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Biology > B6 - beyond the microscope > Flashcards

B6 - beyond the microscope Flashcards

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0
Q

What different shapes can bacteria be?

A

Spherical, rod shaped, spiral or curved rods.

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1
Q

What features do bacteria have that allow them to survive?

A
  • a flagellum for movement
  • a cell wall to maintain shape and stop it from bursting
  • DNA to control the cell’s activities and replication of the cell
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2
Q

How do bacteria reproduce?

A

Bacteria reproduce by splitting into two in a type of asexual reproduction called binary fission.

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3
Q

What technique must be used to get bacteria to reproduce on an agar plate?

A

It is possible to get bacteria to reproduce on an agar plate but all equipment must be sterilised first to prevent contamination by other microbes. This is called aseptic technique.

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4
Q

What are bacterial successful at surviving?

A
  • they can survive on an enormous range of different energy sources
  • they can live in a very wide range of habitats
  • some bacteria live by taking in organic nutrients by others can make their own food
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5
Q

How can the growth rate of yeast be altered?

A
  • changing food availability
  • changing temperature
  • changing pH
  • removing waste products

The growth rate of yeast doubles for every 10 degrees rise in temperature until the optimum is reached.

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6
Q

What’re viruses?

A

Viruses are not living cells but are very small structures made of a protein coat surrounding a strand of genetic material.

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7
Q

Viruses can only produce under certain conditions. What are these conditions?

A
  • they only reproduce in other living cells

- they only attack specific cells, which may be plant, bacterial or animal cells

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8
Q

What will a virus do when it produces?

A
  • attach itself to a specific host cell
  • inject its genetic material into the cell
  • use the cell to make the components of new viruses
  • cause the host cell to split open and die to release the viruses
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9
Q

In what different ways are harmful microorganisms spread and how can they be stopped?

A
  • some microbes, such as salmonella, are spread in food
  • some, such as vibrio cholera, may be spread in water
  • other microbes need direct contact and they can be prevented from spreading by barrier methods
  • many microbes are spread in airborne droplets. They can be stopped from spreading by tissues and isolation of patients.
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10
Q

What’re the four stages in an infectious disease?

A
  • the microbe enters the body
  • it reproduces many times without causing symptoms. This is the incubation period.
  • the microbes cause the production of many toxins.
  • the toxins cause symptoms, such as fever
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11
Q

What four reasons mean that disease occur in areas that have experienced natural disasters?

A
  • damage to sewage systems may lead to water supplies being contaminated
  • damage to electrical supplies may stop refrigerators working, so food decays
  • large numbers of people moving to other areas mean the facilities are not able to cope
  • hospitals may be damaged or there may be a shortage of medical staff
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12
Q

Why do health professionals collect data on the incidence of various diseases?

A

Doctors and health professionals collect data on the incidence of various diseases, such as influenza, food poisoning and cholera, to try and see patterns and make predictions.

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13
Q

Who’re the three most important scientists in terms of making discoveries that helped to prevent microbes causing disease?

A
  • Louis Pasteur, who helped to prove the germ theory of disease by realising that microbes from the air could make food go bad
  • Joseph lister, who invented the first antiseptic, using carbolic acid to prevent wounds become infected
  • Sir Alexander Fleming, who discovered the first antibiotic, penicillin, which is produced from penicillium, a fungus
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14
Q

Since their discovery how have antiseptics and antibiotics been used to control disease?

A
  • antiseptics are used on the outside of the body to kill microbes and prevent their entry
  • antibiotics tend to be used inside the body to kill microbes once they have entered
  • antiseptics work on most microbes but antibiotics have no effect on viruses
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15
Q

What steps do doctors take to try and prevent antibiotic resistance spreading?

A
  • they only prescribe antibiotics when really necessary

- they advise patients to always finish the dose so partially resistant bacteria are killed

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16
Q

How is bacteria developing a resistance to antibiotics?

A

The resistance appears in bacterium by a mutation. Because the bacteria can then survive and reproduce, the resistance is spread by natural selection.

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17
Q

What’re the steps in making yoghurt?

A
  • first, all the equipment is sterilised
  • then the milk is pasteurised by heating it to about 78 degrees C
  • when the milk is cools down it is incubated with a culture of bacteria
  • this is followed by sampling and then adding flavours, colours and packaging
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18
Q

What type of bacterium is added to milk to make yoghurt?

A

The type of bacterium that is added to the milk is lactobacillus. This causes the breakdown of lactose in milk to lactic acid, which makes the yoghurt taste acidic.

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19
Q

What are the word and symbol equations for fermentation?

A

Glucose –> ethanol + carbon dioxide

C6H12O6 –> 2C2H5OH + 2CO2

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20
Q

What’re the steps in fermentation?

