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Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Question 1
Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst. The induced-fit model of enzyme action explains how an enzyme allows for subst... show full transcript
Worked Solution & Example Answer:Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Step 1
Scientists investigated the action of the enzyme ATP synthase. They made reaction mixtures each containing: A TP synthase, buffer (to control pH), substrates. One of the substrates required in these reaction mixtures is inorganic phosphate (Pi). Tick (✓) one box to show which other substrate the scientists must add to the reaction mixtures to produce ATP.
Answer
The scientists must add Adenosine diphosphate (ADP) to the reaction mixtures. ADP is essential for the synthesis of ATP, as it combines with inorganic phosphate (Pi) to form ATP during the reaction catalyzed by ATP synthase.
Step 2
The scientists investigated the effect of concentration of inorganic phosphate (Pi) on ATP synthase activity. after 2 minutes, they stopped each reaction and then measured the concentration of ATP. Suggest and explain a procedure the scientists could have used to stop each reaction.
Answer
To stop each reaction, the scientists could put the reaction tubes in an ice bath. Cooling the reaction mixture reduces the kinetic energy of the molecules, leading to a decrease in enzyme activity and the formation of enzyme-substrate complexes. This method effectively halts the reactions without degrading the components.
Step 3
Explain the change in ATP concentration with increasing inorganic phosphate concentration.
Answer
As the concentration of inorganic phosphate (Pi) increases, the formation of ATP also increases, up to a certain point. This happens because a higher concentration of Pi facilitates more enzyme-substrate complexes, thus increasing the likelihood of ADP and Pi combining to form ATP. However, beyond a certain concentration of Pi, the effect may plateau as other factors become limiting.
Step 4
Explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake.
Answer
Larger animals have higher metabolic rates and greater oxygen demands due to their size and activity levels. A specialised system for oxygen uptake, such as lungs or gills, ensures efficient oxygen delivery to tissues. This facilitates aerobic respiration, allowing for sustained energy production. Additionally, it helps maintain homeostasis by regulating gas exchange, ensuring that oxygen is supplied and carbon dioxide is expelled effectively.