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Lecture

BMEN 515 Lecture Notes - Continental Drift, Radionuclide, Cellular Respiration


Department
Biomedical Engineering
Course Code
BMEN 515
Professor
William Huddleston

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Fossils- the preserved remains of ancient organisms
Paleontologists- scientists who study fossils
Morphology- the body form
Age of rocks cannot be determined by just looking at them, but the age of rocks can only be
determined when comparing one another
Strata- oldest layers in rocks; are known to lie at the bottom, and successively higher strata are
progressively younger
William Smith concluded that:
o Fossils of similar organisms were found in widely separated places on Earth
o Certain organisms were always found in younger rocks than certain other organisms
o Organisms found in higher, more recent strata were more similar to modern organisms
than were those found in lower, more ancient strata
Radioisotopes
Radioactivity- a method of dating rocks; discovered at the beginning of the twentieth century
Half-Life- a successive time interval in which half of the remaining radioactive material of the
radioisotope decays, either changing into another element or becoming the stable isotope of the
same element
For 14C, production in the upper atmosphere is about equal to its natural decay.
In an organism, the ratio of 14C to 12C stays constant during its lifetime.
When an organism dies, it is no longer incorporating 14C from the environment.
The 14C that was present in the body decays with no replacement and the ratio of 14C to 12C
decreases.
As soon as an organism dies, it ceases to exchange carbon compounds with its environment
Isotopes in a sedimentary rock do not contain reliable information about the date of its formation
o Since they are transported over long distances and are deposed in another location
But igneous rocks (e.g., lava or volcanic ash), that have intruded into layers of sedimentary rock can
be dated.
Other radioisotopes are used to date older rocks.
Decay of potassium-40 to argon-40 is used for the most ancient rocks.
Radioisotope dating is combined with fossil analysis.
Lithosphere- is Earth’s crust which consists of a number of solid plates each about 40 kilometers
thick
o Floats on a fluid layer of molten rock or magma; the magma circulates because heat
produced by radioactive decay deep in Earth’s core sets up convection currents in the
fluid
The plates move because magma rises and exerts tremendous pressure
Where plates are pushed together, either they move sideways past each other, or one plate slides
under the other, pushing up mountain ranges and carving deep rift valleys (when they occur under
water, such valleys are known as trenches)
Where plates are pushed apart, ocean basins may form between them
Continental Drift- movement of the lithospheric plates and the continents they contain
Throughout Earth’s history, the plates that carry the continents have drifted apart and moved
back together numerous times.
Plate movement has affected climate, sea level, and the distribution of organisms.
Increase of Oxygen in Atmosphere
Increase in atmospheric oxygen have been largely unidirectional
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