<?xml version="1.0" encoding="UTF-8"?>
<question type="sequence">
<question type="OPTION">
<text>
<p>A sequence question is a series of questions that are regarded as one question.</p>
<p>Besides the growth curve in batch of the
<span style="color: red;">first organism</span> (red diamonds), the growth curve of a
<span style="color: blue;">second organism</span> is drawn (blue boxes) in the graph:<br />
<img src="[attachurl:intro_ld4_17_1.png]" width="378" height="220" /><br />
What is the ratio of
<span style="color: red;">μ<sub>max,organism 1</sub></span> /
<span style="color: blue;">μ<sub>max,organism 2</sub></span>?
</p>
</text>
<hint mintries="1">
What is the meaning of μ<sub>max</sub>? And what is the meaning of the slope of both growth curves?
</hint>
<hint mintries="2">
The volumetric growth rate r<sub>x </sub> = dC<sub>x</sub> / dt (kg / m<sup>3</sup> / h).
When do the organisms grow at μ<sub>max</sub>?
</hint>
<hint mintries="3">
When the organisms grow exponentially, they grow at μ<sub>max</sub>. The formula for r<sub>x</sub> yields:<br />
<b>r<sub>x</sub> = μ<sub>max</sub> • C<sub>x</sub></b> (kg / m<sup>3</sup> / h)<br />
So you'll have to compare dC<sub>x,organism1</sub> / dt and dC<sub>x,organism1</sub> / dt in the beginning of the batch.
</hint>
<hint mintries="4">
The red organisms take 1.25 h to grow to a C<sub>x</sub> of 10 kg / m<sup>3</sup>, the
blue need 2 h. So the red organism is faster, &mu will be higher, so the value must be above 1.<br />
μ<sub>max,organism 1</sub> / μ<sub>max,organism 2</sub> = 1.5
</hint>
<option correct="0">
<choice>It is impossible to tell on basis of this graph</choice>
<feedback>You are wrong. It is possible to tell on basis of this graph</feedback>
</option>
<option correct="0">
<choice>≈ 0</choice>
<feedback>Read the question again, to get an anser of zero, one of the growth rates needs to be zero or infinite, which is obviously not the case.</feedback>
</option>
<option correct="0">
<choice>≈ 0.4</choice>
<feedback>There is no 0.4 X difference in the growth rates.</feedback>
</option>
<option correct="1">
<choice>≈ 0.6</choice>
<feedback>Check again which organism is the first and which is the second.</feedback>
</option>
<option correct="0">
<choice>≈ 0.8</choice>
<feedback>There is no 0.8 X difference in the growth rates.</feedback>
</option>
<option correct="0">
<choice>≈ 1</choice>
<feedback>Assume they grow at the maximum growth rate, the growth rate is definately not the same!</feedback>
</option>
<option correct="1">
<choice>≈ 1.5</choice>
<feedback>That is correct! The slope dC
<sub>x</sub> / dt of the growth curve is given by the volumetric growth rate r<sub>x</sub><br />
Because<br />
<b>r<sub>x</sub> = μ<sub>max</sub> • C<sub>x</sub></b>
(kg / m<sup>3</sup> / h)<br />
in the beginning of the batch:<br />
<b>r<sub>x,organism1</sub> / r<sub>x,organism2</sub> = μ<sub>max,organism 1</sub> / μ<sub>max,organism 2</sub></b>
(-)<br />
Both organisms had the same initial biomass concentration. Organism 1 needed 1.25 h to grow to a C
<sub>x</sub> of 10 kg / m
<sup>3</sup>, organism needed 2 h for that, so μ
<sub>max,organism 1</sub> must be higher then μ
<sub>max,organism 2</sub> so the answer will ne higher then 1.