A
  • first, sugar is extracted by crushing grapes or from barley grains
  • then, yeast is added
  • it is kept warm to allow it to ferment. Air and other microorganisms are kept out.
  • the wine or beer is allowed to clarify. The clear liquid is then drawn off.
  • the wine or beer may then be pasteurised and put into casks or bottles.
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21
Q

Why are the conditions anaerobic during fermentation?

A

When yeast is used in brewing it soon used up all the oxygen in the container by respiring aerobically. This allows the number of cells to increase rapidly. Then conditions are kept anaerobic so that alcohol is made.

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22
Q

What does the process of pasteurisation used in brewing do?

A

The process of pasteurisation is used in brewing to kill harmful microbes. The liquid is kept at an elevated temperature for a predetermined time. The temperate and time depends on the drink that is being brewed.

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23
Q

Why is the alcohol concentration produced by brewing limited?

A

Because high concentrations of alcohol kill yeast cells, although some strains of yeast are more resistant to alcohol than others.

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24
Q

Why is distillation used to make drinks like whisky and brandy?

A

Because the concentration of alcohol made by fermentation is limited.

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25
Q

Give two examples of biofuels:

A
  • fast-growing trees are grown and then the wood is burnt

- biomass such as sugar or waste material is fermented using bacteria or yeast and the product is used as fuel

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26
Q

Give three reasons why biofuels have become popular.

A
  • they are alternative sources to fossil fuels, which are running out
  • their waste makes no net increase in greenhouse gas levels
  • they do not release particulates when they are burnt
27
Q

What problems can occur is areas of land are cleared of other plants in order to grow crops for biofuels?

A
  • this may mean that the fuel is not carbon neutral because the other plants cannot now remove carbon dioxide
  • important habitats may be lost and species may become extinct
28
Q

Biogas is fuel that contains:

A
  • mainly methane
  • some carbon dioxide
  • very small amounts of hydrogen, nitrogen and hydrogen sulfide
29
Q

How is biogas produced on a large scale in a digester?

A

This uses a continuous flow method as organised wastes are constantly added and the gas and removing solids constantly removed.

30
Q

What is biogas used for?

A

It can be:

  • burnt to generate electricity
  • burnt to produce hot water and steam for heating systems
  • used as a fuel for vehicles
31
Q

How is biogas production affected by temperature?

A

Biogas production is affected by temperature because as the temperature increases, the bacteria multiply faster and the enzymes within them work better. Above 45 degrees C, the enzymes are denatured and the bacteria die.

32
Q

What is the fire risk with biogas?

A

Biogas containing more than 50% methane can be burnt in a controlled way, but a lower percentage of about 10% is explosive.

33
Q

How is gasohol made?

A

Alcohol can be made by fermentation and is mixed with petrol to make gasohol. This is used to fuel cars.

34
Q

Where is gasohol and ideal fuel?

A

Where there is ample sugar cane but little oil. It is cheaper than importing oil.

35
Q

Loam is a soil that contains:

A
  • a mixture of clay and sand

- a large amount of partly decomposed animal and plant waste called humus

36
Q

In a sandy soil the particles are smaller than in a clay soil. True of false?

A

True.

37
Q

Give three simple experiments that can be performed in different soil samples to compare the contents.

A
  • humus content can be found by burning off the humus using a Bunsen burner
  • air content can be found by seeing how much water is needed to fill air spaces
  • water content can be found by slowly heating the soul to evaporate the water

If a soil has larger particles, then the air content and permeability is usually higher.

If a soil has larger amounts of humus it will often hold more water and air

38
Q

Why is humus in the soil important to living organisms?

A

Because it will:

  • decompose to release minerals
  • increase the air content of the soil
39
Q

Why are earthworms important to soil structure and fertility?

A

Because they:

  • bury organic material for decomposition by bacteria and fungi
  • aerate and drain the soil
  • mix up soil layers
  • neutralise acid soil
40
Q

What does aeration and draining produced by earthworms allow?

A

The aeration and draining produced by earthworms will allow organisms to respire aerobically.

Neutralising acid soils is important because some plants will not grow if the pH is too low and mixing up soil layers is important so that dead material is decomposed.

Many of these important functions of earthworms were first understood by Charles Darwin.

41
Q

What’re the advantages of living in water?

A
  • there is no risk of water shortage and dehydration
  • the temperature of the water varies less than air temperature
  • water helps provide support
  • waste products are easily disposed of into the water
42
Q

What’re the disadvantages of living in water?

A

The water content of the body can vary and needs to be controlled.

Water is denser than air so resists movement.

43
Q

What’re the advantages of living in water?

A
  • there is no risk of water shortage and dehydration
  • the temperature of the water varies less than air temperature
  • water helps provide support
  • waste products are easily disposed of into the water
44
Q

What’re the disadvantages of living in water?

