B6.2 - Feeding The Human Race

Question 1

Food security

Answer 1

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

Question 2

Factors threatening food security

Answer 2

• 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

Question 3

How can farmers increase food production

Answer 3

• 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

Question 4

Intensive farming techniques

Answer 4

• 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)

Question 5

Organic farming

Answer 5

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

Question 6

Fish farming

Answer 6

• 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

Question 7

Sustainable farming techniques to minimise fertilisers/pesticides

Answer 7

• 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 )

Question 8

Hydroponics

Answer 8

Growing plants in water containing dissolved minerals

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

Question 9

Selective breeding

Answer 9

Breading animals and plants for particular characteristics

Question 10

Why is selective breeding done

Answer 10

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

Question 11

How does a a farmer selectively breed organisms

Answer 11

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

Question 12

New characteristics of wheat due to selective breeding

Answer 12

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

Question 13

Disadvantages of selective breeding

Answer 13

• 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

Question 14

Gene pool

Answer 14

All the genetic material present in a population

Question 15

Genetic engineering

Answer 15

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

Question 16

Examples of genetic engineering in agriculture

Answer 16

• 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

Question 17

How do scientists produce a genetically engineered organism

Answer 17

• 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

Question 18

Risks of genetic engineering

Answer 18

• 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)

Question 19

Scientists genetically engineer bacteria to produce…

Answer 19

• hormones (insulin)
• vaccines
• antibodies

Question 20

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

Answer 20

• restriction enzymes:

- ligase enzymes:

Question 21

Restriction enzymes

Answer 21

• 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

Question 22

Ligase enzymes

Answer 22

• rejoin DNA strands at sticky ends

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

Question 23

Insulin

Answer 23

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

Question 24

Genetic engineering of bacteria to insulin

Answer 24

• 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

Question 25

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

Answer 25

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

Question 26

Biotechnology

Answer 26

Use of biological processes or living organisms to manufacture products

Question 27

Genetic modification crops:

Answer 27

• 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

Question 28

Genetically modifying (engineering) organisms

Answer 28

• 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

Question 29

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

Answer 29

• plasmids
• bacteria
• viruses

Question 30

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

Answer 30

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