B6.2 feeding the human race Flashcards
(25 cards)
What is food security?
Food security is the ability of a human population to access affordable food of sufficient quality and quantity.
What factors threaten food security? (6)
Increasing human population Changing diets in wealthier populations New pests and pathogens Environmental change (more droughts) Sustainability Cost of agricultural inputs
What are possible agricultural solutions to the demand of a growing human population?
Increased use of hydroponics Biological control Gene technology Fertilisers Pesticides
Describe hydroponics and what are it’s advantages and disadvantages?
• Growing plants in water with dissolved minerals, to grow plants quicker
• Storage of these plant in a glass house one above another, so efficient use of space
• Advantages:
○ Mineral levels can be controlled more easily
○ Diseases can be controlled more efficiently
○ Any mineral solution not absorbed can be collected and recycled
• Disadvantages:
○ Lots of fertilisers needed
○ No soil means no where for the roots to anchor, to support plant
Describe biological control and what are it’s advantages and disadvantages?
• Breeding large numbers of predators of crop pests, where they are released onto the pests, where they eat them.
• Reduces the population of the pest but not completely, pests still reproduce.
• Advantages:
○ No chemicals, so can not disrupt the food chain
○ Not much repetition like what would happen with pesticides
• Disadvantages:
○ Sometimes the control species (predators) do something unexpected like not eating the pests
○ Predator could eat useful species
○ Predator species might migrate
○ Predator species might reproduce out of control and become problematic.
Describe gene technology and what are it’s advantages and disadvantages?
• Scientists are developing crop varieties that are more resistant to pests and disease
• Genetic engineering is when scientists select the desired characteristics, isolate it, then insert it into another organism and then the organism replicates with the new characteristic.
• Improves food production as it creates the most desired food with the best characteristics
• Advantages:
○ Can produce crops with a higher yield which are more resistant to disease
○ Cloning of rare animals that could become extinct
○ Curing disorders or having medicinal benefits by using helpful genes
• Disadvantages:
○ Using the same gene in plants means that there is little variation, meaning an environmental pressure could wipe out entire species
○ Long term effects are unknown
○ Could lead to the extinction of plants with unwanted characteristics.
Describe fertilisers and what are their advantages and disadvantages?
• Fertilisers are sprayed onto crops to make them grow well, by providing them with elements like potassium, nitrogen and phosphorus. (NPK fertilisers)
• Advantages:
○ Yields of crops are greatly increased
○ Improves general soil quality, adding to the humus of the soil
• Disadvantages:
○ Fertiliser pollutes water and causes eutrophication
○ Difficult to store and spread
○ Difficult to know or control the balance of different minerals in natural fertilisers.
Describe pesticides and what are their advantages and disadvantages?
• Chemicals used to control pests are sprayed onto the plants
• Includes fungicides, herbicides, and insecticides (kills fungi, weeds and insects)
• Improves food production by ensuring pests do not eat crops, so allows them to grow
• They accumulate in the food chain, in the long term they will cause much indirect damage to other species
• Advantages:
○ Effective in controlling pests
○ Stops disease carrying organisms on crops
• Disadvantages:
○ Expensive and cause environmental damage
○ Pesticides may kill useful plants and animals by accumulating in food chain
○ Pests may become resistant to them, making them ineffective.
What is selective breeding?
Humans use selective breeding to breed other animals and plants for particular characteristics.
What are typical features of plants and animals that are looked for during selective breeding?
Producing crops with a high resistance to disease, to produce high yields.
Animals like cows that produce the most milk, or sheeps with the most wool.
What are the steps of selective breeding?
- Decide which characteristic of the species is desirable.
- Select parents with high levels of this characteristic.
- Breed from these individuals.
- Select the best offspring, breed again.
- Repeat for many generations.
What are the disadvantages of selective breeding?
- It reduces the gene pool of a species so reduces variation. So if a disease arises then there will be less chance of a resisting allele, resulting in possible extinction.
- It increases the chance of inheriting a genetic disease.
What is genetic engineering?
Genetic engineering is when scientists modify an organisms genome to produce an organism with desired characteristics. It is a very accurate process, as single genes can be targeted, and can also occur in one generation.
How are organisms genetically engineered?
Scientists:
1. Identify the genes that code for the desired characteristic
2. Remove the gene from the donor organism
3. Insert the gene into the host organism (often a bacterium)
The host organism will hopefully now display the desired characteristics.
What do enzymes do in genetic engineering.
Enzymes are used to move a gene between genomes.
Descibe the role of restriction enzymes.
Restriction enzymes: cut the donor DNA at specific base sequences (either side of the desired gene). They make a staggered cut, leaving a few exposed unpaired bases on the ends of the DNA strands, called sticky ends. The same restriction enzymes are also used to cut open the bacterial plasmid (a loop of DNA that is repeated from the chromosomal DNA and is able to replicate independently.
Describe the role of ligase enzymes.
Ligase enzymes then rejoin DNA strands at the sticky ends. As both host and donor DNA have the same sticky ends, the new gene is joined into the plasmid DNA.
Describe the main steps of genetic engineering in bacteria to produce insulin.
- Plasmid (loop of DNA) is removed from bacterial cell.
- Insulin is cut from human DNA by restriction enzymes.
- Plasmid is cut using same restriction enzyme.
- Human insulin gene and plasmid are mixed. The human gene becomes inserted between the cut ends of the plasmid. The cut surfaces are repaired using ligase enzyme.
- The repaired plasmid now carries the human gene (now called a vector) and is inserted into a new bacterium.
- The bacteria are now called transgenic bacteria because they have DNA from another organism. They are grown in larger numbers to produce insulin.
What is a vector?
A vector is a vehicle, like a bacterium, used to transfer genetic material into an organism.
How do scientists check that the gene has successfully transferred into the host’s genome?
They can add a gene for antibiotic resistance as a marker:
- insert an antibiotic resistance gene into the plasmid at the same time as inserting the gene coding for the desired characteristic (e.g. insulin).
- transfer the bacteria to an agar plain containing the selected antibiotic. Incubate and allow time for bacteria to grow.
- any bacterial colonies present will survive because they now contain the antibiotic resistance marker gene. These bacteria will also contain the desired gene.
What is biotechnology?
The use of biological processes or living organisms to manufacture products, e.g. genetically modified organisms
Describe golden rice
A gene from daffodils is put into rice. This produces beta-carotene, used by the body to make vitamin A.
Describe BT corn
A gene from ‘Bacillus Thuringiensis’ bacteria is put into maize. The gene codes for protein which is poisonous to insect pests. Thus the corn kills pests that try to eat it.
What is the extra stage included in genetically modifying an organism?
The engineered bacterium or virus carries the modified gene into a plant or animal cell.
