role of catalyst in a biochemical reaction?
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6. Enzymes and Enzyme Kinetics
Enzymes
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How can differences in enzyme concentration affect the rates of photosynthesis and cellular respiration in plant cells?
A
Increasing enzyme concentration generally increases the rates of both photosynthesis and respiration up to a saturation point.
B
Enzyme concentration has no effect on the rates of photosynthesis or respiration.
C
Increasing enzyme concentration decreases the rates of both photosynthesis and respiration.
D
Decreasing enzyme concentration always increases the rates of photosynthesis and respiration.
Verified step by step guidance1
Understand the role of enzymes in biochemical reactions: Enzymes act as catalysts, speeding up reactions by lowering the activation energy required. Both photosynthesis and cellular respiration rely on specific enzymes to facilitate their respective biochemical pathways.
Consider the relationship between enzyme concentration and reaction rate: Increasing enzyme concentration generally increases the rate of a reaction because more enzyme molecules are available to bind substrates and form enzyme-substrate complexes. However, this effect is limited by substrate availability and other factors, leading to a saturation point where further increases in enzyme concentration no longer affect the reaction rate.
Apply this concept to photosynthesis and cellular respiration: In plant cells, enzymes involved in photosynthesis (e.g., RuBisCO) and cellular respiration (e.g., ATP synthase) are critical for these processes. Increasing their concentration can enhance the rates of these processes, provided there is sufficient substrate (e.g., CO₂ for photosynthesis or glucose for respiration) and other conditions are optimal.
Evaluate the provided answer choices: The correct answer aligns with the principle that increasing enzyme concentration generally increases reaction rates up to a saturation point. Other options, such as enzyme concentration having no effect or decreasing enzyme concentration increasing rates, contradict established biochemical principles.
Conclude with the importance of enzyme concentration: While enzyme concentration is a key factor, it is not the sole determinant of reaction rates. Factors such as substrate availability, temperature, pH, and cofactor presence also play significant roles in regulating photosynthesis and cellular respiration.
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