Concept explainers
Compare and contrast the physical and chemical conditions on Earth at the time life first arose with conditions today. From a physiological standpoint, discuss at least two reasons why animals could not have existed on early Earth. In what ways has microbial
Big bang theory states that the entire universe and its subjects exapnded from high temperature and density state. Big bang theory explains that all the planets in the solar system arise from the sun by means of cosmic explosion. Earth formed 4.5 billion years ago by the cosmic explosion. Primitive earth is full of gas in the form of a molten liquid. Gradual cool down process of earth and chemical reaction gives rise to water and living organisms.
Explanation of Solution
The earth surface has changed over the period of time due to several factors. Huge flows of molten rock within the earth surface produced a series of gigantic solid plates known as tectonic plates. These plates have drifted on to the mantle of the planet slowly. The drift of tectonic plates had shown two important effects on the evolution and distribution of the life on the earth. The climate of the earth had shown drastic changes over millions of the years. Sometimes the earth covered with glacial ice and sometimes the ice melted raising the sea levels covering the earth with the oceans and with little land area.
The early earth could not have the magnetic field and gravitation force to hold the gases. Later about 4 billion years ago the earth cooled to form solid crust with dense elements like hydrogen and nitrogen formed in the first atmosphere. The first formed earth was very different from today’s earth as it contained gases like hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water in the form of water vapor. The earth has undergone several collisions with the comets and asteroids and the surface of the earth was cooled by the formation of oceans that drenched the planet with thunder storms. These conditions made the earth inhospitable to the formation of life 4.5 billion years ago.
The evolution of photosynthesis changed the environment and life on the earth. Earlier photosynthetic forms existed on the earth carry the process of photosynthesis under anaerobic conditions. Therefore, the process was known as anoxygenic photosynthesis. This process involved the electron donors like H2S and produced elemental sulfur (So) as a waste product. Later on phototrophs had diverged from the anoxygenic phototrophs (Photosynthetic bacteria) which had the ability to trap the solar radiation and utilized it as energy source. This was occurred about 2.5 to 3.5 billion years ago with the evolvement of cyanobacterial lineage that were capable of oxygenic photosynthesis. In this process the H2S was replaced with H2O reducing the CO2 producing the O2 as waste product. The origin of oxygenic photosynthesis filled the earth’s atmosphere with O2 that caused the evolution of newer forms of life that were able to utilize the O2 for respiration.
In absence of oxygen the iron in the earth would have been existed in the reduced form and most of this might be dissolved in the ocean. Oxygen produced by the cyanobacteria might react with the reduced iron in the oceans and produce iron oxides. The O2 produced by cyanobacteria reduced to the iron oxides that are poorly soluble in water and precipitated the ocean floors forming sedimentary structures called banded iron formations or rocks containing the deposits of iron and silica materials. The banded iron formations contribute to the source of iron ore at present times. Thus, the oxygen produced by cyanobacteria rather accumulate in the atmosphere reduced the iron and then accumulated to reach the 21% in the atmosphere at present. Presence of photosynthesis and oxygen makes the life form to exist on the earth.
Want to see more full solutions like this?
Chapter 13 Solutions
Brock Biology of Microorganisms (15th Edition)
- Many scientists claim that the synthesis of the first organic molecules from inorganic precursors was possible because of the highly reducing atmosphere found on primitive Earth. Which of the following is an appropriate null hypothesis that could be used when investigating the claim? * The level of atmospheric oxygen on modern Earth is significantly higher than on primitive Earth. Organic molecules were transported to primitive Earth by a meteorite or other celestial event. The synthesis of organic molecules from inorganic molecules is possible under current atmospheric oxygen levels as well as those found on primitive Earth. The absence of a significant quantity of atmospheric oxygen is required for the synthesis of organic molecules from inorganic precursors.arrow_forwardA scientist discovered a new group of unicellular organisms that lack mitochondria but possess an organelle related to the endoplasmic reticulum and is involved in energy production. The scientist hypothesizes that this organelle might be a missing link in the evolution of mitochondria. A) Do you agree with this hypothesis? Explain. B) Based on the available evidence, what is the most likely hypothesis for the origin of mitochondria? Provide four pieces of evidence to support this theory and justify why they are valid.arrow_forwardBesides carboxylation, the Calvin Cycle enzyme rubisco can also react with O2 (e.g. oxygenation). The wasteful oxygenation reaction of rubisco is explained by the enzyme developing at time when there was very little O2 in the atmosphere. Since it was developed, why hasn’t rubisco evolved to get rid of the oxygenation reaction? A. Mutations that decrease the affinity of rubisco for O2 probably also decrease the enzyme’s ability to bind CO2. B. Evolution takes time; and since rubisco is found only in eukaryotes, it evolved recently. C. Since it still generates one molecule of 3-phosphoglycerate (PGA), the oxygenation reaction is actually not that wasteful. D. Because in the past few million years the concentration of CO2 in the atmosphere has risen to be much greater than the concentration of O2.arrow_forward
- Why was the development of enzymes fundamental to the evolution of life? a) without enzymes, the activation energy for essential reactions was too low b) enzymes allowed for high rate of catalysis at relatively low temperatures c) enzymes reduced the cellular demand for ATP d) enzymes allowed for reactions to occur spontaneouslyarrow_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_forwardFor questions 30 through 36, select the location where the following events occur. Answers may be used once, more than once, or not at all. Some questions may have one answer, some questions may have more than one answer. a) mitochondrial inner membrane b) mitochondrial intermembrane space c) mitochondrial matrix d) thylakoid membrane e) thylakoid space 30. electron chain components embedded here 31. H+ pumped into here 32. found in plants 33. found in animals 34. ADP+ Pi→ ATP occurs here 35. ATP synthase embedded here 36. Light-capturing pigments embedded here asap please.arrow_forward
- The animals body plans that emerged from the Cambrian Explosion were multi-cellular and significantly larger than animals that predated the Cambrian. This required the ability to use the process of aerobic respiration to more efficiently break down food molecules. What are two milestones that occurred in the Eon(s) that predated the Cambrian explosion that allowed for this more efficient form of energy production? (List both the milestone and the Eon in which it occurred)arrow_forwardConsidering what you know about how atmospheric oxygen changed over the 4.5 billion years that life has existed on earth, which metabolic process, photosynthesis or cellular respiration via oxidative phosphorylation, likely evolved first? Why?arrow_forwardWhy did the evolution of multicellular organisms such as plants and animals have to be preceded by the evolution of oxygen-producing photosynthesis?arrow_forward
- 1) According to the endosymbiotic theory of the origin of chloroplasts, photosynthetic prokaryotic cells________? 2) The tremendous increase in the diversity of animals beginning about 542 million years ago is called the______? 3) Two completely unrelated species that are found in the same environment are observed to have the same adaptation. This observation describes_________?arrow_forwardAccording to the endosymbiotic theory, which of the following is NOT true about the evolution of life on earth? Eukaryotes and prokaryotes appeared at about the same time and evolved independently from each other. O None of the other four answers (all are true statements) Eukaryotes evolved from symbiotic prokaryotes living inside other prokaryotes Mitochondria and chloroplasts are in some ways similar to prokaryotes The first life on earth was simple organisms, similar to today's prokaryotesarrow_forwardIn their laboratory experiments of simulations of early Earth, Miller and Urey observed the abiotic synthesis of abundant amounts of DNA amino acids liposomes genetic systems Which of the following was probably NOT present in the primitive Earth s atmosphere (when life first appeared)? O2 NH3 H2O CH4 CO2arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education