Glossary of Biology Vocab and Key Concepts for Chapter 17 The History of Life
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- scientists who study fossils
- fossil record
- information about past life; organisms grouped together and arrange them in the order in which they lived from oldest to most recent
- species died out
- relative dating
- age of a fossil determined by comparing its placement with that of fossils in othe layers of rock
- index fossil
- used to compare the relative ages of fossils; exist short period but have had a wide geographic range
- length of time required for half of the radioactive atoms in a sample to decay
- radioactive dating
- use of half-lives to determine the age of a sample
- geologic time scale
- represents evolutionary time- Precambrian time, Paleozoic, Mesozoic, Cenozoic
- division of the time between the Precambrian and the present into three eras
- eras subdivided
- what can be learned from the fossil record?
- the fossil record provieds evidence about the historyof life on Earth. it also shows how different groups of organisms have changed over time.
- which type of dating provides an aboslute age for a given fossil? describe how this is done.
- in radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.
- how are eras and periods related?
- after precambrain time, the basic divisions of the geologic time scale are eras and periods.
- proteinoid microsphere
- tiny bubbles formed by large organic molecules under certain conditions; similar to living cells
- microscopic fossils
- endosymbiotic theory
- eukaryotic cells formed from a symbiosis among several different prokaryotic organisms
- what substances probably made up Earth's early atmosphere?
- Earth's early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water
- what molecules were the end products in Miller and Urey's experiments?
- Miller and Urey's experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth
- How did the addition of oxygen to Earth's atmosphere affect life of that time?
- the rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved new, more efficient metabolic pathways that used oxygen for respiration.
- according to the endosymbiotic theory, how might chloroplasts and mitochondria have originated?
- the endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms.
- mass extinction
- many types of living things became extinct at the same time; affected plants and animals
- where did life exist during the early Paleozoic Era?
- early in the paleozoic era, the fossil record became rich with evidence of many types of marine life.
- what evolutionary milestone involving animals occurred during the Devonian Period?
- During the Devonian, animals began to invade the land.
- what are the two key events from the Mesozoic era?
- events during the mesozoic include the increasing dominance of dinosaurs, the mesozoic is marked by the appearance of flowering plants.
- what happened during the cenozoic era?
- during the cenozoic, mammals evolved adaptations that allowed them to live in various environments- on land, in water, and even in the air.with some climate changes from warm in Tertiary and an ice age in the quaternary
- large scale evolutionary changes that take place over long periods of time
- adaptive radiation
- a single species or a small group of species has evolved into several different forms that live in different ways
- convergent evolution
- unrelated organisms come to resemble one another
- two species evolve in response to changes in each other over time
- punctuated equilibrium
- pattern of long, stable periods interrupted by brief periods of more rapid change.
- describe patterns of macroevolution
- mass extinctions, adaptive radiation, convergent evolution, coevolution, puncuated equilibrium, developmental genes
- how did hox genes help reveal how evolution occurred?
- 1st-molecular studies show that homologous hox genes extablish body plans in animals as different as insects and humans
2nd-major evolutionary changes may be based on hox genes
3rd- small changes in timing of genetic control during embryonic develpment makes difference between long legs and short ones- variation involved in natural selection
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