Meat from a fermenter
380 words over 34 numbered lines, then 8 parts worth 16 marks (Linear Paper 2 (4BI1/2B) style, 14–18 marks). Read the article, answer each part, then open its mark scheme and set your mark.
Illustrative article written for Scholar Lab, not a Pearson text. The biology is real; the studies, people and figures are invented or rounded for practice.
Meat from a fermenter
In the 1960s, scientists worried that the world would soon run short
of protein. They began testing thousands of microorganisms to find one
that could be grown cheaply and eaten safely. In a soil sample from a
field in England they found a fungus called Fusarium venenatum. Like
other fungi, it feeds by saprotrophic nutrition. After years of safety
tests, food made from the fungus went on sale in British shops in
1985.
Today the fungus is grown in tall industrial fermenters. Each
fermenter is sterilised with steam before use, and all the air and
nutrients that enter it are filtered or heated. Glucose syrup is added
as the source of energy, and ammonia is added as the source of
nitrogen. Sterile air is bubbled in at the bottom, and as the bubbles
rise they keep the contents mixed.
The temperature is kept at about 30 °C by water flowing through a
cooling jacket around the fermenter. Probes measure the pH and the
oxygen concentration all the time. Under these conditions, the mass of
fungus can double in about five hours. The fungus grows as long, thin
hyphae, which give the final food a texture rather like meat.
The fungus is removed continuously, heated to break down most of its
RNA, and then pressed and mixed with egg white or plant protein. The
result is mycoprotein. It is high in protein and fibre but low in fat,
and it contains no cholesterol. It is sold as minced meat, burgers and
pieces for curries, and is now eaten in more than a dozen countries.
Supporters say that replacing some meat with mycoprotein could help to
slow climate change. Cattle produce methane in their digestive
systems, and large areas of forest have been cleared to graze cattle
and to grow crops to feed them. In an illustrative comparison,
producing 1 kg of mycoprotein released about one tenth of the
greenhouse gases released by producing 1 kg of beef.
However, the fermenters use large amounts of electricity, and the
glucose syrup is made from crops such as maize. Some people also react
badly to mycoprotein, so packets carry a warning. Researchers are now
testing whether the sugars in waste bread or fruit could be used
instead of glucose syrup to feed the fungus.
Read the article. Use the information in the article and your own knowledge to answer the questions. The lines in brackets show where to look; select them to highlight the text.
Use the information in the article and your own knowledge to answer the questions. The lines in brackets show you where to look; select them to highlight the text.
State what is meant by the term saprotrophic nutrition.
(1)Explain why air is bubbled into the fermenter.
(2)Explain why the fungus needs a source of nitrogen.
(2)Explain why the fermenter needs a cooling jacket.
(3)Explain why the fermenter and everything that enters it must be sterile.
(2)A fermenter contains 2 tonnes of fungus. Calculate the mass of fungus after 20 hours if none is removed.
(2)Which is a reason why fibre is important in the diet?
(1)Suggest why producing mycoprotein releases less greenhouse gas than producing beef.
(3)Total for this question: 16 marks
0 / 16 marks · 0 of 8 parts rated
Open each mark scheme, compare it with your answer and set your mark. Only your marks are kept, in this browser on this device; your written answers are never saved. Green is full marks, amber is half or more, red is under half.