Bio-Pac 07: Objective 01-03 Flashcards
Objective 1. List the steps in the formation of life on Earth according to Oparin’s hypothesis.
Alexander Oparin hypothesis was that life began in the early oceans. He suggested that energy from the sun and from lightning triggered chemical reactions to produce simple organic compounds from the substances present. The products of the chemical reactions then rain down into the oceans to form what is called primordial soup, which is organic compounds—amino acids, sugars, etc. According to scientists life is started from the formation of simple organic molecules and the organization of these molecules into complex organic molecules such as proteins.
Objective 2. Explain why the first cells could not have been aerobic bacteria.
The first cells could not have been aerobic bacteria, meaning that the first cells could not have been bacteria that needed oxygen. Scientists believe that the first cells were prokaryotes which likely evolved from some type of protocell. Since Earth’s atmosphere was lacking oxygen these cells were likely anaerobic and got their energy from glycolysis and fermentation. By being in warm water the first prokaryotes probably took in organic molecules for food, making them heterotrophs. Overtime the competition of heterotrophs led to the evolution of autotrophs. These first autotrophs are likely similar to the present day archaebacteria. These bacteria probably made their glucose by chemosynthesis rather than photosynthesis which require light-trapping pigments. Next photosynthesizing prokaryotes evolved, which put oxygen into the oxygen-lacking atmosphere which would cause the evolution of aerobic respiration. This shows that even though aerobic respiration is a more efficient method for energy conservation, the first cells were likely anaerobic bacteria and could not have been aerobic bacteria.
Objective 3. Explain how radioactive dating techniques are used to date fossils.
Scientists use radiometric dating techniques, which involve the use of radioactive isotopes, which are unstable nuclei that break down giving off radiation and forming a different element. The decay rate of each radioactive element is known and continues at a steady rate, which will allow scientists to use them as a steady type of clock. Fossils and archaeological artifacts that are less than 50,000 years old are dated with carbon-14. Carbon-14 breaks down to half its original amount in 5,730 years.
