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IGCSE Biology > Topic 16 Biological Resources > Flashcards

Topic 16 Biological Resources Flashcards

1
Q

what is selective breeding?

A

artificial selection - process by which humans breed plants/animals with desired characteristics

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2
Q

what are the characteristics that a race horse will have been selectively bred for?

A
  • speed
  • muscle mass
  • height
  • size of lungs
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3
Q

what is the process of selective breeding?

A
  1. selection of desired characteristics by humans
  2. crossbreeding of male and female with desired characteristic (if male cannot show characteristic, parent should show it, eg for milk production)
  3. selection of offspring showing desired characteristic, only these are bred together again
  4. repeat process over many generations until allele for desired characteristic increases in frequency
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4
Q

what characteristics are plants selectively bred for?

A
  • disease resistance in food crops
  • increased crop yield
  • hardiness to weather conditions eg drought tolerance
  • better tasting fruits
  • large or unusual flowers
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5
Q

what are the problems with selective breeding?

A
  1. selective breeding can lead to inbreeding, when only ‘best’ animals or plants which are closely related are bred together, reducing gene pool + number of alleles in a population
  2. as inbreeding limits size of gene pool, there is an increased chance of organisms inheriting harmful genetic defects + being vulnerable to new diseases (less chance of resistant alleles being present in gene pool)
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6
Q

what are the differences between artificial and natural selection?

A
  • occurs naturally vs only occurs when humans intervene
  • results in development of populations with features that are better adapted to their environment and survival vs resulst in development of populations with features that are useful to humans and not necessarily to survival of that individual
  • usually takes a long time to occur vs takes less time as only individuals with desired features are allowed to reproduce
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7
Q

what are typical characteristics in animals that people selectively breed for?

A
  • milk production (cows, goats)
  • meat production (cows, sheep)
  • large eggs (chickens)
  • domestic dogs with a gentle nature
  • domestic dogs with particular appearance
  • sheep with good quality wool
  • horses fast pace
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8
Q

what is genetic engineering?

A
  • deliberate modification of genetic material in a living organism - produces organism with a unique set of genes
  • transgenic organism contains genes from another species
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9
Q

describe how genetic engineering occurs

A
  1. restriction enzymes are used to cut DNA from one organism
  2. Ligase enzymes join the cut pieces of DNA into a gap in DNA of another organism
  3. a new gene can be inserted into plasmids and viruses to form recombinant DNA - plasmid and virus act act as vectors
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10
Q

describe how large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter

A
  1. cut open plasmid DNA and cut out human insulin gene using same restriction enzyme
  2. join dna using dna ligase enzyme to make a recombinant plasmid vector
  3. insert plasmid vector into bacterial cell
  4. when bacteria reproduce plasmids are copied as well and so recombinant plasmid can quicly be spread as bacteria multiplu and all express human insulin gene
  5. genetically engineered bacteria placed in fermenter to reproduce quickly in controlled conditions and make large quantities of human protein
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11
Q

why is bacteria used for genetic engineering?

A
  • dna is loose in cytoplasm making it easy to modify
  • grow and replicate fast
  • no ethical concerns
  • contain plasmid which can be used as a vector
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12
Q

what does a bacteriophage do?

A
  • infects bacteria by injecting genetic material down special tube
  • can be used as a vector to transfer foreign DNA into bacterial cells
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13
Q

what are the conditions required in a fermenter?

A
  • aseptic (sterile) to avoid contamination and production of unwanted by products
  • optimum in temperature ph and nutrient levels to allow for maximum yield
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14
Q

what is the function of the cold water outlet?

A
  • fermentation produces heat, so to prevent contents from overheating, fermenter is surrounded by water jacket through which cold water circulates, keeping temp at optimum for growth
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15
Q

what is function of stirring paddles?

A
  • agitate culture medium to ensure microorganisms get exposure to even conc of nutrients, and keep temp even
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16
Q

what is function of pH probes

A
  • microorganisms = sensitive to changes in pH which may occur due to metabolic process - acid or alkali is added to keep pH at optimum + constant
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17
Q

what is function of food inlet?

