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OCR AS/A Level Biology Context > module 6.2 > Flashcards

module 6.2 Flashcards

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1
Q

what is biotechnology

A

the industrial use of living organisms, or parts of living organisms, to produce food, drugs or other products

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2
Q

what is an example of plant natural cloning

A

vegetative propagation

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3
Q

what is vegetative propagation

A

it is a form of asexual reproduction where the offspring is genetically identical to the parent

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4
Q

when does vegetative propagation occur

A

occurs when a plant body part is separated, and then develops into a new plant

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5
Q

what are runners or stolons

A

horizontal stems that grow on the surface of the ground and can produce roots

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6
Q

what is it called if runners/stolons happen underground

A

rhizomes

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7
Q

what is an adaptation of some rhizomes

A

adapted as thickened over-wintering organs from which one or more new stems will grow in spring

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8
Q

what are suckers

A

are new stems that grow out of the roots of a plant and may be close to or far away from the base of the existing plant. each of these parts can be separated off to form a new plant

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9
Q

what are bulbs

A

an overwintering mechanism for many perennial monocotyledonous plants

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10
Q

what do bulbs consist of

A

an underground stem from which can grow a series of fleshy leaf bases

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11
Q

what are corms

A

look similar to bulbs but are solid rather than fleshy. They are underground stems with scaly leaves and buds. They remain in the ground over winter and in the spring the buds grow to produce more new plants

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12
Q

what are some examples of plants that produce corms

A

Croci, Gladioli, and Taro

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13
Q

how does the Kalanchoe plant reproduce

A

asexually by growing clones in its leaf margins. The immature plants drop off the leaf and take root

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14
Q

what are tubers

A

another type of underground stem. potatoes are tubers. one potato will grow into one or more plants. each new plant can then produce many new tubers later that year. these methods are the plant actively trying to clone itself

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15
Q

what is an example of natural clones in animal species

A

formation of twins by embryo splitting

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16
Q

what would wounding the ends of the cut stem by removing the bark

A

helps growth by producing a callus

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17
Q

what are some advantages of natural cloning

A
  • if conditions are good for the growth of the parent they will also be good for growth of the offspring
  • cloning is relatively rapid, so the population size can increase quickly to take advantage of suitable environmental conditions
  • reproduction can be carried out even if there is only one parentw
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18
Q

hat are some disadvantages of natural cloning

A
  • the offspring may become overcrowded
  • there will be no genetic diversity (except by mutation) so the whole population will be susceptible to the same diseases and environmental changes
  • selection is not possible as there is so little variation, so evolution is much less possible
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19
Q

how do gardeners use vegetative propagation to clone plants

A

they do this by taking a cutting from a stem between two leaf joints (nodes). the cut stem is then placed in moist soil. new roots will grow from the tissues in the stem (usually from the node) but they may grow from other parts of the buried stem

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20
Q

how does root cutting made from other parts of the plant

A

root cuttings are made when a section of root is buried just below the soil surface and produces new shoots

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21
Q

how does scion cutting made from other parts of the plant

A

those made with dormant woody twigs

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22
Q

how does leaf cutting made from other parts of the plants

A

made when a leaf is placed on moist soil. the leaves develop new stems and new roots, some leaves may produce many new plants from just one cutting

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23
Q

why is tissue culture used

A

because taking cuttings on a large scale can be time consuming and needs a lot of space. also some plants don’t respond as well to taking cuttings. tissue culture is how most commercially grown houseplants are produced

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24
Q

how does seed banks use tissue culture

A

to store plants at growth stage when they are not too large

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25
Q

why is seed banks using tissue culture important

A

this technique is important in the conservation of species whose seeds do not remain viable for long periods

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26
Q

describe the process of tissue culture

A

a series of techniques used to grow cells, tissues or organs from a small sample of cells or tissue. it is carried out in a nutrient medium under sterile conditions. application of plant growth substances at the correct time can encourage the cells in the growing tissue to differentiate. it is used commercially to increase the number of new plants produced via micropropagation

