Concept explainers
Because there was no oxygen in the earliest atmosphere, the first cells must have derived energy by __________
To review:
The given blank space in the statement, “because there was no oxygen in the earliest atmosphere, the first cells must have derived energy by _______________ metabolism of organic molecules. Oxygen was introduced into the atmosphere when some microbes developed the ability to ___________ and released oxygen as a byproduct. Oxygen was ___________ to many of the earliest cells, but some cells evolved the ability to use oxygen in ___________ respiration, which provided far more _______________.”
Introduction:
Oxygen is one of the most abundant elements on the earth. It is a major constituent of all the living organisms. The first cells found on the earth were prokaryotes, for example, cyanobacteria (blue-green algae). Its genetic material does not contain a nucleus. The origin of oxygen came into existence due to the evolution of prokaryotes.
Explanation of Solution
The evolution of oxygenic photosynthesis during the archean eon was one of the most important events in the history of life on Earth. The release of molecular oxygen by oxygenic Cyanobacteria had major consequence for the geochemistry of Earth’s surface as it involves the redox state changes which modified the bioavailability of redox sensitive metals such as iron, molybdenum, and copper. The first cells obtained energy by absorbing organic molecules from the environment because there was no oxygen present in the environment. The prokaryotes metabolized the organic molecules anaerobically.
When these microbes developed the ability to synthesize food in the presence of sunlight, it led to the release of oxygen as a byproduct and the use of carbon dioxide and water. This process is known as photosynthesis. Oxygen is also necessary for many cells because they perform aerobic respiration. In this process, more and efficient energy is obtained.
Because there was no oxygen in the earliest atmosphere, the first cells must have derived energy by anaerobic metabolism of organic molecules. Oxygen was introduced into the atmosphere when some microbes developed the ability to photosynthesis and released oxygen as a byproduct. Oxygen was harmful to many of the earliest cells, but some cells evolved the ability to use oxygen in aerobic respiration, which provided far more energy.
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Chapter 17 Solutions
Biology: Life on Earth
- Photosynthesis carried out by one group of ________ resulted in Earths first increase in atmospheric oxygen levels. a. archaea c. protists b. bacteria d. algaearrow_forwardA rise in oxygen in Earths air and seas set the stage for the evolution of _______. a. aerobic respiration c. photosynthesis b. fermentation d. sexual reproductionarrow_forwardThe first organisms that oxygenated the atmosphere were ______. a. cyanobacteria b. phootrophic organisms c. anaerobic organisms d. allof the abovearrow_forward
- Which of the following was not present by the end of Precambrian? a. archaea c. fungi b. bacteria d. fisharrow_forwardWhich sequence of events accurately describes the history of the planet (from oldest to youngest)? Eukaryotes appear, Oxygen increases in the atmosphere, Prokaryotes appear, Oxygen increases in the atmosphere, Eukaryotes appear, Prokaryotes appear Prokaryotes appear, Oxygen increases in the atmosphere, Eukaryotes appear Prokaryotes appear, Eukaryotes appear, Oxygen increases in the atmospherearrow_forwardAn abundance of___________ in Earths early atmosphere would have prevented the spontaneous assembly of organic compounds on early Earth. a. hydrogen b. methane c. oxygen d. nitrogenarrow_forward
- The table below shows four organisms and the biological processes each uses. Select the organisms that removes carbon from the atmosphere.arrow_forwardWhich of these steps probably occurred first in the chemical andbiological evolution of life?a. The cell membrane of a protobiont formed.b. The first organic molecules formed.c. The original genetic material was RNA.d. Simple organic monomers formed from inorganic materials.arrow_forwardScientist have determined that the early Earth had no free oxygen anywhere. Briefly explain what evidence in the rock layers that scientists found to prove when the early conditions on earth had free oxygen in the atmosphere.arrow_forward
- Chloroplasts of green algae evolved from_____ . a. cyanobacteria b. archaea c. red algaearrow_forwardThe early earth atmosphere was _____. MULTIPLE CHOICE. Choose only one. a. Reducing and favors biosynthetic reactions b. Reducing, due to absence of carbon dioxide c. Oxidizing, due to abundance of oxygen d. Oxidizing an favors breakdown of moleculesarrow_forwardWhich are thought to have evolved first, aerobic bacteria or photosynthetic bacteria? Explain.arrow_forward
- Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College