B6 Beyond the microscope (B6.1 - B6.4)

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What features do bacteria cells have that allow them to survive?
Flagellum - for movement; cell wall - to maintain shape and stop it bursting; DNA - to control cell's activities and replication
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Which four shapes can bacteria cells be?
Spherical, rod shaped, spiral, or curved
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What is the name of the asexually reproduction by bacteria cells?
Binary fission
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Explain briefly what happens in the aseptic technique
All equipment is sterilised and bacteria is made to replicate on an agar plate
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In terms of numbers, why are bacteria so successful?
They can survive on different energy sources, they can live in a very wide range of habitats, and some bacteria live by taking organic nutrients to make their own
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What can the growth of yeast be altered by?
Changing food, changing temperature, changing pH, and removing waste products
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How does the rate of yeast grow for every 10oC rise?
It doubles until the optimum temperature is reached
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What are viruses?
Very small structures made of protein coat surrounding strands on genetic material
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Which conditions can viruses reproduce under?
They have to be in other living cells, and they only attack specific cells which may be plant, bacterial or animal
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What does a virus do to replicate?
Attatchs itself to a host cell then injects it's own genetic material into the host cell. It then uses the cell to make the components of a new virus and causes the host cell to split open and die which releases the virus
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Give four examples of how diseases can be spread.
In food (e.g. Salmonella), in water (e.g. Vibrio cholera), direct contact and airborne particles
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Describe the four stages of an infectious disease
The microbe enters the body, it reproduces many times without causing symptoms (called incubation period), it produces many toxins, and the toxins then cause symptoms
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Why might disease occur in places that have experienced a natural disaster?
Damaged sewage systems might contaminate water supplies/ Damage to electrical supplies may stop fridges working/ facilities can't cope with large number of people moving to that area/ Hospitals may be damaged with a shortage of staff
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Why do doctors and health professionals collect data on various diseases?
To try and see patterns in the data and make predictions about the future of certain diseases
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Who were the three important scientists that helped prevent disease, and what did the discover?
Louis Pasteur - the germ theory/ Joseph Lister - carbolic spray (an antiseptic for infected wounds)/ Alexandra Flemming - discovered penicillin (an antibiotic) from the fungus Penicillum
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How are antibiotics and antiseptics used to control disease?
Antibiotics - fight and kill bacteria inside the body. Antiseptics - kill microbes outside the body, they can work on all types of microbe
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What is the current problem with some strains of bacteria?
They are developing mutations which enables them to resist certain antibiotics due to natural selection
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How do doctors try and prevent antibiotic resistance spreading?
They only prescribe antibiotics when necessary and they advise patients to always finish the dose so partially resistant bacteria are killed
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Describe the process of yogurt making.
All equipment is sterilised then milk is pasteurise to about 78oC. When the milk is cool, it is incubated in a culture of bacteria which is followed by sampling of flavours, colours and packaging
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Name the type of bacteria added to yogurt and explain why it is used.
Lactobacillus us used to cause the break down of lactose in milk to lactic acid.
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What type of respiration is involved in the fermentation of yeast?
Anaerobic respiration
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How is yeast used in brewing beer or wine?
The sugar is extracted from the plant being used and the yeast is added, it is kept warm to allow it to ferment and air and other microbes are kept out. The beer or wine the clarifies (clears) and the clear liquid is removed from the yeast sediment.
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What happens to yeast once it uses up all the oxygen?
The number of cells increase rapidly and conditions are kept anaerobic so alcohol is made
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Give two examples of how yeast might break down sugar at different rates?
Temperature and the presence or absence of oxygen
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Why is pasteurisation used in brewing?
To kill harmful microbes
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Why is the alcohol concentration produced by brewing limited?
High concentrations of alcohol kill yeast cells although some strains of yeast are more resistant to alcohol than others
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Name two different types of biomass used to make biofuels.
Fast-growing trees and sugars or waste materials being fermented using bacteria or yeast
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Why have biofuels become more popular?
They are an alternative source to fossil fuels, their waste makes no net increase to greenhouse gas levels, and they do not release particulates when they are burnt
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What are particulates?
Particals such as soot released after the burning of fossil fuels
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Why is burning biofuels 'carbon neutral'?
Because there is no net increase of greenhouse gases due to biofuels being burnt at the same rate as the biomass being produced
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What problems may occur if areas of land are cleared to grow plants for biofuels?
Fuels will no longer be carbon neutral because carbon dioxide will not be removed and important habitats and species may become extinct
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Which gases do biogases contain?
Mainly methane, come carbon dioxide and small amounts of hydrogen, nitrogen and hydrogen sulfate
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What are digesters?
They produce biogas on a large scale by using a continuous flow of organic waste and gas and remaining solids
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What happens to biogas once it is made?
It is burnt to generate electricity, it is burnt to produce hot water or heating and it is used as a fuel for vehicles
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What is the optimum temperature for biogas production?
45oC
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Why might biogas containing too much methane be a problem?
It is explosive
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Why is biogas production affected by temperature?
As temperature increases, bacteria multiply faster and enzymes within work better. Above 45, enzymes denature and bacteria dies
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What is mixed with petrol to make gasohol?
Alcohol from fermentation
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What are the advantages of gasohol as a fuel?
It can be used where there is lots of sugar and not much oil - and it is cheaper than importing oil.
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Other cards in this set

Card 2

Front

Which four shapes can bacteria cells be?

Back

Spherical, rod shaped, spiral, or curved

Card 3

Front

What is the name of the asexually reproduction by bacteria cells?

Back

Preview of the front of card 3

Card 4

Front

Explain briefly what happens in the aseptic technique

Back

Preview of the front of card 4

Card 5

Front

In terms of numbers, why are bacteria so successful?

Back

Preview of the front of card 5
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