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The growth of bacteria (lactobacillus) in milk leads to curd formation. A minimum bacterial population density of $0.8$ (in suitable units) is needed to form curd. In the graph below, the population density of lactobacillus in $1$ litre of milk is plotted as a function of time, at two different temperatures, $25^{\circ}$C and $37^{\circ}$C.

Consider the following statements based on the data shown above:

  1. The growth in bacterial population stops earlier at $37^{\circ}$C as compared to $25^{\circ}$C
  2. The time taken for curd formation at $25^{\circ}$C is twice the time taken at $37^{\circ}$C

Which one of the following options is correct?

  1. Only i
  2. Only ii
  3. Both i and ii
  4. Neither i nor ii
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Migrated from GO Mechanical 4 years ago by Arjun

3 Answers

Best answer
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  1. The growth in bacterial population stops earlier at $37^∘$C as compared to $25^∘$C - TRUE.
    From the graph it can be seen that the growth stops after $150$ minutes at $37^∘$C while it stops after $180$ minutes at $25^∘$C
  2. The time taken for curd formation at $25^∘$C is twice the time taken at $37^∘$C - FALSE.
    From the graph it can be seen that curd formation happens in around $90$ minutes at $37^∘$C and in around $120$ minutes at $25^∘$C

Correct Option: A.

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Growth of Bacterial population stops when Bacterial population becomes steady.

It happens after 140 min at 37∘C& at 180 min at 25∘C 180.  it stops earlier at 37∘C

Time taken for curd formation is time required to reach density of 0.8.

At 37∘C time required ≈≈ 90 min

At 25∘C, time required ≈≈ 130 min

Hence only statement -1 is true   2 can not be correct according to above explanation

so A is answer
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According to the given graph, Statement-(i) is correct, The time taken for curd formation in $25^{\circ} = 120$ minutes, the time taken for curd formation in $37^{\circ} C= 80$ minutes, hence (ii) is incorrect.

Hence Option A is correct
Answer:

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