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Biologi Dasar IISemester Genap 2015/2016Tugas Terstruktur 1TT1 - Topic 1Could Nonvascular Plants Have Caused Weathering of Rocks and Contributed to ClimateChange During the Ordovician Period?[T.M. Lenton, et al, First plants cooled the Ordovician.Nature Geoscience5:86-89 (2012)].The oldest traces of terrestrial plants are fossilized spores formed 470 million years ago.Between that time and the end of the Ordovician period 444 million years ago, the atmosphericCO2 level dropped by half, and the climate cooled dramatically. One possible cause of the dropin CO2 during the Ordovician period is the breakdown, or weathering, of rock. As rockweathers, calcium silicate (Ca2SiCO3) is released and combines with CO2 from the air,producing calcium carbonate (CaCO3). In later periods of time, the roots of vascular plantsincreased rock weathering and mineral release by producing acids that break down rock andsoil. Although nonvascular plants lack roots, they require the same mineral nutrients as vascularplants. Could nonvascular plants also increase chemical weathering of rock? If so, they couldhave contributed to the decline in atmospheric CO2 during the Ordovician.How the Experiment Was DoneThe researchers set up experimental and control microcosms, or small artificial ecosystems, tomeasure mineral release from rocks. First, they placed rock fragments of volcanic origin, eithergranite or andesite, into small glass containers. Then they mixed water and macerated(chopped and crushed) moss of the speciesPhyscomitrella patens. They added this mixture tothe experimental microcosms (72 granite and 41 andesite). For the control microcosms (77granite and 37 andesite), they filtered out the moss and just added the water. After 130 days,they measured the amounts of various minerals found in the water in the control microcosmsand in the water and moss in the experimental microcosms.Data from the ExperimentThe moss grew (increased its biomass) in the experimental microcosms. The table shows themean amounts in micromoles (µmol) of several minerals measured in the water and the mossin the microcosms.
Interpret the Data1.Make two bar graphs (for granite and andesite) comparing the mean amounts of eachelement weathered from rocks in the control and experimental microcosms.2.Overall, what is the effect of moss on chemical weathering of rock? Are the results similar ordifferent for granite and andesite?3.“Life has profoundly changed the Earth.” Explain whether or not these experimental resultssupport this statement.TT1 - Topic 2What Can Genomic Analysis of a Mycorrhizal Fungus Reveal About Mycorrhizal Interactions?[F. Martin et al., The genome ofLaccaria bicolorprovides insights into mycorrhizal symbiosis,Nature452: 88–93 (2008)]The first genome of a mycorrhizal fungus to be sequenced was that of the basidiomyceteLaccaria bicolor.In nature,L. bicoloris a common ectomycorrhizal fungus of trees such aspoplar and fir, as well as a free-living soil organism. In forest nurseries, it is used in large-scaleinoculation programs to enhance seedling growth. The fungus can easily be grown alone in