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27
Q

describe the steps of micropropagation

A

1.in micropropagation suitable plant material is collected and cut into small pieces called explants. these could be tiny pieces of root, stem, or bud. meristem tissue is often used as it is always free from virus infection
2. the explants are then sterilised using dilute bleach or alcohol. this is essential to kill any bacteria and fungi, as these would thrive in the conditions supplied to help the plant to grow well.
3. the explants are then placed on a sterile growth medium (usually agar gel) containing suitable nutrients such as glucose, amino acids, and phosphates. the gel also contains high concentrations of plant growth hormones auxin and cytokinin. this stimulates the cells of each explant to divide by mitosis and form a callus (a mass of undifferentiated totipotent cells)
4. once the callus has formed it is divided to produce a larger number of small clumps of undifferentiated cells
5. these small clumps are stimulated to grow, divide, and differentiate into different plant tissues. this is achieved by moving the cells to different growth media. each medium contains different ratios of auxin and cytokinin. the first media contains 100 auxin : 1 cytokinin, and this stimulates roots to form. the second medium contains the ration 4 auxin : 1 cytokinin and stimulates shoots to form
6. once the tiny plantlets have been formed they are transferred to a greenhouse and grown in compost or soil and acclimatised to normal growing conditions

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28
Q

what are some advantages of artificial cloning of plants

A
  • cloning is a relatively rapid method of producing new plants compared to growing plants from seed
  • cloning can be carried out when sexual reproduction is not possible. plants that have lost their ability to reproduce sexually such as commercially grown banana plants can be reproduced, as can those that are hard to grow from seed
  • plants produced will be genetically identical to the parent plant, and will therefore display the same desirable characteristics such as high yield, resistance to a common pest or disease, or a particular colour of flower
  • if the original plant had an unusual combination of characteristics due to selective breeding or genetic modification, this combination can be retained without the risk of losing the combination through sexual reproduction
  • the new plants are all uniform in their phenotype, which makes them easier to grow and harvest
  • using apical bud (meristem) as an explant for tissue culture ensures that new plants are free from viruses
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29
Q

what are some disadvantages of artificial cloning in plants

A
  • tissue culture is labour intensive
  • it is expensive to set up facilities to perform tissue culture successfully
  • issue culture can fail due to microbial contamination
    All cloned offspring are genetically identical and are therefore susceptible to the same pest and/or diseases. The crops are grown in monoculture, which allows for the rapid spread of diseases or pests between closely planted crop plants
    There is no genetic variation except for that introduced by mutation
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30
Q

what are the names of horizontal stems some plants can grow and form into roots

A

runners or stolens

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31
Q

describe how runners cause a genetically identical plant to grow

A
  • a structure forms from meristems, which can differentiate into an entire other plant
  • grows up or around parent plant
  • then becomes independent from the parent plant
  • swollen with stored food buds develop from vertical shoots which become independent plants
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32
Q

how do buds form independent plants

A
  • swollen with stored food
  • buds develop from vertical shoots
  • and become independent plants
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33
Q

what mechanism is associated with the growth of bulbs

A

overwintering

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34
Q

describe the bulbs overwintering mechanism

A
  • lead bases swell with stored food from photosynthesis
  • buds form internally which develop into shoots and new plants
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35
Q

do tubers grow over or underground

A

underground stem

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36
Q

describe how tubers form

A
  • tip of underground stem becomes swollen with stored foods
  • to become a tuber or storage organ
  • buds on the storage organ develop to produce new shoots
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37
Q

what are the advantages of natural cloning

A
  • clones are already adapted to certain conditions
  • rapid reproduction
  • asexual reproduction
  • offspring may become overcrowded
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38
Q

what are the disadvantages of natural cloning?

