HL Origin of Life

What characterized the atmosphere of early Earth?

• Presence of free oxygen

• Low levels of carbon dioxide

• High levels of oxygen

• High levels of carbon dioxide, methane, ammonia, and water vapor

Answer explanation

High levels of carbon dioxide, methane, ammonia, and water vapor characterized the atmosphere of early Earth.

What did the Miller-Urey experiment demonstrate?

• Formation of complex organisms

• Formation of DNA

• Formation of simple organic molecules under prebiotic conditions

• Formation of cellular structures

Answer explanation

The Miller-Urey experiment demonstrated the formation of simple organic molecules under prebiotic conditions.

What is considered the fundamental unit of life?

• Viruses

• Proteins

• Cells

• Nucleic acids

Answer explanation

Cells are considered the fundamental unit of life, as they are the basic structural and functional units of all living organisms.

What is a major challenge in explaining the spontaneous origin of cells?

• Formation of water

• Formation of inorganic molecules

• Formation of organic molecules and self-replicating systems

• Formation of oxygen

Answer explanation

The major challenge in explaining the spontaneous origin of cells is the formation of organic molecules and self-replicating systems.

What is the RNA world hypothesis?

• Proteins were the first to catalyze reactions

• RNA molecules were precursors to current life forms

• DNA was the first genetic material

• RNA molecules were the first to form life

Answer explanation

The RNA world hypothesis suggests that RNA molecules were precursors to current life forms, indicating they were the first to form life.

What do fatty acids spontaneously form?

• RNA

• Vesicles with bilayer membranes

• DNA

• Proteins

Answer explanation

Fatty acids spontaneously form vesicles with bilayer membranes, not RNA, DNA, or proteins.

What is the presumed first genetic material?

• DNA

• Proteins

• RNA

• Lipids

Answer explanation

The presumed first genetic material is RNA, not DNA, proteins, or lipids. RNA is believed to have played a crucial role in the origin of life due to its ability to store genetic information and catalyze chemical reactions.

Where is water on Earth thought to have originated from?

• Comets and asteroids

• Atmospheric condensation

• Volcanic eruptions

• Photosynthesis

Answer explanation

Water on Earth is thought to have originated from comets and asteroids, making the correct answer choice.

Why is water crucial in the search for extraterrestrial life?

• It is a form of genetic material

• It is a structural component of cells

• It is a source of energy

• It is a solvent for biochemical reactions

Answer explanation

Water is crucial in the search for extraterrestrial life because it is a solvent for biochemical reactions, allowing for essential processes to occur in potential extraterrestrial organisms.

What protects water on Earth from solar wind?

• Earth's atmosphere

• Earth's gravity

• Earth's temperature

• Earth's magnetic field

Answer explanation

Earth's magnetic field protects water on Earth from solar wind by deflecting charged particles away from the planet.