A lot of germinating seeds takes in 50 mL of oxygen and releases 44 mL of carbon dioxide…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A lot of germinating seeds takes in mL of oxygen and releases mL of carbon dioxide. Suppose that the seeds respire only carbohydrate, with an RQ of , and fat, with an RQ of .
- What is the RQ of the seeds?
- What per cent of the oxygen is used on carbohydrate?
- Why is the RQ not equal to or to ?
Need a reminder? The key ideaShow
. It is for carbohydrate, about for protein, for fat, and above for organic acids. KOH takes in carbon dioxide, so the fall of volume in a tube with KOH is the oxygen taken in.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Oxygen: mL. Carbon dioxide: mL.
Plan. Find the RQ. Then split the oxygen between the two substrates.
Step 1. RQ. .
Step 2. The split. Let be the fraction of the oxygen used on carbohydrate. Then , so .
Step 3. Solve. , so , which is .
Step 4. Why. The seeds respire a mixture. The RQ of a mixture lies between the values of its parts.
Answer: ; ; the substrate is a mixture.
Check. carbohydrate and fat give .
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