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A level biology > m6 ch22 > Flashcards

m6 ch22 Flashcards

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1
Q

explain how natural cloning takes place in plant bulbs

A

leaf bases swell with stored food from photosynthesis, and búds form internally which develop into new shoots & plants next growing season

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2
Q

explain how natural cloning takes place in plant runners

A

lateral stems grow away from parent plant and roots develop where the runner touches the ground

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3
Q

explain how natural cloning takes place in rhizomes (e.g. marram grass)

A

the horizontal stem running underground swells with food stores- buds develop and form new vertical shoots which become independent plants

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4
Q

explain how natural cloning takes place in stem tubers (potatoes e.g.)

A

the tip of an underground stem becomes swollen with stored food to form a tuber or storage organ- buds on storage organ develop to produce new shoots

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4
Q

explain the ways farmers use natural plant cloning in horticulture (3)

A
  • splitting up bulbs
  • removing young plants from runners
  • cutting up rhizomes
    cheap way
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5
Q

explain how to take plant cuttings for natural cloning.

A
  • remove short section of stem
  • rooting hormone applied to base of a cutting
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6
Q

state the factors that increase the successfullness of vegetative propagation (cloning) when taking a cutting of a plant. (6)

A
  • use a non flowering stem: all plant resources available for growing new roots
  • make an oblique cut in stem: maximises SA available for rooting powder
  • use hormone rooting powder
  • reduce leaves to 2 or 4: minimises water loss
  • keep cutting well watered: reduces water stress
  • cover cutting with plastic bag for a few days: keeps air humid and so reduces water loss by transpiration
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7
Q

explain why propagation from cuttings is more advantageous than planting.
state the main disadvantage of using cuttings

A
  • faster
  • guarantees quality of plants- can take cuttings from good stock
  • lack of genetic variation in the offspring increases vulnerability to new diseases/pests
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8
Q

explain how sugar cane is propagated by cloning

A
  • short lengths of cane with 3 nodes are cut and buried in a clear field with shallow trenches, and covered with a thin layer of soil
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9
Q

explain what micropropagation is.

A

process of making large numbers of genetically identical offspring from a single parent plant using tissue culture techniques.

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10
Q

outline when micropropagation is used (5)

A

when a desirable plant:
- does not readily produce seeds
- doesn’t respond well to natural cloning
- is very rare
- has been gm’ed or selectively bred with difficulty
- is required to be pathogen free by growers

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11
Q

what are perennating organs.
how are they involved in plant cloning and survival (4)

A
  • organs in a plant which contain stored food from photosynthesis
  • can remain dormant in the soil
  • allows the plant to survive between growing seasons
  • enables asexual reproduction in plants
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12
Q

outline the basic principles of micropropagation

A
  1. remove small sample of tissue from plant
  2. sample is sterilised- immersion in sterilising agents (bleach/ethanol) - material removed is called the explant
  3. explant placed in sterile culture medium containing balance of plant hormones- cells proliferate and form a callus (mass of idential cells)
  4. callus divided up & individual cells/clumps transferred to new culture medium containing mixture of hormones which stimulates development of tiny gen identical plantlets
  5. plantlets are potted into compost where they grow into small plants
  6. young plants are planted out to grow and produce a crop
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13
Q

outline the arguments for micropropagation

A
  • rapid production of large numbers of plants with known genetic makeup- will yield good crops
  • disease free plants
  • makes it possible to to produce viable numbers of plants after genetic mod of plant cells
  • very large numbers produced- meets consumer demand
  • way of growing plants that are naturally infertile/difficult to grow from seed e.g. orchids
  • way of reliably increasing numbers of rare/endangered plants
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14
Q

outline the arguments against micropropagation

A
  • produces monoculture: all sucseptible to same diseases
  • expensive & requires skilled workers
  • explants and plantlets are vulnerable to infection by moulds and other diseases during prod process
  • in some cases large numbers of new plants are lost
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15
Q

distinguish natural cloning in vertebrates and invertebrates

A

vertebrates:
formation of monozygotic twins
- occurs when the early embryo splits to form 2 separate embryos

invertebrates:
can regenerate entire animals from fragments
e.g. starfish and hydra, developing genetically identical clones

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16
Q

outline the similarities and differences between artificial twinning and the natural production of twins in vertebrates.

