Biology 9700 · AS & A Level · Natural and artificial selection
Natural and artificial selection — practice question
The filamentous fungus, Fusarium venenatum, may be cultivated in a fermenter and then collected as mycoprotein. It is marketed as food in several different countries. The fungus is produced in continuous culture in $150\,000\,\text{dm}^3$ airlift fermenters, where compressed air bubbles both supply oxygen and mix the contents. Because the fungus grows as thin, branched filaments, the harvested mycoprotein has a naturally chewy, fibrous texture. About $300\,\text{kg}$ of fungus can be harvested each hour.
(a)[2]
Explain what is meant by the term continuous culture.
(b)[4]
After roughly six weeks, mutants may develop in the fungal population, such as a form of the fungus with more extensive branching. Every six weeks, the fermenter is emptied, cleaned and restocked with the original strain of $F.\,venenatum$. Explain why the fermentation process should be stopped before mutants appear.
(c)[1]
Around $12\%$ of the harvested fungus is protein. Calculate the approximate mass of protein harvested in one day during continuous culture. Show your working.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Fresh medium added and product with spent medium removed at a constant rate” …