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Gcse Biology > B6.2 - Feeding The Human Race > Flashcards

B6.2 - Feeding The Human Race Flashcards

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1
Q

Food security

A

The ability of human populations to access affordable food of sufficient quality & quantity

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2
Q

Factors threatening food security

A
  • increasing human population
  • changing diets (more wealth = more varied diet, more meat than plants)
  • climate change (global warming will cause more droughts & deserts will expand, more co2 in atmosphere = increased yield of crops)
  • new pests & pathogen may evolve
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3
Q

How can farmers increase food production

A
  • maximise photosynthesis: light levels, temp, water supply controlled in industrial glasshouses
  • fertilisers: as plant grows minerals removed from soil, fertilisers help land remain fertile
  • removing competition & pests: herbicides - kill weeds, insecticides - remove insects, fungicides - destroy disease-causing fungi
  • planting varieties of crops that are pest resistant / produce higher yield
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4
Q

Intensive farming techniques

A
  • using fertilizers & pesticides to aid plant growth
  • maximising animal growth rates
  • maximising labour inputs by using machinery

(Produces maximum food product yield from minimum area of land)

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5
Q

Organic farming

A

Uses more natural methods of producing crops & rearing animals
Avoids use of artificial chemicals
Yields generally smaller so products may be more expensive

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6
Q

Fish farming

A
  • fish bred/reared in large cages in sea/rivers
  • protects fish from predators, easier to catch, allows wild populations to recover
  • if fish kept close together, disease can spread quickly
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7
Q

Sustainable farming techniques to minimise fertilisers/pesticides

A
  • replace soil nutrients by spreading manure
  • crop rotation: planting different crops each year, soil can recover,
  • gene technology: developing crop varieties more resistant to pests/disease
  • biological control: using a natural predator to control a pest population (predators bred in large numbers, released onto crops, eat pests )
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8
Q

Hydroponics

A

Growing plants in water containing dissolved minerals

commercial growers ensure plant receives needed mineral, plants grow quickly eg, in glasshouse

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9
Q

Selective breeding

A

Breading animals and plants for particular characteristics

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10
Q

Why is selective breeding done

A
  • to produce highest yield (choose best plants/animals to breed)
  • to feed our increasing population (plants)
  • to produce crops with high resistance to disease
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11
Q

How does a a farmer selectively breed organisms

A
  1. Decide which characteristic of species is desirable
  2. Select parents with high levels of this characteristic
  3. Breed from these individuals
  4. Select best offspring, breed again
  5. Repeat for many generations
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12
Q

New characteristics of wheat due to selective breeding

A
  • larger ears with many seeds
  • stronger stalks that ears stay on
  • ears ripen at same time
  • stalks grow to same heigh
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13
Q

Disadvantages of selective breeding

A
  • reduces no. of alleles (gene pool) of a species, reduces variation
    (If new disease arises, may not be organism in existing gene pool containing allele resistant to disease so species may become extinct)
  • increases chance of inheriting genetic disease
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14
Q

Gene pool

A

All the genetic material present in a population

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15
Q

Genetic engineering

A

Scientists altering an organisms genome to produce an organism with desired characteristics

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16
Q

Examples of genetic engineering in agriculture

A
  • Cotton: to increase crop yield from same area of land
  • Corn: to produce toxins that kill insects, makes plant resistant to pests, less pesticides needed
  • Bacteria: to produce medical drugs (insulin) / drugs to treat diseases in domesticated animals
17
Q

How do scientists produce a genetically engineered organism

A
  • removes genes that code for desired character tics (foreign genes)from donor organism
  • insert foreign genes into plant/animal cells at early stage of host organisms development
  • as host organism develops, displays characteristics coded for by foreign genes
18
Q

Risks of genetic engineering

A
  • eating genetically engineered organisms may lead to health problems (may introduce new allergens)
  • genetically engineered crops may cross-pollinate with wild plants, introducing new gene into wild plants, could disrupt balance of an ecosystem
  • some feel it is unethical (science interfering with nature)
19
Q

Scientists genetically engineer bacteria to produce…

A
  • hormones (insulin)
  • vaccines
  • antibodies
20
Q

What enzymes are used to move a gene between genomes during genetic engineering

A
  • restriction enzymes:

- ligase enzymes:

21
Q

Restriction enzymes

A
  • cut donor DNA at specific base sequences
  • make staggered cut, leaving few exposed unpaired bases on ends of DNA strands = sticky ends
  • same restriction enzymes cut open bacterial plasmid
22
Q

Ligase enzymes

A
  • rejoin DNA strands at sticky ends

- host & donor DNA have same sticky ends = new gene joined into plasmid DNA

23
Q

Insulin

A

Hormone which stimulates liver to turn glucose into glycogen,
decreasing blood sugar levels

24
Q

Genetic engineering of bacteria to insulin

A
  • insulin gene removed from human DNA by restriction enzymes
  • plasmid (loop of bacterial DNA) removed from bacterial cell
  • plasmid cut open using same restriction enzyme
  • human insulin gene inserted between cut ends of plasmid using ligase enzyme, plasmid = vector as carries human gene
  • repaired loop of DNA inserted into new bacterium = transgenic bacteria (have DNA from another organism)
  • transgenic bacteria grown in large numbers to produce insulin
25
Q

How do scientists check gene has successfully transferred to the host genome

A

Add a gene marker (gene for antibiotic resistance)

  • insert antibiotic resistance gene and desired characteristic gene into plasmid
  • transfer bacteria to agar plate containing selected antibiotic, incubate, allow time for bacteria to grow
  • the bacteria that survive contain the antibiotic resistance marker gene and desired gene
26
Q

Biotechnology

A

Use of biological processes or living organisms to manufacture products

27
Q

Genetic modification crops:

A
  • golden rice: created when gene taken from daffodil placed into rice, produces beta-carotene, body uses to make vitamin A
  • Bt corn: produced by inserting gene from bacteria into maize, gene codes for protein poisonous to insect pests, corn produces poison, killing pests that eat it
28
Q

Genetically modifying (engineering) organisms

A
  • gene cut out of pesticide-resistance plant using restriction enzymes
  • DNA of carrier/vector cut open using same restriction enzyme
  • useful gene spliced into carrier DNA & combined DNA placed in a virus, virus injected into plant cell = insertion
  • new gene inserted into host DNA
  • new gene begins to work, host = transgenic organism (genetically modified)
  • GM organism cloned, producing large number of identical individuals, all resistant to pesticides
29
Q

What can be used as vectors to transfer foreign DNA into an organism

A
  • plasmids
  • bacteria
  • viruses
30
Q

What extra stage is used to genetically modify plants/animals which is different from genetically engineering bacteria

A
  • engineered bacterium/virus carries modified gene into a plant/animal cell

Gcse Biology (15 decks)

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