BIO Chapter 25: The History of Life on Earth (Upto 25.3)

What are three large-scale processes that cause changes in the organisms on Earth over time?

Continental drift, Mass extinction, Adaptive radiation.

What happens during adaptive radiation?

A lineage gives rise to many new species.

Summarize the four stages of origin of life.

1. Abiotic synthesis of small organic molecules. 2. Joining of these molecules into macromolecules. 3. Packaging of molecules into protocells. 4. Origin of self-replicating molecules.

How old is the planet?

Approximately 4.5 billion years.

What is the earliest evidence of life on Earth?

About 3.5 billion years ago.

What was most likely the first genetic material?

RNA.

What are ribozymes?

RNA molecules that can catalyze biochemical reactions.

What type of rock is the richest source of fossils?

Sedimentary rock.

What is the age range for which carbon-14 dating may be used?

Up to approximately 50,000 years.

What does it indicate if 1/8 of the original carbon-14 isotope remains?

The skeleton is approximately 17,190 years old.

When did prokaryotes originate on the geologic timescale?

3.5 billion years ago.

When did the colonization of land occur on the timer scale?

7 minutes ago or approximately 500 million years ago.

What unique ability originated with cyanobacteria?

Oxygenic photosynthesis.

What are three lines of evidence that support the model of endosymbiosis?

1. Inner membranes have enzymes homologous to prokaryotes. 2. Mitochondria and plastids replicate similarly to prokaryotes. 3. These organelles contain circular DNA not associated with histones.

What challenges did plants and animals face to colonize land?

They had to adapt to reproduce on land and prevent dehydration.

What other life form appears to have colonized land associated with plants?

Sponges, cnidarians, mollusks, etc.

What group of animals colonized land about 450 million years ago?

Arthropods.