A
  • no genetic diversity
  • little variation
  • selection not possible
  • whole population susceptible to changes in environment
  • overcrowding of offspring
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39
Q

what is the growth like for rhizomes

A

eg marram grass same growth as runners but underground

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40
Q

describe what a cutting is in horticulture

A
  • a part of stem is cut and the cut ends grows into new plants when placed in moist soils
  • take cuttings from stem as there are the necessary hormones required for growth in there
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41
Q

describe layering in horticulture

A
  • stem of the plant is bent down until it touches the soil
  • the stem is then cut once it develops roots and grows into a new plant
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42
Q

describe grafting in horticulture

A
  • stem of plant is cut and then fitted on another strong plant and covered with grafting wax
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43
Q

describe air layering in horticulture

A
  • a slanting cut is made in the stem and kept separate with a toothpick
  • moss and plastic is wrapped around til roots grow
  • new plant is cut and planted separately
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44
Q

a woodland tree has been cut down near ground. describe how vegetative propagation would proceed afterwards

A
  • root suckers
  • from meristem
    group up/around felled tree
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45
Q

why may vegetative propagation be less effective at enabling trees to survive disease than natural disasters eg fire

A
  • no genetic variation/new sprouts are clones so genetically identical
  • new sprouts are as susceptible to new disease as the parent
  • pathogen/bacteria/fungus remains in tree/system
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46
Q

what is the cheapest method to clone plants

A

take cuttings and grow them in a damp atmosphere until roots develop

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47
Q

describe cutting method

A
  • cut part of the stem of the plant (healthy shoot) or sometimes a leaf at a slant
  • reduce leaves to 2-4 when picking preventing water loss via transpiration or cover with plastic bag
  • dip in hormone rooting powder
  • plant in damp compost and keep well watered to ensure there is enough water for photosynthesis
  • lots of light in the room
  • optimum temp
  • the cutting will grow to a whole new plant after a few weeks if kept in right condition
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48
Q

why are stems cut at a slant

A
  • to allow for greater surface area
  • a corresponding water uptake
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49
Q

what are the positives of using cuttings

A
  • some crop plants cannot produce sexually
  • quicker than growing from seed/sexual reproduction
  • predictable shape, size, quality, and yield
  • easier to harvest as propagation can be done any time of the year
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50
Q

what are the disadvantages of using plant cuttings

A
  • all genetically identical
  • vulnerable if new pest occurs or climate change or disease
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51
Q

describe how to clone a plant by taking a cutting

A
  • use a healthy shoot
  • cut stem at a slant
  • between nods
  • dip in rooting powder /plant hormone /auxin
  • place in soil and add water
  • to reduce transpiration cover with plastic bag/ remove some leaves
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52
Q

identify 3 advantages of vegetative propagation in agriculture

A

1) quicker than growing from seed
2) predicatble size/quality
3) easier to harvest

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53
Q

define tissue culture

A

growing new tissues, organs or plants from certain tissues cut from sample plants

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54
Q

define micropropagation

A

tissue culture technique used to produce larger numbers of genetically identical plants (clones quickly

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55
Q

describe how micropropagation works

A
  • small pieces of the plant are cut called explants
  • explants sterilised with bleach/sodium hypochlorite
  • explants are grown on sterile agar containing nutrients, and hormones to make cell sfrom undifferentiated callus
  • each explant grows into a tiny plantlet with shoots and roots
  • small plantlets are then grown in soil
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56
Q

what are the control variables for micropropagation

A
  • humidity
  • temperature
  • light
  • CO₂
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57
Q

advantages of cloning

A
  • all plants have desirable characteristics since all genetically identical
  • large numbers or plants can be produced from a single plant
  • fast
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58
Q

disadvantages of cloning

A
  • all plats would be susceptible to same disease
  • as all genetically identical
  • expensive (requires human labour and specialised facilities-
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59
Q

what are the requirements for tissue culture and micropropagation

A
  • explant
  • suitable growth medium
  • aseptic conditions as microorganisms grow much more quickly than plant and animals tissue and therefore prevent contamination
  • growth regulators
  • frequent subculturing to ensure adequate nutrition and to avoid the build up of waste metabolites
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60
Q

what are some aseptic techniques used to prevent contamination

A
  • washing hands
  • disinfect working area
  • bunsen burner operating nearby
  • as it heats air, causes air to rise and prevents airborne microbes from settling (convection current)
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61
Q

what is autoclaving

A
  • moist heat under pressure
  • nutrient medium and all equipment must be sterilised
  • 121℃ for 5 mins
  • kills all living organisms
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62
Q

why is the asepctic technique called ‘flame necking’ used?

