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Ap Bio Reading Guide Fred And Theresa Holtzclaw Answers Full PDF
This process of natural selection leads to the evolution of new species. Part of Biology (Single Science) Genes, inheritance and selection Add to My Bitesize Add to My Bitesize Twitter Facebook WhatsApp Share Share this with Twitter Facebook WhatsApp Copy link Read more about sharing Revise quiz Test previous 1 2 3 4 5 6 7 8 Page 4 of 8 next Darwin's theory of evolution by natural selection Charles Darwin Charles Darwin was an English naturalist who studied variation in plants, animals and fossils during a five-year voyage around the world in the 19th century. Darwin visited four continents on the ship HMS Beagle. Darwin observed many organisms including finches, tortoises and mockingbirds, during his five-week visit to the Galapagos Islands, near Ecuador in the Pacific Ocean. He continued to work and develop his ideas once he returned from his voyages. Darwin’s theory of evolution by natural selection challenged the idea that God made all the animals and plants that live on Earth. This idea contradicted the commonly held Christian views of his era. Darwin’s world expedition and observations, were backed by many years of experimentation, discussions with like-minded scientists and his developing knowledge of geology and fossils. Finally he felt able to propose his theory of evolution by natural selection. Darwin published his scientific work and ideas 28 years after his voyage. Darwin proposed that: individual organisms within a particular species show a wide range of variation for a characteristic individuals with characteristics most suited to the environment are more likely to survive to breed successfully the characteristics that have enabled these individuals to survive are then passed on to the next generation This theory is called natural selection.Get advice here Links Personalise your Bitesize. Sign in, choose your GCSE subjects and see content that's tailored for you. The BBC is not responsible for the content of external sites.
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Read about our approach to external linking. All living species are classified using the system developed by Linnaeus. Part of Biology (Single Science) Natural selection and genetic modification Add to My Bitesize Add to My Bitesize Twitter Facebook WhatsApp Share Share this with Twitter Facebook WhatsApp Copy link Read more about sharing Revise quiz Test previous 1 2 3 4 5 6 7 8 9 Page 1 of 9 next Darwin's theory of evolution Charles Darwin Charles Darwin was an English naturalist who studied variation in plants, animals and fossils during a five-year voyage around the world in the 19th century. Darwin visited four continents on the ship HMS Beagle. Darwin observed many organisms including finches, tortoises and mocking birds, during his five week visit to the Galapagos Islands, near Ecuador in the Pacific Ocean. He continued to work and develop his ideas once he returned from his voyages. Darwin's theory of evolution challenged the idea that God made all the animals and plants that live on Earth, which contradicted the commonly held Christian views of his era. He did not publish his scientific work and ideas until 28 years after his voyage. Finally, as a result of Darwin's world expedition and observations, which were backed by many years of experimentation; his discussions with like-minded scientists and his developing knowledge of geology and fossils; he proposed the theory of evolution by natural selection. Darwin proposed that: individual organisms within a particular species show a wide range of variation for a characteristic individuals with characteristics most suited to the environment are more likely to survive and to breed successfully the characteristics that have enabled these individuals to survive are then passed on to the next generation This theory is called natural selection.Get advice here Links Personalise your Bitesize. Sign in, choose your GCSE subjects and see content that's tailored for you.
The BBC is not responsible for the content of external sites. Read about our approach to external linking. When you purchase through links on our site, we may earn an affiliate commission. Learn more Individuals with traits that allow them to adapt to their environments will help them survive and have more offspring, which will inherit those traits. Individuals with less adaptive traits will less frequently survive to pass them on. Over time, the traits that allow species to survive and reproduce will become more frequent in the population and the population will change, or evolve. Through natural selection, Darwin suggested, a diverse life-forms could arise from a common ancestor. In natural selection, it's the natural environment, rather than a human being, that does the selecting. Darwin did not know the mechanism by which traits were passed on, according to National Geographic; that is, he did not know about genetics, the mechanism by which genes encode for certain traits and those traits are passed from one generation to the next; he also didn’t know about genetic mutation, which is the source of natural variation. But future research by geneticists provided the mechanism and additional evidence for evolution by natural selection (see “Modern Understanding,” below). It is one of the best-substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines, including not just genetics (which shows that different species have similarities in their DNA) but also paleontology and geology (through the fossil record, which shows how that species that existed in the past are different from those present today), and developmental biology (species that seem very different as adults pass through similar stages of embryological development, suggesting a shared evolutionary past). (See the open-access textbook Concepts of Biology for more information about these lines of evidence.) How did whales evolve.
