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Chapter 18: Problem 74

The radiant energy emitted by a star gradually increases after its birth. During the Hadean eon, while the molten Earth cooled and life emerged, the Sun provided approximately 25% less radiant energy than it does now. Ignoring effects due to differences in the composition of Earth's atmosphere between then and now, this means that the average surface temperature of the surface would be about 25 掳C below the freezing temperature of water. Evidence of liquid water on Earth during the Hadean eon is provided by geologic structures known only to form in liquid water, such as lava pillows and the stromatolites that are the fossilized layers of photosynthetic cyanobacteria. Pose a scientific question that guides inquiry into early Earth conditions that supported the innovation of photosynthesis.

Short Answer

Expert verified
How did geothermal heat and atmospheric conditions during the Hadean eon create an environment conducive to the innovation of photosynthesis?

Step by step solution

01

Identify Key Information

Identify and note down the main points mentioned in the exercise: The Sun provided approximately 25% less radiant energy during Hadean eon. The surface temperature was about 25 掳C below the freezing temperature of water. Evidence of liquid water during Hadean eon is provided by geologic structures.
02

Understand the Phenomenon

Understand that despite lower radiant energy from the Sun and colder surface temperatures, there was liquid water on Earth. This implies that some conditions allowed liquid water to exist.
03

Recognize the Focus of Inquiry

The task is to formulate a scientific question that guides an investigation into early Earth conditions supporting photosynthesis innovation.
04

Brainstorm Relevant Factors

Think about what factors could allow liquid water and support photosynthesis: geothermal heat, greenhouse gases, atmospheric conditions, etc.
05

Formulate the Scientific Question

Combine the key information and factors to pose a scientific question. For example: 'How did geothermal heat and atmospheric conditions during the Hadean eon create an environment conducive to the innovation of photosynthesis?'

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Hadean eon
The Hadean eon is named after Hades, the ancient Greek god of the underworld, reflecting the extreme and volatile conditions of early Earth. It spans from the formation of the Earth about 4.6 billion years ago to approximately 4 billion years ago. During this period, Earth was incredibly hot and largely molten due to frequent asteroid impacts and intense volcanic activity.

Despite these harsh conditions, the Hadean eon is crucial because it laid the foundations for the planet's future development. Early oceans formed as the planet began to cool and water vapor condensed. These early bodies of water created a potential cradle for the origins of life.
  • Intense volcanic activity
  • Frequent asteroid impacts
  • Formation of early oceans
Understanding the Hadean eon helps us grasp how Earth evolved from a hostile environment to one capable of supporting life.
radiant energy
Radiant energy from the sun is essential for life on Earth. During the Hadean eon, the Sun emitted about 25% less radiant energy than it does today. This reduction implies that Earth received less heat, affecting the planet's surface temperature significantly. The average temperature was roughly 25掳C below the freezing point of water.

Despite this, liquid water existed, suggesting that other factors compensated for the lower radiant energy. Radiant energy drives processes like photosynthesis and regulates the climate, proving essential for sustaining life.

Key aspects:
  • Reduced by 25% during Hadean eon
  • Influences Earth's surface temperature
  • Essential for processes like photosynthesis
Understanding radiant energy variations helps explain early Earth's climate and the potential for life.
geologic structures
Geologic structures are physical features formed by various geological processes. During the Hadean eon, evidence of liquid water is provided by structures such as lava pillows and stromatolites. Lava pillows form when lava erupts underwater, creating rounded structures. Stromatolites are fossilized layers built by photosynthetic cyanobacteria, indicating shallow marine environments.

These structures are crucial in interpreting early Earth conditions and confirming the presence of liquid water despite low temperatures. Key points include:
  • Lava pillows
  • Stromatolites
  • Indicate liquid water presence
Studying these structures helps us understand the environment and climate of early Earth, providing crucial context for the conditions needed for life.
photosynthesis
Photosynthesis is the process by which organisms, like cyanobacteria, convert light energy into chemical energy. During the Hadean eon, evidence of photosynthesis comes from stromatolites, indicating that photosynthetic organisms existed even under harsh conditions.

Photosynthesis requires not just light but also liquid water and atmospheric carbon dioxide. The presence of liquid water and the ability of early cyanobacteria to photosynthesize suggest an intricate interplay of environmental factors. Key elements include:
  • Requires light energy and water
  • Evidenced by stromatolites
  • Supports early life
Understanding how photosynthesis began and was sustained helps explain the evolution of early life forms and the development of Earth's atmosphere.
geothermal heat
Geothermal heat refers to the heat from Earth's interior, which can significantly affect surface conditions. During the Hadean eon, geothermal heat likely played a crucial role in maintaining liquid water on Earth's surface despite lower radiant energy from the sun.