A
  • flaming tube causes air to expand
  • pushes away bacteria
  • so less likely to settle on tube
  • kills all bacteria on neck of tube
  • ensures no microorganisms enter the mouth of the vessel to contaminate the culture or the medium
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63
Q

what is inoculation

A

the act of introducing microoganisms or suspension of microoganisms into a culture medium

64
Q

describe aseptic technique for inoculation

A
  • hold inoculating loop in the bunsen burner flame until it glows red to ensure all bacteria is destroyed
  • must not touch other surfaces
  • holding petri dish at an angle for a short duration avoids infection
65
Q

compare cuttings to micropropagation

A
  • cuttings: less expensive, less time and less number of offspring
  • micropropagation: more expensive, more time and more cloned offspring
66
Q

when is micropropagation used

A
  • when the desirable plant doesnt produce many seeds
  • doesnt respond well to natural cloning
  • rare
  • selectively bred
  • needs to be pathogen free
67
Q

advantages of artificial cloning

A
  • rapid reproduction
  • disease free plants
  • increase no. of rare plants
  • large number of seedless plants which meets consumer needs
  • naturally infertile plants grown
  • envrionmentally sustainable
  • higher yield
  • develop plant varities with specific properties for survival
  • in local regions
68
Q

disadvantages of artificial cloning

A
  • monoculture
  • expensive
  • requires skilled workers
  • explants and plantlets are vulnerable to mould
  • if source plant becomes infected all new plants/clones are infected
69
Q

how do identical twins form

A

a zygote divides into an embryo which splits at the totipotent stage

70
Q

describe the process of artifical embryo twinning in cows

A

1) desirable cow is treated with hormones so she super ovulates
2) ova fertilised artifically via artifical insemination or naturally
3) the zygote divides by mitosis to form a ball of cells
4) early embryos flushed out of uterus
5) embryonic cells separated and allowed to continue dividing by mitosis producing genetically identical cells (clones)
6) each of the split embryos grown in lab for few days to ensure they are viable
7) each mass of cells pplaced into uterus of surrogate mother as single pregenancy
8) embryos born as foetus’ normally

71
Q

give another way to artificially twin cows

A
  • desirable trait cow injected with hormones to super ovulate
  • eggs collected and fertilised in petri dish
  • here cells of early embryos split while totipotent to produce several smaller embryos capable of becoming foetuses
  • each split embryo grown in lab for a few days to ensure they are viable
  • inserted into surrogate
72
Q

advantages of artificial twinning

A
  • high yielding farm animals can produce many more offspring then normal reproduction
  • fast increase in pop. size
  • success of a sire genes can be passed on and desirable traits determined
  • embryos then frozen, assessed for success then re-used
  • rare breeds conserved
73
Q

disadvantages of artificial twinning

A
  • inbreeding
  • losing genetic diversity
  • greater chance of inheriting recessive allele caused diseases
  • unknown long term side effects
74
Q

embryos are split into 4 and developed into new embryos. why are the new embryos produced clones

