10T5 - Food Production & Nitrogen Cycle
Food production
Glasshouses and polyethene tunnels
The enclosed environment protects the crops from harsh weather conditions
The levels of carbon dioxide are controlled so the rate of photosynthesis can be increase
Heat is trapped from the sun, so the optimum temperature of enzymes can be reached
The plants are protected from pests that can damage plants or carry diseases
Increasing carbon dioxide and temperature to effect crop yield
Carbon dioxide - paraffin lamps can be burned to increase carbon dioxide levels. This ensures that carbon dioxide is not the limiting factor in the rate of photosynthesis
Temperature - The heat trapped by the sun in the glasshouses raises the temperature. This allows enzymes in photosynthesis to work at the optimum temperature so the rate of photosynthesis increases
Fertiliser
Fertilisers contain nutrients that allow plants to grow faster
Nitrates are required to make amino acids for proteins, to allow the plants to grow
Phosphates are required for respiration and root growth
Potassium is needed for growth of flowers as fruit, as it allows enzyme reactions to take place
Pest control
Pest control is the use of pesticides or biology control to prevent insects eating the plants and pesticides. Pesticides include fungicides, herbicides and insecticides.
Advantages - Quick, efficient and can kill entire populations
Disadvantages - organisms can develop resistance, non-specific so kills other organisms, bioaccumulation can make it toxic to others in the food chain and that have to be continuously be applied
Nitrogen cycle
Step 1 - The nitrogen in the atmosphere is converted to ammonia and then into ammonium compounds by nitrogen fixing bacteria. This is nitrogen fixation. A similar process happens with lightening strikes. The nitrogen in the atmosphere reacts with the oxygen in the atmosphere to form nitrous oxides. These then dissolve in clouds and fall to the ground dissolved in rain. This is called lightening fixation.
Step 2 - Ammonium compounds are converted into nitrites and then into nitrates. This process is called nitrification, and is carried out by nitrifying bacteria.
Step 3 - The nitrates in the soil are being actively transported into plant root hair cells. This process uses energy from respiration. Nitrates are then used to make amino acids, which are used to make proteins.
Step 4 - Some nitrogen fixing bacteria live in the root nodules of legumes, and convert nitrogen into ammonium compounds. They are then absorbed by the plants and converted into amino acids to make proteins.
Step 5 - Animals eat plants and digest the proteins to make their own proteins
Step 6 - Animals excrete waste, that contains ammonium compounds, into the soil.
Step 7 - When plants and animals die they are decomposed by decomposers which feed on dead organic matter. This releases compounds containing ammonium ions into the soil.
Step 8 - Denitrifying bacteria convert nitrates in the soil to nitrogen. This process is called denitrification
Eutrophication
If farmers apply too much fertiliser to their crops than the excess mineral ions may leach into the water systems , leading to eutrophication
MP1 - Nitrates and phosphates entering lakes are absorbed by algae, whihc grow rapidly (leading to algae bloom)
MP2 - Algae block light, causing death of plants living beneath the surface of the lake
MP3 - Plant death means that less photosynthesis occurs in the lake, reducing oxygen production
MP4 - Decomposers including bacteria multiply and respire as they decompose dead plants, reducing further oxygen concentration in the lake
MP5 - Aquatic animals die from reduced oxygen concentration, providing even more dead material for decomposers to feed on