The History of Life on Earth

These flashcards cover significant events and concepts in the history of life on Earth, including fundamental biological processes, timelines, and definitions related to key evolutionary milestones.

What is the age of the Earth?

4.5 billion years old.

What was the oldest known form of life?

Prokaryotes, which are cells lacking nuclei or organelles enclosed in membranes.

What are stromatolites?

Layers of sediment and prokaryotes, including cyanobacteria.

What is the equation for photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2.

What happened to oxygen in the ocean 2.7 billion years ago?

Iron was all oxidized by oxygen.

What is the main product of photosynthesis in relation to the atmosphere?

The current atmosphere is a product of photosynthesis.

What are the three main effects of increased oxygen levels in the atmosphere?

1) Respiration takes up oxygen. 2) Photorespiration increases. 3) Fires increase.

When did Eukaryotes first appear?

1.8 billion years ago.

What are two key characteristics of Eukaryotic cells?

They have a nucleus and organelles enclosed in membranes.

What is the endosymbiotic origin theory related to?

Chloroplasts and mitochondria.

How many mass extinctions have there been in geological history?

The big five mass extinctions.

What is background extinction rate?

The low, average rate of extinction between mass extinctions.

What triggers mass extinction events?

Climate changes or large cataclysmic events.

What is adaptive radiation?

When a lineage diversifies into many species occupying different niches.

What are two causes of adaptive radiation?

1) Evolutionary innovation. 2) Colonization of new habitats.

What is the mass extinction event criteria?

When over 60% of species go extinct within 1 million years.