Please help me with this Biology question on Earths History in the Evolution Unit?

Question

Ok this is on the Earths History. Out of 25 questions, i did 22 and i cant figute these 3 out plz help me.

Explain how the half-life of a radioactive isotope affects the usefulness of that isotope in dating specific types of fossils.

Why do some scientists think that areas protected by the atmosphere might have favored the production of organic compounds on early earth?

Why was the discovery of microspheres and coacervates an important contribution to the understanding of how life might have originated on Earth?

plz help me i just need these to be done with my homework THX!

Answer 1

1. Radiometric dating of rocks and fossils depends on a known rate of decay. The half-life is the measure of how fast the isotope decays. If it decays too fast (the half-life is too small), then it cannot be used for dating fossils that are too old. For example, many people think that radiocarbon dating is used for fossils ... but with a half-life of only 5,730 years, it can only be used to date things up to about 60,000 years old ... beyond that, and there is just not enough left to make an accurate measurement. But Potassium-40 has a half-life of 1.26 *billion* years, and so is very useful for dating fossils.

2. That's an odd question. What areas *aren't* protected by the atmosphere? Perhaps they are referring either to the lack of oxygen in the early atmosphere (as oxygen is toxic to organic compounds), or the protection by the atmosphere against UV radiation.

3. "Oparin, who first outlined the theory of the chemical origin of life, worked on coacervates. Coacervation is a process occurring in aqueous solutions of highly hydrated polymers. Two phases separate spontaneously and one of these may consist of hollow, polymer-rich, microscopic droplets suspended in the surrounding medium. Gums are anionic polysaccharides from plants and bind well to positive or neutral proteins. Protein plus polysaccharide or RNA will often form coacervates and enzymes can be trapped inside the droplets when they form." (See source 2.)

Hope that helps.

Answer 2

1. Some isotopes have a short half-life. While you can use those only to measure the age of relatively young materials, you can determine your age range to a finer presicion. The ones with the longer half-lives can be used for much older substances, but are less precise.

Not sure enough about the other two to help. Don't you have a textbook to read? Class notes to look at? Read those.