Review Chapter 10 PDF

Review Grade 10 10.1- Principles of Evolution u Evolution - the process of biological change by which descendants come to differ from their ancestors. u Species - a group of organisms that are closely related and can mate to reproduce fertile offspring. u Fossil - traces of organisms that...

Review Grade 10 10.1- Principles of Evolution u Evolution - the process of biological change by which descendants come to differ from their ancestors. u Species - a group of organisms that are closely related and can mate to reproduce fertile offspring. u Fossil - traces of organisms that existed in the past. u Catastrophism - The theory of catastrophism states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to become extinct in the process. u Gradualism - changes observed in landforms resulted from slow changes over a long period of time. u Uniformitarianism - This theory states that the geologic processes that shape Earth are uniform through time. Early Ideas about evolution-(4 Scientists) Theories of Geologic Change u French zoologist Georges Cuvier did not think that species could change. However, he did think that they could become extinct, an idea considered radical by many of his peers. u Fossils are traces of organisms that existed in the past. He found that the fossils in the deepest layers were quite different from those in the upper layers, which were formed by more recent deposits of sediment. u Cuvier explained his observations in the early 1800s with the theory now known as catastrophism. Principles of Geologic Change 3 Principles of Geologic Change 1. Catastrophism - states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. This shaped landforms and caused species to become extinct. The appearance of new species in each rock layer resulted from other species moving into the area from elsewhere after each catastrophic event. 2. Gradualism - James Hutton proposed that the changes he observed in landforms resulted from slow changes over a long period of time. the laying down of soil or the creation of canyons by rivers cutting through rock was not the result of large-scale events. 3. Uniformitarianism - The geologic processes that shape Earth are uniform through time. Uniformitarianism soon replaced catastrophism as the favored theory of geologic change. 10.2-Darwin’s Observations 1. Variation – the difference in the physical traits of an individual from those of other individuals in the group to which it belongs. 2. Adaptation - An adaptation is a feature that allows an organism to better survive and reproduce in its environment. Variation u Variation can occur either among members of different species (interspecific variation) or among individuals of the same species (intraspecific variation). u Darwin noted that the species found on one island looked different from those on nearby islands and that many of the islands’ species looked different from those on the nearest mainland. u These observations led Darwin to realize that species may somehow be able to adapt to their surroundings. u Adaptations can lead to genetic change in a population over time Fossil and Geologic evidence u Darwin found fossil evidence of species changing over time. In Argentina, he found fossils of huge animals, such as Glyptodon, a giant armadillo. u The fact that these fossils looked like living species suggested that modern animals might have some relationship to fossil forms. u These fossils suggested that, in order for such changes to occur, Earth must be much more than 6000 years old. u Darwin later experienced an earthquake during his voyage and saw firsthand the result: land that had been underwater was moved above sea level. Darwin’s observations on his voyage supported Lyell’s theory that daily geologic processes can add up to great change over a long period of time. Practice u Correct the false statement by re-writing the sentence: 1-An Adaptation is the difference in the physical traits of an individual from those of other individuals in the group to which it belongs. 2- Interspecific variation is variation among members of same species. 3-The theory of uniformitarianism states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to become extinct in the process. 4-Species are traces of organisms that existed in the past. Correction u Correct the false statement by re-writing the sentence: 1-An Adaptation is the difference in the physical traits of an individual from those of other individuals in the group to which it belongs. Variation is the difference in the physical traits of an individual from those of other individuals in the group to which it belongs. 2- Interspecific variation is variation among members of same species. Intraspecific variation is variation among members of same species 3-The theory of uniformitarianism states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to become extinct in the process. Catastrophism states that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to become extinct in the process. 4-Species are traces of organisms that existed in the past. Fossils are traces of organisms that existed in the past. Practice u Explain the term “Adaptation” and give 2 examples of organisms that have adapted over time. u An adaptation is a feature that allows an organism to better survive and reproduce in its environment. u Examples include: -Saddle-Backed Tortoises with long necks and legs live in areas with tall plants. -Domed Tortoises with short necks and legs lived in wet areas rich in short plants. 