A

similarities: both start with one embryo that splits into 2 identical embryos

differences:
- artificial twinning is carried out manually where the embryos are split in a lab, whereas natural twins the embryo divides itself
- artificial twinning: each embryo implanted into a different adult mother

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17
Q

outline the 5 stages in artificial twinning, using cows as an explained example

A
  1. cow with the desirable traits is treated with hormones so she super ovulates- releasing more mature ova than normal
  2. ova are fertilised either naturally or by artificial insemination, the early embryos are gently flushed out the uterus
  3. around day 6, when the cells of the embryo are still totipotent (can divide into anything) the cells of the early embryo are split to produce several smaller embryos
  4. each of the embryos is grown in the lab for a few days and then implanted into different mothers
  5. embryos develop into foetuses and are born normally, all genetically identical
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18
Q

outline the steps of somatic cell nuclear transfer
(4)

A
  1. nucleus removed from a somatic cell of an adult animal
  2. nucleus removed from mature ovum harvested from different female animal of same species (enucleated)
  3. nucleus from adult somatic cell placed into the enucleated ovum. mild electric shock is given to fuse them together and begin dividing
  4. embryo that develops is transferred into uterus of a 3rd animal
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19
Q

outline the arguments for animal cloning
(4)

A
  • high yield of farm animals
  • desirable genes can be passed on through artificial twinning
  • important in pharming- genetic engineering of farming animals e.g. milk
  • potential for rare/endangered/potentially extinct species to be reproduced
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20
Q

outline the arguments against animal cloning
(4)

A
  • inefficient: for most animals it takes many eggs to produce one successful cloned offspring
  • many cloned embryos fail to develop/miscarry/malformed
  • many have shortened life spans
  • attempts previously to clone v rare species have been unsuccessful
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21
Q

define biotechnology

A

applying biological organisms/enzymes to the synthesis/breakdown/transformation of materials in the service of people

22
Q

outline the benefits of using microorganisms in biotechnology
(6)

A

+ no welfare issues associated
+ large range of microorganisms available
+ can GM microorganisms
+ rapid growth rate- can produce huge amounts V quickly if conditions optimal
+ requires low temp conditions to grow
+ provide their own catalysts in form of enzymes

23
Q

state the 4 different processes using microorganisms in biotechnology for food production

A
  1. baking
  2. brewing
  3. cheese making
  4. yoghurt-making
24
Q

outline the process of baking using microorganisms.

A

yeast is used to make bread
- mixed with sugar and water to respire aerobically
- Co2 produced which makes the bread rise
- yeast cells are killed during baking

25
Q

outline the process of brewing using microorganisms.

A

yeast is used to make beer
- respires anaerobically to produce ethanol
- yeast ferments and drops, leaving clear beer
(genetically moded yeast ferments at lower temperatures)

26
Q

outline the process of cheese making using microorganisms

A

bacteria is used
- bacteria feed on the lactose in milk, inhibiting growth of the bacteria that makes milk go off
1. milk pasteurised
2. mixed W/ bacteria cultures
3. milk separated into solid curds and liquid whey

27
Q

outline the process of yoghurt making using microorganisms

A

bacteria is used
- often lactobacillus & streptococcus

  1. skimmed milk powder added to milk, mixture pasteurised and cooled
  2. milk mixed with 1:1 raio of lactobacillus & streptococcus & incubated @ 45* for 4-5hrs
  3. thick set yoghurts are mixed and ferment in pot
28
Q

briefly outline the use of a microorganism in the production of a brand of food

A

quorn
unicellular fungus is grown in large fermenters using glucose syrup as food source

