B6.2 Feeding The Human Race Flashcards
Factors affecting food security:
Increasing human population
Changing diets
Climate change- increase in C02 may lead to increasing yields of some crops
New pests and pathogens may evolve
How to increase food production:
Maximising photosynthesis
Using fertilisers- helps land remain fertile
Removing competition and pests
Planting varieties of crops that are pest resistant
Organic farming
Using natural methods of producing crops and rearing animals avoiding the use of artificial chemicals. Yields are generals smaller, so products may be more expensive.
Intensive farming
Using fertilisers and pesticides to aid plant growth
Maximising animal growth rates
Minimising labour inputs by using machinery
What is sustainable food production
Producing food in ways that can be continued indefinitely such as fish farming
Features of fish farming
Fishing quotas- provide limits on the numbers and types of fish that may be caught in an area so that they can maintain their population
Mesh size of nets- bigger holes mean that younger, less developed fish can escape through the holes
How to reduce the use of fertilisers
- replace soil nutrients by spreading manure instead of using fertilisers
- crop rotation, different crops require different nutrients
- biological control, use natural predators to kill crop pests which are often present in intensive farming
What is a hydroponic system
Growing a plant in water containing dissolved minerals to ensure it receives the mineral it needs, enables crops to grow quickly
What is selective breeding
Purposely breeding plants or animals which have desirable features
How does a farmer selectively breed organisms
Decide which characteristics of a species is desirable and select parents with high levels of this characteristic. Breed from these individuals. Then select the best offspring and breed again- repeat for many generations.
How has selective breeding changed wheat
- it’s made it easier to harvest and produces higher yields
Differences between wild and modern wheat plants
Modern: stalks grow at same length, large ears with many seeds, stronger stalks, ears ripen at same time
Wild: small ears with few seeds, brittle stalks that ears often fall off, ears ripen at different time, stalks grow at different lengths
Disadvantages of selective breeding
- it reduces variation meaning that if a disease were to come, it would wipe out a lot of the population due to a reduced gene pool of the species, species may become extinct
- increases the chance of inheriting a genetic disease
What is genetic engineering
Altering an organisms genome to produce an organism with desired characteristics. It can occur in one generation and single genes can be targeted.
Benefits of using genetic engineering in agriculture. List examples.
Cotton- increase crop yield from same area of land
Corn- to produce toxins that kill insects making the plant more resistance to pest, meaning less pesticide is needed
Bacteria- to produce medical drugs such as insulin
Risks of genetic engineering
- eating genetically engineered organisms may lead to health problems e.g. may introduce new allergens that may cause some people to allergic to the organism
- genetically engineered crops may cross pollinate with wild plants, introducing a new gene to wild plants which could disrupt the balance of the ecosystem
What problems to some people have with genetic engineering?
- it can be viewed as unethical as altering an organisms genome is seen as science interfering with nature
- some people don’t like the idea of eating genetically engineered organisms
How are organisms genetically engineered?
1) identify genes that code for the desired characteristics
2) remove the gene from the donor organism
3) insert the gene into the host organism, often a bacterium
Summarise genetic engineering
Using enzymes to move a gene between genomes
Restriction enzymes
They cut the donor at a specific base sequence. They make a staggered cut, leaving a few exposed, unpaired DNA strands called sticky ends. The same restriction enzyme is used to cut the bacterial plasmid DNA to create complementary sticky ends.
Ligase enzymes
They rejoin DNA strands at sticky ends. As both the host and the donor have the same sticky ends, the new gene is joined into the plasmid DNA.
Cloning vs Genetic Engineering
Cloning: produces exact genetic copies, genes copied within the same species
Genetic Engineering: produces unique set of genes, genes transferred between species
How is golden rice genetically modified?
A gene taken from a daffodil is placed into rice which makes the rice produce beta carotene, which the body uses to make vitamin A
Problems with using pesticides
- are often harmful to humans, so must be used in low levels
- can harm animals which aren’t pests which can affect the food chain negatively
Advantages of using biological control instead of pesticides
- does use chemicals so there is less pollution and chemicals don’t get passed along food chains
- biological control can have longer lasting effects on the pest population than chemical pesticides
- less harmful to wildlife
Why might a farmer choose to grow crops that have been genetically modified to be herbicide -resistant?
So they could spray his crops with herbicides to kill weeds without affecting the crop itself. This could increase crop yield.
Disadvantages of using hydroponics
- you need to add lots of fertiliser to the nutrient solution
- the cost of setting up hydroponics can be very high
How to test if your genetic engineering is successful
Insert a gene which codes for antibiotic resistance (a marker gene) into the plasmid at the same time as the gene for the desired characteristic. Then grow the host bacteria on a special plate containing antibiotics. Only the bacteria containing the marker gene will be able to survive and reproduce (antibiotics will kill the rest).
How to genetically engineer a bacteria.
Use a restriction enzyme to cut out the useful gene from the human DNA. Use the same enzyme to cut open the plasmid, leaving both the plasmid and human DNA with complementary sticky ends. Then use ligase enzymes to join the two pieces or DNA together. These plasmid vectors containing the new DNA are then inserted into the host bacteria.
What does crop rotation do?
- Different crops take different nutrients from the soil
- It gives soil a chance to recover, and maximises plant growth
- It also prevents building up a population of a particular crop pest.
