D3 Human Evolution | BioNinja
Using Geological Layers & Radioactive Dating to Determine the Earth's Age . make uranium-lead dating one of the most reliable methods of radiometric dating because Uranium is not the only isotope that can be used to date rocks; we do see . Ch 3. Characteristics of Atomic Number and Mass Number; States of . Page 1 D Outline the method for dating rocks and fossils using radioisotopes, with D Describe the major anatomical features that define humans as. Start studying Human Evolution (D3). Learn vocabulary Outline the method for dating rocks and fossils using radioisotopes, with reference to 14C. All living.
So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive. When the isotope is halfway to that point, it has reached its half-life.
- Navigation menu
- You must create an account to continue watching
- Radiometric Dating
Uranium-Lead Dating There are different methods of radiometric dating that will vary due to the type of material that is being dated. For example, uranium-lead dating can be used to find the age of a uranium-containing mineral.
It works because we know the fixed radioactive decay rates of uranium, which decays to lead, and for uranium, which decays to lead So, we start out with two isotopes of uranium that are unstable and radioactive.
They release radiation until they eventually become stable isotopes of lead. These two uranium isotopes decay at different rates. In other words, they have different half-lives. The half-life of the uranium to lead is 4.
The uranium to lead decay series is marked by a half-life of million years.
These differing rates of decay help make uranium-lead dating one of the most reliable methods of radiometric dating because they provide two different decay clocks. This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.
Absolute Dating Absolute dating is used to determine a precise age of a rock or fossil through radiometric dating methods. This uses radioactive minerals that occur in rocks and fossils almost like a geological clock. So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks.
Dating Fossils – How Are Fossils Dated? - n3ws.info
The atoms in some chemical elements have different forms, called isotopes. These isotopes break down at a constant rate over time through radioactive decay. By measuring the ratio of the amount of the original parent isotope to the amount of the daughter isotopes that it breaks down into an age can be determined. We define the rate of this radioactive decay in half-lives.
If a radioactive isotope is said to have a half-life of 5, years that means after 5, years exactly half of it will have decayed from the parent isotope into the daughter isotopes.
Dating Fossils – How Are Fossils Dated?
Then after another 5, years half of the remaining parent isotope will have decayed. While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils.
Protobionts, or aggregates of abiotically produced molecules, accumulate organic materials like polypeptides from the environment. However, they probably do not possess a mechanism for replicating their particular characteristics so life cannot start. However, an information storage mechanism like RNA would allow them to pass on their characteristics.
Short strands of RNA, perhaps most importantly the RNA called ribozymes, could have copied themselves and could have catalysed other reactions. They could then align nucleotides according to a certain pattern when bound to clay. Thus RNA could be replicated and passed on. This is supported by the fact that RNA plays an important role in genetic control in cell life today. Living cells may have been preceded by protobionts, aggregates groups of abiotically produced molecules.
IB Biology Option D D3 Human Evolution IB Biology Option D D3 Human Evolution ppt download
To form life they need to compartmentalise themselves from the surrounding water. Some protobionts in the presence of lipids form a molecular bilayer liposome around the protobiont droplet when shaken.
This resembles the lipid bilayer of modern cells. The liposomes can break, reform and merge with others and mix their contents. Within these droplets reactions could be catalysed and RNA could replicate itself. The most successful liposomes at surviving would pass on their characteristics and develop into early prokaryotes.
Eukaryotic cells were probably symbiotic groupings of prokaryotic cells with smaller species living within larger prokaryotes. The endosymbiotic theory focuses on the origins of chloroplasts and mitochondria.
The ancestors of these organisms photosynthetic prokaryotes like algae or respiring bacteria originally entered the host cell as undigested prey or internal parasites.
Normally the invaders would be digested but in this case they were not.
Radiometric Dating: Methods, Uses & the Significance of Half-Life
The host cell would allow them to live and exploit these orginisms provide food and energy. Those which absorbed prokaryotes which became chloroplast and mitochdria formed plants, those without the chloroplasts became animal cells. The evidence that supports this theory is: Mitochondria and chloroplasts have bacteria-like RNA and ribosomes 70S as opposed to 80S in eukaryote cytoplasms that enable them to make their own proteins and divide independently of the host cell.
Mitochondria and chloroplasts both have double membranes, the inner one probably that of the original cell, and the outer that which was created when the cell was absorbed. Thylakoids resemble structures found in blue-green bacteria. Chloroplasts and mitochondria have naked DNA like prokaryotes.
Chlorophyll a is found in both prokaryotes and eukaryotes. Christae in mitochondria resemble mesosomes in bacteria. Lamarcks theory of inheritance of acquired characteristics states that the modifications an organism acquired during its lifetime could be passed along to its offspring. The common idea is that if a giraffe stretches up to reach high leaves, it can pass a long neck onto its offspring.
There is no evidence that acquired characteristics can be inherited. Characteristics that can be passed on are in your genes. If you are not born with genes programming for certain characteristics, you cannot pass down characteristics acquired during your lifetime as these characteristics do not reach sex cells. Populations tend to produce more offspring than an environment can support but populations tend to remain constant There is a struggle for survival among organisms in a species with varied characteristics Those individuals which are best adapted to their environments are most likely to survive Only these pass on their positive characteristics in the form of genes to their offspring who also survive While on his Beagle voyages, Darwin became intrigued with the different types of finches found in the Galapagos.
All the species of birds were very similar, just like a species on the mainland of South America but between the islands they differed in size and beak shape. Darwin found that the birds fed on different types of food. Their beaks were adapted to eat different types of leaves, worms and seeds and other types of diets. Darwin explained all his observations and thoughts about the origin of species by the concept of "natural selection". This theory states that great diversity in a species ensures that some members of a population will be more suited to their environment than others.
These individuals will be more likely to live long enough to reproduce and pass on their well-suited genes. Therefore, because those that are best suited the food on an island are the ones who have the most children, a population will, over time, adapt itself to its environment. The change in the frequency of characteristics genes in a population with a common gene pool is evolution. Panspermia is the theory which suggests that life arose elsewhere in the universe and travelled to Earth through space in comets or meteors.
Special creation states that a creator s formed life directly. Panspermia - Organic compounds and amino acids have been recovered from modern meteorites. This theory is not incompatible with evolution, which would have occurred once life reached Earth.