A
  • produced by mitosis
  • genetically identical
75
Q

what is nuclear transfer

A

the nucleus of a body cell is put into an egg cell

76
Q

what is SCNT

A

Somatic Cell Nuclear Transfer

77
Q

describe the process of SCNT

A
  • nucleus removed from somatic cell from an adult animal
  • a nucleus removed from a mature egg ovum from a different female of the same species
  • nucleus from somatic cell placed into egg ovum. fused and division by electric shock
  • embryo divides, showing it is viable and then placed in a third animal (surrogate) to grow full term
  • new animal is a clone of where the somatic cell came from
78
Q

what is electrofusion

A

both cells fuse then divide

79
Q

why may clones produced by SCNT not be considered complete clones

A
  • some genes present in mitochondria from egg cell
  • random/spontaneous mutations
80
Q

give arguments for artificial cloning of animals

A
  • rapid production of a larger number of individuals
  • cloning endangered animals to prevent extinction
  • genetically modified animals that grow organs that have potential use in transplants
  • supply of stem cells via human embryo
  • mass produce animals with desirable characteristics
81
Q

arguments against artificial cloning in animals

A
  • very difficult
  • time-consuming
  • expensive
  • high failure rate
  • no genetic variability
  • high value animals not necessarily produced with undesirable characteristics always passed on
  • clones may not live long
82
Q

outline the process by which an animal may be cloned to produce a population

A
  • somatic cell nucleus
  • fused with
  • empty/enucleate egg cell
  • from another animal of same species
  • electric shock/ electrostimulation
  • cell or embryo grown in vitro
  • early embryo/blastocyst split
  • embryo replaced in surrogate mothers/other females
83
Q

define biotechnology

A

large scale industrial use of living organisms to produce food, medicine and other products

84
Q

what microorganism makes yoghurt

A

lactobacillus

85
Q

what microorganism makes beer

A

yeast

86
Q

what microorganism makes penicillin

A

penicillium

87
Q

explain why microorganisms are used in most biotechnology processes

A
  • grow rapidly
  • faster production of DNA
  • easy to genetically modify DNA
  • can be grown in fermenters in almost any location
  • can be grown using waste products from other industrial processes
  • processes usually occur at low temp so cheaper and safer to maintain
88
Q

order of events when brewing beer using yeast

A
  • malting
  • mashing
  • fermentation
  • maturation
  • finishing
89
Q

describe the step of malting when brewing beer using yeast

A

barley germinates, enzymes are produced that break starch into sugars for yeast to respire

90
Q

describe the step of malting when brewing beer using yeast

A
  • malt mixed with hot water (55-65 degrees)
  • enzymes break down starch producing wort hops added for flavour
91
Q

describe the step of fermentation when brewing beer using yeast

A
  • yeast added to wort
  • fermentation occurs (20-28 degrees)
  • yeast eventually killed as pH lowers, ethanol builds up and oxygen decreases
92
Q

describe maturation and finishing steps when brewing beer from yeast

A

maturation: beer conditioned for 4-29 says
finishing: beer filtered, pasteurised, bottled/canned

93
Q

how does ethanol form in yeast and some plants

A
  • pyruvate is decarboxylated to form ethanal using pyruvate decarboxylase
  • enzyme alcohol dehydrogenase removes hydrogens from NADH and transfers to ethanal converting it to ethanol
94
Q

what is ethanol production in yeast dependent on

A
  • species of yeast
  • number of yeast cells
95
Q

what factors inhibit the production of yeast

A
  • sugar concentration falls too low
  • pH falls too low, conditions become too acidic, decrease in pH causes enzymes to denature
  • high ethanol concentration damages/posiions/inhibits, yeast
96
Q

what causes bread made using yeast to rise

A

CO2

97
Q

describe the commercial process for baking using yeast

A
  • active yeast mixture added to flour and other ingredients, left in warm environment to rise
  • dough is knocked back (excess air removed), kneaded, shapes and allowed to rise again
  • cooked in hot oven so CO2 bubbles expand
  • yeast cells killed during cooking
98
Q

describe how cheese is made using bacteria

A
  • milk is pasteurised - heated to 95 deg for 20s to kill off unwanted natural bacteria, no competition anfd unwanted reactions
  • milk is homogenised-fat droplets even;y distributed
  • bacteria and chymosin enzyme are added
  • milk separates into solid curds and liquid whey
  • whey used in animal feeds
99
Q

explain why making cheese can be described as a biotechnological process

A
  • microbes/living organisms
  • make product/carry out industrial process
100
Q

suggest 2 benefits of the pasteurisation stage

A
  • microbes killed
  • enzymes denatured
  • so no competitors
101
Q

rennin is a protein that can be obtained from the stomach lining of calvses. It is used in the cheese-making process in the ratio one part rennin to 10000 parts milk. suggest what type of protein rennin is and explain how a very small quantity of rennin is able to convert a large quantity of milk