10.3- Theory of Natural Selection 1. Artificial Selection: The process by which humans change a species by breeding it for certain traits. 2. Heritability: The ability of a trait to be passed down from one generation to the next. 3. Natural Selection: A mechanism by which individuals that have inherited beneficial adaptations show differential reproductive success. 4. Population: All the individuals of a species that live in an area. 5. Fitness: A measure of the ability to survive and produce more offspring relative to other members of the population in a given environment. Artificial Selection u Darwin noticed a lot of variation in domesticated plants and animals. Through selection of certain traits, breeders could produce a great amount of diversity. The process by which humans change a species by breeding it for certain traits is called artificial selection. For thousands of years, humans had been breeding pigeons that showed many different traits. In order for artificial—or natural— selection to occur, the trait must be heritable. Struggle for survival Resources such as food, water, and shelter were natural limits to population growth and human population would grow very fast if these were unlimited. BUT disease and limited food get populations smaller. So. If resources were limited, and organisms then had more offspring than could survive, why do some survive, and others don’t? Some individuals had variations that were very well suited for their specific environment. What is a Population? A population is all the individuals of a species that live in an area. 4 Main Principles of the Natural Selection Theory! 1. Variation: Variations are the basis for natural selection. Whether these differences were inherited or whether they resulted from gene mutations. 2. Overproduction (More of): More offspring will improve chances for survival, it also results in competition between offspring for resources. 3. Adaptation: Variation through adaptation allows individuals to survive better. These successful individuals are then naturally selected to produce more offspring with those adaptations. 4. Descent with modification: Over time, more individuals will have the trait in every following generation, as long as the environmental conditions continue to remain beneficial for that trait. Natural selection acts on existing variation Natural selection mainly acts on physical traits rather than genetic material itself. A. Changing environments: A trait that is already in a population becomes favorable for survival because of a change in the environment, and thus is passed on to future generations. B. Adaptions as compromises (settling for something): Adaptive characteristics passed down over a long-time does not always result in individuals that are perfectly suited to their surroundings. Practice u Fill in the blanks to complete the following sentences. -Food, water and shelter were natural limits to population ____________. -___________is a measure of the ability to survive and produce more offspring relative to other members of the population in a given environment. -A trait that was already in the population become___________ for survival because of a change in the environment, and thus was passed on to future generations. - Some individuals had variations that were very well suited for their specific _____________________. Correction u Fill in the blanks to complete the following sentences. -Food, water and shelter were natural limits to population growth. -Fitness is a measure of the ability to survive and produce more offspring relative to other members of the population in a given environment. -A trait that was already in the population become favorable for survival because of a change in the environment, and thus was passed on to future generations. -Some individuals had variations that were very well suited for their specific environment 10.4- Evidence of Evolution u Biogeography: refers to the study of the distribution of organisms around the world. u Homologous structures are features that are similar in structure but appear in different organisms and have different functions. u Analogous structures are structures that perform a similar function but are not similar in origin. u Vestigial structures are remnants of organs or structures found in an early ancestor that no longer serve a useful function or may now serve a different function. u Darwin Found evidence from a wide range of sources to support his argument for evolution. The most important and convincing support came from : u 1-Fossils u 2-Geography u 3-Developmental Similarities u 4-Anatomy Evidence for evolution from different sources A. Fossils: Scientists who study fossils focus on more than just the fossil itself. They also think about its age, its location, and what the environment was like when the organism it came from was alive. B. Geography: Biogeography refers to the study of the distribution of organisms around the world. An example includes Darwin saw that island plants and animals looked like, but were not identical to, species on the South American continent. He extended this observation, proposing that island species most closely resemble species on the nearest mainland. Evidence for evolution from different sources u C-Developmental Similarities: A study proposing a relationship between barnacles which are fixed in place as adults and crabs which are mobile at all stage in their life cycles (their larvae look very similar in appearance) u D-Anatomy: This evidence came from comparing the body parts of different