Need help with some fairly simple biology questions. 1. What is chemical selection? 2. How do paleontologists determine the age of a fossil? 3. Define evolution. What is the difference between microevolution and macroevolution? Solution 1. Chemical selection occurs when a chemical within a mixture has special properties or advantages that cause it to increase in number compared to other chemicals in the mixture. Initially, scientist speculate that the special properties that enabled certain RNA molecules to undergo chemical selection were its ability to self-replicate and to perform other enzymatic functions. 2. Scientists combine several well-tested techniques to find out the ages of fossils. The most important are relative dating, in which fossils and layers of rock are placed in order from older to younger, and radiometric dating, which allows the actual ages of certain types of rock to be calculated. Relative Dating. Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age, (i.e. estimated age). In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another. Fossils are found in sedimentary rocks that formed when eroded sediments piled up in low-lying places such as river flood plains, lake bottoms or ocean floors. Sedimentary rock typically is layered, with the layers derived from different periods of sediment accumulation. Almost any place where the forces of erosion - or road crews - have carved through sedimentary rock is a good place to look for rock layers stacked up in the exposed rock face. If we look at a layer cake, we will that the layer at the bottom was the first one the baker put on the plate, and the upper ones were added later. In the same way, geologists figure out the relative ages of fossils and sedimentary rock layers; rock layers, and the fossils they contain, toward the bottom of a stack of sediments are older than those found higher in the stack. Radiometric Dating. The use of radiometric dating was first published in 1907 by Bertram Boltwood. Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. Now it the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms Radiocarbon dating: It involves determining the age of an ancient fossil or specimen by measuring its carbon-14 content. Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecu.

1. Need help with some fairly simple biology questions.
1. What is chemical selection?
2. How do paleontologists determine the age of a fossil?
3. Define evolution. What is the difference between microevolution and macroevolution?
Solution
1. Chemical selection occurs when a chemical within a mixture has special properties or
advantages that cause it to increase in number compared to other chemicals in the mixture.
Initially, scientist speculate that the special properties that enabled certain RNA molecules to
undergo chemical selection were its ability to self-replicate and to perform other enzymatic
functions.
2. Scientists combine several well-tested techniques to find out the ages of fossils. The most
important are relative dating, in which fossils and layers of rock are placed in order from older to
younger, and radiometric dating, which allows the actual ages of certain types of rock to be
calculated.
Relative Dating. Relative dating is the science of determining the relative order of past events
(i.e., the age of an object in comparison to another), without necessarily determining their
absolute age, (i.e. estimated age). In geology, rock or superficial deposits, fossils and lithologies
can be used to correlate one stratigraphic column with another.
Fossils are found in sedimentary rocks that formed when eroded sediments piled up in low-lying
places such as river flood plains, lake bottoms or ocean floors. Sedimentary rock typically is
layered, with the layers derived from different periods of sediment accumulation. Almost any
place where the forces of erosion - or road crews - have carved through sedimentary rock is a
good place to look for rock layers stacked up in the exposed rock face.
If we look at a layer cake, we will that the layer at the bottom was the first one the baker put on
the plate, and the upper ones were added later. In the same way, geologists figure out the relative
ages of fossils and sedimentary rock layers; rock layers, and the fossils they contain, toward the
bottom of a stack of sediments are older than those found higher in the stack.
Radiometric Dating. The use of radiometric dating was first published in 1907 by Bertram
Boltwood. Radiometric dating or radioactive dating is a technique used to date materials such as
rocks or carbon, in which trace radioactive impurities were selectively incorporated when they
were formed. The method compares the abundance of a naturally occurring radioactive isotope
within the material to the abundance of its decay products, which form at a known constant rate
of decay. Now it the principal source of information about the absolute age of rocks and other

2. geological features, including the age of fossilized life forms
Radiocarbon dating: It involves determining the age of an ancient fossil or specimen by
measuring its carbon-14 content. Carbon-14, or radiocarbon, is a naturally occurring radioactive
isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which
then oxidize to become carbon dioxide. Green plants absorb the carbon dioxide, so the
population of carbon-14 molecules is continually replenished until the plant dies. Carbon-14 is
also passed onto the animals that eat those plants. After death the amount of carbon-14 in the
organic specimen decreases very regularly as the molecules decay. Carbon-14 has a half-life of
5,730 ± 40 years, meaning that every 5,700 years or so the object loses half its carbon-14.
Samples from the past 70,000 years made of wood, charcoal, peat, bone, antler or one of many
other carbonates may be dated using this technique.
3. Evolution is the process by which different kinds of living organism are believed to have
developed from earlier forms during the history of the earth. Evolutionary processes give rise to
biodiversity at every level of biological organisation, including the levels of species, individual
organisms, and molecules.
Microevolution
Macroevolution
1. Microevolution is evolutionary change happening below the species level.
1. Macroevolution is an evolutionary change happening at or below he species level.
2. It occurs within a single population.
2. It occurs on a scale that transcends the boundaries of a single species.
3. Microevolution can be caused by natural or artificial selection, mutation, migration, non-
random mating, or genetic drift. All of these processes cause a change in allele frequencies
within a population over time.
3. Macroevolution can be caused by speciation and extinction.
4. The time scale necessary to observe microevolution, as it occurs in relatively small
population,more precisely only a few generations.
4. Macroevolution is merely a result of a lot of microevolution over a long period of time.
5. It relatively produce a small-scale (“micro”) changes within a population.
5. It produce large-scale (“macro”) changes within a population that means it results in the
formation of new species.
Microevolution
Macroevolution
1. Microevolution is evolutionary change happening below the species level.
1. Macroevolution is an evolutionary change happening at or below he species level.

3. 2. It occurs within a single population.
2. It occurs on a scale that transcends the boundaries of a single species.
3. Microevolution can be caused by natural or artificial selection, mutation, migration, non-
random mating, or genetic drift. All of these processes cause a change in allele frequencies
within a population over time.
3. Macroevolution can be caused by speciation and extinction.
4. The time scale necessary to observe microevolution, as it occurs in relatively small
population,more precisely only a few generations.
4. Macroevolution is merely a result of a lot of microevolution over a long period of time.
5. It relatively produce a small-scale (“micro”) changes within a population.
5. It produce large-scale (“macro”) changes within a population that means it results in the
formation of new species.