Population Growth Essay

Bio 1130 Exam #1 Study Guide

a.) Explain how natural Selection Works: Two very important claims made by Charles Darwin and Alfred Russel Wallace about patterns that exist in the natural world. 1. Species are related by common ancestry. 2. Characteristics of species can be modified from generation to generation. Darwin called this descent with modification. Evolution is a change in characteristics of a population over time, meaning species are not independent and unchv ch h entities but are related to one another and can change through time. Evolution by natural selection occurs whenever two conditions are met. 1. Individuals within a population vary in characteristics that are HERITABLE (traits can be passed on to offsprings.) 2. In a particular environment, certain versions of these heritable traits help individuals survive better OR reproduce more than do other versions. If certain HERITABLE traits lead to increased success in producing offspring, then those traits become MORE COMMON in the population over time. ---The population’s characteristics change as a result of Natural Selection acting on individuals. -->Natural selection acts on individual. -->Evolutionary change occurs in populations.
b.) The Scientific Method: “The scientific method, Thomas Henry Huxley once wrote, “is nothing but the normal working of the human mind.” That is to say, when the mind is working; that is to say further, when it is engaged in correcting its mistakes. -Neil Postman. Steps of the Scientific Method -ask a question -Testable hypothesis -Test Hypothesis by performing a controlled experiment -Analyze data and formulate a conclusion -communicate results
The scientific method always begins with a question. After a question has been asked formulate a strong testable hypothesis. Testability of a hypothesis comes down to an “if...then” bit of reasoning. A good hypothesis will lead to a prediction, and predictions are at the heart of the testing. A good hypothesis has to also be falsifiable, meaning when a prediction based on the hypothesis is made and the test is done, at least one of the possible outcomes would contradict the hypothesis. After a hypothesis has been formulated, the next step is to test hypothesis by performing a controlled experiment. Experiment should yield some results that will either support or contradict hypothesis. Results should be interpreted and a conclusion will be made.

c.) Controlled experiment: A scientific experiment contains both a controlled group and an experimental group to compare results. The controlled group and experimental group will be kept under similar variables apart from the factor under study so that the effect or influence of that factor can be identified or determined.

recall from chapter 1:
Pasteur’s experiment was created to test the all-cells-from-cells hypothesis; cells are produced only when preexisting cells grow and divide. All the variables were kept the same in both controlled and experimental groups. Controlled variables→ Same type of broth used, broth boiled at same temperatures and time, and glass flasks used in both groups. Experimental variable→ Swan-necked flask to trap preexisting cells from air. Result: No cells appeared in swan-necked flask and cells did appear in straight-necked flask. This experiment rejected the Spontaneous generation hypothesis; cells arise spontaneously from non living materials. `` 1?.
d.) Abiotic factor effects on a population: Optimal Range, Physiological Stress, Zones of˛c vm,./ Intolerance. No one species has the capability to survive the full range of environmental conditions present on Earth. Temperature is particularly important in determining the distribution and abundance of any particular species because temperature has a big impact on the physiology of organisms, and organisms are limited in their ability to regulate their own temperatures.

q2` from lecture, Peter

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