Chapter 20: Biotechnology

Question 1

What is fermentation? (2)

Answer 1

-The term fermentation applies to a wide range of reactions brought about by micro-organisms
-Alcoholic fermentation is a form of Anaerobic respiration.

Question 2

Fermentation

Answer 2

C6H12O6 —> CO2 + C2H5OH + energy

Question 3

What is biotechnology? (2)

Answer 3

-Using organisms usually microorganisms to produce required substances.
-It involves using living organisms to carry out processes that make substances that we want.

Question 4

What are yeast? (2)

Answer 4

-Yeast has been used to make bread and alcohol.
-Bacteria have been used to make yoghurt and cheese.

Question 5

Why does biotechnology use only microorganisms? (5)

Answer 5

-Bacteria are very small and are easy to grow in a laboratory. They do not take up a lot of space.
-Bacteria reproduce very quickly. They are able to make a huge range of different chemical substances.
-Bacteria can make complex molecules that are useful to humans.
-No one minds what is done to bacteria and fungi. There are a few ethical issues like those that might arise if we used animals.
-As well as their main DNA- their ‘chromosome’- bacteria also have little loops of DNA called plasmids. They are quite easy to transfer from one cell to another. We can use plasmids for moving genes from the cells of one organism to another.

Question 6

Products of yeast anaerobic respiration

Answer 6

Yeast is able to respire anaerobically. When it does so it produces ethanol and carbon dioxide
glucose —> ethanol + carbon dioxide

Question 7

Alternative to reduce fossil fuels pt 1
(2)

Answer 7

-One alternative is to use plants to provide sugars which yeast can then break down to form ethanol.
-Ethanol sometimes called bioethanol can then be used as fuel.

Question 8

M and S process

Answer 8

-Maize and sugarcane are two of the crops that are used in to process.
-Maize is first treated with amylase enzymes which break down stored starch to glucose.
-Sugarcane does not need to be treated with enzymes because it stores most of its carbohydrates as sucrose rather than starch.
-Yeast is then added and allowed to use the glucose in anaerobic respiration.
-The ethanol that is produced can then be extracted from the mixture by distillation.

Question 9

The disadvantage of plant fuel (2)

Answer 9

-Although alcohol burns well it does not contain as much energy per litre as fossil fuels.
-It is therefore normally mixed with gasoline (petrol) to make biofuel that is used in vehicle engines.

Question 10

Advantage of biofuel (4)

Answer 10

-It is a sustainable resource
-We can keep growing more maize to make more fuel.
-It also helps to reduce the amount of carbon dioxide that we add to the atmosphere.
-Although carbon dioxide is produced when the biofuel is burnt the plants that are grown to make the fuel will have recently taken in carbon dioxide from the air during photosynthesis using it to make the sugar and starch.

Question 11

The disadvantage of fossil fuel

Answer 11

-Burning fossil fuels causes us to release co2 into the air that has been stored in the earth for millions of years.

Question 12

Disadvagde of biofuel (3)

Answer 12

-The crops take up land that could otherwise be used to grow food for people.
-Using large quantities of maize the other crops to make biofuels puts up their price, making it more expensive for people to buy food.
-The land on which the crops are grown may originally have contained a biodiverse natural ecosystem which was cleared to increase the area for growing the monoculture crop.

Question 13

Biofuel

Answer 13

A fuel that is made by mixing ethanol (made by the anaerobic respiration of yeast) with petrol.

Question 14

Making bread

Answer 14

-Bread is made from flour which is made by grinding the grains (seeds) of cereal crops. Most bread is made from wheat flour.
-Flour contains a lot of starch and also protein especially a protein called gluten. To make bread the flour is mixed with water and yeast to make dough.
-Amylase enzymes break down some of the starch in the dough to make maltose and glucose which yeast can use in anaerobic respiration. Il produces bubbles of CO2. These get trapped in the dough.
-Gluten makes the dough stretchy so the carbon dioxide bubbles cause the dough to rise.

Question 15

Pectinase

Answer 15

An enzyme that is used to digest pectin increases the quantity of juice that can be extracted from fruit, and clarifies the juice.

Question 16

What is pectin? (2 )

Answer 16

-Fruit juices are extracted using an enzyme called pectinase.
-Pectin is the substance which helps to stick plant cells together. A fruit such as an apple or orange contains a lot of pectin. Pectinase breaks down pectin. This makes it much easier to squeeze juice from the fruit.

Question 17

Why is pectinase used? (3)

Answer 17

-Pectinase also helps to make the juice clear rather than cloudy. The cloudiness in fruit juice is often caused by insoluble carbohydrates that float in the juice.
-Pectinase and other enzymes such as cellulase(which breaks down cellulose) can be added to the cloudy juice.
-They break the insoluble substances to soluble ones so the juice becomes clear.