A

nutrients are required as source of energy to respiire

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18
Q

what is function of air inlet?

A
  • sterile air is pumped in at bottom
  • stirrers help distribute oxygen required for aerobic respiration
19
Q

why is the fermenter made from stainless steel?

A

microorganisms produce acidic waste products, so fermenters have to be made of materials which will not corrode

20
Q

why is the fermenter made from stainless steel?

A

microorganisms produce acidic waste products, so fermenters have to be made of materials which will not corrode

21
Q

why are genetically modified plants useful?

A
  • increased resistance to range of pests and pathogens
  • increased heat and drought tolerance
  • to extend shelf lives
  • resistant to herbicides (weed killers) so crop is not affected but maximum weeds can be killed
  • increased protein, vitamin content
22
Q

pros and cons of GM crops

A

pros:
- reduced use of chemicals such as herbicides and pesticides - better for environment/cheaper/less time consuming for farmers
- increased crop yields as not competing with weeds for resources or suffering from pest damage
cons:
- increased cost of GM seeds, cover cost of developing them
- risk of inserted genes being transferred to wild plants by pollination which could reduce usefulness of GM crop eg if weeds also gain gene that gives them herbicide resistance)
- reduced biodiversity as there are fewer plant species when herbicides have been used, impacts insects and insect eating birds

23
Q

how can a plant be cloned by cutting?

A
  1. tear off a side shoot from a plant
  2. dip side shoot in rooting powder (to encourage root formation)
  3. place under glass, warm environment to allow them to grow
24
Q

what is a cloned plant?

A

genetically identical to parent (apart from environmental factors)
- this is because as the cuttings grow/explants grow, they form new cells by mitosis, copying the genes in the existing cells exactly, making them genetically identical

25
Q

why is taking cuttings not sufficient for commercial purposes

A

not a large scale process
number of plants that can be grown is limited
parent plant will die if too many cuttings are taken

26
Q

what advantages are there to micropropagation?

A
  • large numbers of genetically identical plants can be produced rapidly
  • species that are difficult to grow from seed or from cuttings can be propagated by this method
  • plants can be produced at any time of year in controlled conditions
  • genetic modifications can be introduced into thousands of plants quickly after modifying only a few plants
27
Q

what advantages are there to micropropagation?

A
  • large numbers of genetically identical plants can be produced rapidly
  • species that are difficult to grow from seed or from cuttings can be propagated by this method
  • plants can be produced at any time of year in controlled conditions
  • genetic modifications can be introduced into thousands of plants quickly after modifying only a few plants
28
Q

describe how to micro propagate plants in vitro

explant -> callus -> plantlet

A
  1. cells are scraped from parent plant (cells = explants)
  2. surface of explants sterilised using disinfectant followed by rinse in sterile water
  3. sterilised explants are transferred to a sterile petri dish containing sterile nutrient agar (contains plant hormones)
  4. growth medium encourages explant cells to grow and divide into small masses of cells = callus
  5. each callus is transferred to a fresh growth medium that contains a range of plant growth regulators - these hormones cause callus to grow roots, stems, leaves = plantlet
  6. plantlets transferred -> potting trays
28
Q

describe how to micro propagate plants in vitro

explant -> callus -> plantlet

A
  1. cells are scraped from parent plant (cells = explants)
  2. surface of explants sterilised using disinfectant followed by rinse in sterile water
  3. sterilised explants are transferred to a sterile petri dish containing sterile nutrient agar (contains plant hormones)
  4. growth medium encourages explant cells to grow and divide into small masses of cells = callus
  5. each callus is transferred to a fresh growth medium that contains a range of plant growth regulators - these hormones cause callus to grow roots, stems, leaves = plantlet
  6. plantlets transferred -> potting trays
28
Q

describe how to micro propagate plants in vitro

explant -> callus -> plantlet

A
  1. cells are scraped from parent plant (cells = explants)
  2. surface of explants sterilised using disinfectant followed by rinse in sterile water
  3. sterilised explants are transferred to a sterile petri dish containing sterile nutrient agar (contains plant hormones)
  4. growth medium encourages explant cells to grow and divide into small masses of cells = callus
  5. each callus is transferred to a fresh growth medium that contains a range of plant growth regulators - these hormones cause callus to grow roots, stems, leaves = plantlet
  6. plantlets transferred -> potting trays
29
Q

what are the benefits of producing genetically modified animals?

