ANTH 101 Practice Test Questions with Correct Answers

ANTH 101 Practice Test Questions with Correct Answers Explain how fossils are formed and why they are not equally prevalent in all areas. - Answer-fossils are the remains of past life forms that have been partially or wholly transformed into rock and displaced through a long process of chemical replacement. minerals in bones and teeth are replaced with rock forming minerals like iron and silica. can be from any body part however 99% are made up of teeth and and bones. taphonomy (how fossils are made) explains the processes which must occur for a dead organism to become a fossil. a fossil cannot be made if its remains are left exposed for any length of time. if exposed for over a day scavengers such as wolves may come and eat the soft tissue. once flesh is gone the bones will wither, break and dissapear. because of the unlikelehood of a quick burial not brought by humans very few once living organisms will end up as fossils. however even if burried protected from scavengers the remains must stay in an oxygen free (anoxic) enviorment so decompistion and bacterial activity are limited. however factors like groundwater and acidic soils can dissolve bones and teeth and geologic activity can distort the appearance of any potential fossils. the presence of fossils can very by the presence of sedimentary rock where it is most common. many times carnivores dropped the remains of animals into caves. fossilziation can also occur where volcanic activity has buried animals in volcanic ash. however representation of fossils is important to understand the entirety of populations. many fossils have been found from 55 mya representing early primates many taxa are known from a limited fossil record (from 20 mya the earliest of apes) key stages are missing because plaeontologist have searched for fossils only in some places, fossills have been perserved in some places and not others and rock sequences containing fossills are not complete in all places. the fayum depression for exam 8B. Define the terms eon, era, period, and epoch and specify modern humans' place in geologic time. - Answer-Eras are the the three major eras of life forms which are the Plaeozoic, Mesozoic and the Cenozoic. and each is subdivided by epochs which inside of epochs are periods. Eons are the largest parts of time ranging from a half billion to 2 billion years the hadeath is the first eon which is when the earth was in a hell like state this eon ends when the cooling of the earth from this state is the eon which bacteria began to appear and our current eon which is phanerzoic which is where we see life like today. next is eras which is within our current eon which paleozoic and an explosion of life this is where pangea was in formation and a mass extenction ended this era the paleozoic next is mesozoic which is the reptile era which was ended by another extiction. our current era is which cenozoic and runs from today until the last major extinction. during this era the cenzoic saw an increase in mammals and they thrived we also see times of ice ages. periods are spaces of times within eras no more than a hundred million years today we live in the qautrinary period. within periods we have epochs which include miocene, pleocine and paleocene epochs. our current epoch is the holocene epoch which starte 12,000 years ago. overall eons, eras, periods, epochs are seprarted by extinctions and emegences of life 8C. Compare relative age and relative dating methods with numerical age and absolute dating methods. - Answer-Stenos law of superposition which states relative dating which basically states the object found on the bottom is the oldest and the event or object imidatley above is the oldest and so on. now numerical age is is expressed in absolute years such as 2,000 years ago, or 1.3 billion. relative dating which was developed long before numerical dating can be accomplished through several methods. as far as relative methods Stratigraphic correlation which is the geologic correlation of strata from multiple locations in a region which is matched up by physical features, chemical composition fossils or other properties. for example when ash from a volcanic eruption has an individual and highly specific chemical composition fossils found in those strata the ash from the volcano can be spread across the world this variation has across the world. chemical dating is used since soil across the world have specific compostions reflecting histories some contain fluorine for example. if a bone is found in this soil the amount of fluroine absorbed in the bone will determine its age. biostratigraphic (faunal) dating which draws on the first appearance of the fossil record, the organisms devoloutinar development over time and the organisms extinction. certain organisms have more significant evoloutionary change. cultural dating can provide tools on age like primitive stone tools date to 3.3 mya. Now absolute methods of dating include dendochrenology which is the tree ring method, but only works in wood that is excellently pereserved. Radiocarbon dating shows age reflecting from the decay of radioactive elements and involved carbon-14 isotopes. the time it takes for hald of the radio isotope to decay is called a halflife. Radiopotassium method which accomdates all of primate evolution the strength of this method comes from volcanic rocks in 8D. Describe examples of relative methods of dating, including the limitations of each method. - Answer-relative methods of dating include stratigraphic correlation, which is dependent on relative positions of let's say ash from a volcano which erupted. however, the ash can scatter over many miles depending on the size of the eruption. next is chemical dating since soil contains fluorine, limitations may be that it does do not produce accurate results because fluorine levels may be higher or lower in the certain soil. 8E. Describe examples of absolute methods of dating, including the date range that each method can measure. - Answer-Absolute methods of dating include radiocarbon dating which uses the carbon 14 method. involving dating carbon isotopes which are variants based on the number of neutrons in the atoms nucleus. some isotopes of an element are stable and some are unstable. 14C decays into 14N in about 5,000 years. can go up to 50,000yBP dates can be determined for another 25,000 years or so beyond that. radiopotassium dating which is good for all primate evolution uses traces of argon. and can go up to 5 million years. fission track dating uses radioactive decay of naturally occurring Uranium 238 when isotopes decays fragments produced in the decay or fission leaves tracks, this method can date the past several million years. non radiometric methods include amino acid dating can go past 200,000 yBp. in tropical settings and to nearly 3 mya in cooler settings. paleomagnetic dating is based on the changes in the earths magnetic field. electron spin resonance dating relies on the measurement of radioisotope concentrations for example uranium that have accumulated in fossils over periods of time. electron spin resonance dating relies on the measurement of radioisotope concentrations and can range from a few thousand to more than a million years old. thermolusince dating is based on the amount of the suns energy trapped in materials like stone this method can go back to about 800,000 yBP 8F. Define the molecular clock and explain its importance for human evolution. - Answer-the DNA for living organisms which says more closely related DNA means closer links. the molecular clock explains human evolution which says old world monkeys first diverged from all other primates at around 25 mya, gibbons diverged at about 18 mya, orangutangs at around 14 mya and gorillas at 12 mya. hominims and chimps split at 9 mya.