Lecture 15 - History of Life on Earth

According to radioactive decay data, how old is the earth?

According to radioactive decay data, THE EARTH IS 4.6 billion years old

What was the Miller-Urey apparatus and what did it demonstrate?

Miller Urey’s apparatus was used to test Oparin’s hypothesis of the early atmosphere

IT GENERATED THE AMINO ACIDS AND OTHER ORGANIC MOLECULES USED BY LIVING ORGANISMS TODAY

What did the Murchison meteorite demonstrate (ET better not show up in your answer)?

The Murchison Meteorite demonstrated the arrival of 80 amino acids, lipids, sugars, and uracil 4.5 billion years ago

Why is it hypothesized that RNA was the 1st genetic material used on the planet?

It’s hypothesized that RNA was the 1st genetic material used on the planet since

RNA and protein polymers SPONTANEOUSLY FORM WHEN MONOMERS WERE DROPPED ON HOT CLAY OR SAND

What is a ribozyme and what can it do?

Ribozymes are RNA that can act as enzymes

CAN SELF REPLICATE

MOST LIKELY 1st GENETIC MATERIAL

What is radioactive dating and how is it used to date fossils?

Radioactive dating uses the decay rate of isotopes to determine the age of a sample

BASED ON HALF LIFE OF A GIVEN RADIOACTIVE ISOTOPE

Therefore, for fossils they compare C-12 to C-14 levels to determine fossil age

In what way is the fossil record biased?

The fossil record biases for species that:

• WERE ABUNDANT

• HAD WIDE DISTRIBUTIONS 

• LIVED IN CERTAIN ENVIRONMENTS 

• HAD HARD SKELETONS OR SHELLS

What are the 4 Eons of the geological record? What was the Earth/life like during each eon?

Order from oldest to most recent

1. Hadean - Earth inhospitable to life

2. Archaean - origin of all life, LITTLE ATMOSPHERIC OXYGEN 

3. Proterozoic - ORIGIN OF EUKARYOTES AND MULTICELLULAR ORGANISMS, increased oxygen levels

4. Phanerozoic - livable and ideal conditions

Which appears first: prokaryotes or eukaryotes?

PROKARYOTES APPEARED BEFORE EUKARYOTES

What is the oxygen revolution? What caused it? How did it affect the evolution of life on this planet?

The oxygen revolution was a period where there was a sudden increase in atmospheric oxygen

It was caused by oxygenic photosynthesis releasing O2 into the atmosphere

As a result, aerobic respiration was made possible TRIGGERED THE 1st EXTINCTION EVENT

What is the endosymbiosis theory? What is some of the support for this theory?

The Endosymbiosis Theory is the idea that mitochondria and chloroplasts were both prokaryotes living symbiotically in a larger cell AND EVENTUALLY INTEGRATED AS PART OF THE CELL

Support comes from the fact that they have circular DNA like a prokaryotic genome, DNA replication like modern prokaryotes, have ribosomes

How has continental drift affected the evolution of life on this planet?

Continental drift has affected evolution of life on Earth as it

CREATES GEOLOGICAL BARRIERS (speciation etc)

ALTERS SEA LEVEL

ALTERS GLOBAL CLIMATE

ALTERS LOCAL HABITATS 

PROMOTES ALLOPATRIC SPECIATION 

How does the fossil record support Darwin’s theory of descent with modification?

The fossil record shows that EVOLUTION MODIFIES WHAT ALREADY EXISTS 

THINK OF DOLPHINS ONCE BEING LAND ANIMALS 

What are mass extinction events and how have they affected the evolution of life on this planet?

Mass extinction events refer to moments where LARGE NUMBERS OF SPECIES BECOME EXTINCT ON A GLOBAL SCALE

LOSS OF LINEAGES 

LOSS OF DIVERSITY 

ALTERS ECOLOGICAL COMMUNITITES 

What was the mass extinction event in the late/end of the Cretaceous? What caused it, when did it
occur? How did it affect the evolution of life on this planet?

The mass extinction event OCCURED 65MYA and was CAUSED BY A LARGE ASTEROID OR COMET, IT KILLED OFF ALL NON AVIAN DINOSAURS LEADING TO THE END OF THOSE LINEAGES

What causes adaptive radiation? Identify 2 examples of an adaptive radiation and why they occurred
(we’ve discussed many)?

Adaptive radiation is a RESULT FROM MANY NEW ENVIRONMENTAL OPPORTUNITIES 

OCCURS AFTER A MASS EXTINCTION 

OCCURS AFTER A NEW ISLAND OR LAKE FORMS

What do we mean when we say that speciation is not goal oriented?

Speciation not being goal oriented means that EVOLUTION IS CONSTANTLY WORKING, BUILDING ON WHAT CAME BEFORE 

ADAPTATIONS ACCORDING TO THE CHANGING ENVIRONMENT 

Define protocells

Protocells are VESICLES OR LIPOSOMES that FORM SPONTANEOUSLY and can BRING ORGANIC MOLECULES INSIDE 

Define Ribozymes

Ribozymes are RNA WITH THE ABILITY TO CATALYZE REACTIONS

Define Half-Life

Half-Life is the TIME IT TAKES for 50% OF THE ISOTOPES TO DECAY

Define Edicarian biota 

Edicarian biota WERE THE 1st COMPLEX MULTICELLULAR FOSSILS

Define Cambrian explosion and plate tectonics 

The CAMBRIAN EXPLOSION is a point in time where FOSSILS OF MANY MODERN ANIMAL PHYLA SUDDENLY APPEARED, ALSO THE FIRST SIGNS OF PREDATORS

PLATE TECTONICS are the plates of the earth crust FLOATING AND MOVING on top of the HOT MANTLE