A
  • enzymes
  • ESC forms
  • products released at the end
  • enzymes remains unchanged
102
Q

rennin could in theory be immobilised for cheese making. give 2 potential advantages of this

A
  • enzymes can be used again
  • enzyme can leave pure product
  • enzyme more stable/more efficient
103
Q

describe the process of penicillin production

A
  • demands: p.chrysogenum needs high levels of oxygen, rich nutrient medium
  • sensitive to pH and temperature
  • first stage fungus grows second stage it produces penicillin (secondary metabolite) made in stationary phase end of cycle
  • drug is extracted and purified
  • small fermenters as difficult to maintain high levels of oxygen in big bio reactors
  • continuously stirred for oxygenation
  • rich nutrient medium
  • buffer solution in growth medium pH 6.5
  • temp maintained at 25-27 deg
104
Q

define what a primary metabolite is

A

any metabolite formed as part of the normal growth of a microorganism

105
Q

define what a secondary metabolite is

A

a metabolite produced by a microorganism usually in the latter stages of growth as the culture ages
- usually have antibiotic properties

106
Q

define batch culture

A

a culture of microorganisms taht takes place in a single fermentation
- products separated from mixture at the end of the fermentation process

107
Q

define continuous culture

A

a culture of microorganisms set up in a reaction vessel to which substrates are added and from which products are removed as the fermentation process continues

108
Q

what type of culture is penicillin grown by and why

A
  • batch culture
  • only produced once the population had reached a certain size (secondary metabolite)
109
Q

describe the commercial process of making yoghurt

A
  • sterilisation of equipemnt-heat to kill bacteria
  • skimmed mlk powder added to milk - pasteurisation
  • add bacteria culture and incubate for 4-5 hrs
  • sampling
  • end of fermentation (add flavour etc)
  • take some culture to add to next batch
110
Q

what is a mycoprotein/single-celled protein (SCP)

A

fungal protein /microorganism used to produce proteins for human consumption as food

111
Q

what is a common used of SCP

A
  • different fungi can be used to create proteins with similar amino acid profiles to that of plants and animals
  • can grow on almost any organic substrate
112
Q

why is SCP used to make proteins

A
  • beef has greater total fat content compared to the protein produced by microorganisms
  • beef and lamb also contain more saturated fat content- greater contribution to herosclerosis
  • people on a weight reduction diet prefer fungal protein as it has less energy than meat
113
Q

describe the advantages of using microorganisms to make protein and other products

A
  • can be much faster than being produced by animal or plant
  • production can be increased/decreased according to demand
  • no animal welfare issues
  • protein contains no animal fat or cholesterol
  • microorganisms can be GM to adjust the aa content of the protein
  • not affected by seasonal variations
  • not much land is needed
114
Q

describe the disadvantages of using microorganisms to produce proteins and other products

A
  • some people may not want to eat fungal protein or food grown on waste
  • need to isolate protein from the medium it is grown in
  • protein has to be purified
  • culture can become infected easily due to optimum growing conditions
  • different taste/texture to traditional protein sources
115
Q

what microorganism is used in baking and brewing and what is its role

A

microorganism: yeast
role: in baking aerobic resp. in brewing anaerobic resp.

