The bacterium E.coli was cultured in a growth medium containing 0.6 mM glucose and 0.6 mM lactose for 180 minutes - Scottish Highers Biology - Question 8 - 2019
Question 8
The bacterium E.coli was cultured in a growth medium containing 0.6 mM glucose and 0.6 mM lactose for 180 minutes. Glucose and lactose concentrations were measured e... show full transcript
Worked Solution & Example Answer:The bacterium E.coli was cultured in a growth medium containing 0.6 mM glucose and 0.6 mM lactose for 180 minutes - Scottish Highers Biology - Question 8 - 2019
Step 1
Using values from the table, describe changes in the concentration of lactose over the 180 minutes of the experiment.
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Answer
From 0 to 60 minutes, lactose concentration remains constant at 0.6 mM. From 60 to 180 minutes, lactose concentration decreases steadily, falling to 0 mM.
Step 2
Using information from the table, identify the time when E.coli started producing beta-galactosidase.
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Answer
E.coli started producing beta-galactosidase at 60 minutes, as the glucose concentration dropped to 0.38 mM.
Step 3
Suggest a benefit to E.coli of producing beta-galactosidase only when lactose is present.
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Answer
Producing beta-galactosidase only when lactose is present saves energy and amino acids, preventing unnecessary energy expenditure and resource wastage.
Step 4
In terms of activation energy, state how enzymes increase the rates of reactions in living cells.
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Answer
Enzymes reduce the activation energy required for reactions, thus increasing the rate of reactions in living cells.
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