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UNCW BIO 105 - Exam 2 Study Guide

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Bio 105 1st Edition Exam # 2 Study GuideLecture 7How do we know that something is alive? I. Characteristics of lifeA. There is a fundamental similarity among all living things on Earth and their challenges. B. All living things are composed of cells, consisting of internal cytoplasm surrounded by a membrane. C. Life has a complex, hierarchical organization. Cells are constructed from thousands of kinds ofmolecules, found in highly organized arrangements. In multicellular organisms, the cells form tissues, which form organs and organ systems. D. All organisms need energy provided by metabolic reactions. Examples of metabolic reactions include respiration and photosynthesis. E. Cells require homeostasis, the ability to maintain constant environmental conditions.F. Living things undergo growth and development. Cells grow to make larger organisms and/or more organisms. Organisms develop in response to their genetic programs and environmental influences. G. All organisms reproduce and pass their genes to the next generation. Many species can reproduce both sexually and asexually.H. All living organisms respond to stimuli. Animals run from danger, capture food, and build nests. Plants and microorganisms also respond to their environments, often through the production of chemicals or changing their growth pattern. I. All organisms adapt to their environments through the process of evolution by natural selection. a. Evolution allows us to organize our understanding of living organisms and their relationships. It provides context for new facts and ideas about plants and animals.How did Lamarck, Darwin, and Wallace contribute to our understanding of evolution?Definition of evolution: A gradual process in which something changes into a different and usually more complex or better form. (Biology) The theory that... species change with time so that descendants differ morphologically and physiologically from their ancestors (Am. Heritage Dictionary)I. History of evolution A. Anaximander and Lucretius believed that living things were related to one another and had changed over time. 1. Aristotle wrote of a ‘ladder of nature’ with perfection increasing from inanimate objects up to Greek men. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. Evolutionary thought was later overshadowed by medieval biblical interpretations of nature. B. Until the 18th century, most Western scientists believed that life was created by God, including the ideas that 1. Life is organized into a fixed number of species. 2. Species arose during the Creation and did not change thereafter. 3. Creationism is not a scientific hypothesis, but it provides testable predictions: a. All species and the Earth itself should be the same age b. The species composition of the Earth has not changed over time. C. By the late 1700’s these predictions were found to be incorrect. The Earth is extremely ancient, and organisms were discovered that had lived in the past but were now extinct. 1. The theory of gradualism stated that geological processes in the past operated like they do today. a. Geologists showed that if processes like erosion, mountain building, cave formation, etc. occurred in the past at today’s rate, the Earth must be billions of years old. 2. Biologists realized that fossils are actual remnants of ancient organisms, and that in general, the farther down a fossil was found, the older it was, so the order of fossils in the rock reflected when organisms had lived. 3. Most scientists in the 1800’s accepted the idea of changes in the diversity of life on earth, or evolution, but they could not explain it. 4. Jean Baptiste Lamarck offered an early idea: inheritance of acquired characteristics. He proposed that (1) organisms change as they get adaptations that they need through interaction with the environment, and (2) that their offspring inherit these changes. a. Lamarck hypothesized that giraffes stretched their necks to reach higher leaves, and this stretching slowly lengthened their necks. Their offspring inherited these lengthened necks, and stretched them more, so over time giraffes' necks become longer. b. A weakness in Lamarck's hypothesis it that he did not offer a mechanism to explain how these inheritance changes may have occurred and been inherited. But, genetics and inheritance were a mystery to everyone at that time. i. Experiments done to test Lamarck’s hypothesis invariably did NOT support it. ii. Even after many generations of cutting the tails off mice, the baby mice were always bornwith tails. The environmental alteration of losing their tails was never inherited by the offspring. iii. Human example: Arnold Schwarzenegger's kids have to work out to get muscles; they aren't born with them!KEY POINT: Lamarck proposed an unsuccessful hypothesis for evolution, the inheritance of acquired characteristics.D. Another evolutionary hypothesis was developed by Charles Darwin and Alfred Russell Wallace.1. Neither Lamarck nor Darwin and Wallace were the first to propose evolution. The idea had been around a long time; Darwin's grandfather Erasmus Darwin studied it. 2. Darwin and Wallace were the first to suggest a believable mechanism, supported by evidence, by which evolution could occur. This mechanism is evolution by natural selection. 3. Why were Darwin and Wallace able to make this breakthrough? a. They differed from other European naturalists in an extensive knowledge of the diversity of life, stemming from travel in the tropics. b. They were both island explorers, and evolution is fast and impressive on islands. 4. Darwin traveled around the world on the Beagle, as a naturalist and companion to the ship's captain, Robert FitzRoy. His main duty was to eat dinner with the captain, but he was free to travel inland and explore when the ship was in port. a. Darwin studied extensively in South America and its surrounding islands. The Galapagos islands were particularly important for the development of his hypotheses. They are a group of small, arid volcanic islands over 1000 km west of the coast of Ecuador. i. There he found many similar, but distinct, species of finches and tortoises. ii. Darwin became obsessed with understanding how and why this came to be. b. He


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