species. -Homologous structures are features that are similar in structure but appear in different organisms and have different functions. example: Forelimbs of Humans & Forelimbs of bats. Their appearance across different species offers strong evidence for common descent. It would be unlikely for many species to have such similar anatomy if each species evolved independently. -Analogous structures are structures that perform a similar function but are not similar in origin. Example: Bats wings have the same bone structure as an elongated hand connected by thin skin ,in contrast insect wings do not have bones only membranes that are supported y a series of long veins. u Some organisms have structures or organs that seem to lack any useful function, or at least are no longer used for their original purpose. u Vestigial structures are remnants of organs or structures found in an early ancestor that no longer serve a useful function or may now serve a different function. u In humans, the appendix is often cited as an example of a vestigial structure. The appendix is a remnant of the cecum, a major part of the large intestine in plant-eating mammals. u For example, snakes have tiny pelvic bones and stump-like limbs, even though snakes don’t walk. u For example: Wings of Ostriches Practice u Define the following: -Biogeography: -Analogous Structures -Vestigial Structures Correction u Define the following: -:Biogeography: The study of the distribution of organisms around the world. - Analogous structures:Are structures that perform a similar function but are not similar in origin. - Vestigial structures :Are remnants of organs or structures found in early ancestor that no longer used for their original purpose. 10.5- Evolutionary Biology Today What does the word Paleontology mean? u Paleontology is the study of fossils or extinct organisms, continues to provide new information and support current hypotheses about how evolution occurs. u Why can it be said that the fossil record is NOT complete? -Most living things do not form into fossils after they die -Fossils have not been looked for in many areas of the world. However, no fossil evidence that contradicts evolution has ever been found. u Scientists classify organisms into groups, the mix of traits in transitional species often makes it difficult to tell where one group ends and another begins. Molecular and Genetic evidence u DNA sequence analysis: depends on the fact that the more related two organisms are, the more similar their DNA will be. Due to mutations, the sequences of nucleotides change over time. Thus, comparing the sequences of DNA in organisms can show evolutionary relationships among the organisms. u Pseudogenes: Sequences of DNA nucleotides known as pseudogenes also provide evidence of evolution. Pseudogenes are like vestigial structures. They no longer function but are still carried along with functional DNA. u Protein Comparisons: Similarities among cell types across organisms can be revealed by comparing their proteins, a technique called molecular finger printing. A unique set of proteins are found in specific types of cells, such as liver or muscle cells. u Homeobox: Homeobox genes control the development of specific structures. These sequences of genes are found in many organisms, from fruit flies to humans. They also indicate a very distant common ancestor. Evolution unites all fields of biology u Scientists from many fields of science are shedding new light on the mechanisms and patterns of evolution. In some cases, the use of modern technology has supported fossil evidence. u Shifts in skull shape, modified limb structures, and changes in tail length provide evidence for the descent of modern whales from a common ancestor with the group of hoofed mammals that includes deer, antelope, and hippopotamuses. u The idea of common descent helps biologists understand where new diseases come from, as well as how to best manage endangered species. Practice u Fill in the blanks to complete the following sentence. -The__________ record is not complete, because most living things do not form into fossils after they die, and because fossils have not been__________ for in many areas of the world. -All living organisms share the same____________ code and use the same _____ amino acids. -Paleontology, the study of fossils or ____________ organisms continues to provide new ____________and support current hypotheses about how evolution occurs. -The idea of common descent helps biologists understand where new _____________come from, as well as how to best manage ______________species. -Scientists classify organisms into groups , the ____________ of traits in ______________ species often makes it difficult to tell where one group ends and another begins. Correction u Fill in the blanks to complete the following sentence. -The Fossil record is not complete, because most living things do not form into fossils after they die, and because fossils have not been looked for in many areas of the world. -All living organisms share the same genetic code and use the same 20 amino acids. -Paleontology, the study of fossils or extinct organisms continues to provide new information and support current hypotheses about how evolution occurs. -The idea of common descent helps biologists understand where new disease come from, as well as how to best manage endangered species -Scientists classify organisms into groups , the mix of traits in transitional species often makes it difficult to tell where one group ends and another begins.