Science Test 4 Review Sheet PDF

Fossils - Remains of organisms preserved in the Earth There are 2 ways to date fossils 1) Relative dating a) One fossil is compared to another (depth in soil) 2) Absolute dating a) When fossil is formed b) Find radioactive elements found in rocks and fossils...

Fossils - Remains of organisms preserved in the Earth There are 2 ways to date fossils 1) Relative dating a) One fossil is compared to another (depth in soil) 2) Absolute dating a) When fossil is formed b) Find radioactive elements found in rocks and fossils c) Measuring amounts or uranium & lead d) More lead = older Fossil record - Info about fossils found in a particular region Unicellular organisms - Organisms made up of a single cell Organisms 3.8 billion years ago were unicellular Atmosphere did not contain as much oxygen Multicellular organisms - Living things made up of many cells (around 1.2 billion years ago) Individual cells are specialized Earliest multicellular organisms were tiny seaweeds 250 million years - No mountains, shallow water 70 million years - Flat shallow seas 53 million years - Replaced by tropical rainforest 37 million years - Volcanic eruption covers land with hot ash 16,000 - Similar to what we see today 500 million years ago, the first multicellular organisms moved from water to land Mass extinctions - Periods when huge numbers of species have died or become extinct in a very short time Permian Extinction - 250 million years ago, 90% of the species in the ocean became extinct - Many land-dwelling animals disappeared Cretaceous Extinction - 65 million years ago, dinosaurs disappeared - Link to Chicxulub crater Extinction of species help new species develop Evolution - Refers to the process through which species change over time - Results from a change in the genetic material passing to other generations Jean Baptiste de Lamark - French scientist - 1st scientist to propose a model of how life evolves - Proposed explanation for evolution based on the idea that organism can acquire new traits during their lifetime and pass them onto offsprings - Unable to provide any evidence Darwin (50 years later) - Charles Darwin - British naturalist - Spent 5 years as a naturalist aboard the Beagle - Began to compare new animals he say with ones back home - Published basis of modern evolution theory - Noticed many animals in different places had separate traits to help them survive Artificial Selection - Process breeders use to acquire different traits Natural Selection - Members of species best suited to live survive & reproduce at higher rates than others - Based on overproduction, variation, adaptations, & selection Overproduction - When an animal reproduces, itt usually makes more offspring than the environment can support - Only few survive - Ex. Only few of the thousands of salmon eggs hatch and survive Variation - Within a species, there are natural differences (variations) - Sometimes, the genetics material itself changes, causing a new variation - Passed on from one generation to the next Adaptation - Any inherited trait that give san organism an advantage in the environment - Caused by mutations - Ex. Slight change in tail fin shape can help fish swim faster Selection - Darwin believed that individual organisms with particular adaptation were most likely to survive to reproduce - The species is evolving through natural selection In 1859, Darwin published On the Origin of Species Speciation - Evolution of new species from an existing species - Occurs when environment changes either dramatically or gradually Isolation - Many new species had evolved after populations separated from the mainland - Darwiin reasoned that isolation of populations contribute to the process of a speciation Theory - Widely accepted statement based on scientific evidence that explains a group of facts Fossil evidence supports evolution (shows ancestors) - Specimens Darwin collected provided evidence that species in the past are similar to those now - Evidence that 2 species with common ancestor can develop differently in different locations - Ancestor - Early form of an organism from which later forms descend - Idea of common an ancestor is important to the theory of natural selection Biological evidence supports evolution (Shows what is observed) - Structure and development of living things are involved - Evidence for evolution can be observed within physical structure of adult organisms - Vestigial organs - Physical structures that were fully developed and functional in ancestors of organisms but reduced and unused in later species Similar structures with different functions - Similarity in structure indicates organisms shared a common ancestor - Process of natural selection caused variations - The environment influenced the selection of traits Similarities in Development - Scientists noted that some animals looked similar in early stages of life and became more different as they grow - Embryos look similar DNA contains the info all organisms need to grow and to maintain themselves DNA bases are A, T, C, G Located in DNA are genes Gene - Segment of DNA that relates to a specific trait or function of an organism Scientists have identified the clock gene in many mammals - Function of sleeping and waking More matches in sequence of bases, the more closely they are DEFINITIONS Fossils - Remains of organisms preserved in the Earth Relative Dating - The dating of fossils age relative to another Absolute Dating - The actual estimation of a fossil age Fossil Record - Info about fossils found in a particular region Unicellular Organisms - Organisms made up of a single cell Multicellular Organisms - Living things made up of many cells Mass Extinctions - Periods when huge numbers of species have died or become extinct in a very short time Permian Extinction - Time period when 90% of land animals disappeared Cretaceous Extinction - Mass extinction when dinosaurs became extinct Evolution - Refers to the process through which species change over time Artificial Selection - Process breeders use to acquire different traits Natural Selection - Members of species best suited to live survive & reproduce at higher rates than others Theory - Widely accepted statement based on scientific evidence that explains a group of facts Ancestor - Early form of an organism from which later forms descend Vestigial Organs - Physical structures that were fully developed and functional in ancestors of organisms but reduced and unused in later species Gene - Segment of DNA that relates to a specific trait or function of an organism Clock Gene - Gene relating to the function of walking and sleeping