21 Questions
Which gases were likely present in Earth's first atmosphere?
Hydrogen and helium
What caused Earth's second atmosphere?
Volcanic outgassing
Why was there very little oxygen in Earth's second atmosphere?
It reacted with other elements
Which two scientists proposed nearly identical hypotheses for the steps of how life could have originated on Earth?
Alexander Oparin and J. B. S. Haldane
What is the final step proposed by Oparin and Haldane for the origin of life on Earth?
Packaging of molecules into compartments with an internal chemistry different from the surroundings
Which type of molecules can be large with many atoms and are usually associated with living organisms?
Organic molecules
What is the first step in the Oparin-Haldane origin of life hypothesis?
Formation of simple organic molecules from inorganic precursors
Which type of molecules contain carbon and hydrogen and are usually associated with living organisms?
Organic molecules
What is the first step in the Oparin-Haldane origin of life hypothesis?
Formation of inorganic molecules
Which process do most living things use to get the energy to synthesize molecules?
Cellular respiration
How did organic molecules form from inorganic precursors on early Earth?
Through the input of energy
Which experiment demonstrated evidence for the origin of carbon compounds?
Miller and Urey experiment
Which organic molecules can spontaneously form spherical bilayers, potentially encapsulating self-replicating molecules?
Fatty acids
What is considered to be the smallest unit of life on Earth?
Cells
Which molecules may have been able to spontaneously form polymers on early Earth via anabolic reactions?
Amino acids
Approximately how long ago is there evidence that life existed on Earth?
3.8 billion years ago
What is the length of time over which life has been evolving on Earth?
3 billion years
Which of the following is NOT mentioned as an approach used to estimate the dates of major events in the evolution of life on Earth?
Carbon dating
During which event did the oxygen concentration in the Earth's atmosphere increase from 0% to around 20%?
The Great Oxygenation Event
When did photosynthesis first evolve?
3200 million years ago
What changes did photosynthesis cause to the Earth's atmosphere?
Enormous changes
Test your knowledge of Earth's prebiotic atmospheres and how they originated. Learn about the role of hydrogen and helium, and explore the formation of Earth's second atmosphere.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
