Concept explainers
Energy Efficiency of Biofuel Production Most of the plant material currently used for biofuel production in the United States consists of food crops—mainly corn, soybeans, and sugarcane. In 2006, David Tilman and his colleagues published the results of a 10-year study comparing the net energy output of various biofuels. The researchers grew a mixture of native perennial grasses without irrigation, fertilizer, pesticides, or herbicides, in sandy soil that was so depleted by intensive agriculture that it had been abandoned. They measured the usable energy in biofuels made from the grasses, and also from com and soy, then measured the energy it took to grow and produce biofuel from each kind of crop (FIGURE 6.18).
FIGURE 6 .18 Energy inputs and outputs of biofuels made from three different crops. One hectare is about 2 .5 acres.
2. Which of the biofuels tested had the highest ratio of energy output to energy input?
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Biology: The Unity and Diversity of Life (MindTap Course List)
- 1.1 Microbes in the soil could be beneficial to plants and one way to evaluate this is by determining the R/S ratio. Define the R/S ratio. 1.2 Both rhizospheric and root-free soils were collected from five (5) plants before (BT) and after (AT) treatment. Using the microbial biomass that appear in Table 1, the R/S ratios before (BT) and after (AT) can be determined. Use these values to determine the respective R/S ratios. Kindly show all workings. Microbial population Before Treatment (BT) Plants R/S Microbial population After Treatment (AT) R/S ratio ratio (BT) (AT) Rhizospheric Non- soil (CFU) Rhizospheric Non- rhizospheric soil (CFU) soil (CFU) rhizospheric soil (CFU) Typha sp. 764 168 988 186 Pistia sp. 286 86 386 112 Salvinia 397 132 528 166 sp. Lemna sp. 274 121 406 152 Eichhornia 443 140 648 196 sp.arrow_forwardNutrient and Energy Acquisition Assignment: 1. Describe the flow of electrons during the light reactions. Be sure to include the following: water, PS-1, PS-I, PQ, Cyt-b6f, PC, Fd, NADP". 2. Phosphate deficiency in plants causes necrosis. Describe the reason behind the necrotic response in relation to its role in plants.arrow_forwardAzlina wanted to maximize the bio-char yield in her experiment so that she can utilize the biochar in the subsequent pot trials to improve the crop yield. She decided to run a torrefaction reaction on biomass at a moderate temperature of 240 oC whereby the biochar yield was 20 wt%. Later on, she found out that biochar can be produced by pyrolysis with a higher yield of 40 wt% but operating at a higher temperature of 500 oC. The amount of biochar yield almost doubled from her yield from the torrefaction process. Explain whether any error involved in her experiment, then describe the error involved and suggest the method to improve the biochar yield.arrow_forward
- Ethanol can be produced either from plant biomass using microbial fermentation or from ethylene using chemical synthesis way. Lütfen birini seçin: О а. True O b. Falsearrow_forwardQuestion 1 Which of the following statements describes the semi-dwarf wheat varieties developed in the Green Revolution? Their harvest is easier with heavy machinery. O They were bred for lodging sensitivity, which is an advantage in the field. As they are shorter, grain heads can touch the ground and give the plant more stability. These plants need more time to make enough carbohydrates to grow.arrow_forwardAccording to the water potential values shown in the image, which ones are wrong and why? W air (22 °C, 50% HR) -100 MPa Cas V sheet -0.2 MPa W stem -0.01 MPa to -0.1 MPa W soil -1 MPa to -0.51 MPa -4 MPa W root -0.1 MPa toarrow_forward
- Part F - How to determine transpiration rates by the whole plant method Which of the following best explains why the plant in front of the fan lost more mass than the control plant in normal room conditions? The leaves of the plant in front of the fan had the highest initial water potential and therefore lost the most water. The control plant had lower initial water potential in the root area and therefore lost less water. The control plant had a lower initial mass and so lost water at a decreased rate. The fan rapidly moves water molecules away from the leaf surface, lowering the water potential.arrow_forwardThe number of twigs on your tree: 154,000 twigs Based on transpiration measurements that we have made in previous years; each twigtranspires about 3 grams of water per hour on a warm spring day. That is, multiply your tree’s twigs by 3. This is a rough average for all sides of the tree (the south side, exposed to the sun, and the north side, with indirect light.) Calculate the number of grams of water per hour that your tree transpires. ____________g/hr Now convert your grams of water to kilocalories. Remember that the evaporation of a gram of water uses about 0.6 kilocalories of heat, which comes from the air. _____________ kcal/hr Assume that a day is 10 hours long and a month is 30 days. How many kilocalories per month does your tree account for? _________ kcal/mo How many kilowatt hours of electricity would it take to have an air conditioner use this number of kilocalories? One kilowatt hour takes about 860 kilocalories of evaporation. Transpiration in your tree…arrow_forward(3) Based upon what we have read, all of the following are potential negative effects of our concentration on growing biofuels (e.g. corn for ethanol production) except: (a) Disappearing Brazilian rainforest used for growing corn (b) Destruction of natural petroleum reservoirs beneath the Alaskan National Wildlife Reserve (c) Decreased resources to fight famine in Africa and other impoverished areas in the world (d) National focus to find or develop practical resources for future energy productionarrow_forward
- Why will alcoholic fermentation preserve the nutritive value of fruit juice or grains in the absence of refrigeration? O alcoholic fermentation will lower the pH to -1 thus killing all microbes who would use up the nutrients in the fruit juice of grain the ethanol/alcohol inhibits the growth of spoilage microbes which would destroy the nutritive value of the plant juice or grain O it won't- this is a trick question!! O alcoholic fermentation increases the salt concentration which in turn inhibits growth of spoilage microbesarrow_forwardSwitchgrass is used for ethanol production. The composition of the switchgrass is 37% cellulose, 24% xylan, 3% galactan, 4% arabinan, 20% lignin, 7% extractives, and 5% ash. A dilute acid pretreatment method is applied to the switchgrass before enzymatic hydrolysis and fermentation. The pretreatment hydrolyzes 10% hexosan and 90% pentosan into monomeric sugars. Approximately 30% of the hydrolyzed pentoses further react & are decomposed to furfural. Assume that there is no decomposition of the hydrolyzed hexoses. Further Assume that lignin, extractives, and ash do not change during the pretreatment. • How much of each lignocellulosic sugar (glucose, xylose, galactose, and arabinose) is produced when pretreating 1,000 kg (dry matter) switchgrass? How much furfural is formed? • Is water consumed or produced in these pretreatment hydrolysis and dehydration reactions? How much in each?arrow_forwardDespite CAM photosynthesis having a comparatively higher water use efficiency relative to C3 and C4 plants, its distribution is restricted primarily to desert succulents. In terms of water use efficiency, explain why CAM photosynthesis has not spread more widely.arrow_forward
- Biology: The Unity and Diversity of Life (MindTap...BiologyISBN:9781305073951Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa StarrPublisher:Cengage Learning