B6.2 Flashcards
Describe some factors affecting levels of food security
-increasing human population: difficult to ensure that everyone has food
-change in diets of wealthier countries: more people can afford to consume more meat and fish, which is less efficient than eating plants (takes up more space than crops)
-global warming: leads to droughts -> more difficult to grow crops
-new pests and pathogens: constantly enter, but genetic modification and selective breeding of certain crops and animals = increased vulnerability to new pathogens
Explain some possible agricultural solutions to the demands of the growing human population
-hydroponics: growing crops (e.g. in glasshouses) by replacing soil with a mineral solution, allowing careful controlled growth by adjusting temperature, etc
-biological control: releasing natural predators into areas where crops are being grown, normally to kill pests. However, this may affect other organisms in the food web and the predator might be hard to control
-gene technology: modifying crops/animals for better yields (e.g. plants producing bigger fruit)
-herbicides: eliminates competition between plants and pests, but reduces biodiversity in the process
-insecticides/pesticides: eliminates animals that eat the crops, but reduces biodiversity and may affect the food web
-fertilisers: as plants grow, they remove minerals from the soil, but fertilisers ensure that the lands remains fertile
Explain the pros and cons of the selective breeding of food plants and domesticated animals
pros:
-can produce a variety of better quality food to meet the demands of a growing population (economical importance)
-can create animals that are more domesticated (e.g. dogs)
cons:
-reduced gene pool (number of alleles): less variation = organisms are vulnerable to new pathogens, as there may not be an individual who is resistant to the disease, so the species can become extinct
-increases chance of inheriting genetic diseases
-unforeseen physical problems (e.g. large chickens struggle to walk)
Describe genetic engineering as a process which involves modifying the genome of an organism to introduce desirable traits
-scientists identify the genes that code for the desired characteristic
-remove the gene from the donor organism
-insert the gene into the host organism (often a bacterium
-the host organism will now display the desired characteristics
Explain the process of selective breeding
-decide which characteristic of the species is desirable
-select parents with high levels of the characteristic
-breed from these individuals
-select the best offspring and breed again
-repeat for many generations, so that the characteristic becomes more common
Describe the main steps in the process of genetic engineering
-restriction enzymes cut the donor DNA at specific base sequences making a staggered cut, leaving ‘sticky ends’ (short sections of exposed, unpaired bases)
-a virus or bacterial plasmid is cut using the same restriction enzyme to also create sticky ends. this also contains an antibiotic marker gene
-the loop and gene sticky ends are joined together by DNA ligase enzymes
-the combined loop is placed in a vector, e.g. bacterial cell, and then allowed to multiply with the modified gene
-as the bacteria grows, we can see which ones are antibiotic resistant
-these will be the ones producing the modified gene, as they were inserted together
Explain some possible benefits and risks of using gene technology in modern agriculture
Benefits:
-useful in medicine to mass produce certain hormones in microorganisms like bacteria and fungi
-improves yield in agriculture by improving growth rates, introducing modifications that allow crops to grow in different conditions, and allows them to make their own pesticide/herbicide
-crops with extra vitamins can be produced in areas where they are difficult to obtain
-greater yields can help solve world hunger, which is becoming an increasingly concerning issue
Risks:
-genetic engineering may be misused for humans and not just crops (e.g. babies may be designed)
-the full effects of GM crops on human health have not been explored yet
-GM crops are infertile so if these genes are spread into wild plants, other species may also be infertile
-they pose a selection pressure, which could lead to increased resistance in other species, creating super weeds and pests
Describe and explain some possible biotechnological solutions to the demands of the growing human population
crops can be modified genetically to contain nutrients in countries where these nutrients are difficult to obtain naturally
Example: Golden Rice
-created with beta-carotene from a daffodil, in order to make Vitamin A in the body
-prevents Vitamin A deficiency in some countries where a large variety of crops can’t be imported or grown