116
Q

state what is meant by biotechnology using suitable examples from different areas of biotechnology and explain why microorganisms are used in biotechnological processes

A
  • biotechnology is a large scale commercial use of living organisms
  • to produce food eg beer using yeast
  • can be used to produce drugs eg penicillin using penicillium
  • used to make useful enzymes eg for detergents
    advantages:
  • fast growth
  • microobes can be genetically engineered
  • processes occur at low temperatures
  • low temp
  • safer and cheaper to maintain
  • products are easy to separate
  • grown on unwanted food
117
Q

what is bioremidation

A

the use of microorganisms to clean the soil and underground water on polluted sites
- microorganisms convert toxic substances to less harmful substances

118
Q

what conditions are needed to stimulate the growth of a microbe that uses a contaminant as a source of food

A
  • water
  • suitable temperature
  • suitable pH
  • oxygen
119
Q

define exponential growth in bacteria

A

population doubles each generation in bacteria which divide by binary fission

120
Q

define carrying capacity

A

maximum population that can be supported by habitat due to limiting factors, disease and predation

121
Q

what is the lag phase of the population growth curve

A
  • time required for enzymes which will enable medium to be used
  • for division
  • small number of individuals reproduce
122
Q

describe the log phase (exponential) for the population growth curve

A

ever-increasing number of individuals reproduce. the population doubles with each generation (providing optimum pH, oxygen, no/less competition)

123
Q

describe the stationary phase of the population growth curve

A

population declines until it remains stable w cyclic fluctuations

124
Q

describe the death phase of the population growth curve

A

nutrients run out eg carbon source, minerals run out (limiting factor) waste builds up (toxic metabolites)
- eventually all will die

125
Q

a mixture of 3 sugars is added to batch fermenter at the beginning of the process. a monosaccharide glucose which the yeast uses up first during days 0 to 2. Ddsaccharide, maltose which is used during days 1 to 5. trisaccharide maltotriose which is used during days 4 to 5. suggest why yeast uses sugars in this order

A
  • glucose can be used/enters glycolysis directly without being broken down first
  • maltose must be hydrolysed
  • enzyme maltase only made when maltose is present/ when needed
  • enzyme induced/gene switched on
  • transcription and translation of protein takes time
  • maltotriose requires more (2) hydrolysis reacts
126
Q

describe the pattern of growth of yeast in a fermenter

A
  • lag phase initially (GIVE DATA THROUGHOUT)
  • log phase at days xyz
  • rate of increase slows during days xyz
  • stationary phase. population levels off duirng remaining days xyz
127
Q

give the equation to calculate number of bacteria

A

N = N₀ x 2^n
- where n is the number of divisions
- N₀ is number of bacterial cells at the start

128
Q

what are bioreactors (fermenters) used for

A

large scale production of microorganisms

129
Q

what do microorganisms in a bioreactor produce

A
  • primary metabolites
  • secondary metabolites
130
Q

when does production using microorganisms usually begin in a bioreactor

A

after the main growth phase of the microorganisms towards stationary phase

131
Q

describe batch fermentation

A
  • microorganisms inoculated into a fixed volume of medium at start
  • nutrients get used up, new biomass builds up, waste builds up
  • short rapid growth phase
  • primary metabolites produced in early and rapid growth phase
  • stationary phase- overall growth stops but microbes carry out biochemical changes to form desired products
  • secondary metabolites-required products made during stationary phase
  • process stopped before death phase
  • products harvested
  • cleaned, sterilised and new batch started
132
Q

describe the process of continuous fermentation

A
  • microorganisms inoculated into sterile medium
  • sterile nutrient medium added continually once it reaches exponential growth
  • the product is made during normal growth (primary metabolite)
  • product, cells and waste are removed regularly to keep conditions optimum
  • biomass continues decrease then rise
133
Q

what stages of the population growth curve are mainly primary metabolites produced

A
  • lag phase
  • log phase
134
Q

what stages of the population growth curve are mainly secondary metabolites produced

