chapter 22

Question 1

what is natural cloning

Answer 1

a structure that forms off a plant that then becomes its own differentiated new plant that is genetically identical to the parent

Question 2

benefit of vegetative propagation involving perennating organs

Answer 2

a perennating organ stores enough nutrients to sustain the organism during the unfavourable season

Question 3

4 ways natural plant cloning occurs

Answer 3

bulbs
runners
rhizomes
stem tubers

Question 4

how does bulbs cause natural cloning

Answer 4

leaf bases swell with stored food from photosynthesis (perennating organ). buds form internally which develop into new shoots and new plants in the next growing season

Question 5

how do runners cause natural cloning

Answer 5

a lateral stem grows away from the parent plant and roots develop where the stem touches the ground. a new plant develops - the runner eventually withers away leaving the new individual independent

Question 6

how do rhizomes cause natural cloning

Answer 6

a rhizome is a specialised horizontal stem running underground, often swollen with stored food. buds develop and form new vertical shoots which become independent plants

Question 7

how do stem tubers cause natural cloning

Answer 7

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

Question 8

plant cuttings

Answer 8

cutting off non-flowering stem from budding plant, dipping it in plant hormones root powder, to encourage growth, fungicide, to prevent infection, and then growing in soil

Question 9

micropropagation

Answer 9

taking only a tissue sample, sterilising it (e.g with ethanol) and growing w hormones (auxins and cytokines) on agar until roots have developed. a callus forms and this is split into cells and transferred to a new agar plate and eventually, the small plantlets that form and pitted in soil

Question 10

advantages of micropropagation

Answer 10

• rapid production of plants
• creates disease-free plants
• can clone seedless plants, like seedless varieties of grapes
• produce large numbers of rare/endangered plants
• can grow plants that do not grow from seeds easily

Question 11

disadvantages of micropropagation

Answer 11

• expensive and requires skilled workers
• if original cells have a viral infection, all the plants produced will have the virus too
• monocultures are grown and the gene pool is reduced, so all the plants are susceptible to the same diseases

Question 12

embryo splitting

Answer 12

1. two parents w desired characteristics, such as two healthy cows w a female that produces nutrient-rich milk, are selected
2. the female is given hormones to make her produce many eggs
3. samples of their eggs and sperm are used for IVF, or sometimes the eggs are naturally fertilised
4. embryo formed is split apart into many single, identical cells
5. these are inserted into the uterus of different host mothers and all the offspring would be clones of each other (not the parents)

Question 13

somatic cell nuclear transfer

Answer 13

1. somatic cell is taken from animal to be cloned
2. an egg cell is taken from a female and the nucleus is removed and discarded
3. the nucleus is then removed from somatic cell and inserted into empty egg cell
4. small electrical current is applied to make egg cell start to divide
5. once the embryo is a bundle of cells, the cells are separated and inserted into the uterus of different host mothers
6. each of these inserted cells are genetically identical to each other and the animal it came from

Question 14

advantages of animal cloning

Answer 14

• animals w desirable characteristics will produce more offspring than w natural reproduction
• SCNT enables genetically engineered embryos to be cloned
• it could be used to increase the numbers of rare and endangered animals

Question 15

disadvantages of animal cloning

Answer 15

• SCNT is not efficient, usually 1 embryo is formed from many eggs
• there is a high miscarriage rate when implanting embryos from SCNT
• animals produced by SCNT often have a shorter lifespan

Question 16

microorganism have been used to make the following foods:

Answer 16

bread - when yeast respires they produce CO2
brewing - yeast respires anaerobically producing ethanol
cheese - bacteria use lactose in milk as respiratory substrate causing the milk to separate into curds and whey, curds is used to make cheese
yoghurt - bacteria produce ethanol or lactic acid resulting in the milk forming polymers that give yoghurt a thicker and smooth texture
mycoprotein (Quorn) - the fungus
/Fusarian venetatum/ is grown and used ti make Quorn

Question 17

reasons for using microorganisms in food production

Answer 17

economics - microbes are small and so can be grown in smaller spaces than animals + nutrient requirement is cheaper than animals. temperatures they grow are are low so harvesting them is cheaper

short life cycle - bacteria can reproduce every 20 minutes, therefore food production is faster than waiting for animals to grow

growth requirements are basic, reducing the cost and making it easier to grow them. they only need warmth, water, oxygen, and food

Question 18

medicines produced by microorganisms

Answer 18

penicillin - antibiotic produced by the mould /Penicillium notatum/, /Penicillium chrysogenum/ is now used as it results in a higher yield of penicillin. fungus is grown in fermenters, stirred w oxygen and nutrients and penicillin produced is harvested and purified

insulin - produced by genetically modified bacteria which have the human gene for insulin inserted into one of their plasmids

Question 19

bioremediation

Answer 19

use of microorganisms to digest pollutants and contaminants. naturally occurring microbes break down pollutants like sewage and crude oil. microbial growth can be encouraged to increase in population size to help break down pollution. technique is commonly used on contamination sites (e.g. oil spills). scientists are looking at genetically modifying bacteria to increase range of pollutants they can break down

Question 20

advantages of using microorganisms in biotechnology

Answer 20

• microbes grow rapidly
• microbes can be genetically engineered
• microbes can be flavoured to taste like anything
• no ethical concerns about growing microbes
• microbes are rich in protein and low in fat

Question 21

disadvantages of using microorganisms in biotechnology

Answer 21

• microbes can also produce toxins if growing conditions are not carefully controlled
• microbes must be grown in aseptic conditions
• some people dont like the idea of eating microns
• microbes have no natural flavour, so additives have to be used

Question 22

4 stages in growth curve

Answer 22

1. lag phase - bacteria population is low to begin with
2. exponential/log phase- numbers of bacteria is rapidly increasing
3. stationary phase
4. death phase - when nutrients run out or toxins build up

no death phase usually in open systems as nutrients are constantly being replaced

Question 23

immobilised enzymes

Answer 23

when the enzyme is fixed to inert substance and substrate is passed over it

no need to purify the enzyme from product at the end of the, therefore they can be reused (economically beneficial), less sensitivity to changes therefore higher temperatures can be used increasing RoR without denaturing the enzymes

Question 24

4 methods of using immobilised enzymes

Answer 24

1. surface immobilisation - adsorption to inorganic carrier
2. surface immobilisation- covalent or ionic bonding to inorganic carriers
3. entrapment- in matrix e.g. polysaccharides, gelatin, activated carbon
4. encapsulation - trapping enzyme within membrane or capsule

Question 25

evaluating use of adsorption

Answer 25

advantages:
- simple and cheap
- used w many different processes
- enzymes are readily in contact with the substrate
disadvantages:
- enzymes can detach and be lost

Question 26

evaluating use of covalent and ionic bonds

Answer 26

advantages:
- enzymes are strongly bonded - less likely to be lost
- enzymes are readily in contact with the substrate
- pH and substrate conc will have little effect on enzyme activity
disadvantages:
- cost varies
- bonding could change the shape of active site, reducing its effectiveness

Question 27

evaluating the use of entrapment

Answer 27

advantages:
- can be used for many different processes
disadvantages:
- expensive
- can be difficult to entrap in matrix
- takes a long time for substrate to diffuse through matrix to enzyme
- can impact enzyme activity

Question 28

evaluating the use of encapsulation

Answer 28

advantages:
- simple process
- small effect on enzyme activity
- widely applicable to different processes
disadvantages:
- expensive
- diffusion of substrate/product through membrane can take a long time