A student writes five lines about household microbes…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student writes five lines about household microbes. Two of them are wrong.
- Curd is made when yeast ferments the lactose of milk.
- The vitamin B12 of curd is higher than that of milk.
- Dough rises because the yeast gives out oxygen.
- Toddy is made by fermenting the sap of palms.
- Swiss cheese has large holes because of carbon dioxide made by a bacterium.
- Which two lines are wrong?
- Write each of them correctly.
Need a reminder? The key ideaShow
Lactic acid bacteria (Lactobacillus) ferment lactose to lactic acid and set milk as curd. Baker's yeast, Saccharomyces cerevisiae, ferments sugar to ethanol and carbon dioxide: . Swiss cheese has holes from the carbon dioxide of Propionibacterium. Roquefort cheese is ripened by a fungus. A bacterium that divides every minutes doubles its number times in each hour. For a gas, with L atm per mol per K.
The worked solution
Have you tried it?
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.
Step 1. Line 1 is wrong. Curd is made by lactic acid bacteria, not by yeast. They ferment lactose to lactic acid.
Step 2. Line 3 is wrong. Dough rises because the yeast gives out carbon dioxide, not oxygen.
Step 3. The other lines. Line 2 is right: curd has more vitamin B12. Line 4 is right: toddy is the fermented sap of palms. Line 5 is right: Propionibacterium sharmanii makes the carbon dioxide.
Answer: (a) lines 1 and 3. (b) Curd is made by lactic acid bacteria. Dough rises because of carbon dioxide.
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