BIOL 111 - Midterm #2 Flashcards
Where are fossils preserved?
Sedimentary rocks
What differences would be observed in older rock layers compared to newer?
Older layers contain fossils that diverge from modern forms. More recent layers contain fossils more closely resembling living species.
What is used to define different periods in Earths history?
Changes in the fossil record.
How are absolute ages of time periods determined?
Radiometric dating
What are some of the oldest fossils?
Stromatolites from 3.5 billion years ago, during the Archean eon.
(Colonies of microbes that grow in shallow water)
Difference in age between prokaryotic and eukaryotic domains?
Two prokaryotic domains were both present 3.5 billion years ago.
Eukaryotes appeared over 1.5 billion years later.
Where did oxygenic photosynthesis evolve?
Cyanobacteria - 3 billion years ago.
When did atmospheric O2 start to rise?
2.5 billion years ago.
Only approached modern levels after the evolution of land plants 500 million years ago.
What is correlated with the evolution of larger organisms overtime?
Increasing atmospheric O2 levels.
What colonized land over 2 billion years ago?
Cyanobacteria and other prokaryotes.
1.5 billion years before first multi cellular plants.
How old are the oldest eukaryotic fossils?
2 - 1.5 billion years ago.
What allows eukaryotic cells to be larger and more complex that prokaryotic cells?
Complex internal membrane and cytoplasm.
When did the first multicellular red and green algae appear?
1 billion years ago.
What did land plants evolve from?
Green algae.
When did the first multicellular animals evolve?
1 billion to 600 million years ago.
When did multicellular plants and fungi colonize land?
500 million years ago.
What is sister taxon to all other insects?
Silverfish
What is adaptive radiation?
The rise of diversity of ecological roles and role specific adaptations within a lineage.
A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches.
How long do most species survive?
1-10 million years.
In relation to extinction what does the hominin fossil record show?
Rapid turnover of species, many surviving less than 1 million years.
How many mass extinctions has there been?
5
When was the largest mass extinction?
At the end of the Permian Period 252 million years ago.
90% of marine species went extinct in less that 0.1 million years.
When was the most recent mass extinction?
End of the Cretaceous period.
Caused by meteor strike.
What marks the ends of the Paleozoic and Mesozoic Eras?
Mass extinctions.
What is continental drift?
Movement of the continents across the earth.
What is one event that has led to the patterns of biodiversity we see today?
After Cretaceous extinction, many new species evolved on isolated land masses.
In regards to speciation and extinction rates what can be said about the fossil record of the last 200 million years?
Speciation rates have been higher than extinction rates.
What allows new species to occupy different habitats?
Adaptive radiation.
What is the leading model for the origin of eukaryotes?
Mitochondria evolved from bacteria when the ancestors of mitochondria merged with an archeae.
What are modern biogeographic realms related to?
Continental drift.
What were some consequences of the Cretaceous mass extinction?
Extinction of the dinosaurs.
The extinction of dominant groups opened up ecological niches, leading to adaptive radiations among the surviving species. Paved the way for the evolution of modern mammal orders and the eventual dominance of mammals in the Cenozoic Era.
What conditions promote adaptive radiation?
Ecological opportunity: Availability of unexploited resources or ecological niches.
Ex: Organisms colonized per a new area (islands)
Environmental change: Changes in the environment can create new opportunities prompting organism to adapt.
Ex: Mass extinction.
Genetic variation and reproductive isolation: Can provide the raw material for adaptation. Being isolated can help new species to continue to diverge from their relatives.
How has continental drift affected the evolution of life in the Cenozoic era?
Many new species evolved on isolated land masses, leading to the patterns of biodiversity we see today.
Four eons oldest to most recent:
Hadean, Archean, Proterozoic, Phanerozoic
Phanerozoic eras oldest to most recent:
Paleozoic, Mesozoic, Cenozoic.
First and last periods of the three eras of the Phanerozoic:
Paleozoic: Cambrian -> Permian
Mesozoic: Triassic -> Cretaceous
Cenozoic: Paleogene -> Quaternary.
What is a mass extinction?
A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world’s species being lost in a short period of geological time
In which eon did each occur?
Origin of prokaryotes, Oxygenation of atmosphere, Origin of eukaryotes, origin of multicellular eukaryotes, origin of animals, colonization of land by plants.
Archean
Late Archean to Proterozoic
Proterozoic
Proterozoic
Proterozoic to Phanerozoic
Phanerozoic
What are autotrophs?
Producers of organic matter.
Use CO2 which is an inorganic carbon.
Heterotrophs
Consume organic matter
Osmotrophs vs phagotrophs
Osmotrophs absorb
Phagotrophs eat
What holds animal cells together?
Specialized protein junctions and an extracellular matrix.
What four kinds of tissue do animals have?
Epithelial, Skeletal muscle tissue, loose connective tissue, nervous tissue.
Nerve and muscle are electrically excitable tissues.
Diploblastic vs Triploblastic
Diploblasts have two embryonic germ layers - Ectoderm and an endoderm.
Triploblasts have a third germ layer - the mesoderm.
What tissues and organs does each germ layer give rise to?
Ectoderm - Nervous system, skin
Endoderm - Endocrine glands, lungs, digestive tract, liver.
Mesoderm - Muscle, skeleton, kidneys, reproductive system.
What % of living species are animals/
75% most being insects.
What clade involves all animals?
Metazoa
Which four phyla have simple body plans?
Ctenophora, porifera, placozoa, Cnidaria.
All other animals belong to clade Bilateria.
When did the first animal fossils appear?
560 million years ago including bilaterian animals.
Molecular clocks put the origin of animals between 700 and 800 million years ago.
What did animals evolve from?
Colonial protozoans.
Cnidarian
Diploblastic animals with radial symmetry.
Gut is simple gastrovascular cavity with single opening.
What type of digestive tract do most bilaterians have?
A complete through-gut with distinct mouth and anus.
What is the function of the coelom?
What is it as well.
Fluid filled body cavity lined with mesoderm.
Functions as a hydrostatic skeleton.
Pseudocoelomates mesodermal only lines one side of the body
Difference in nerve chord between deutrosomes and protosomes.
Protostomes nerve cord on ventral side versus dorsal side for deuterostomes.
Which are the two largest animal phyla?
Mollusca and Arthropoda combine for 85% of all animal species.
What is the position of the heart and nerve cord in vertebrates/
Nerve cord is dorsal, heart ventral.
Which is the largest phylum?
Arthropods with about 1.2 million species.
What percent do chordata make up?
5%
What invertebrates are included in Chordata?
Cephalochordata and Urochordata
What are the four shared derived characters of Chordata?
Dorsal hollow nerve chord, pharyngeal gill slits, post-anal tail, Notochord.
Seen in adult cephalochordates and in embryos of urochordates and vertebrates.
When do the fossils of most animal phyla appear?
In the early Cambrian period.
The “Cambrian explosion” records the evolution of skeletonized structures.
Prior animals were all soft-bodied and did not leave an extensive fossil record.