A sequence question is a set of normal questions that count as one.

<?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;">&mu;<sub>max,organism 1</sub></span> /
        <span style="color: blue;">&mu;<sub>max,organism 2</sub></span>?
      </p>
    </text>
    <hint mintries="1">
      What is the meaning of &mu;<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 &mu;<sub>max</sub>?
    </hint>
    <hint mintries="3">
      When the organisms grow exponentially, they grow at &mu;<sub>max</sub>. The formula for r<sub>x</sub> yields:<br />
      <b>r<sub>x</sub> = &mu;<sub>max</sub> &bull; 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 />
      &mu;<sub>max,organism 1</sub> / &mu;<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>&asymp; 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>&asymp; 0.4</choice>
      <feedback>There is no 0.4 X difference in the growth rates.</feedback>
    </option>
    <option correct="1">
      <choice>&asymp; 0.6</choice>
      <feedback>Check again which organism is the first and which is the second.</feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 0.8</choice>
      <feedback>There is no 0.8 X difference in the growth rates.</feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 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>&asymp; 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> = &mu;<sub>max</sub> &bull; C<sub>x</sub></b>
        &nbsp;&nbsp;&nbsp;(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> = &mu;<sub>max,organism 1</sub> / &mu;<sub>max,organism 2</sub></b>
        &nbsp;&nbsp;&nbsp;(-)<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 &mu;
        <sub>max,organism 1</sub> must be higher then &mu;
        <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;">&mu;<sub>max,organism 1</sub></span> /
      <span style="color: blue;">&mu;<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>&asymp; 0</choice>
      <feedback></feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 0.4</choice>
      <feedback></feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 0.6</choice>
      <feedback></feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 0.8</choice>
      <feedback></feedback>
    </option>
    <option correct="1">
      <choice>&asymp; 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 &mu;<sub>max</sub>. This can be explained using the formula for r<sub>x</sub>:<br />
        <b>r<sub>x</sub> = &mu; &bull; C<sub>x</sub></b>&nbsp;&nbsp;&nbsp;(kg / m<sup>3</sup> / h)<br />
        Organism 3 started with a higher initial biomass concentration than organism 1, so with equal &mu;, it's
        r<sub>x</sub> became higher.
      </feedback>
    </option>
    <option correct="0">
      <choice>&asymp; 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>