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Presumably in the first billion years of the Earth’s existence, there were many
- a) With the above scenario in mind, discuss the significance (to life on earth) of the original development of photosynthesis in some bacteria (withoutO2formation) .(6)
- b) Discuss the significance of the Blue-Greens and the production of O2. (Keep in mind that this was long before Eukaryotes developed.)
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- In the prebiotic world, the chemical evolution scenario proposes that: Small inorganic compounds gave rise to simple biomolecules from meteorites impacts on the Earth surface. Large inorganic compounds gave rise to simple biomolecules when sparked by lighting Small inorganic compounds gave rise to simple biomolecules when dissolved in sulfuric acid Simple biomolecules were created by primitive bacteria Small inorganic compounds gave rise to simple biomolecules when sparked by lighting.arrow_forwardWhich of the following questions about the origin of life on Earth is most scientifically testable? * Why were the earliest life-forms created using only twenty amino acids? Did life originate to make the universe a better place? Was catalytic RNA used by ancient organisms as a stepping stone to acquire protein enzymes? Can simple organic molecules form spontaneously in an oxygen-free atmosphere?arrow_forwardIn the 1950s, scientists Miller and Urey conducted a classic experiment in which water, methane, ammonia, and hydrogen were sealed in a flask containing a pair of electrodes. An electric spark was fired between the electrodes, and after a week's time, they found that amino acids were present in the flask. Which of the following best explains the significance of this experiment in explaining the origin of life on Earth? A. It showed that any raw materials could produce the compounds necessary for life to exist on early Earth. B. It showed that life must have started somewhere else since organic compounds only come from living thin C. It showed how biological molecules can be formed from the very simple molecules that were available on early Earth. D. It showed how lightning can cause organic matter to decompose into amino acids, which were the first molecules on early Earth.arrow_forward
- Which of the following is least reasonable regarding the Urey-Miller experiment? Group of answer choices The experiment was an important breakthrough in the study of the origin of life. The experiment conifirmed that several of the key molecules of life could have been synthesised naturally on the primitive Earth. The amino acids and other molecules produced in the experiment, and possibly present in the early atmosphere, could have participated in 'prebiotic' chemical processes, ultimately creating life. This experiment, and others which followed, suggests that simple biologically significant molecules can evolve naturally under sets of conditions that may have existed not only on early Earth, but potentially elsewhere in the solar system and beyond. The experiment was the first demonstration of abiogenesis (life from non-life).arrow_forwardOne of the simplest definitions of a life-form is anything with the capacity to reproduce and regulate itself. Before life began, the complex organic, or hydrocarbon-bearing, molecules that makeup RNA and DNA, the building blocks of life, must have formed. No one knows exactly how life is formed from these molecules, but many ideas have been put forward. As you enter this area, go toward the large video screen on the right and explore the “Life at the hydrothermal Vents” label deck. Some scientists theorize that life begins at deep-sea vents. Find three lines of evidence to support this claim.arrow_forwardCritics of evolution often cite the fact that several hypotheses are being tested to help explain various stages of the origin of life. Explain how having several hypotheses for the evolution of monomers does not negate the fact that evolution of monomers was the first stage in the evolution of life?arrow_forward
- why is carbon considered the backbone of life?arrow_forwardThe Earth’s atmosphere consists of 78% nitrogen. Why do you think that plants and animals can’t use nitrogen as it is found in the atmosphere?arrow_forwardStanley Miller and Harold Urey provided the first experimental evidence that . Group of answer choices Inorganic molecules could be created from organic precursors Darwin's theory of evolution by natural selection could be correct Organic molecules could be created from inorganic precursors The atmosphere of Early Earth contained inorganic moleculesarrow_forward
- Some scientists propose that Silicon might be a suitable alternative to Carbon as the basicatom that forms the “backbone of life”. Why is this?arrow_forwardAn astrobiologist discovers a new form of life on another planet. Life here appears to have evolved using DNA as the information storage molecule and proteins to carry out cellular function, much like on Earth, however the individual building blocks on this planet are different. On this planet, there appear to be 3 different nucleotides in the DNA and 30 different amino acids in the proteins. Which of the following conclusions about this form of life would be most justified? These organisms can produce proteins no more than 30 amino acids in length. These organisms must produce 30 different forms of mRNA Amino acids must be coded by sets of 3 nucleotides in the DNA of the organisms on this planet. Amino acids must be coded by sets of at least 4 nucleotides in the DNA of the organisms on this planet. These organisms cannot produce more than 30 kinds of protein.arrow_forwardRadioactive isotopes are routinely used to investigate processes in living things. In 1941, biologists exposed photosynthesizing cells to water containing a heavy oxygen isotope, designated 18-O. The labelled isotope appears in the oxygen gas released in photosynthesis, demonstrating that the oxygen came from water. Explain where the 18-O would have ended up if the researchers had used 18-O-labelled carbon dioxide.arrow_forward
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