Complete revision notes for Topic 20 of the CIE IGCSE Biology course: Biotechnology and genetic engineering. Explanations with diagrams for every specification point. These notes are written for candidates taking the Extended paper.
State that bacteria are useful in biotechnology and genetic engineering due to their rapid
reproduction rate and their ability to make complex molecules
Microorganisms can be used by humans to produce foods and other useful substances.
The most common type of microorganisms used in biotechnology are bacteria.
They are useful because they are capable of producing complex molecules (e.g., certain
bacteria added to milk produce enzymes that turn the milk into yoghurt).
They are also useful because they reproduce rapidly, meaning the amount of chemicals they
can produce can also rapidly increase.
Discuss why bacteria are useful in biotechnology and genetic engineering, limited to:
Lack of ethical concerns over their manipulation and growth
Genetic code shared with all other organisms
Presence of plasmids
20.2 Biotechnology
Describe the role of anaerobic respiration in yeast during production of ethanol for biofuels
Yeast is a single celled fungus that uses sugar as its food source.
When it respires, ethanol and carbon dioxide are produced (and energy is released).
The ethanol produced in this reaction is increasingly being used as a biofuel (a fuel
made from living organisms rather than a fossil fuel like oil, coal or gas)
In countries such as Brazil, biofuel is partly replacing petrol as the fuel for cars and
other vehicles
Plant material is used as the substrate for producing ethanol (as a source of glucose)
– it is chopped up into small pieces and mixed with yeast which respires
anaerobically and produces ethanol
The liquid is separated from the remaining solids and any water is removed, leaving
a concentrated solution of ethanol
Sometimes the waste parts of crop plants, such as the stalks or outer leaves, are used, but in
other places, crops are grown specifically to be harvested for making ethanol
In some places, this is causing concern that there is less land available for local
people to grow food crops needed for survival
Describe the role of anaerobic respiration in yeast during bread-making
Yeast will respire anaerobically if it has access to plenty of sugar, even if oxygen is available.
, This is taken advantage of in bread making, where the yeast is mixed with flour and water
and respires anaerobically, producing carbon dioxide.
The carbon dioxide produced by the yeast during respiration is caught in the dough, causing
the bread to rise.
Investigate and describe the use of pectinase in fruit juice production
Fruit juice is produced by squeezing the fruits to remove the juice.
Chopping the fruit up before squeezing helps to release a lot more juice, but this does not
break open all the cells, so a lot of juice is lost.
By adding an enzyme called pectinase to the chopped-up fruit, more juice is released
Pectinase works by breaking down a chemical called pectin that is found inside plant
cell walls
Once pectin is broken down, the cell walls break more easily, and more juice can be
squeezed out of the fruit
Adding pectinase to fruits also helps to produce a clearer juice as larger polysaccharides like
pectin can make the juice seem cloudy – once they are broken down into smaller molecules,
the juice becomes clearer.
Investigate and describe the use of biological washing powders that contain enzymes
Many stains on clothes are organic molecules – oil from skin, protein from blood, fat and
protein from food.
Detergents that only contain soap can remove some of these stains when mixed with hot
water, but it can take a lot of time and effort and very high temperatures to remove the
stains entirely.
Biological washing powders contain enzymes similar to the digestive enzymes produced in
the alimentary canal that help to break down large food molecules.
Using biological washing powders has several advantages, including:
Quickly breaking down large, insoluble molecules such as fats and proteins
into smaller, soluble ones that will dissolve in washing water
They are effective at lower temperatures, meaning less energy (and money) has to
be used in order to wash clothes to get them clean as washing water does not need
to be heated to higher temperatures
They can be used to clean delicate fabrics that would not be suitable for washing at
high temperatures
Investigate and explain the use of lactase to produce lactose-free milk
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller williambennett. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.03. You're not tied to anything after your purchase.