A
  • manufacture of human proteins such as antibodies
  • increased production of a particular product eg higher milk yield in cows, greater muscle mass in animals slaughtered for meat
  • increased resistance to disease
  • production of organs for transplantation
30
Q

what are the benefits of cloning transgenic animals?

A
  • large numbers of genetically identical genetically modified animals can be produced -> can be used for production of human proteins
  • many organs can be produced for transplant, eg transgenic pigs with genes that code for human antigens, thus organs less likely to be rejected by patient
31
Q

what is a clone?

A

genetically identical individual

32
Q

what is a clone?

A

genetically identical individual

33
Q

what is a clone?

A

genetically identical individual

34
Q

describe the stages in the production of cloned mammals eg dolly the sheep

A
  1. egg cell of donor sheep was removed and enucleated
  2. mammary cell from Dolly’s genetic mother was taken and diploid nucleus placed into enucleated egg cell
  3. egg cell stimulated by an electric current to start dividing by mitosis
  4. embryo transferred into uterus of surrogate sheep
  5. dolly born
35
Q

what are the applications of cloning?

A
  • can be used to make copies of genes researchers wish to study
  • production of animals which have a protein in their milk which could be used to treat a medical condition eg blood clotting factors
  • testing of new drugs - animals genetically identical so should all react in similar way
  • build up populations of endangered plants/animals
36
Q

drawbacks of cloning

A
  • reproductive cloning = inefficient
  • variety of organ defects have been seen
  • premature aginh
  • potential of producing a human identical to one which already exists (illegal)
  • confliction with religious views and societal ethical views
37
Q

describe how glasshouse and polythene tunnels can be used to increase yield of crop plants

A
  • artificial heating (fuels can be burnt)
  • artificial lighting
  • regular watering
  • plant mineral nutrition eg nitrates
  • increasing co2 content of air
38
Q

describe effect on crop yield of increased co2 and increased temperature in glass houses

A
  • by heating to optimum temp for photosynthesis, enzymes work most efficiently, photosynthesis rate increases - increase yield
  • by increasing conc of co2, rate of photosynthesis increases, increases yield
39
Q

describe how use of fertiliser can increase crop yield

A
  • organic fertilisers eg manure can be used -> decomposers decompose manure to release mineral ions slowly into soil -> does not release harmful chemicals, less risk of leaching + eutrophication
  • inorganic fertilisers eg nitrogen, phosphorus and potassium -> mineral ions need to be absorbed from soil for growth + replaced by fertilisers to make crops grow faster + bigger
  • aerating soil by ploughing fields helps soil microbes and uptake of minerals and water, as root cells have enough oxygen for aerobic respiration
40
Q

describe reasons for pest control in modern farming methods

A
  • pesticides are used because pests can damage crops by eating them, reducing yield
  • herbicides are used to kill weeds that may compete with crops
  • biological control uses a natural predator to reduce pest population for same reasons
41
Q

describe advantages and disadvantages of chemical pest control on crop plants

A

+
- easily accessible and cheap
- have an immediate effect
- kills entire population of pests
-
- kills other organisms that are beneficial
- bioaccumulation -> pesticides accumulate in top predators
- needs to be applied regularly
- pests can develop resistance

42
Q

describe advantages and disadvantages of biological pest control of crop plants

A

+
- natural method, no pollution
- no potential for resistance
- can target specific species
- long lasting
- does not need reapplied as predators reproduce themselves

-
- may consume other beneficial organism
- takes longer period of time to be effective
- cannot kill entire population
- may become pest itself

IGCSE Biology (22 decks)

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