Chapter 19: Life's Origin and Early Evolution (Review)

Genetic analysis suggests that LUCA lived in a(n) _ environment rich in metal ions, where it obtained energy by metabolizing hydrogen.

high-temperature

Genetic analysis suggests that LUCA lived in a(n) high-temperate environment rich in metal ions, where it obtained energy metabolizing _.

hydrogen

RNA world hypothesis

hypothesis that RNA served as the genetic information of early life

endosymbiont hypothesis

hypothesis that mitochondria and chloroplasts evolved from bacteria

iron-sulfur world hypothesis

hypothesis that the metabolic reactions that led to the first cells took place on the porous surface of iron-sulfide-rich rocks at hydrothermal vents

Precambrian era

interval from Earth's formation to 541 million years ago

The porous rocks that form around deep-sea hydrothermal vents are rich in which compounds?

iron sulfides

protocell

membranous sac that contains interacting organic molecules; hypothesized to have formed prior to the earliest life-forms

Before the ozone layer formed, in which habitats could organisms live?

only aquatic

Over time, lipids produced by reactions inside a chamber could have accumulated and lined the chamber wall, forming a _, which is a membrane-enclosed collection of interacting molecules.

protocell

The presence of the mineral _ in and around the spherical fossil cells suggest the cells were metabolically similar to modern sulfur bacteria.

pyrite

Self-replication molecules and products of other early synthetic reactions would have floated away from one another unless something enclosed them. If the first reactions took play in tiny _ chambers, the chamber would have acted as a boundary.

rock

hydrothermal vent

rocky, underwater opening where mineral-rich water heated by geothermal energy streams out

ozone layer

upper atmospheric region in ozone that screens out incoming ultraviolet (UV) radiation

big bang theory

well-supported hypothesis that the universe originated by a nearly instant distribution of matter through space

Mitochondria are thought to have evolved from which type of organism?

Aerobic bacteria

Australian sandstone rocks that date back _ billion years provide another glimpse of early life. These rocks include spherical fossils nestled among sand grains from an ancient beach.

3.4

Archean eon

Precambrian interval extending from 4 billion years ago to 2.5 billion years ago. First eon for which there is evidence of life.

Hadean eon

Precambrian interval that extends from Earth's formation to 4 billion years ago

To date, the oldest fossils that most scientists agree are eukaryotic date to about 1.8 billion years ago during the _ eon, the final portion of the Precambrian.

Proterozoic

ribozymes

RNA that functions as an enzyme

stromatolite

Rocky, layered structure that forms over time as a mat of aquatic prokaryotic cells traps sediments

What organism was the result of endosymbiosis between a host eukaryote and its cyanobacteria?

alga

The oldest fossils resemble the resting stage cells of some modern single-celled _. The age of these fossils is consistent with molecular clock studies.

algae

Who proposed the iron-sulfur world hypothesis?

Wachtershauser

Which is not a characteristic of LUCA? a) It was the first cellular life. b) It was anaerobic. c) It metabolized hydrogen. d) It was prokaryotic. e) It was adapted to high temperatures.

a) It was the first cellular life.

What organic molecules, common to all living things, formed during Miller and Urey's reaction chamber experiment? a) amino acids b) simple sugars c) nucleotides d) lipids e) fatty acids

a) amino acids

Photosynthesis first arose in some _ lineages. a) protistic b) bacterial c) plant d) archaeal e) eukaryotic

b) bacterial

The ozone layer is important for life on Earth because it _. a) blocks meteorites b) blocks harmful UV radiation c) sterilizes the surface layer d) let in the appropriate radiation to reach Earth to allow for mutations e) filters sunlight to allow only the wavelengths necessary for photosynthesis

b) blocks harmful UV radiation

RNAs that function as enzymes are known as _. a)introns b) ribozymes c) organic polymers d) protocells e) tRNA

b) ribozymes

According to the Big Bang Theory, the universe began about _ years ago. a) 14 million b) 500 billion c) 14 billion d) 25 billion e) 100 billion

c) 14 billion (13.7 billion years ago according to slides)

By about _ years ago, representatives of all major lineages had evolved by the seas. a) 100 million b) 435 million c) 900 million d) 1.2 billion e) 2.7 billion

c) 900 million

In Miller and Urey's reaction chamber experiment, what was the source of the nitrogen for the organic molecules that formed? a) methane b) hydrogen c d) water e) electrodes

c) ammonia

The first cells were likely _. a) aerobic protists b) anaerobic eukaryotes c) anaerobic prokaryotes d) aerobic eukaryotes e) aerobic eukaryotes

c) anaerobic prokaryotes

What membrane-enclosed collection of interacting molecules possibly preceded cells? a) polymers b) ribozymes c) protocells d) nucleotides e) fatty acids

c) protocells

Luca was not the first _ life, but rather the last shared ancestor of all modern life.

cellular

Which organisms are responsible for the increase of oxygen content on Earth?

cyanobacteria

About _ years ago, oxygen released by cyanobacteria began to rise significantly in the Earth's atmosphere. a) 100 million b) 500 million c) 1 bilion d) 2.5 billion e) 5 billion

d) 2.5 billion (2.8 bya according to slides)

By about _ years ago, water had begun to pool on Earth's surface. a) 20 million b) 500 million c) 2.4 billion d) 4.4 billion e) 25 billion

d) 4.4 billion

According to the _ hypothesis, mitochondria evolved from bacteria. a) protocell b) eukaryotic divergence c) exoculluar d) endosymbiont e) bacteriophage

d) endosymbiont

As Earth's oxygen content increased, many species went extinct. What were the unable to do?

detoxify free radicals

_ are thought to have given rise to chloroplasts. a) Rickettsia b) Archaea c) Protists d) Protocells e) Cyanobacteria

e) Cyanobacteria

Wachterschauser's iron-sulfur world hypothesis hods that life originated at _. a) meteor craters b) volcanoes c) hot springs d) hyper-saline pools e) deep-sea hydrothermal vents

e) deep-sea hydrothermal vents

What term refers to a relationship in which one organism lives inside another?

endosymbiosis

Over time, lipids produced by reactions inside a chamber could have accumulated and lined the chamber wall, forming a protocol, which is a membrane-enclosed collection of interacting molecules. Their membranes probably consisted of a variety of _, rather than the phospholipids that make up the bulk of modern cell membranes.

fatty acids

Proterozioic eon

final eon of the Precambrian era; 2.5 billion to 541 million years ago