Living Earth

The diagram below shows the experimental setup of the Miller-Urey experiment. When originally performed in 1952, this experiment was thought to provide conclusive evidence for the theory that life originated as the result of chemical reactions in the primitive Earth's atmosphere. Which of the following is currently considered by scientists to be a potential flaw in this classic experiment?

• The experiment only produced some of the organic compounds necessary to produce life.
• The gases used in the experiment are no longer believed to accurately represent the composition of the primitive atmosphere.
• There was no lightning in the primitive atmosphere to provide energy for chemical reactions.
• The primitive ocean would not have had a source of heat.

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NGSS.HS-ESS1-6

The RNA World Hypothesis proposes that life originated from self-replicating RNA molecules, prior to the existence of DNA and proteins. Which of the following pieces of evidence does not support this hypothesis?

• The fact that the parts of the ribosome that function to carry out translation are RNA, and not proteins, supports the idea that RNA could have been used to catalyze reactions before proteins existed.
• RNA has the ability to store genetic information.
• RNA is a less stable molecule than DNA.
• Ribozymes are RNA molecules that can catalyze reactions.

Which of the following pieces of evidence can be used to support the theory that complex organic molecules, such as amino acids and nucleic acids, could have originally formed in the Earth's oceans?

• Non-photosynthetic ecosystems have been discovered near hydrothermal vents in the ocean floor.
• Water is a known by-product of reactions that synthesize complex organic molecules from simpler ones.
• Earth's oceans contain a great diversity of living organisms.
• Water and organic compounds have been identified in asteroids in the solar system.

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NGSS.HS-ESS1-6

The significance of water is a common component of most leading theories on the origin of life on Earth. Which of the following statements best explains why scientists believe that water played an essential role in the development of complex organic compounds on Earth?

• The structure of a water molecule gives it properties similar to organic compounds.
• Water has not been found anywhere else in the solar system besides Earth.
• Adding water to a simple organic molecule creates a complex organic molecule.
• Water is an inorganic molecule that has been found to be essential in all living systems.

Prokaryotic, a term meaning first nucleus, portrays the scientific theory explaining that these types of organisms __________________________.

• existed prior to the evolution of the true eukaryotic nucleus.
• evolved ingesting smaller eukaryotic cells.
• have a true, complex nucleus surrounded by a double membrane.
• existed after the evolution of the eukaryotic nucleus.

Scientists have developed theories to help analyze the complexity of the cell. Which of the following statements best explains the origin of chloroplasts?

• The chloroplasts originated from inward foldings of the outer cell membrane.
• Photosynthetic bacteria lived within larger bacteria, leading to evolution of chloroplast.
• Chloroplasts were produced by eukaryotic cells to defend against parasitic prokaryotes.
• Energy-producing bacteria lived in larger bacteria, eventually evolving into chloroplasts.

Scientists have discovered various pieces of scientific evidence to explain the complexity of the cell. Which of the following provides evidence for the origin of the endoplasmic reticulum?

• All cells contain DNA material which composes the endoplasmic reticulum.
• Eukaryotic cells contain mitochondria produced by the endoplasmic reticulum.
• Bacterial cells contain no internal organelles.
• Bacteria have inward foldings of outer membranes that extend into the cytoplasm.

The ability of lipids to self-assemble into more complex structures, such as lipid bilayers, without outside help or direction is key to the development of membrane-bound cells, and thus the existence of life on Earth. Which of the following explains why lipids self-assemble into a bilayer?

• The tails of lipids orient toward each other to avoid contact with water.
• The tail of each lipid forms hydrogen bonds with neighboring tails.
• Enzymes lower the energy required for lipids to form longer chains.
• Similar charges of lipid head groups repel each other.

Scientific evolutionary theories can be used to explain the complexity of modern organisms. Scientists analyze less complex organisms and try to relate them to organisms capable of performing complicated functions.Which of the following describes an example of this theory?

• The well developed nucleus of prokaryotic cells formed from the engulfment of eukaryotic cells.
• Prokaryotic and eukaryotic cells evolved from multiple ancestors of different types of cells.
• Prokaryotic cells evolved from eukaryotic cells.
• Eukaryotic cells evolved from prokaryotic cells.

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NGSS.HS-LS4-1

As scientists study the distribution of life forms over geographical areas, they have found numerous examples ofadaptive radiation. The existence of these groups provides evidence of common ancestry from one starting population.
Which of the following is not an example of adaptive radiation? 

• Several hundred species of fruit flies in Hawaii have evolved, each species occupying a different habitat.
• Several species of finches with similar beaks have evolved randomly throughout Europe, Africa, and Antarctica.

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NGSS.HS-LS4-1

NGSS.HS-LS4-2

NGSS.HS-LS4-4