<br />
<em>Click continue to go to part 2 of this question.</em>
</feedback>
</option>
</question>
<question type="OPTION">
<text>
Now the growth curve of a
<span style="color: blue;">third organism</span> (blue x-es) is shown together with the
<span style="color: red;">first organism</span> (red diamonds):<br />
<img src="[attachurl:intro_ld4_17_2.png]" width="378px" height="220px" /><br />
What is the ratio of
<span style="color: red;">μ<sub>max,organism 1</sub></span> /
<span style="color: blue;">μ<sub>max,organism 3</sub></span>?
</text>
<hint mintries="1">
Keep in mind that both growth curves have a different initial biomass concentration C<sub>x</sub> (0)
</hint>
<hint mintries="2">
The bacteria grow only at their maximum speed in the beginning of a batch
</hint>
<hint mintries="3">
Organism 1 needs about 1 hour to grow from C<sub>x</sub> = 5 - 10 kg / m<sup>3</sup>.
How much does organism 3 need to grow from 5-10 kg / m<sup>3</sup>?
</hint>
<hint mintries="4">
The answer is that they grow at an identical specific growth rate, the answer is 1!
</hint>
<option correct="0">
<choice>It is impossible to tell on basis of this graph</choice>
<feedback></feedback>
</option>
<option correct="0">
<choice>≈ 0</choice>
<feedback></feedback>
</option>
<option correct="0">
<choice>≈ 0.4</choice>
<feedback></feedback>
</option>
<option correct="0">
<choice>≈ 0.6</choice>
<feedback></feedback>
</option>
<option correct="0">
<choice>≈ 0.8</choice>
<feedback></feedback>
</option>
<option correct="1">
<choice>≈ 1</choice>
<feedback>Yes! On first sight, it may look if organism 3 grows faster than organism 1. Organism 3 does have a higher
<i>volumetric</i> growth rate r<sub>x</sub> than organism 1, but both have the same maximal specific
growth rate μ<sub>max</sub>. This can be explained using the formula for r<sub>x</sub>:<br />
<b>r<sub>x</sub> = μ • C<sub>x</sub></b> (kg / m<sup>3</sup> / h)<br />
Organism 3 started with a higher initial biomass concentration than organism 1, so with equal μ, it's
r<sub>x</sub> became higher.
</feedback>
</option>
<option correct="0">
<choice>≈ 1.5</choice>
<feedback></feedback>
</option>
</question>
<question type="PATTERN" duplicates="0">
<text>Select and order the needed steps. This example question contains only one target box.</text>
<option identifier="a">
<choice>Step A.</choice>
<description name="a">
<b>Step A:</b><br />A description of step A.
</description>
</option>
<option identifier="b">
<choice>Step B.</choice>
<description name="b">
<b>Step B:</b><br />A description of step B.
</description>
</option>
<option identifier="c">
<choice>Step C.</choice>
<description name="c">
<b>Step C:</b><br />A description of step C.
</description>
</option>
<option identifier="d">
<choice>Step D.</choice>
<description name="d">
<b>Step D:</b><br />A description of step D.
</description>
</option>
<option identifier="e">
<choice>Step E.</choice>
<description name="e">
<b>Step E:</b><br />A description of step E.
</description>
</option>
<option identifier="f">
<choice>Step F.</choice>
<description name="f">
<b>Step F:</b><br />A description of step F.
</description>
</option>
<hint mintries="1">first hint</hint>
<sequence correct="1">
<pattern>^bcd$</pattern>
<feedback>Correct. You only need steps B, C and D.
</feedback>
</sequence>
<sequence correct="0">
<pattern>^[^b]*c.*$</pattern>
<feedback>You can not do step C unless you first do step B.</feedback>
</sequence>
<sequence correct="0">
<pattern>.*</pattern>
<feedback mintries="1">Nope, that't not correct. Try again.</feedback>
<feedback mintries="2" maxtries="2">You only need three steps.</feedback>
<feedback mintries="3">You need steps BCD.</feedback>
</sequence>
</question>
</question>