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 earths Fishers surface is used in Large fish eg. sharks photosynthesis producing 170 billion mall fish eg. whiting tons of organic invertebrates eg crabs, puppies material per year. carbon dioxide +water -- sugars +oxygen + energy Trophic structure(food W业出速业边业业边速业业速即 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 table15. 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 Mg 80,000 Phosphorus, P H, PO4, HPO42- 60,000 Sulfur s SO4 30,000 Micronutrients Chlorine, CI Cr 3000 Iron. Fe Fe3+, Fe2 2000 Boron. B H,BO3 2000 Manganese, Mn Mn2t 1000 Zinc Zn Zn2 300 Copper, Cu Cut. Cult 100 Molybdenum Mo MoO.2 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 nitrogenase fig 15.4 two pathways for nitrogen fixation a source of nitrogen for Soil Root plants.(a)both free bacteria nodule N+8H++6e living bacteria in the soil and microorganisms In root nodules produce ammonium ions. b lightning provides the lightening energy needed to form nitrate ions from atmospheric nitrogen N2+3O2+2e 2NO3
• 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
Plants need phosphorus to build nucleic acids, phospholiqids, and ATP Potassium ions activate many of the enzymes essential for photosynthesis and respiration Plants also utilize calcium, magnesium, and sulfur Calcium ions are essential for building cell walls Magnesium ions are essential for the formation of chlorophy ll Cluster of phyll b pigment molecules CH, in chlorophy 一GH-cH Granum (stack of thylakoids) hurin ring Thylakoid drocarbon tail (H atoms not shown) CopytigHt O Pearson Education, ine, pushing as Berkman Cumming
• Plants need phosphorus to build nucleic acids, phospholiqids, and ATP. • Potassium ions activate many of the enzymes essential for photosynthesis and respiration. • Plants also utilize calcium, magnesium, and sulfur • Calcium ions are essential for building cell walls. • Magnesium ions are essential for the formation of chlorophyll
15.3 Soil fertility is determined by soil structure and nutrient retention Topsoil usually contains sand. silt a Soil Layers and clay 口0 Horizon( humus) Fertile topsoil is a A Horizon (topsoil) mixture of at least E Horizon(eluviation layer) four components 0°°:1 B Horizon( ( subsoil mineral particles water, aIr, organIc C Horizon (regolith matter R Horizon(bedrock
15.3 Soil fertility is determined by soil structure and nutrient retention • Topsoil usually contains sand, silt, and clay. • Fertile topsoil is a mixture of at least four components: mineral particles, water, air, organic matter
Soil readily retains positively charged ions Mineral particle Positively charged nutrient ions minera Plant root phenolate Ne Fig 15.10 the negatively charged surfaces of soil mineral particles and humus help retain positively charged nutrients
Soil readily retains positively charged ions humus Positively charged nutrient ions Plant root mineral Mineral particle phenolate Fig 15.10 the negatively charged surfaces of soil mineral particles and humus help retain positively charged nutrients
The ph value of soil is largely a function of carbon dioxide present A healthy soil may have enough carbon dioxide as a product released from to give a pH value of 4-7 Hydronium ions are able to displace nutrient ions held to mineral particles and humus ②CO2 Reacts with H2O forming H2CO3 ③H2CO3 reacts with H2O, forming HCO3 and H3O+ ① Root releases CO2 ④H3O+ displaces nutrient Soil then available to root particle root Fig15 11 by releasing carbon dioxide, a plant guarantees a steady flow of nutrients from the soil to its roots
• The pH value of soil is largely a function of carbon dioxide present. A healthy soil may have enough carbon dioxide as a product released from to give a pH value of 4-7. • Hydronium ions are able to displace nutrient ions held to mineral particles and humus. Fig15.11 by releasing carbon dioxide, a plant guarantees a steady flow of nutrients from the soil to its roots ① Root releases CO2 ② CO2 Reacts with H2O, forming H2CO3 ③ H2CO3 reacts with H2O, forming HCO3 - and H3O+ ④ H3O+ displaces nutrient ion (K+ shown), which is then available to root Soil particle root
15.4 Natural and synthetic fertilizers help restore soil fertility ° Natural occurring fertilizers are compost(堆肥) and minerals. The natural occurring minerals are limited In 1913, a German scientist, Fritz Haber, developed a process for producing ammonia from hydrogen and nitrogen 2500 0 1500 0 是。 °5657585966162636465666766707n2 Fig 15.13 between 1956 Year and 1972 world crop yields Crop yield Nitrogen fertilizer need grew in tandem with increases in the use of N-P-K system nitrogen fertilizers
15.4 Natural and synthetic fertilizers help restore soil fertility • Natural occurring fertilizers are compost (堆肥) and minerals. • The natural occurring minerals are limited. • In 1913, a German scientist, Fritz Haber, developed a process for producing ammonia from hydrogen and nitrogen. N-P-K system Fig 15.13 between 1956 and 1972 world crop yields grew in tandem with increases in the use of nitrogen fertilizers Year