29
Q

outline the advantages of using microorganisms in food production (6)

A
  • faster protein production
  • high protein content, low fat
  • can use wide range of waste materials to grow- reducing costs
  • microorganisms can be GMed to produce the desired protein
  • not weather dependent (like plants e.g.)
  • can be made to taste like most things
30
Q

outline the disadvantages of using microorganisms in food production (6)

A
  • microorganisms can produce toxins if conditions are not maintained at the optimum
  • sterile conditions must be used and carefully controlled
  • many people have concerns about consuming GMed food
  • protein must be purified to ensure it contains no toxins/contaminants
  • many dislike the idea of eating microorganisms grown on waste
  • has little natural flavour- needs many additives
31
Q

explain how biotechnology has contributed to the developments of antibiotics in medicine

A
  • penicillin is produced by mould (fungi)
  • produces penicillin which is extracted and purified
32
Q

outline the requirements necessary to produce penicillin from fungus

A
  • uses small fermenters
  • mixture continuously stirred to keep it oxygenated
  • rich nutrient medium used
  • growth medium contains a buffer to maintain a PH around 6.5
  • bioreactors maintained around 25-27*c
33
Q

explain how insulin used to be obtained, and outline the disadvantages of this method.

A

used to be extracted from the pancreas of animals that were slaughtered for meat
BUT:
- the supply of insulin would depend on the demand for meat, which was unpredictable
- some people were allergic to the animal insulin as it was impure (but later pure forms were developed)

34
Q

state how insulin is produced now to meet the demand of diabetics

A

genetically engineered bacteria which produces human insulin

35
Q

explain what is meant by the term bioremediation

A

when microorganisms are used to break down pollutants and contaminants in soil or water

36
Q

outline the 2 approaches to bioremediation
apply an example to each

A
  1. using natural organisms
    - many microorganisms naturally break down material, producing co2 and water
    - e.g. in oil spill, nutrients can be added to promote microbial growth & oil can be dispersed into smaller particles
  2. genetically modified organisms
    - bacteria strains have been engineered so that they can remove mercury contamination from water (mercury is v toxic)
37
Q

distinguish batch and continuous fermentation

A

batch fermentation:
- industrial fermentation that runs for a set time
- once culture cycle is complete, product is removed
- fermenter cleaned and new watch of microorganisms is grown

continuous fermentation:
- waste products continually removed (culture broth)
- more nutrient medium is continuously added

38
Q

explain what aseptic techniques are

A

techniques used to culture microorganisms in sterile conditions so they are not contaminated with unwanted microorganisms

39
Q

outline the factors affecting growth rates in a culture of bacteria (5)

A

nutrients available: as n/of microorganisms multiplies, nutrients are used up

oxygen levels: as the population of product increases, the demand for o2 increases

temperature: enzyme controlled reactions w/in microorganisms are affected by temperature of the culture (too low=slow / too high= denatured)

waste build up: as bacterial numbers rise, the build up toxic material may inhibit further growth & can poison/kill culture

PH change: more resp of culture = greater production of co2= - PH , too low PH will negatively affect enzyme activity

40
Q

state the different stages of growth of bacteria when labelling a growth curve.
outline what each one means

A
  1. lag phase: when bact are adapting to new environment & population growth is inhibited
  2. exponential phase: when rate of bact reproduction is at its max
  3. stationary phase: when net growth rate= 0 because rate of binary fission and death rate are equal (no change in popN)
  4. death phase: reproduction rate is almost 0 and death rate is much higher
41
Q

outline what a primary metabolite is.
give an example

A

substances that are formed as an essential part of the normal functioning of a microorganism
- ethanol (product of anaerobic respiration in yeast)

42
Q

outline what a secondary metabolite is.
give an example

A

substances that are produced that aren’t essential for normal growth, but still used by the cells
- penecillin and many antibiotics