The idea didn't go over very well with the public or with other scientists. Darwin was so embarrassed by the ridicule he received that the swimming-bear passage was removed from later editions of the book. Scientists now know that Darwin had the right idea but the wrong animal. Instead of looking at bears, he should have been looking at cows and hippopotamuses. The story of the origin of whales is one of evolution's most fascinating tales and one of the best examples scientists have of natural selection. What is natural selection. Natural selection can alter a species in small ways, causing a population to change color or size over the course of several generations. Take the example of whales: By using evolution as a guide and understanding how natural selection works, biologists knew that the transition of early whales from land to water occurred in a series of predictable steps. The evolution of the blowhole, for example, might have started with random genetic changes that resulted in at least one whale having its nostrils farther back on its head. The whales with this adaptation would have been better suited to a marine lifestyle, since they would not have had to completely surface to breathe. Such individuals were more successful and had more offspring. In later generations, more genetic changes occurred, moving the nose farther back on the head. Other body parts of early whales also changed. Front legs became flippers. Back legs disappeared. Their bodies became more streamlined, and they developed tail flukes to better propel themselves through water. Darwin also described a form of natural selection that depends on an organism's success at attracting a mate — a process known as sexual selection. The colorful plumage of peacocks and the antlers of male deer are both examples of traits that evolved under this type of selection. But Darwin wasn't the first or only scientist to develop a theory of evolution.
Around the same time as Darwin, British biologist Alfred Russel Wallace independently came up with the theory of evolution by natural selection, while French biologist Jean-Baptiste Lamarck proposed that an organism could pass on traits to its offspring, though he was wrong about some of the details. He thought organisms did this by changing their behavior and, therefore, their bodies — like an athlete working out and getting buff — and that those changes were passed on to offspring. For example, Lamarck thought that giraffes originally had shorter necks but that, as trees around them grew taller, they stretched their necks to reach the tasty leaves and their offspring gradually evolved longer and longer necks. Lamarck also believed that life was somehow driven to evolve through the generations from simple to more complex forms, according to Understanding Evolution, an educational resource from the University of California Museum of Paleontology. Though Darwin wasn't sure of the mechanism by which traits were passed on, he did not believe that evolution necessarily moved toward greater complexity, according to Understanding Evolution; rather, he believed that complexity arose through natural selection. A Darwinian view of giraffe evolution, according to Quanta, would be that giraffes had natural variation in their neck lengths, and that those with longer necks were better able to survive and reproduce in environments full of tall trees, so that subsequent generations had more and more long-necked giraffes. The main difference between the Lamarckian and Darwinian ideas of giraffe evolution is that there's nothing in theDarwinian explanation about giraffes stretching their necks and passing on an acquired characteristic. What is modern evolutionary synthesis. That came later, with the discovery of how genes encode different biological or behavioral traits, and how genes are passed down from parents to offspring.
Mutations can be caused by random errors in DNA replication or repair, or by chemical or radiation damage. Usually, mutations are either harmful or neutral, but in rare instances, a mutation might prove beneficial to the organism. If so, it will become more prevalent in the next generation and spread throughout the population. But natural selection isn't the only mechanism by which organisms evolve, she said. For example, genes can be transferred from one population to another when organisms migrate or immigrate — a process known as gene flow. And the frequency of certain genes can also change at random, which is called genetic drift. The reason Lamarck's theory of evolution is generally wrong is that acquired characteristics don't affect the DNA of sperm and eggs. A giraffe's gametes, for example, aren't affected by whether it stretches its neck; they simply reflect the genes the giraffe inherited from its parents. But as Quanta reported, some aspects of evolution are Lamarckian. For example, a Swedish study published in 2002 in the European Journal of Human Genetics found that the grandchildren of men who starved as children during a famine passed on better cardiovascular health to their grandchildren. For instance, a chemical modification called methylation can affect which genes are turned on or off. Such epigenetic changes can be passed down to offspring. In this way, a person's experiences could affect the DNA he or she passes down, analogous to the way Lamarck thought a giraffe craning its neck would affect the neck length of its offspring. What is the evidence for evolution. Even though scientists could predict what early whales should look like, they lacked the fossil evidence to back up their claim. Creationists viewed this absence, not just with regard to whale evolution but more generally, as proof that evolution didn't occur, as pointed out in a Scientific American article.
