Need Help with interpreting this graph! Calibrating a Standard Radioactive Isoto

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Need Help with interpreting this graph!

Calibrating a Standard Radioactive Isotope Decay Curve and Interpreting Data 0.9 How Long Might Neanderthais Have Co-Existed with Modern Humans (Homo sapiens)? Neanderthals (Homo neanderthalensis) were living in Europe by 350,000 years ago and may have coexisted with early Homo sapiens in parts of Eurasia for 0.5 undreds or thousands of years before Neanderthals became extinct.o Researchers sought to more accurately determine the extent of their overlap by pinning down the latest date Neanderthas still lived in the area. They used carbon-14 dating to determine the age ofa Neanderthal fossil from the most recent (uppermost) archeological layer containing Neanderthal bones. In this exercise you will calibrate a standard carbon-14 decay curve and use it to determine the age of this Neanderthal fossil. The age will help you approximate the last time the two species may have coexisted at the site where this fossil was collected. 0.3 0.2 Time before present hatf-lwes) R. Pinhaal Data from end of the Maale Pala!thich the northern Caucaan sata Ravd ag ot lace Neandarthal occupaton and tha How the Experiment Mas Done Carbon-14??) is a radioactive isotope of carbon that decays to "N at a constant rate. 14C is present Acaoamy of Scancs LEA 147 3811-851 120111 dl 10.107onas.1018108 the atmosphere in small amounts at a constant ratio with both ECand C, two other isotopes of carbon. When carbon is taken up from the atmosphere by a plant during photosynthesis, C and fraction of "C that will remain after one half-life. Calculate the at each half-life and write the fraction fraction of "C remaining isotopes are incorporated into the plant in the same prop in which they were present in the atmosphere. These proportions remain the same in the tissues of an animal that eats the plant While an organism is alive, the C in its body constantly decays to "N but is constantly replaced by new carbon from the environment. Once an organism dies, it stops taking in new C but the C in its tissues con- tinues to decay, while the C in its tissues remains the same because the graph near arrows pointing to the data points. Convert each fraction to ? decimal number and round off to?maximum of three significant digits (zeros at the beginning of the number do not count as significant digits). Also write each decimal num- ber in scientificnotation. 2. Recall that "C has a half-life of 5,730 years. To calibrate the x-axis oactive and does not decay. Thus, scientists can caloulate for C decay, write the time before present in years bel how long the pool of original Chas been decaying in a fossil by measuring the ratio of "C to Cand comparing it to the ratio of 3. The researchers found that the Neanderthal fossil had approximately C to Cpresent originally in the atmosphere. The fraction of in a fossil compared to the original fraction of C can be converted to years because we know that the half-life of C is 5,730 years-i other words, half of the C in a fossil decays every 5,730 years. 0.0078 as much "C as found originally in the atmosphere. (a) Using mbers on your graph, determine how many half-lives have passed since the Neanderthal died. (b) Using your Ccalibration axis, what is the approximate age of the Neanderthal fossli Data from the Experiment The researchers found that the leanderthal fossil had approximately 0.0078 (or, in scientific notation, 7.8 × 10 ") as much-C as the atmosphere. The following questions will guide you through translating this fraction into the age of the fossil. ars (round off to the nearest thousand)? ()Apprccimate did Neanderthals become extinct ccording to this stu researchers cite evidence that modern humans (H. apiens) became established in the same region as mately 39,000 42,000 years ago. What does this sugget about the last Neanderthals approod lap of Neanderthals and modern humans 4. Carbon-14 dating works for fossils up to about 75,000 years old; INTERPRET THE DATA foasils older than that contain too little "C to be detected. Moat dinosaurs went extinct 65.5 million years ago. (a) Can "C be used to date dinosaur bones? Explain. (b) Radioactive uranium-235 has a half-life of 704 million years. If it was incorporated into dincaaur bones, could it be used to date the dinosaur fossils? Explain. 1.A standard curve of radioactive isotope deay is shown at the top of the right column. The graph line shows the fraction of the radioactive isotope over time before present) in units of half- lives. Recall that a half-life is the amount of time it takes for half of the radioactive isotope to decay. Labeling each data point with the corresponding fractions will help orient you to this graph. Draw an arrow to the data point for half-life-1 and write the Instructors: A version of this Scientific Skills Exercise can be assigned in MasteringBiology

Explanation / Answer

The graphical representation in the information refers to a graph between quantitative estimate of the radioactive carbon in the fossils and their relative time of existence on the planet. It can be clearly seen from the graph that as the time of existence increases (becomes older), the extent if radioactive carbon content decrease and ceases to zero. This is because older is the sample, more carbon would have decayed put of the sample. Conversely, more strong is the radioactive signal, more recent is the fossil sample.

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