43
Q

outline the advantages of using isolated enzymes in biotechnological processes
(3Ms2Ls)

A
  • More efficient: work @ much higher concentrations than is possible when they are part of the whole organism
  • More specific: no unwanted enzymes present- :. no wasteful side reactions take place
  • Maximises efficiency: isolated enzymes can be given ideal conditions for max product formation
  • Less wasteful: microorganisms use up the subs growing & reproducing, producing biomass rather than product. isolated enzymes don’t do this.
  • Less downstream processing: isolated enzymes produce pure product (m’organisms give a variety of products in the final broth so it is harder to isolate desired product)
44
Q

outline the reasons for using isolated extracellular enzymes rather than intracellular enzymes
(3)

A
  • easier to use: e’cellular enzymes are secreted so easier to isolate
  • m’organisms produce much fewer e’cellular enzymes than i’cellular- much easier to identify & isolate required one
  • extracellular much more robust- temp outside cell less controlled, :. e’cellular enzymes are better adapted to cope with greater variations in temp & PH
45
Q

explain why intracellular enzymes are still isolated and used in some cases, providing an example.

A

because intracellular enzymes are greater in variety- so sometimes they are used in manufacturing processes
- e.g. penicillin cyclase: converting natural penicillin into semi synthetic drugs

46
Q

outline what immobilised enzymes are, and how they are used in biotechnology.

A
  • enzymes that are held stationary during the catalytic process
  • attached to inert support system over which the substrate passes and is converted to product
  • can be recovered from reaction mixture and reused time after time
47
Q

outline the advantages of using immobilised enzymes. (6)

A
  • can be reused: cheaper
  • easily separated from reactants- reduces downstream processing
  • more reliable: high degree of control over process as insoluble support provides stable environment
  • greater temp tolerance: less easily denatured by heat
  • ease of manipulation: catalytic properties can be altered to fit the process
  • do not need to be replaced frequently
48
Q

outline the disadvantages of using immobilised enzymes in biotechnology.

A
  • reduced efficiency: process of immobilising an enzyme may reduce its activity rate
  • higher initial cost of materials- immobilised enzymes more expensive than free enzymes/m’organisms
  • higher initial cost of bioreactor: system needed for immobilised enzymes is different from traditional fermenters (more can go wrong
49
Q

state the 4 methods of immobilising enzymes

A

surface immobilisation

surface immobilisation using ionic & covalent bonds

entrapment in matrix

encapsulation

50
Q

distinguish the 2 methods of surface immobilisation of enzymes. (2)
discuss which method is more effective (6)

A

type 1: adsorption to inorganic carriers
- attached to inorganic carrier
type 2: ionic/covalently bonded to inorganic carrier
- not directly attached- connected to inorganic carrier by ionic/covalent bonds

type 1:
+ simple and cheap
+ enzyme is v accessible to substrate
+ can be used w/ many different processes
- enzymes can be lost from matrix easily

type 2:
+ cost varies so can be cheap
+ enzymes strongly bonded- unlikely to be lost
+ enzyme v accessible to substrate
+ ph & subs conc often have little effect on enzyme activity
- cost varies!!
- active S of enzyme may be modified in process= could become less effective

51
Q

explain the method of entrapment of mobilising enzymes. (2)
outline its advantages and disadvantages (5)

A

enzymes are entrapped in matrix, e.g. polysaccharides, gelatin, activated carbon
+ widely applicable to different processes
- may be expensive
- can be difficult to entrap
- diffusion of substrate to A.S and product from A.S can be slow
- entrapment may affect enzyme activity

52
Q

outline the method of immobilising enzymes by encapsulation.
discuss the advantages and disadvantages associated with this method

A

membrane entrapment in microcapsules, or behind semi permeable membrane
+ relatively simple to do
+ relatively small effect on enzyme activity
+ widely applicable to different processes
- relatively expensive
- diffusion of substrate to A.S and product from A.S can be slow (hold up reaction)

A level biology (19 decks)

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