But since the early 1990s, scientists have found evidence from paleontology, developmental biology and genetics to support the idea that whales evolved from land mammals. These same lines of evidence support the theory of evolution as a whole. Its forelimbs had fingers and small hooves, but its hind feet were enormous relative to its size. The animal was clearly adapted for swimming, but it was also capable of moving clumsily on land, much like a seal. When it swam, the ancient creature moved like an otter, pushing back with its hind feet and undulating its spine and tail. Modern whales propel themselves through the water with powerful beats of their horizontal tail flukes, but A. natans still had a whip-like tail and had to use its legs to provide most of the propulsive force needed to move through water. For example, in 2007, a geologist discovered the fossil of an extinct aquatic mammal, called Indohyus, that was about the size of a cat and had hooves and a long tail. Scientists think the animal belonged to a group related to cetaceans such as Ambulocetus natans. Researchers knew that whales were related to artiodactyls, but until the discovery of this fossil, there were no known artiodactyls that shared physical characteristics with whales. After all, hippos, thought to be cetaceans' closest living relatives, are very different from whales. Indohyus, on the other hand, was an artiodactyl, indicated by the structure of its hooves and ankles, and it also had some similarities to whales, in the structure of its ears, for example. Over 60 million years, several transitional forms evolved: from top to bottom, Indohyus, Ambulocetus, Rodhocetus, Basilosaurus, Dorudon, and finally, the modern humpback whale. (Image credit: NOAA) Genetic evidence also supports the idea that whales evolved from land mammals and provides information about the exact branching of the evolutionary tree.
Before 1985, researchers thought pigs were more closely related to whales, but this 1999 study overturned that idea, as the Associated Press reported. In 2019, researchers reported in the journal Science Advances about which genes within the whale genome were inactivated during the process of the creature's evolution from land mammals, as Science Friday reported. The researchers could tell that certain genes, including one involved in making saliva, had been inactivated because there are remnants of them, which the researchers call genomic fossils, in whale genomes. This indicates that whales evolved from a salivating creature. There's also evidence of cetacean evolution from developmental biology. Developmental biology illustrates the fact that animals that are very different as adults share similarities as embryos because they are evolutionarily related. For example, as embryos, cetaceans started to develop hind limbs, which disappear later in development, while the forelimbs remain and develop into flippers, according to the journal Evolution: Education and Outreach. This suggests that cetaceans evolved from a four-legged ancestor. Is the theory of evolution controversial. Despite the wealth of evidence from the fossil record, genetics and other fields of science, some people still question the theory of evolution's validity. Some politicians and religious leaders denounce the theory, invoking a higher being as a designer to explain the complex world of living things, especially humans. School boards debate whether the theory of evolution should be taught alongside other ideas, such as intelligent design or creationism. Additional reporting by contributors Alina Bradford and Ashley P. Taylor. Additional resources The National Oceanic and Atmospheric Administration has a presentation on whale evolution. To understand the difference between a theory and fact, see this National Academy of Sciences website.
Related: Live Science Topic: Evolution — News and information on evolution and the battle with proponents of so-called creation science. You will receive a verification email shortly. Please refresh the page and try again. You can unsubscribe at any time and we'll never share your details without your permission. Visit our corporate site. New York. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine. Internet Explorer 5 and above or Netscape 6 and above. As we get asked If you would like to Scientists do not use these terms that way and when scientists talk about the theory of evolution they are not expressing reservations about its truth. For scientists a theory is a rigorously tested statement of general principles that explains observable and recorded aspects of the natural world. Typically considerable evidence is gathered first and the theory will develop from that. A theory can incorporate facts, laws, inferences, and tested hypotheses and is a well-substantiated explanation of some aspect of the natural world. No amount of validation changes a theory into a law. Darwin's theory of evolution has withstood the test of time and thousands of scientific experiments; nothing has disproved it since Darwin first proposed it more than 150 years ago. Many scientific advances, in a range of scientific disciplines including physics, geology, chemistry, and molecular biology, have supported, refined, and expanded evolutionary theory far beyond anything Darwin could have imagined. These facts can be tied together and provide evidence and support for the theory of evolution. The absence of direct observation does not make conclusions from the evidence less certain.