Question 18

What do biological washing powders contain? (3)

Answer 18

-Enzymes are found in the biological washing powders and detergents. They remove stains made from animal or plant substances such as blood or egg stains.
-Protease catalyse the breakdown of protein molecules to amino acids. Eg- Blood stains
-Some enzymes are lipases which catalyse the breakdown of fats into fatty acids and glycerol for greasy stains.

Question 19

Enzymes removing blood stains (2)

Answer 19

-Blood contains the red protein haemoglobin.
-The proteases in biological washing powders break the haemoglobin molecules into smaller molecules which are not coloured and can dissolve easily in water and can be washed away.

Question 21

How do prevent enzymes digesting protein and fats don’t the skin? (2)

Answer 21

-The enzyme is packed into microscopic capsules.
-The capsules break open when the washing powder is mixed with water.

Question 21

Reasons for treating milk with lactase. (2)

Answer 21

-For people who don’t make lactase thel\melsves can drink milk or eat products from lactose-free milk. Some people stop breaking down lactase when their adults and hence cannot digest lactose leading them to feel ill when consuming lactose products.
-For producing galactose and glucose for making sweets.

Question 22

fermenter

Answer 22

a vessel usually made of steel or glass in which microorganisms can be grown in order to produce a required product.

Question 23

sterilised

Answer 23

treated- eg with steam to destroy all living cells.

Question 24

culture

Answer 24

a population of microorganisms growing in a nutrient liquid or on agar jelly.

Question 25

steps to growing microorganisms in a fermenter

Answer 25

Sterilisation
Providing nutrients
Providing air
Mixing the contents
Adding the microorganisms
Measuring and maintaining temperature
Measuring and maintaining pH
Harvesting the product
Purifying the product

Question 26

Sterilisation

Answer 26

Before the fermenter is used, it is thoroughly washed and sterilised.
This is usually done by passing steam through it.
This kills all the microorganisms that are in the fermenter so that they will not contaminate the culture.

Question 27

Providing nutrients

Answer 27

Water and the nutrients that the microorganisms need for growth are added to the fermenter.
The exact nutrients required depend on the microorganisms that are being cultured and the product that we want.
Glucose may be added which the microorganisms can use in respiration to provide them with energy.
Amino acids or nitrate ions may be added to provide a source of nitrogen so the microorganisms

Question 28

Providing air

Answer 28

If the microorganisms will respire aerobically air is bubbled through the contents of the fermenter.
This provides oxygen.
The fermenter has an outer through which waste gases can escape to make sure that the pressure inside the fermenter does not build up.

Question 29

Mixing the contents

Answer 29

In most fermenter, sa motor turns paddles that keep the contents mixed up.
However, if the fermenter is being used to grow a fungus made up of LNG hyphae there are usually no paddles becomes they would get tangled up with the hyphae.
Air bubbles also help with mixing the contents This makes sure that the microorganisms in every part of the fermenter are supplied with nutrients and oxygen.

Question 30

Adding the microorganisms

Answer 30

When all this has been done the microorganisms are added

Question 31

Measuring and maintaining temperature

Answer 31

A temperature probe measures the conditions inside the fermenter.
The temperature must be kept at the correct level so that the enzymes in the microorganisms can work effectively to produce the required product.
-As the microorganisms respire they release heat energy which can cause the temp to rise over optimum to avoid this from happening cold water is then passed around the fermenter to lower the temperature.
If the temperature falls below optimum hot water or steam is passed around the fermenter.

Question 32

Measuring and maintaining pH

Answer 32

The pH of the fermenter contents is measured using a probe.
It is important to keep the pH at the optimum level for the microorganisms’ enzymes
If the microorganisms are producing carbon dioxide this will lower the pH.
pH is adjusted by adding small quantities of acidic or alkaline liquids to the contents of the fermenter.

Question 33

Harvesting the product

Answer 33

When the microorganisms have had time to produce the required product, the contents of the fermenter can be harvested.
This may be done by allowing some of the contents to run out through an outlet tube or something so the whole fermenter is emptied out at once.

Question 34

Purifying the product

Answer 34

The contents of the fermenter include other substances such as microorganisms themselves and the required product.
The required product is separated from the microorganism to be used or sold.

Question 35

eg of products from fermenters that are used commercially

Answer 35

-insulin made by genetically modified bacteria.
-teh antibiotic penicillin, produced by the fungus penicillium
-a food called mycoprotein produced by the fungus called furasium.