Chapter 25 - History of Life on Earth

Question 1

Macroevolution -

Answer 1

the broad pattern of evolution above the species level

Question 2

The four main stages that are hypothesized to have have produced simple cells:

Answer 2

1. The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases
2. The joining of these small molecules into macromolecules, such as proteins and nucleic acids
3. The packaging of these molecules into protocells, droplets with membranes that maintained internal chemistry different from that of their surroundings
4. The origin of self-replicating molecules that eventually made inheritance possible

Question 3

Hypothesis’s by both A. I. Oparin and J. B. S. Haldane:

Answer 3

Earth’s early atmosphere was a reducing (electron-adding) environment, in which organic compounds could have formed from simpler molecules

Question 4

Hydrothermal vents -

Answer 4

areas on the seafloor where heated water and minerals gush from Earth’s interior into the ocean

Question 5

Black smokers -

Answer 5

a type of hydrothermal vent that release water so hot that organic compounds formed there may have been unstable

Question 6

Alkaline vents -

Answer 6

a type of hydrothermal vent that release water that has a high pH (9–11) and is warm rather than hot, an environment that may have been more suitable for the origin of life

Question 7

The first genetic material was most likely _____, not DNA

Answer 7

RNA: RNA molecules with certain nucleotide sequences may have shapes that enable them to replicate faster and with fewer errors than other sequences

Question 8

the known fossil record is biased in favor of species that _______________________________________

Answer 8

existed for a long time, were abundant and widespread in certain kinds of environments, and had hard shells, skeletons, or other parts that facilitated their fossilization

Question 9

Radiometric dating -

Answer 9

dating based on the decay of radioactive isotopes

Question 10

Half-life -

Answer 10

the time required for 50% of the parent isotope to decay, which the rate of decay is expressed by

Question 11

by measuring the ratio of _______ to _______ in a fossil, we can determine the fossil’s age

Answer 11

carbon-14; carbon-12

Question 12

A geologic record -

Answer 12

a standard time scale that divides Earth’s history into four eons and further subdivisions

Question 13

The Phanerozoic eon -

Answer 13

roughly the last half billion years, encompasses most of the time that animals have existed on Earth

Question 14

Three era’s the Phanerozoic eon is subdivided into:

Answer 14

the Paleozoic, Mesozoic, and Cenozoic

Question 15

Mesozoic era -

Answer 15

sometimes called the “age of reptiles” because of its abundance of reptilian fossils, including those of dinosaurs

Question 16

Stromatolites -

Answer 16

layered rocks that form when certain prokaryotes bind thin films of sediment together

Question 17

An endosymbiont -

Answer 17

a small engulfed cell, a cell that lives within another cell

Question 18

Eukaryotic cells -

Answer 18

more complex organism; have a nuclear envelope, mitochondria, endoplasmic reticulum, a well-developed cytoskeleton, and other internal structures. Can engulf other organisms by changing their shape

Question 19

Endosymbiosis -

Answer 19

process/theory in which a prokaryotic cell engulfed a small cell that would evolve into an organelle found in all eukaryotes the mitochondrion

Question 20

Serial endosymbiosis hypothesis -

Answer 20

hypothesis that mitochondria evolved before plastids through a sequence of endosymbiotic events

Question 21

Supporting evidence for the endosymbiotic origin of mitochondria and plastids

Answer 21

The inner membranes have enzymes and transport systems same as those in plasma membranes of living bacteria

Mitochondria and plastids replicate by a splitting process that is similar to that of certain bacteria.

Mitochondria and plastids have cellular machinery needed to transcribe and translate DNA into proteins (separate of larger organism)

Mitochondria and plastid ribosomes are more similar to bacterial ribosomes; size, RNA sequences, and sensitivity to certain antibiotics

Question 22

Larger and more diverse multicellular eukaryotes do not appear in the fossil record until about __________

Answer 22

600 million years ago

Question 23

Cambrian explosion -

Answer 23

where many present-day animal phyla appear suddenly in fossils formed 535–525 million years ago, early in the Cambrian period.

Question 24

Arthropods -

Answer 24

most widespread and diverse land animals

Question 25

Theory of plate tectonics -

Answer 25

the continents are part of great plates of Earth’s crust that essentially float on the hot, underlying portion of the mantle

Question 26

Continental drift -

Answer 26

process where movements in the mantle cause the plates to move over time

Question 27

Mass extinction -

Answer 27

• in which large numbers of species become extinct worldwide

Question 28

The Permian mass extinction -

Answer 28

defines the boundary between the Paleozoic and Mesozoic eras, claimed about 96% of marine animal species

Question 29

The Cretaceous mass extinction -

Answer 29

occurred 66 million years ago. This event extinguished more than half of all marine species and eliminated many families of terrestrial plants and animals, including all dinosaurs

Question 30

Adaptive radiations -

Answer 30

periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles, or niches, in their communities

Question 31

Heterochrony -

Answer 31

an evolutionary change in the rate or timing of developmental events

Question 32

Paedomorphosis -

Answer 32

where the sexually mature stage of a species may retain body features that were juvenile structures in an ancestral species

Question 33

Homeotic genes -

Answer 33

aka master regulatory genes determine such basic features as where a pair of wings and legs will develop on a bird or how a plant’s flower parts are arranged.

Question 34

Hox genes -

Answer 34

one class of homeotic genes provides positional information in an animal embryo. This information prompts cells to develop into structures appropriate for a particular location.