A
  • stationary phase
  • death/decline phase
135
Q

advantages of batch culture

A
  • easy to set up and maintain
  • if contamination occurs, only one batch is lost
  • very useful for processes involving the production of secondary metabolites
136
Q

disadvantages of batch culture

A
  • slower growth rate as nutrient level declines with time
  • less efficient- fermenter is not in operation all of the time
137
Q

advantages of continuous culture

A
  • faster growth rate as nutrients are continuously added
  • more efficient- fermenter operates continuously
  • very useful for processes involving the production of primary metabolites
138
Q

what are the advantages of using a bioreactor

A
  • conditions can be manipulated to achieve the maximum possible yield of the product
  • eg oxygen conc
  • eg pH
139
Q

why is it an advantage that oxygen concentration can be manipulated in a bioreactor

A

can keep it high constantly to ensure bacteria are respiring aerobically and to avoid anaerobic resp. not the case if product is ethanol

140
Q

why is it an advantage of being able to manipulate pH in a bioreactor

A

ensures pH is suitable for enzymes to work

141
Q

why is it an advantage of being able to manipulate substrate concentration in a bioreactor

A

ensures there’s enough respirator substrates for organisms

142
Q

why should waste products be removed from a bioreactor

A

if toxic, build up will kill the microorganisms

143
Q

what is done first before microorganisms are put into a fermenter

A
  • essential to kill other microorganisms (sterilisation)
  • this prevents competition
  • they would use nutrients and not allow the desired microorganisms to grow to their maximum yield
  • fermenter is sterilised with high pressure steam. everything added to it is also sterilised
144
Q

why is pressure vented in a fermenter

A
  • to prevent build up
  • for safety
145
Q

why are nutrients added to a fermenter

A
  • source of carbohydrates
  • respiration to keep microbes alive and nitrogen (nitrates for nucleic acids) are added such as sugar and ammonium ions
  • this is added to the food culture medium
  • both contribute to an increase in biomass
146
Q

why is an optimum temperature needed for fermenters

A
  • this is so enzymes in the microorganism can work at a fast rate but don’t get denatured
  • as the microorganisms produce heat by respiration, the fermenters must be cooled using a water jacket
  • temp is measured by electronic temp sensor
147
Q

why is an optimum pH needed for a fermenter

A
  • enzymes work at max rate at optimum pH
  • change can reduce activity of the eenzyme and growth rate
  • lead to denaturing enzyme
  • electronic probe used to assess pH
  • buffer solution in place to ensure optimum
148
Q

why is oxygen needed in a fermenter

A
  • bubbling sterile air into the fermenter allows the microorganisms to respire aerobically
  • a lack of oxygen leads to unwanted products of anaerobic respiration and a reduction in growth rates
149
Q

why is agitation/stirring necessary in a fermenter

A
  • produced by a stirrer to mis the oxygen for oxidative phosphorylation and nutrients into all of the liquid
  • prevents blocking of cells of inlet
150
Q

explain why sterile air is pumped into the fermenter

A
  • provides oxygen for aerobic respiration
  • for oxidative phosphorylation
  • sterile to prevent contamination
  • mixes fungus with substrate
151
Q

in what form is carbon and nitrogen added to the culture

A

carbon: glucose
nitrogen: amino acids

152
Q

why is it necessary to pump water into the jacket surrounding the culture

A
  • water is for cooling
  • maintains constant/optimum temperature
  • respiration produces heat
  • which would denature enzymes/kill cells
  • heat also produced by stirrer/motor
153
Q

state why pH is monitored and describe how it is controlled

A
  • will affect enzyme action
  • denatures enzymes
  • affects metabolic rate
  • add a buffer
154
Q

explain the importance of maintaining aseptic conditions in manufacturing penicillin in fermentation

A
  • to avoid unwanted microbe entry/presence
  • so no competition for nutrients
  • so conditions remain unchanged
  • no contamination of batch
  • to prevent escape of microbes
155
Q

state 3 physical or chemical factors within the fermenter other than nutrient levels that need to be monitored and controlled

A
  • temperature as it effects enzymes
  • pH as it affects enzymes
  • oxygen content as it affects aerobic respiration
156
Q
A

OCR AS/A Level Biology Context (24 decks)

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