BIOLOGY 1M03 Study Guide - Midterm Guide: Neanderthal, Homo Habilis, Homo Erectus
8 Oct 2017
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D. 3. 1 outline the method for dating rocks and fossils using radioisotopes, with reference to 14c and 40k. Radioisotopes are used to determine the age of rocks containing fossils. The age is determined by analysing how much the isotope has decayed. Carbon-14 (14c) and potassium-40 (40k) dating, the age in half-lives can be deduced from the decay curve. 14c has a half-life of 5730 years, so it can only give accurate measurements for samples that are 1000-100,000 years old. The percentage of 14c isotopes remaining is measured. 40k has a half-life of 1250 million years, so it is used for dating samples older than 100,000 years. The proportion of parent isotope 40k is compared to the daughter isotope 40ar. The time taken for the radioactivity to fall to half of its original level. D. 3. 3 deduce the approximate age of materials based on a simple decay curve for a radioisotope. D. 3. 4 describe the major anatomical features that define humans as primates.
