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54 Cards in this Set
- Front
- Back
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Define adaptation |
an inherited trait that helps an organism survive |
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Define evolution |
the process of how organisms acquire adaptations over time |
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What is a cladogram? |
a tree-like diagram that displays evolutionary relationships among living species and their ancestors |
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Define ancestor |
An organism from which others have descended |
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What are the 3 pieces of evidence that provide that basis for the theory of evolution? |
Comparative anatomy, DNA analysis, and the fossil record. |
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Define homologous structures |
Body structures that have a common origin but do not necessarily perform the same function. |
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Define analogous structures |
Structures that serve the same function but come from different origins.
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How do comparative anatomists compare embryos to prove the Theory of Evolution?
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The early stages of the embryos look very similar to each other.
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How do scientists use DNA evidence to prove the theory of evolution? |
Species that share more similarities in their DNA base sequences are more closely related than those that share fewer similarities. |
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Define fossil |
A remnant of trace of an organism from the past embedded and preserved in Earth's crust. |
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How are fossils formed? |
An organism's body is quickly covered in sediments from an event like a mudslide. After a long time, the chemicals in the body parts are replaced with rock-like minerals. |
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What is the fossil record? |
A historical sequence of life on Earth. The upper layers are earlier and the lower layers are older. |
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Why are their gaps in the fossil record? |
Because most ancient species did not fossilize. |
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Define natural selection |
The process by which organisms with favorable adaptations survive and reproduce at a higher rate than organisms with less-favorable adaptations. |
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Define artificial selection |
The process in which humans select the traits they desire in an organism and force the two organisms to mate. |
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What are the 4 laws of evolution? |
1. Organisms change over time 2. All organisms are descended from common ancestors by a process of branching 3. Evolution is gradual, taking place over a long time 4. The mechanism of evolution is natural selection |
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True or False: populations tend to grow faster than their food supply |
True |
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What are the 4 environmental variables that affect the size of a population? |
Predator's, food supply, disease, and climate |
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What are the 4 steps in the process of natural selection? |
1. Populations over-populate 2. Individuals in a population vary (genetic variation) 3. Favorable traits are selected by the environment 4. Favorable adaptations accumulate |
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What causes variations in the population of a species? |
Mutations |
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Why is genetic variation important? |
To ensure a better chance of survival in case of an environmental change that requires a certain trait to be able to live. |
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What are the 3 basic steps for a new species to evolve? |
1. Isolation: A population is divided by an event. 2. Adaptation: as the environment changes, the population undergoes natural selection and changes. 3. Differentiation: When the population becomes so different that they cannot interbreed with the original population if put back together. |
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Define extinction |
When the environment changes and the adaptations of a species are no longer sufficient for its survival. The entire species dies off. |
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In what orientation do sedimentary rock layers form? |
Horizontally |
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Define superposition
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The principle that states that in layers of sedimentary rocks the lowest layers were the earliest to be deposited. |
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Why might rock layers be found bent or shifted? |
Due to slow and very powerful movements of Earth's crust. |
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Define relative dating |
A method of sequencing events in the order in which they happened. |
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What are cross-cutting relationships? |
A vein of rock that cuts across a rock's layers is younger that the layers. |
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What is an inclusion? Is the inclusion older or the surrounding rock? |
Rock pieces found inside other rocks. Sediments or melted rock surround the inclusion. The inclusion is older. |
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What is faunal succession? |
It means that fossils can be used to identify the relative age of the layers of sedimentary rock. |
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How are eras determined? |
By the dominant life forms that were present at the time. |
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How are each eras divided? |
Into smaller chunks called periods. |
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What are periods based off of? |
The types of fossils found within each area. |
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What is the order of the eras from oldest to youngest? |
Precambrian, Paleozoic, Mesozoic, Cenozoic |
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When did the first prokaryotic cells appear? |
More than 3 billion years ago. |
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When did the first eukaryotic cells appear? |
About 2 billion years after the first prokaryotic cells. |
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What happened in the Silurian period? |
Fishes with backbones appeared. |
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What do scientists believe mammals evolved from? |
Therapsids |
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What was the dominant life in the Mesozoic era? |
Dinosaurs |
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What significant event happened in the Jurassic period? (not Jurassic Park!) |
The first birds appeared |
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In what period of the Cenozoic era did modern humans appear? |
The Quanternary period |
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Define mass extinction |
Periods of large-scale extinction
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What was the largest mass extinction and what percentage of life did it kill? |
The Permian extinction killed 90% of Earth's living organisms. :'( |
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What extinction wiped out the dinosaurs and what do scientists believe it was caused by? |
The Cretaceous-Tertiary extinction happened by a large asteroid hitting Earth. (R.I.P Dino's) |
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Why do scientists believe we are in a 6th mass extinction right now? |
Because many species have become extinct over the last couple hundred years. Scientists believe it is caused by humans. |
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Define absolute dating
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A method of estimating the age of a rock sample in years. |
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Define half-life |
The amount of time it takes for half of the unstable atoms in a sample to decay. |
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What is radioactive decay? |
Unstable atoms contain more particles that can be held together by strong forces. They undergo radioactive decay by releasing some of those particles. |
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How do scientists use absolute dating to estimate the age of fossils? |
By measuring the ratio of unstable atoms to stable atoms in a sample of rock from a fossil. |
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What are the seven levels of classification of the Kingdom Animalia from broadest to most specific?
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Kingdom, Phylum, Class, Order, Family, Genus, Species |
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What is a scientific name?
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The two-part, scientifically recognized name given to an organism, consisting of its genus and species. |
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Define systematics |
The process of classifying living things according to evolutionary relationships. |
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What is an evolutionary tree?
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A diagram with many branched that shows evolutionary relationships among organisms, both living and extinct. |
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What are the six different kingdoms? |
Animalia, Fungi, Plantae, Protista, Archae-bacteria, Eubacteria |
