Chapter 15 Optimizing food production Golden rice: two European scientists created a new strain of rice enriched in B-carotene, which the body uses to make vitamin a. this is a kind of transgenic plant(转基因植物)
Chapter 15 Optimizing food production • Golden rice: two European scientists created a new strain of rice enriched in β-carotene, which the body uses to make vitamin A. This is a kind of transgenic plant (转基因植物)
15. 1 Humans eat at all trophic levels Only about 1 percent of the solar energy A food pyramid reaching the Earth's Fishers surface is used in Large fish eg. sharks photosynthesis producing 170 billion small fish eg. whiting tons of organic Small invertebrates eg crabs, puppies material per year carbon dioxide; water→→ sugars+ oxygen+ energy Trophic structure(food k业速2W业速 chains Producers, eg mangroves seagrasses or algae Sun's energy
15.1 Humans eat at all trophic levels • Only about 1 percent of the solar energy reaching the Earth’s surface is used in photosynthesis, producing 170 billion tons of organic material per year. • Trophic structure (food chains)
No more than 10 percent of the energy contained in the organic material of one trophic level is incorporated into the next higher level The higher the trophic level the smaller the possible population of organisms Eating meat is a luxury: The amount of biochemical energy people will obtain from eating the chickens is minuscule compared with the amount of biochemical energy in raising the chickens. In the US, more than 70 percent of grain production is fed to livestock If people in US ate 10 percents less meat, the savings in resources could feed 100 million people
• No more than 10 percent of the energy contained in the organic material of one trophic level is incorporated into the next higher level. • The higher the trophic level, the smaller the possible population of organisms. • Eating meat is a luxury: The amount of biochemical energy people will obtain from eating the chickens is minuscule compared with the amount of biochemical energy in raising the chickens. In the US, more than 70 percent of grain production is fed to livestock. • If people in US ate 10 percents less meat, the savings in resources could feed 100 million people
15.2 Plants require nutrients table 15. 1 essential elements for most plants Element From available to plants Relative number of ions in dry plant material Macronutrients Nitrogen. N NO3, NH4 1,000,000 Potassium K 250,000 Calcium. Ca Ca2+ 125,000 Magnesium, Mg Mg2+ 80,00 Phosphorus, P H,PO4, HPO4 60,000 Sulfur s SO4 30,000 Micronutrients Chlorine, CI CH 3000 Iron. Fe Fe3t fel+ 2000 Boron. B H,BO3 2000 Manganese Mn Mn2+ 1000 Zinc Zn 300 Copper, Cu Cut. Cu2+ 100 Molybdenum, Mo Moo2 Measured relative to moly bdenum=1 Source: Salisbury and ross, plant physiology. Belmont, CA: Wadsworth, 1985
15.2 Plants require nutrients Element From available to plants Relative number of ions in dry plant material Macronutrients Nitrogen, N NO3 - , NH4 + 1,000,000 Potassium, K K+ 250,000 Calcium, Ca Ca2+ 125,000 Magnesium, Mg Mg2+ 80,000 Phosphorus, P H2PO4 - , HPO4 2- 60,000 Sulfur, S SO4 2- 30,000 Micronutrients Chlorine, Cl Cl- 3000 Iron, Fe Fe3+,Fe2+ 2000 Boron, B H2BO3 - 2000 Manganese, Mn Mn2+ 1000 Zinc, Zn Zn2+ 300 Copper, Cu Cu+ , Cu2+ 100 Molybdenum, Mo MoO4 2- 1 table15.1 essential elements for most plants Measured relative to molybdenum=1 Source: Salisbury and ross, plant physiology. Belmont, CA: Wadsworth, 1985
Plants utilize nitrogen, phosphorus, and potassium Plants need nitrogen to build proteins and a variety of other biomolecules, such as chlorophyll(叶绿素) Nitrogen fixation nitrogen fig 15. 4 two pathways for nitrogen fixation, a source of nitrogen for Soil Root plants.(a) both free bacteria nodule N2+8H++6e 2NH+ living bacteria in the soil and Icroorganisms root nodules produce ammonium ions. ( b lightning prov ides the lightening energy needed to form nitrate ions from atmospheric nitrogen V2+3O2+2e 2NO
• Plants utilize nitrogen, phosphorus, and potassium • Plants need nitrogen to build proteins and a variety of other biomolecules, such as chlorophyll (叶绿素). • Nitrogen fixation Soil bacteria N2+8H++6e- 2NH4 + nitrogenase lightening N2+3O2+2e- 2NO3 - fig 15.4 two pathways for nitrogen fixation, a source of nitrogen for plants. (a) both freeliving bacteria in the soil and microorganisms in root nodules produce ammonium ions. (b) lightning provides the energy needed to form nitrate ions from atmospheric nitrogen. Root nodule