Rather than labelling species as more or less fit, natural selection works by giving individuals who are better adapted to a given set of environmental conditions an advantage over those that are not as well adapted. These better adapted individuals are more likely to successfully reproduce and leave offspring, so that over time their genes spread through the population. To survive but not pass on one's genes to the next generation is to be biologically unfit. Diversification of a species from single ancestors may be due to geographical or behavioural reasons and can help a species to adapt in changing environments. The field of evolution is divided into at least two broad areas: microevolution and macroevolution. Microevolution looks at changes within species over time using laboratory tests and observation. Macroevolution studies how taxonomic groups above the level of species change from examining collected evidence provided by fossil record and DNA comparisons that help to reconstruct how various organisms may be related. These days even most creationists acknowledge that microevolution has been upheld by tests and observation.Historical sciences like astronomy, geology and archaeology, as well as evolutionary biology, can test hypotheses by checking whether they accord with physical evidence and whether they lead to verifiable predictions about future discoveries. Pick up any issue of a peer-reviewed biological journal, and you will find articles that support and extend evolutionary studies or that embrace evolution as a fundamental concept. When confronted by statements of scientific authorities that are supposed to question evolution always ask for the original article or book they came from. The original version from the scientist-author will almost certainly present evolution in a supportive light. The parent species may Extinction is often When conditions change, some Certain pieces of that puzzle are clearly missing, but others seem very much in place.
Just as with energy flow, the key to both early and present-day membranes lies in the nature of electrons and their polarity. Just as electrons and nuclei attract one another because of their opposite charges, the oppositely charged ends of polar molecules bind weakly to one another. These nutrients formed as the result of the energy of lightning and ionizing radiation Astrochemical analyses hint that quantities of these compounds might have originated in space and fallen to earth in comets, a scenario that may solve the problem of how those constituents arose under the conditions that prevailed when our planet was young. We were not As long as the forces of selection stay constant, natural selection can push evolution in one direction and produce sophisticated structures in surprisingly short times. These individuals pass their genes and advantageous traits to their offspring, giving the offspring the same advantages. Each tiny change in a structure is dependent upon changes in all the other structures. In this way, individual parts of a system evolve in unison to be both structurally and functionally compatible. Entropy is a physical concept often described as the amount of disorder in a system. The word disorder as a physical term differs significantly from the conversational use of the word. The Second Law states that in a closed system no energy gain or loss can happen, unless other compensating activities are taking place. Earth is not a closed system, because there is a continual input of energy from the sun thus the Second Law of Thermodynamics does not apply to A mutation can be defined as a change in genetic material that results from an error in replication of DNA. Mutations can be beneficial, harmful, or neutral. Apparently harmful mutations may be beneficial in some contexts. A good example is sickle-cell anaemia, a recessive condition caused by a single mutation.
While individuals who have 2 copies of the harmful allele face a whole range of health problems (not only severe anaemia), individuals who are heterozygous (possess one normal and one harmful allele) are protected against malaria. This maintains the recessive allele in the population. Similarly, people who are heterozygous for thalassaemia (another form of anaemia) are also protected against malaria. Consequently, both the sickle-cell allele and the thalassaemia allele are more common in regions where malaria is endemic (sickle-cell in Africa, thalassaemia in the Mediterannean). Functional modules within genes can be spliced together in novel ways. Whole genes can be accidentally duplicated in an organism's DNA, and the duplicates are free to mutate into genes for new, complex features, which natural selection can then test for possible uses. Populations evolve. Because individuals in a population vary, some in the population are better able to survive and reproduce given a particular set of environmental conditions. These individuals generally survive and produce more offspring, thus passing their advantageous traits on to the next generation. Over time the general population changes. Changes would accumulate in the isolated population. If those changes became so significant that the splinter group could not or routinely would not breed with the original stock, then the splinter group would be reproductively isolated and on its way toward becoming a new species (allopatric speciation). Often, transitional fossils combine some traits of older, ancestral species with traits of more recent species (for instance, a series of transitional fossils documents the evolution of fully aquatic whales from their terrestrial ancestors). One of the most famous fossils of all time is A sequence of fossils spans the evolution of modern horses from the tiny They assert that their criticism of evolution is scientific, not religious.
