History of Life on Earth - Ch. 18

Question 1

Fossil records

Answer 1

how scientists date and record and reconstruct history. Fossils can be found in sedimentary rock, mineralized, and organic. The fossil record is an incomplete record, this is because some organisms may not have been preserved, some destroyed, and some not found yet.

Question 2

Relative dating

Answer 2

uses the order of rock strata to determine relative age of fossils.

Question 3

Radiometric dating

Answer 3

measures decay of radioactive isotopes present in layers where fossils are found - uses half life, which is the amount of time it takes for 50% of the substance to decay

Question 4

How many years ago was the first prokaryote present?

Answer 4

3.5 billion years ago

Question 5

When did O2 start to accumulate in the atmosphere?

Answer 5

2.7 billion years ago

Question 6

When were the first eukaryotes present?

Answer 6

2.1 billion years ago

Question 7

When did the first multicellular eukaryotes appear?

Answer 7

1.2 billion years ago

Question 8

When did plants start colonization?

Answer 8

500 million years ago

Question 9

When did humans appear?

Answer 9

200,000 years ago

Question 10

Endosymbiat theory

Answer 10

mitochondria and plastids were once individual and small prokaryotes. eventually the prokaryotes joined together with a smaller cell and worked cohesively together, eventually forming what is known today as a eukaryotes.

Question 11

Evidence of endosymbiat theory

Answer 11

replication of binary fission, single and circular DNA, ribosomes to make proteins, enzymes similar to living prokaryotes, and two membranes

Question 12

Pangea

Answer 12

was a super continent that formed about 750 million years ago. continental drift helps explain many bio-geographical puzzles, such as the separation of the continents. movement of the continental plates change geographically and climate of earth and caused mass extinctions.

Question 13

Pre-cambrian era

Answer 13

microscopic fossils, development of photosynthesis and eukaryotic species (endosymbiat theory)

Question 14

Paleozoic era

Answer 14

cambrian explosion, plants invade the land and animals start to appear. During this era the permian extinction occurs, causing 96% of species to go extinct

Question 15

Mesozoic era

Answer 15

age of reptiles and plants and the origin of mammals, formation of pangea, there is a cretaceous extinction that occurs because of an asteroid off Mexico’s coast

Question 16

Cenozoic

Answer 16

primates form

Question 17

Evolutionary development (Evo Devo)

Answer 17

evolutionary developmental biology. evolution of new forms results from changes in DNA or regulation of developmental genes

Question 18

Gene regulation

Answer 18

also called homeotic genes, and they are responsible for master regulatory genes that determine location and organization of body parts

Question 19

Heterochony

Answer 19

evolutionary change in rate of developmental events

Question 20

Hox genes

Answer 20

an example of homeotic genes.
a group of related genes that control the body plan of an embryo along the cranio-caudal axis (head tail axis).
After the embryonic segments have formed, the Hox proteins determine the type of segment structures (e.g. legs, antennae, and wings in fruit flies or the different types of vertebrae in humans) that will form on a given segment.

Question 21

Exaptations

Answer 21

structures that evolve but become co-opted for another function. an example would be bird feathers = thermoregulation and flight

Question 22

Speciation

Answer 22

the formation of two species from one original species
for speciation to occur, two new populations must form from one original population and evolve in that it becomes impossible for individuals from two populations to interbreed

Question 23

Microevolution

Answer 23

changes in allele frequencies (different versions of a gene) within a single gene pool

Question 24

Macroevolution

Answer 24

evolutionary change above the species level

Question 25

Species

Answer 25

population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

Question 26

Morphological

Answer 26

Another defintion of species, refers to the body shape, size, and other structural features

Question 27

Ecological

Answer 27

Another definition of species, refers to the niche/ role in a community

Question 28

Phylogenetic

Answer 28

Another definition of species, refers to the a share in a common ancestor, form one branch on the tree of life

Question 29

Allopatric speciation

Answer 29

geographically isolated populations, cause by geological events. evolves by natural selection and genetic drift

Question 30

Sympatric speciation

Answer 30

overlapping populations within the same geographical area. gene flow can be blocked by polypoidy (no proper separation of chromosomes), habitat differentiation, and sexual selection

Question 31

Autopolypoid

Answer 31

extra sets of chromosomes, failure of cell division

Question 32

Allopolypoid

Answer 32

2 species produces a hybrid

Question 33

Prezygotic barriers

Answer 33

prevent mating or hinder fertilization

Question 34

Types of prezygotic barriers

Answer 34

habitat isolation, temporal isolation, behavioral isolation (mating calls/rituals), mechanical isolation (can’t be enseminated), gametric isolation (mating occurs but no fertilization)

Question 35

Postzygotic barriers

Answer 35

prevent hybrid zygote from becoming an adult

Question 36

Types of postzygotic barriers

Answer 36

reduce hybrid variability (won’t live past adolescence), reduced hybrid fertility (cannot reproduce), and hybrid breakdown (offspring is infertile)

Question 37

Gradualism

Answer 37

type of time course of speciation, has a common ancestor, the change is slow and constant. The organism comes from one ancestor, but eventually, slowly over time, the common ancestor will divulge into two different species

Question 38

Punctuated equilibrium

Answer 38

type of time course of speciation, long periods of stasis punctuated by sudden change seen in fossil record. Long pause, then all of a sudden a new species occur . This may occur because the fossil record is incomplete or sparse

Question 39

Hybrid zones

Answer 39

incomplete reproductive barriers, possible outcomes for this can be reinforcement, fusion, and stability

Question 40

Reinforcement

Answer 40

hybrids will be much less fit than the original species. Eventually the species will not be able to produce more hybrids or will not survive

Question 41

Fusion

Answer 41

the barriers between two species reproducing will weaken, and two species will fuse or join together and become one species

Question 42

Stability

Answer 42

over time, the hybrids will be become fixed and continue to be reproduced

Question 43

How did life arise?

Answer 43

1.Small organic molecules were synthesized
2.Small molecules, macromolecules (proteins, nucleic acids)
3.Packaged into protocells(membrane-containing droplets)
4.Self-replicating molecules allow for inheritance
“RNA World”: 1st genetic material most likely RNA First catalysts = ribozymes (RNA)

Question 44

Theory of how biomolecules developed

Answer 44

Early atmosphere = H2O vapor, N2, CO2, H2, H2S methane, ammonia
Energy = lightning & UV radiation
Conditions favored synthesis of organic compounds - a “primitive soup”