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Biology B4-6 > B6 > Flashcards

B6 Flashcards

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1
Q

Who developed the germ theory of disease?

A

Louis Pasteur, 1860’s
Knew that microorganisms in the air caused food decay which lead to the theory the microorganisms caused disease and infection

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2
Q

Who developed antiseptics?

A

Lister (surgeon), 1865

Released that carbolic acid prevented wound infection. Carbolic acid is an antiseptic and stops the spread of disease.

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3
Q

Who discovered penicillin (antibiotic)?

A

Fleming, 1938
Some of his bacteria culture plates got contaminated with penicillum mound and he noticed that it killed the bacteria, he used the mould to make the antibiotic

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4
Q

What are the steps for making yoghurt?

A
  • Sterilise equipment
  • Pastuerise raw milk (heat to 80°c and cool rapidly)
  • Add live bacteria tissue culture to WARM milk
  • Incubate for several hours
  • Bacteria reproduce and feed on lactic sugar to make lactic acid
  • The lactic acid makes it thick, preserves it and gives a sharp taste
  • Sample and add flavours and colours
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5
Q

What is fermentation? incl. equasions

A

Anaerobic respiration of yeast:
Glucose —> ethanol + carbon dioxide
C6H12O6 —> 2C2H5OH + 2CO2
(Glucose comes from seed/fruit sugars)

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6
Q

How do you brew beer?

A
  • Extract sugar (mix barley seeds with water and allow to sprout so seed starch turns into sugars)
  • Add hops for flavour
  • Add yeast to ferment the sugars into alcohol (must be warm for reproduction)
  • Seal the tank so anaerobic respiration happens and to stop microorganisms entering
  • Clarifying - add a chemical to allow yeast to settle
  • Beer is pasteurised to kill microorganisms
  • Beer is bottled
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7
Q

Why must yeast be killed or extracted?

A

Because if not, they will continue to produce carbon dioxide and the bottle would explode

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8
Q

How is beer pasteurised?

A

By heating to 72°c for 15 seconds then cooled rapidly. Kills microorganisms

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9
Q

How are spirits distilled?

A

Liquid is heated and alcohol is evapourated, then the concentrated alcohol is trapped and cooled (condensed) into a liquid. It is a commercial process and you need a license.

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10
Q

Why is there a limit to the alcohol in brewed drinks?

A

Because eventually the yeast are killed by the alcohol they produce, but some strains of yeast can tolerate higher concentrations of alcohol so it is used to brew strong beers.

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11
Q

What are three examples of biomass fuels?

A

Fast-growing trees - pine is burned to release energy
Manure or other waste - Broken down by bacteria or yeast in a fermenter to release methane (biogas)
Sugarcane - Broken down by yeast in a fermenter

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12
Q

What does biogas contain?

A

Methane
Carbon dioxide
Hydrogen, nitrogen and hydrogen sulphide

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13
Q

How is biogas made?

A

Using biogas digesters

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14
Q

How does temperature effect biogas digesters?

A

Over 45°c bacteria are denatured, low temperature and little is produced

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15
Q

What happens in a biogas digester?

A

Waste material is added daily and the gases are trapped by a metal gas holder, the residual digested sludge is used as fertilisers.

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16
Q

What are the advantages and disadvantages of biofuels?

A

Advantages- Little greenhouse gases produced, No/very little carbon produced
Disadvantages- Hard to store, cars would have to be changed to use it as fuel, areas of land are destroyed

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17
Q

What is in soil?

A

Different sized mineral particles, humus, water, living organisms (protozoans, worms, insects and bacteria), air/oxygen

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18
Q

What is humus?

A

Large particles of animal/ plant matter which helps retain moisture and oxygen because the air spaces are big

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19
Q

How do you measure water content of soil?

A

Weigh a sample, put it in a drying oven, weigh it again and work out the difference (mass of water)

%of water = mass of water
————-——-—
Initial mass

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20
Q

How do you measure air content of soil?

A

Put soil in a measuring cylinder and fill to 100cm3, put lid on, shake to release air bubbles, record new water level

Initial reading - new volume = volume of air cm3

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21
Q

How do you measure humus content of soil?

A

Weigh a DRY soil sample, heat strongly with Bunsen burner to incinerate humus, weigh and record sample, repeat until no further loss in mass.

1st mass - 2nd mass = mass of humus
%of humus= mass of humus
                      ———————— X100
                            1st mass
It works because when humus is burned it turns into carbon dioxide and water, both escape as gas.
22
Q

How do earthworms increase fertility and drainage of soil?

A

Their burrow mix up soil layers, the aerate the soil, they drag plant and animal material (humus) down to deep soil, the neutralise acidic soil by producing calcium carbonate.

23
Q

What did Charles Darwin find out about earthworms?

A

Humus layer is produced, minerals are released from decomposing material, nutrients are taken down into the soil, which prevents nutrients from being washed away

24
Q

What are the advantages of living in water?