But the various aspects of intelligent design theory have not yet been subjected to the normal process of scientific experimentation and debate, nor have they been accepted by the scientific community. They say that the eye's ability to provide However, Biology Another example of how Scientists from many fields have examined these ideas and have found them to be scientifically insupportable. For example, evidence for a very young Earth is incompatible with many different methods of establishing the age of fossils and geological formations. Furthermore, because the basic proposals of creation science are not subject to test and falsification like scientific theories, these ideas do not meet the criteria for science. Finally, the question of whether there is an intelligent designer is un-testable using the methods of science, and therefore is not a scientific claim. His father, Robert Darwin, was a physician, Charles's mother, Susannah Wedgwood Darwin, died He later enrolled in Cambridge University to After receiving his degrees in 1831, Darwin accepted an He died on April 19, 1882, and lies buried If extrapolated beyond its role as a scientific theory, it The same fear exists today.All rights reserved. His theory sets about explaining Darwin made the following five Those individuals This, by definition, is Adaptations are anatomical structures, There are three key conclusions to Therefore, It must be remembered This is seen in the fact that In this sense. It has known security flaws and may not display all features of this and other websites. Learn how to update your browser Grades 5 - 8 Subjects Biology, Ecology, Earth Science, Geology, Geography, Physical Geography He concluded that those ancestors must be fish, since fish hatch from eggs and immediately begin living with no help from their parents. From this reasoning, he proposed that all life began in the sea.
His idea, however, was not a theory in the scientific meaning of the word, because it could not be subjected to testing that might support it or prove it wrong. In science, the word “theory” indicates a very high level of certainty. Scientists talk about evolution as a theory, for instance, just as they talk about Einstein’s explanation of gravity as a theory. When it comes to the evolution of life, various philosophers and scientists, including an eighteenth-century English doctor named Erasmus Darwin, proposed different aspects of what later would become evolutionary theory. But evolution did not reach the status of being a scientific theory until Darwin’s grandson, the more famous Charles Darwin, published his famous book On the Origin of Species. Darwin and a scientific contemporary of his, Alfred Russel Wallace, proposed that evolution occurs because of a phenomenon called natural selection. Those that are better physically equipped to survive, grow to maturity, and reproduce. Those that are lacking in such fitness, on the other hand, either do not reach an age when they can reproduce or produce fewer offspring than their counterparts. Natural selection is sometimes summed up as “survival of the fittest” because the “fittest” organisms—those most suited to their environment—are the ones that reproduce most successfully, and are most likely to pass on their traits to the next generation. Natural selection was such a powerful idea in explaining the evolution of life that it became established as a scientific theory. Biologists have since observed numerous examples of natural selection influencing evolution. Today, it is known to be just one of several mechanisms by which life evolves. For example, a phenomenon known as genetic drift can also cause species to evolve. In genetic drift, some organisms—purely by chance—produce more offspring than would be expected.
Those organisms are not necessarily the fittest of their species, but it is their genes that get passed on to the next generation. A hypothesis is tested to determine if it is accurate. The Rights Holder for media is the person or group credited. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.If no button appears, you cannot download or save the media. You cannot download interactives.Alfred Russel Wallace noted the similarities and differences between nearby species and those separated by natural boundaries in the Amazon and Indonesia. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species. Use the resources below to teach the theory of evolution in your classroom. However, what most people do not know is that another scientist, Alfred Wallace, a naturalist, a geographer, and a socialist, also deserves some credit for the theory. Use these ideas to teach about the water cycle in your classroom. Alfred Russel Wallace noted the similarities and differences between nearby species and those separated by natural boundaries in the Amazon and Indonesia. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species. Use the resources below to teach the theory of evolution in your classroom. However, what most people do not know is that another scientist, Alfred Wallace, a naturalist, a geographer, and a socialist, also deserves some credit for the theory. Use these ideas to teach about the water cycle in your classroom.
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