evolution <-> my own notes Flashcards
(29 cards)
evolution
changes in the inherited characteristics of populations over mulitple generations
homologous structures
body structures that share a common origin; ex -> vertebrate forelimbs
body structures that share a similar function but very origins
analagous structures -> bird wing and insect wing
body structures that no longer
have a function but are homologous to structures in
other organisms
vertigial structures -> tail bone
what are the three key elements of evolution
Descent with modification over time
Modification or changes in phenotype (observable characteristics) due to mutations or gene reshuffling
Evolution is unpredictable and natural, involving chance, natural selection, and changing environments
What is a population in evolutionary terms?
A group of organisms of the same species that occupy the same geographic area.
how old is earth?
4.6 billion years old
What was the early atmosphere of Earth like?
Consisted of carbon dioxide, water vapor, hydrogen, nitrogen, methane, and ammonia; no liquid water, oxygen gas, or ozone; bombarded with UV radiation.
When did the first life forms appear?
About 3.8 billion years ago (prokaryotic cells).
What kind of environment did the first cells live in?
Harsh and devoid of oxygen; organisms were anaerobic and oxygen was toxic to them
How did photosynthesis change Earth’s atmosphere?
Photosynthesis produced oxygen as a by-product, leading to an increase in atmospheric oxygen about 2.7 billion years ago, enabling the evolution of aerobic organisms.
How did organic molecules form on early Earth?
From atmospheric gases through energy from intense heat, UV radiation, and electrical discharges, forming amino acids, sugars, and fatty acids dissolved in warm seas.
What is the Urey-Miller experiment?
A 1953 experiment that demonstrated organic molecules could form from atmospheric gases under early Earth-like conditions
How did self-replicating molecules form?
Self-replicating RNA and later DNA formed on clay templates or under dry, hot conditions near volcanoes
How did the first living cells form?
Self-replicating DNA and other organic molecules became enclosed in lipid/protein membranes, forming anaerobic cells
What are prokaryotes?
Cells without membrane-enclosed organelles; the only life forms for about 2 billion years.
What is the endosymbiont theory?
The theory that complex cells (eukaryotes) evolved when larger cells engulfed smaller prokaryotic cells, which became mitochondria and chloroplasts.
When did multicellular eukaryotes first appear?
About 1.4 billion years ago.
What are the main points of Darwin’s theory of evolution?
Inheritable variations exist among population members
More individuals are produced than can survive
Individuals with adaptive traits are more likely to reproduce
Populations become well-adapted over time
Many different species result, each adapted to specific environments
What is natural selection?
The process by which individuals with advantageous traits are more likely to survive and reproduce.
What is experimental evidence for natural selection?
Selecting fruit flies for a specific trait (e.g., geotaxis) over generations results in populations predominantly showing that trait; removing selection pressure causes reversion to wild type
What are examples of natural selection in the wild?
moth wing color evolution for camouflage
Rapid changes in Galapagos finch beaks
What is comparative anatomy?
The study of homologous structures (common origin, different function), analogous structures (same function, different origin), and vestigial structures (no longer functional but homologous
How are fossils formed?
Bodies must be quickly covered by sediment or ash; hard elements are mineralized over time and may be exposed by erosion or excavation.
