Unit 1 PAL Flashcards
Define stratigraphy
analysis of the order and position of layers and their place in the geological time scale
Define strata
layers of rock
higher layers of strata often contain (blank)
fossils resembling extant species
Define paleontology
study of fossils
How is geologic time divided?
Eon, Era, Period, Epoch
What eon are we currently in?
Phanerozoic
What era are we currently in?
Cenozoic
What period are we currently in?
Quaternary
What epoch are we currently in?
Anthropocene
What word is used to unify the first 3 eons?
Precambrian (Hadean, Archean, Proterozoic)
How old is the Earth?
4.5 bya
How old are homo sapiens?
200,000 years
How old are animals?
500-600 my
How old are prokaryotes/life?
3.7 by
What are igneous rocks?
form when molten rock cools and forms a solid (no fossil)
What are metamorphic rocks?
formed when existing rocks are allowed due to extreme heat/pressure (may contain fossils)
What are sedimentary rocks?
form from fragments/sediment deposited by water or air (FOSSILS)
Describe the conditions of the early atmosphere
- very little O2
- mostly methane, carbon monoxide, and ammonia
What caused the increase of oxygen in the atmosphere?
photosynthetic organisms (cyanobacteria) released oxygen as a waste product (CO2+H2)–Sugar+O2)
What is BIF and how did it form?
Banded Iron Formation
formed when oxygen combined with dissolved iron in sea water and formed insoluble iron oxides which precipitated out and formed a thin layer on the ocean floor
Anaerobic
no oxygen to live
Strictly anaerobic
die in presence of oxygen
aerobic
needs O2 to live
What is the Great Oxygenation Event (GOE)?
O2 in atmosphere (bio induced) killed mass amounts of anaerobes leading to more aerobic bacteria
What did the rise of aerobic life lead to?
- evolution of eukaryotes and multicellularity
- higher O2 content supports larger cells
- plants invaded land and further increased O2
- large animals evolved (ex giant dragonflies)
What event led to the decrease of O2 around 250 MYA and what caused this event?
Great Dying and cause unknown
Describe the general carbon trends over the past 400,000 years
regular fluctuations of CO2 in atmosphere which largely mirrored gradual cycles in the Earth’s orbit and levels of planetary ice coverage
What has happened in the last few centuries to the level of CO2 in the atmosphere?
- CO2 levels have been drastically increasing due to the burning of fossil fuels
- Sept 2016 reached a milestone- CO2 levels reached a permanent 400 ppm
What is an end moraine?
mass of rocks and sediment carried down and deposited by a glaciar
What is a kame?
a hill of sand/debris laid by a melting glaciar
What is an esker?
a ridge of sediment/debris deposited by a retreating/melting glacier
What is a coteau?
plateau formed from thick glacial deposits of repeated glaciations
Describe the relationship between sea level and retreating glaciars
sea level rises as glaciers melt
What are the three principles of fossil discovery?
- Age of rock
- Type of rock
- Rock must be exposed
What is the significance of Tiktalik?
“missing link” in the evolution of life from water to land, it helps bridge the gap between fish and tetrapods
What are some of the characteristics of Tiktaalik that are different from fish?
- head could pivot
- functional wrists; fins/feet suited to crawl
- had lungs (or lung like organ)
Define homologous traits and give ex
traits that share a common ancestor; ex= bones in arms
Define analogous and give ex
traits that were not present in the most recent common ancestor, ex = wings
Define evolution
changes in allele frequency in a population over time
Define allele
a variation of a gene
Define homozygous
organism has two copies of the same allele
Define heterozygous
organisms has two different alleles
Define genotype
genetic makeup
Define phenotype
physical/observable traits
Define dominant
only needs one copy of dominant allele to express the phenotype
Define recessive
needs two copies of the recessive allele to express phenotype
Define gene pool
the set that contains all of the alleles in all individuals of a population
Define locus
a particular site on a chromosome
What are two common misconceptions about evolution?
1- theory> hypothesis (theory tested and extensively supported by evidence))
2- individuals don’t evolve, populations do
List 5 mechanisms of evolution
mutation, gene flow, genetic drift, nonrandom mating, natural selection
Define mutation and discuss some of the main concepts of this mechanism
- change in the nucleotide sequences of DNA
- most harmful or neutral
- ultimate cause of genetic variation
- not goal directed
What is gene flow?
- migration of individuals between populations
- causes movement of alleles
- increases similarity between populations
What is genetic drift?
- random changes in allele frequencies
- affects small populations the most
- can reduce genetic variation
- examples include bottleneck and founder
What is the Bottleneck effect?
-occurs when a population is drastically reduced by a catastrophe and it reduces the genetic variation because only some individuals survive to pass on genes
What is the Founder effect?
-a small amount of a population moves to another place; only these “founders” contribute genes to the next generation
What is the significance of nonrandom mating?
-some traits are favored by potential mates which increases the likelihood of mating and therefore increases the likelihood of the trait
What is the difference between artificial and natural selection?
Artificial= humans purposefully select for specific phenotypes Natural = nature selects for favorable traits
What did Darwin propose as the mechanism of evolution?
natural selection
How does artificial selection differ from natural selection?
Artificial selection is the purposeful selection of a certain phenotype by humans. Natural selection is not purposeful or goal directed.
Describe three observations made by Darwin that led to his theory of natural selection.
1) Earth is really old.
2) He observed artificial selection with pigeons.
3) He observed differences in species and populations while he was on the HMS beagle.
Describe three ingredients for evolution by natural selection:
1) variation- individuals differ from one another
2) heritability- traits are passed from parent to offspring
3) differential fitness- variation in phenotypes allows increase or decrease in individuals ability to survive and reproduce
define adaptation
a feature that improves fitness
define sexual selection
reproductive success of males based on female choice; usually based on attractive traits (a peacocks pretty tail) or the male’s ability to out compete another male (big-horn sheep)
The current geologic period is the
quaternary
Fitness in an evolutionary sense is measured in
the number of viable offspring produced
