Bio Ch 18

Question 1

Last Universal Common Ancestor (LUCA)

Answer 1

all life on Earth can be traced back to a single ancestor

Question 2

Biomolecules

Answer 2

molecules of living things; organic molecules

Question 3

Organic monomers

Answer 3

simple organic molecules

Question 4

Protocells

Answer 4

organic polymers became enclosed in a membrane to form the 1st cell precursors; AKA probionts; structure characterized by having an outer membrane

Question 5

Abiogenesis

Answer 5

origin of life from nonliving matter

Question 6

Primordial Soup Hypothesis

Answer 6

Oparin-Haldane Hypothesis; proposes that early Earth had very little oxygen but instead was made up of water vapor, hydrogen gas, methane, and ammonia

Question 7

Abiotic synthesis

Answer 7

chemical evolution driven by redox reactions

Question 8

Iron-Sulfur World Hypothesis

Answer 8

dissolved gases emitted from thermal vents, such as carbon monoxide, ammonia, and hydrogen sulfide, pass over iron and nickel sulfide minerals, also present at thermal vents; iron and nickel sulfide molecules act as catalysts that drive the chemical evolution from inorganic to organic molecules

Question 9

Proteinoids

Answer 9

small polypeptides that have some catalytic properties

Question 10

Microspheres

Answer 10

when placed in water, proteinoids form these structures composed only of protein that have many properties of a cell

Question 11

Protein-First Hypothesis

Answer 11

assumes that protein enzymes arose prior to the 1st DNA molecule

Question 12

RNA-First Hypothesis

Answer 12

suggests that only the macromolecule RNA was needed to progress toward formation of the 1st cell or cells

Question 13

Micelles

Answer 13

fatty acids assemble into small spheres; single layer of fatty acids organized with their heads pointing out and tails pointing toward the center of the sphere

Question 14

Vesicles

Answer 14

under appropriate conditions, micelles can form these; larger than micelles, surrounded by a bilayer of fatty acids, similar to the phospholipid bilayer of modern cell membranes

Question 15

Coacervate Droplets

Answer 15

concentrated mixtures of macromolecules tend to give rise to these complex units which have a tendency to absorb and incorporate various substances from the surrounding solution

Question 16

Liposomes

Answer 16

Alec Bangham discovered that when he extracted lipids from egg yolks and placed them in water, the lipids would naturally organize themselves into double-layered bubbles roughly the size of a cell; AKA “Bangham’s bubbles”

Question 17

Membrane-First Hypothesis

Answer 17

1st cell had to have a plasma membrane before any of its other parts

Question 18

Fossils

Answer 18

remains and traces of past life or any other direct evidence of past life

Question 19

Paleontology

Answer 19

science of discovering and studying the fossil record, and from it, making decisions about the history of life, ancient climates, and environments

Question 20

Sedimentation

Answer 20

process that has been going on since the Earth was formed; gradual settling of particles of eroded and weathered rock and soil (silt) that are carried by a flow of water

Question 21

Sediment

Answer 21

silt is gradually deposited, forming layers of particles that vary in size and nature

Question 22

Stratum

Answer 22

recognizable layer of sediment in a stratigraphic sequence

Question 23

Index fossils

Answer 23

geologists discovered that each stratum of the same age contained these that serve to identify deposits made at apparently the same time in different parts of the world

Question 24

Relative Dating

Answer 24

determining the age of fossils by noting their sequential relationships in strata

Question 25

Absolute Dating

Answer 25

relies on radiometric techniques to assign an actual date to a fossil

Question 26

Radiometric

Answer 26

all radioactive isotopes have a particular half-life, the length of time it takes for half of the radioactive isotope to change into another stable element; this technique is used in absolute dating methods

Question 27

Radiocarbon dating

Answer 27

uses the radioactive decay of Carbon 14, a rare carbon isotope

Question 28

Geologic Timescale

Answer 28

divides the history of the Earth into eras, then periods, then epochs; derived from accumulation of data from the age of fossils in strata all over the world

Question 29

Stromatolites

Answer 29

domed structure found in shallow seas consisting of cyanobacteria bound to calcium carbonate

Question 30

Ozone Shield

Answer 30

accumulation of O3, formed from oxygen in the upper atmosphere; a filtering layer that protects Earth from ultraviolet radiation

Question 31

Endosymbiotic Theory

Answer 31

a nucleated cell engulfed prokaryotes, which then became organelles; the nucleated cell and the engulfed bacteria co-evolved the ability to synthesize ATP via oxidative phosphorylation

Question 32

Extinction

Answer 32

total disappearance of all the members of a species or higher taxonomic group

Question 33

Mass extinctions

Answer 33

disappearance of a large number of species or higher taxonomic groups within an interval of just a few million years

Question 34

Gymnosperms

Answer 34

non-flowering seed plants

Question 35

Megafauna

Answer 35

giant ground sloths, beavers, wolves, bison, wooly rhinoceroses, mastodons, and mammoths

Question 36

Continental Drift

Answer 36

confirmed in the 1960's; established that continents are not fixed; their positions and the positions of the oceans have changed over time

Question 37

Plate Tectonics

Answer 37

Earth's crust is fragmented into slablike plates that float on a lower, hot mantle layer

Question 38

Bolide

Answer 38

large, crater-forming projectile that impacts Earth