BIO 1M03 Exam Questions & Answers

Deductive Thinking - Answer - science proceeds by advancing hypotheses and comparing them to facts. - facts can be observed from nature, or we can construct experiments to test specific hypotheses Thinking Conceptually - Answer - logical interpretation and inference is simple, but not always easy - being on familiar grounds helps us think clearly Logical Equivalence - Answer - if they express the same fact in different words. In other words, if either one is true, the other one must be true. - different people find it useful to think about logical equivalence in different ways. The Cell Theory - Answer - all living organisms are composed of cells - highly organized compartment bounded by a membrane - Genes -- DNA - Proteins -- amino acids The Pasteur Experiment - Answer - an experiment that tested the cell theory using a broth in two separate flasks (one with a swan neck and one without); the swan neck flask did not accumulate in bacteria because it was not exposed to air due to condensation Hypotheses - Answer -we purse science by evaluating hypotheses. These are proposed explanations of facts -We use hypotheses to make predictions, and use experiments and observations to attempt to falsify hypotheses. -When we can prove they are false, we support them Observational Studies - Answer - look for ways to collect data that will support or challenge hypotheses - scientists are cautious about making conclusions from Control - Answer - good experiments are controlled: we have two or more groups that differ only in some factor we want to study -Groups should be similar as possible, except for the factor that we wish we study. Replication - Answer - good experiments are replicated: each group has more than one replicate. - replicates in the same group should not have anything in common (except for the factor we are studying) -replicates often planned first, then assigned randomly to groups. Evolution - Answer -the theory of evolution has replaced the theory of special creation in science -The theory of evolution asserts that species have changed through time Fossils - Answer -is a physical trace of an organism that lived in the past -fossils can be dated using (complicated) radiometric and geological techniques Extinction - Answer -many fossils have been left by organisms that are no longer around -evidence that species are changing Transitional Forms - Answer -when a species disappears from the fossil record, a similar species often appears. Vestigial Traits - Answer - is a structure that has no function, but is similar to functioning structures in related species Direct Observed Evolution - Answer -although much evolution occurs very slowly, some kinds of evolution can be and have been observed on faster scales Relationships Between Species - Answer -if species evolved from a common ancestor, we expect to see evidence that they are related to each other. -fall naturally into groups -geographic patterns of relatedness Geographic Relationships - Answer -species in the same geographic area often seem to be closely related Evolution and Similarity - Answer -in nature we observe many, often surprising, similarities between organisms. -identical developmental genes -similar limb bone structures Homology - Answer -is a similarity that is due to common ancestry -similarities apparently due to homology are widespread. Genetic Homology - Answer - at the level of genetic coding Developmental Homology - Answer - in the traits of embryos (developing organisms) Structural Homology - Answer - at the level of devleoped organisms Identifying Homology - Answer - the idea that many similarities are due to homology seems to explain many observed patterens -fall naturally into groups -genetic evidence and morphological evidence often agree Natural Selection - Answer -Darwin's big idea was not evolution, but natural selection -The first real theory of evolution was developed by Lamarck - More famous for being wrong about how evolution occurs Natural Selection Drives Evolution - Answer - Darwin's theory of natural selection can be explained using four logical steps: Variation - Answer -The individuals that make a population vary in the traits they possess, like size, shape, physiological details Heritability - Answer -Some of these differences can be inherited by offspring. For example, tall people may be more likely to produce tall offspring. Differential Reproductive Success - Answer - In each generation, some organisms leave more offspring than others Selection - Answer -Reproductive success is not random, but is influenced by differences in traits, including heritable Natural Selection (Short Version) - Answer Evolution by natural selection will occur if there is: - Heritable variation in traits - Selection (i.e., differential reproductive success) based on these traits ∗ Survival is one component of reproductive success; if you don't survive, you can't reproduce. Fitness - Answer - means simply an ability to do well under natural selection - Fitness is thus defined as average reproductive success, given a suite of heritable traits Other Models - Answer - Natural selection is not the only possible model for how evolution could occur - Inheritance of acquired characteristics (Lamarck) - Goal-directed evolution Inheritance of Acquired Characteristics - Answer - This is the idea that individuals change in response to their environment, and pass those changes on to their offspring -It is now known that while individuals do often change in response to their environment, such changes are not (usually) passed on to offspring Goal-Directed Evolution - Answer - This is the idea that organisms evolve towards specific goals - Complex, multicellular organisms - Big-brained humans Evaluating Competing Hypotheses - Answer -we challenge hypotheses with experiments and observation Acclimation - Answer - is the ability of organisms to respond directly to their environment - When organisms acclimate this does not affect the traits of their offspring Adaptation - Answer -is genetic change that increases the fitness of organisms - Adaptation does not occur as a direct response to the environment - Adaptation is usually very slow - Adaptations are passed on to offspring, and form the basis of evolutionary change The Good of the Species - Answer -Selection operates on individuals; individuals are not adapted to act for the good of the species -The evolution of co-operation always involves tension between what is good for the group, and what is good for the individual Tradeoffs - Answer - Much of adaptation is the result of compromise between conflicting goals - Brightly colored individuals are more attractive to mates, and to predators - Larger individuals compete more effectively, but are less efficient at reproducing Historical Constraints - Answer - Evolution proceeds by small steps - What is possible is guided by what has gone before Some gentics - Answer -Our basic traits are determined by genes -A location where a gene can occur is called a locus (pl. loci) -A particular version of a gene is called an allele -Complex organisms usually have two alleles at each locus - These can be the same, or different Loci - Answer -Complex organisms usually have two alleles at each locus - These can be the same, or different Heterozygous - Answer -An organism with different alleles at a particular locus Homozygous - Answer -An organism with two copies of the same allele at a particular locus Two Definitions of Evolution - Answer -Lecture : heritable changes in species traits over time -Book : changes in allele frequencies -means the same tho Genotypes - Answer - the collection of an individual's genes Phenotypes - Answer - is the collection of an individual's physiological and physical traits -Phenotype is largely (but by no means entirely) determined by genotype Hardy Weinberg Distribution - Answer -The Hardy-Weinberg distribution is the distribution expected if alleles work like coins (random and independent). Hardy Weinberg Equilibrium - Answer -Alleles selected at random from the previous generation: - Random mating within a closed population - No differences in fitness between genotypes -Hardy-Weinberg distribution, with no change in allele frequencies from generation to generation Difference From Equilibrium - Answer -If we observe large differences from the Hardy-Weinberg equilibrium, this is usually a sign that mating is not random, or that natural selection is operating -The analysis tells us that something is going on, but not what Null Model - Answer - it tells us what to expect if complicating effects are absent