Food Production

Modern advances in farming techniques and biotechnology have been employed to increase food production around the world. Unfortunately, there are still millions of people who go each day without enough to eat - this is known as food insecurity.

Please note that this topic is only included on the AQA triple science syllabus.

Factors Affecting Food Security

Food security is having enough food to feed a population. It is estimated that 800 million people around the world face daily hunger and a lack of access to adequate food. Food security in some countries is threatened due to the following biological factors:

• Increasing birth rate

• Changing diets in developed countries means limited food resources are transported to other countries around the world

• New pests and pathogens that damage crops / livestock

• Weather changes e.g. droughts mean there is not enough water to grow crops

• Cost of agricultural inputs

• Conflicts / war which affect the availability of food or water

Farming Techniques

More energy is transferred between trophic levels if the organisms waste less energy through respiration or maintaining body temperature. Many farms therefore try to limit the movement of animals (e.g. battery hens) and keep them indoors at warm temperatures. Some animals are also fed high protein foods to increase growth. These practices cause the animals to grow bigger and more quickly, meaning that more food is available to a growing human population. However, these farming techniques can be cruel to animals and reduce their quality of life.

Sustainable Fisheries

Catching fish in the wild is unsustainable and can have a negative impact on our environment. Such large numbers of fish have been caught in the past that their populations have dwindled, impacting the rest of the food chain. For example, cod are at risk from overfishing and their population size has become so depleted that they may never recover. In addition, modern fishing techniques such as dredging and bottom-trawling can damage coral reefs and impact the sea-floor habitat.

A much more sustainable way of producing fish is by fish farming, where fish are grown in freshwater tanks and enclosures. As the fish are living closer together than they would be in the wild, the farmer needs to ensure that fish of different ages and species are kept in separate tanks to reduce intraspecific and interspecific competition.

The farmer also carries out the following steps to ensure the maximum growth of fish:

• Regular cleaning of water - this reduces disease (by removing pathogens) and prevents the build up of waste which could lead to eutrophication and reduced oxygen levels

• Use of antibiotics and separating fish to avoid crowded conditions - this prevents the spread of disease

• Fencing and scarecrows - to prevent predation of fish

• Frequent feeding with small food pellets - feeding the fish a small quantity of food more often prevents the accumulation of excess food in the water and allows the fish to grow rapidly

• Selective breeding - this technique can produce fish which grow much more quickly than fish in the wild

• Genetic modification - fish can be genetically modified for disease resistance. Using less energy to fight an infection means more energy can be used for growth.

Fish farming is not only more sustainable than wild fishing but it gives the farmers more control of the species and age of fish that they want to catch. Wild fishing often results in catching unwanted fish or young fish which are often dead or injured when they are thrown back to sea. Fish farming is also much quicker and the fish are easier to catch than catching fish in the ocean. The disadvantages to fish farming are that the fish tend to be closely related, which facilitates the spread of disease as they are equally susceptible to the same diseases. This can be overcome through the use of antibiotics and regularly cleaning the water which can be expensive and time-consuming.

Role of Biotechnology

Genetic modification involves taking a gene from one species and placing it in another species to produce useful characteristics in that organism. An organism containing DNA from another species is called transgenic. It can be used in agriculture to produce bigger or more nutritious plants. One of the most common uses is the production of insulin by genetically modified bacteria for the treatment of diabetes.

Restriction enzymes are used to cut DNA at specific sites to extract a gene of interest. The same restriction enzymes are used to cut plasmid DNA, creating complementary sticky ends. DNA ligase joins the two pieces of DNA together so that the gene of interest is now contained within a plasmid. This is called recombinant DNA. This is either placed in a virus, which will infect organisms with the recombinant DNA, or the plasmid will be taken up by bacteria. Plasmids and viruses which carry the DNA molecule are called vectors.

This process is used for the production of insulin.

1. The insulin gene is removed from human DNA using restriction enzymes.

2. A plasmid is also cut with restriction enzymes.

3. DNA ligase joins the complementary sticky ends to form the recombinant DNA.

4. The recombinant plasmid is taken up by bacteria.

5. The transgenic bacteria are grown in large fermenters to produce large amounts of insulin, which can then be extracted.

Genes can be inserted into plant species to provide:

• Resistance to insect attack

• Herbicide resistance

• Increased yield

• Higher nutritional content

The beta-carotene gene was added to wild rice, to create a new strain called golden rice with increased nutritional value. Beta carotene is used to synthesise vitamin A which is needed for healthy vision. Golden rice can be used in areas where vitamin A deficiency is common to protect against blindness.

Modern biotechnology techniques, such as the use of large-scale fermenters, enable large quantities of microorganisms to be cultured for food. Examples of microbes which are grown for food production include Lactobacillus bacteria which is found in yoghurt and the fungus Fusarium which is an ingredient in Quorn and other protein-rich vegetarian food. The fungus is grown on glucose syrup, in aerobic conditions, and the biomass is harvested and purified.