Evolution of Life on Earth

These flashcards cover the critical concepts discussed in the lecture regarding the evolution of life on Earth, focusing on early prokaryotic life, significant geological and atmospheric events, and the development of more complex life forms.

What is the age of the Earth?

4.5 billion years old.

When do the oldest prokaryotic fossils date back to?

3.5 billion years ago.

What significant atmospheric change occurred 2.7 billion years ago?

Oxygen accumulated in the atmosphere.

What type of bacteria significantly contributed to the oxygen revolution?

Cyanobacteria.

What is the process by which prokaryotes transfer genes?

Transformation, conjugation, and transduction.

What type of prokaryotes are considered nitrogen fixers?

Those that convert nitrogen gas into ammonia.

What is binary fission?

Asexual reproduction method used by prokaryotes.

What are the two main groups of prokaryotes in the three-domain system?

Bacteria and Archaea.

What is the primary role of bacteria in ecosystems?

Decomposing organic matter.

What is the difference between gram-positive and gram-negative bacteria?

Gram-positive have simpler cell walls; gram-negative have complex cell walls and can be more harmful.

What was the significance of Stanley Miller's experiment in 1953?

It simulated early Earth conditions and produced organic compounds like amino acids.

How do prokaryotes contribute to the nitrogen cycle?

Prokaryotes convert ammonia into nitrite and nitrate, and fix nitrogen gas.

What is the role of ribozymes in early life forms?

They acted as RNA catalysts for molecular replication.

What is a protobiont?

An aggregate of abiotically produced molecules that exhibit some properties of life.

What adaptation allowed plants to colonize land?

Thick cuticles, pollen/seeds, and vascular tissue ultimately helped prevent dehydration.

How did the Snowball Earth affect the evolution of life?

It confined life to hot springs or deep-sea vents until thawing allowed diversification.

What is the result of the endospores in bacteria?

They allow bacteria to endure harsh conditions and can remain dormant for long periods.

What are the ecological implications of antibiotic-resistant bacteria?

They pose serious health threats as common antibiotics may no longer be effective.

What are obligate anaerobes?

Prokaryotes that are poisoned by oxygen and cannot grow in its presence.

What are some benefits of the symbiotic relationships between prokaryotes and hosts?

Mutualism provides benefits to both parties; for example, bacteria aiding in digestion.

What was Whittaker’s 5 Kingdom System?

A classification system that divided life into Prokaryotes (Monera) and Eukaryotes (Plantae, Fungi, Animalia, Protista).

What significant change did cyanobacteria bring to early Earth's atmosphere?

They contributed to the shift from a reducing atmosphere to an oxidizing environment.

What are protists?

Eukaryotic organisms that do not fit into the kingdoms of Plantae, Fungi, or Animalia.