A

No water shortage, less temperature variation, waste easily disposed, more support

25
Q

What are the disadvantages of living in water?

A

It is dense and restricting, difficult to control water absorbtion (osmosis)

26
Q

What are phytoplankton and what do they do?

A

They are microscopic plants that live in water, they rely on currents, the are producers and make sugars through photosynthesis, so they rely on temperature, light, minerals i.e. They grow faster in summer.

27
Q

What is marine snow?

A

Continuous falling of plant and animal matter to the deep areas of the ocean, consumed by microbes and zooplankton and filter feeding animals.

28
Q

What is the role of bacteria deep in the ocean?

A

Some bacteria act as producers, they use chemicals to make glucose, so many food chain rely on them.

29
Q

How can water be polluted?

A

Sewage, oil, PCBs fertilisers, pesticides, detergents

30
Q

What are PCBs?

A

Chemicals used to insulate electrical equipment which plankton eat and they accumulate in the food chains so that animals at the top such as whales have a badly affected immune system and could die.

31
Q

What is DDT?

A

A powerful and persistent pestcide

32
Q

What conditions can bloodworms and raittailed maggots survive in?

A

Deoxygenated water

33
Q

What conditions can mayfly and stoneflies survive in?

A

Only very clean, oxygenated water

34
Q

Why is it hard for organisms in water to control water content and how do amoeba balance water content?

A

Because the freshwater they live in is more dilute than their cytoplasm, water constantly diffuses into the cell by osmosis. They also don’t have a cell wall to prevent bursting so it has to use active transport to pump water into vacuoles which join to form and contractile vacuole which pushes water out of the cell.

35
Q

What are some examples of enzyme uses?

A
  • Seperating curds and whey when making cheese
  • To extract juice from fruit
  • To improve food flavourings
  • In medical products (i.e. Reagent sticks)
  • In biological washing powders
36
Q

What enzymes do biological washing powders contain and why are they needed?

A

Lipase, Amylase and Protease. To break down insoluble particles into soluble ones

37
Q

What is sucrose?

A

The most common sugar in foods which is made of two smaller sugars and can be broken down using the enzyme sucrase (aka invertase)

38
Q

What is sucrose broken down into and why is that useful?

A

Sucrose —> fructose + glucose

Both are much sweeter so they are used as flavourings in diet foods because not much needs to be added (lower calories)

39
Q

Why is someone lactose intolerant and what happens if they consume it?

A

It means that don’t have the lactase enzymes so they can’t break down the lactic sugar in milk, so the lactose travels to the large intestine where bacteria ferment it, producing diahoera and gas.

40
Q

Why is it useful to reclaim enzymes after they have been used?

A

Because they don’t get used up in reactions and they are expensive to extract and purify

41
Q

How can you immobilise enzymes and why do you do it?

A

-By making them into alginate jelly beads by putting them in alginate then calcium chloride
-By putting them on reagent sticks
It means that the products of a reaction aren’t contaminated with the enzyme and they can easily be reused, and used in continuous flow processing.

42
Q

What is the Benedict’s test?

A

It’s a test for sugar: you need a sample of blood or urine and then you heat it with Benedict’s reagant and it turns from blue to red if sugar is present

43
Q

How is genetic engineering possible?

A

Because all organisms have the same DNA structure

44
Q

What happens in genetic engineering? Step-by-step

A
  1. Desirable gene is indentified
  2. Gene is removed
  3. DNA of organism is cut open and gene is inserted
  4. New gene works in the transgenic organism
  5. The transgenic organism replicates the DNA (cloned)
45
Q

How are enzymes used in genetic engineering?

A

Restriction enzymes- cut open DNA leaving sticky ends

Ligament enzymes- rejoin DNA strands using sticky ends

46
Q

What is the technique that scientists use to indentify transgenic organisms and why is it needed?

A

Assaying, because not all organisms will take up new genes

47
Q

What are the uses of genetic engineering?

A
  • Vaccines
  • Medicines
  • Human proteins (insulin)
  • To improve crop plants
48
Q

What is the loop of bacterial DNA called and where is it found?

A

Plasmid, in the cytoplasm of bacterial cells

49
Q

How is human insulin produced? Step-by-step

A
  1. Human insulin gene is identified and removed using enzymes
  2. The enzyme is used to cut open a plasmid
  3. Enzymes insert the human insulin gene into the DNA loop
  4. The loop is reinserted into bacteria (vector) and it divides rapidly, replicating the insulin gene
  5. The transgenic bacteria are cultured by cloning in fermenters so commercial quantities of insulin can be obtained
50
Q

What is the name for an organism that has new genes inserted into it?

A

A transgenic organism.

51
Q

What are the stages of DNA fingerprinting?

A
  1. DNA is extracted
  2. DNA cut into fragments using restriction enzymes
  3. DNA sections are separated using electrophoresis
  4. DNA fingerprint is analysed by comparing it with a different sample

Biology B4-6 (4 decks)

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