This heat comes from radioactive decay of elements and residual heat from Earth's formation. It could create localized warm areas, supporting liquid water and possibly life. Key points include:
  • Heat from Earth's interior
  • Influences surface conditions
  • Supports liquid water presence
Geothermal heat's role in early Earth conditions highlights its importance in creating habitable environments despite cooler surface temperatures.
greenhouse gases
Greenhouse gases, like carbon dioxide (CO鈧�) and methane (CH鈧�), trap heat in Earth's atmosphere, warming the planet. During the Hadean eon, higher levels of these gases could have compensated for the reduced radiant energy from the sun.

By trapping heat, greenhouse gases would maintain surface temperatures above the freezing point of water, allowing liquid water to exist. Key aspects include:
  • Trap heat in the atmosphere
  • Compensate for lower solar energy
  • Essential for maintaining liquid water
Understanding how greenhouse gases function in early Earth conditions helps explain the preservation of liquid water and the potential for early life forms.

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Most popular questions from this chapter

Until recently, these three species of short-tailed pythons, Python curtus, Python brongersmai (middle), and Python breitensteini were considered one species. However, due to the different locations in which they are found, they have become three distinct species. What is this an example of? a. divergent evolution b. sympatric speciation c. allopatric speciation d. variation

Mutations in the glucose 6-phosphate dehydrogenase (G6PD) gene can cause a rare anemia when inherited. However, homozygotes with this mutation are less prone to malaria infection, a disease that historically was the most widespread deadly disease among humans. Predict how this mutation would affect the fitness of individuals living in countries where malaria is endemic.

Give an example of convergent evolution and explain how it supports the theory of evolution by natural selection. a. An example of convergent evolution is the development of the same function, swimming, in organisms that live in different parts of the globe, such as Arctic beluga whales and Antarctic right whales. The fact that organisms that do not come in contact with each other have developed the same traits suggests that natural selection can produce similar adaptations in organisms who share a similar environment b. An example of convergent evolution is the set of adaptations, such as better running speed or more efficient hunting, developed by a species in response to competition with a new species that moves into the same region. The fact that a species adapts after it comes into contact with a competitor suggests that natural selection works more quickly with higher selective pressures. c. An example of convergent evolution is the development of an ancestral structure, a limb, into two different modern structures, such as a hand and a flipper. The fact that natural selection can cause a structure to develop down two different pathways due to different environmental conditions supports the theory of evolution d. An example of convergent evolution is the development of the same function, flying, in organisms that do not share a recent common ancestry, such as insects and birds. The fact that wings that allow flight have developed from very different original structures suggests that the process of natural selection can produce similar adaptations in two very different types of organisms who share a similar environment

Prior to 1800 in England, the typical moth of the species Biston betularia (peppered moth) had a light pattern. Dark colored moths were rare. By the late 19th century, the light-colored moths were rare, and the moths with dark patterns were abundant. The cause of this change was hypothesized to be selective predation by birds (J.W. Tutt, 1896). During the industrial revolution, soot and other wastes from industrial processes killed tree lichens and darkened tree trunks. Thus, prior to the pollution of the industrial revolution, dark moths stood out on light-colored trees and were vulnerable to predators. With the rise of pollution, however, the coloring of moths vulnerable to predators changed to light. Commonly used in biology textbooks, the peppered moth is a classic example of evolutionary change in action. The example describes changes in a population鈥檚 allele frequencies-a small-scale change, evolutionarily speaking. The presence of both light and dark forms within the gene pool is demonstrated by the story, but the peppered moth stays a peppered moth. Which scenario, if it were to occur, would be a model for large-scale evolutionary change? a. Conditions change such that the dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, the dark form is vulnerable, and the light form returns to prevalence. b. Conditions change such that the dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable, and the dark form is eradicated due to predation. c. Conditions change such that dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, and both forms have equal prevalence. d. Conditions change such that dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable. It develops an adaptation that shields it from predation.

Which of the following statements is false? a. Graudal speciation and punctuated equilibrium both result in the divergence of species. b. Punctuated equilibrium is most likely to occur in a large population in a stable environment. c. In the punctuated equilibrium model, gradualism is not excluded. d. In the gradual speciation model, traits change incrementally
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