A

The water content of the body can vary and needs to be controlled.

Water is denser than air so resists movement.

45
Q

What do organisms, such as amoeba, have to store any excess water?

A

Organisms such as amoeba have a contractile vacuole that can store any excess water. The vacuole can then fuse with the cell memorable and empty the water to the outside.

46
Q

What’re phytoplankton and zooplankton?

A

Phytoplankton are tiny aquatic plants and zooplankton are tiny aquatic animals.

47
Q

Food webs of marine organisms can provide useful information. The webs rely on different sources of food. What are these sources?

A
  • most rely directly on green plants
  • others deeper in the ocean feed on dead material called marine snow that floats down
  • some rely on bacteria, deep in the ocean, acting as producers
48
Q

The numbers of phytoplankton and zooplankton vary at different depth and in different seasons. Why?

A

Because factors that affect the photosynthesis of phytoplankton will vary:

  • there will be less light in winter and deeper in the water
  • the temperature will be lower in winter and deeper in the water
  • minerals are used up towards the end of summer
49
Q

Some chemicals such as PCBs and DDT can kill animals at the top of marine food chains. This is because the chemicals:

A
  • are toxic
  • do not break down quickly and so accumulate and become concentrated higher up the food chain
  • affect animals with a long lifespan, such as whales
50
Q

Give three enzymes and their job in biological washing powders.

A
  • amylase, to digest carbohydrates such as starch
  • lipase, to digest fat and remove fatty stains
  • protease, to digest protein and remove protein stains
51
Q

Why might biological washing powders work in acidic or alkaline tap water?

A

Because this is not the optimum for enzymes and they might start to denature.

52
Q

Why does biological washing powder contain enzymes?

A

Because after treatment with enzymes, the products of digestion are soluble and so will easily wash out of the clothes.

53
Q

Sucrose can be broken down by the enzyme, sucrase (invertase) what does invertase convert sucrose into and what impact does this have on the food industry?

A

Invertase converts sucrose into glucose and fructose.

Glucose and fructose are sweeter than sucrose, so less has to be added to the food, lowering the cost and the energy content.

54
Q

How can enzymes be immobilised in gel beads?

A

By:

  • mixing the enzyme with alginate
  • dropping the mixture into calcium chloride solution
55
Q

Why are immobilised enzymes useful in reactions?

A
  • the mixture does not become contaminated with the enzyme

- they can be used in continuous flow processing

56
Q

Why are some people or animals lactose intolerant and what affect does this have on them?

A

Some people are lactose intolerant because they cannot produce the enzyme lactase. This means that bacteria in the gut ferment lactose, which produces diarrhoea and wind.

57
Q

How is milk treated got the lactose intolerant?

A
  • immobilised lactase is used to convert lactose in milk into glucose and galactose
  • glucose and galactose can then be absorbed from the milk with no side effects
58
Q

What are the four main stages in genetic engineering?

A
  • identifying and removing a desired gene from one organism
  • cutting open the DNA in another organism
  • inserting the new gene into the DNA
  • making sure that the gene works in the transgenic organism
59
Q

What does genetic engineering involve?

A

Transferring a gene from one organism to another. The organism that receives the new gene is called a transgenic organism.

60
Q

Why does the process of GE work?

A

Because the genetic code is universal. This means that genes from one organism will produce the same protein in another organism.

61
Q

What are restriction and ligase enzymes used for in GE?

A

Restriction enzymes are used to cut open DNA. They leave several unpaired based on the cut end. This acts as a ‘sticky end.’

Ligase enzymes will join DNA strands because the sticky ends in each cut section of DNA can join by complementary base pairing.

62
Q

How is bacteria genetically engineered to produce human insulin?

A

-cutting the gene for producing human insulin out of human DNA
-cutting open a loop of bacterial
DNA
-inserting the insulin gene into the loop
-inserting the loop into a bacterium

Many copies of the bacteria are cultures by cloning and large quantities of insulin are harvested.

The loops of DNA in this process are called plasmids. They are found in the cytoplasm of bacteria and because they can be taken up by bacteria, they can be used as vectors for genes.

63
Q

What is an assaying technique, use for finding out whether a bacterium has taken up a plasmid?

A
  • scientists add genes that make the bacteria resistant to antibiotics
  • the bacteria are then flooded with the antibiotic by being grown on nutrient agar containing the antibiotic
  • scientists then choose the bacteria that survive
64
Q

What’re the four stages involved in the production of DNA fingerprint?

A
  • extracting DNA from a sample, eg. blood
  • cutting up or fragmenting the DNA using reaction enzymes
  • separating the fragments using electrophoresis
  • making the fragments visible using a radioactive probe

Biology (3 decks)

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