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

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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