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Bio 112 Lab Exam 1
| Question/Term | Answer/Definition |
|---|---|
| Describe the importance of genetic variation (i.e. heritable variation) to evolution. | Genetic variation plays an important role in the survival and adaptability of a species. When an environment changes, a population will have to adapt to survive, and natural selection (mech) can't act if there is no genetic variation. |
| How does genetic variation influence Natural Selection? | Genetic variation is essential b/c natural selection can only increase/decrease freq of alleles that already exist in the population. It provides the phenotypic variation upon which natural selection acts. |
| What other factor is necessary for Natural Selection to occur? | Heritibility |
| Heritable traits vs. Acquired traits | Genetics vs Learned behaviors (i.e., hair color, skin color, eye color vs. talking, walking, swimming, or playing an instrument) |
| How can Natural Selection affect the evolution of a population? | Relative fitness, forms of natural selection, sexual selection, limitations of natural selection |
| List and describe the 5 assumptions made in the Hardy-Weinberg Equilibrium Model. | 1) No mutations 2) Random mating 3) No natural selection 4) Very large population size 5) No gene flow in/out |
| Understand the electrophoresis activity we conducted/discussed in class. What data did we obtain? How was that data used? | The activity distinguished the 3 genotypes of normal, anemia, and carriers. Normal (HbA x 2) traveled very far, sickle-anemia (HbS x 2) traveled mid, and carriers (HbS/A) displayed 2 close bands or a smear of them. |
| Natural Selection | Mechanism for evolution via reproduction of individuals w/ favorable genetic traits that survive environmental changes |
| Gene Pool | Collection of all the genes in a population |
| Adaptation | An inherited feature that helps an organism's survival and reproduction in its present environment |
| Population Genetics | Branch of genetics that studies how genetic differences change w/in and btw populations over time/space |
| Hardy-Weinberg Equilibrium | If a large population sexually reproduces at random, then the genetic frequencies should not change in the next generation |
| Genetic Drift | Changes in genetic frequency often in small populations due to random events |
| In what types of populations are the effects of Genetic Drift strongest? | Small populations |
| Founder Effect | An instance of genetic drift where a founder population breaks away from original source, leading to a random, less diverse population |
| Bottleneck Effect | An instance of genetic drift where an event drastically reduces the populations' size, resulting in a smaller, less diverse population |
| Fixation/Extinction of alleles | An outcome where a single allele for a specific gene becomes the only variant present in a population, usually after members carrying other alleles go extinct. |
| In what types of situations is fixation likely to occur? | Small but effective population sizes increase the likelihood that mating events will occur between close relatives, leading to an increase in inbreeding and subsequent loss of heterozygosity (thereby allele fixation). |
| Recessive Refuge | Phenomenon that enables a deleterious recessive allele to persist in a gene pool by "hiding out" in heterozygous individuals. Refuge becomes easier as the recessive allele becomes more rare |
| Heterozygote Advantage | Phenomenon where the heterozygous genotype has an advantage over either homozygous genotypes |
| How does heterozygote advantage affect allele frequencies? | Heterozygote advantage can increase the freq of a +/- mutant allele in a population b/c heterozygotes are more likely to survive, so natural selection maintains a variety of fluctuating alleles in the population. |
| How is a person who is heterozygous for the sickle cell allele a good example of heterozygote advantage? | Hetero indivs for sickle-cell (HbS/A) will continue to survive natural selection and outlive people who possess either the dom homo gene (HbA) or rec sickle-cell anemia (HbS). These individuals will increase in numbers, obtaining a heterozygote advantage. |
| What is the relationship between rainfall, mosquitos, malarial transmission, frequency of HbS allele in the population, and frequency of Sickle-cell Anemia? | When rainfall increases, mosquito population increase, thereby by increasing the possibility of malarial transmission. As malaria prevalence rises, the HbS allele freq increases in defense, resulting in more people developing sickle-cell anemia. |
| Why do we see more sickle-cell anemia deaths in the generation(s) following a large malaria outbreak? | If the malaria death rate increases, then sickle-cell deaths will increase as more people receive either the nonresistant homozygous alleles or the sickle-cell anemia homozygous gene. |
| Images for: - Sickle-cell Anemia - Malaria - Completely normal blood - A possible carrier for Sickle-cell Anemia | - Sickle cell Anemia: evident sickles found in sample - Malaria: normal cells w/ small internal parasites [dots] - Completely normal blood: normal round clean cells - A possible carrier for Sickle-cell Anemia: some sickle/oval-shaped cells |
| Apomorphy | A new, derived character state on a phylo tree |
| Plesiomorphy | A primitive or ancestral trait on a phylo tree |
| Synapomorphy | An apomorphy shared by 2+ groups on a phylo tree |
| Autapomorphy | An apomorphy unique to 1 group on a phylo tree |
| Symplesiomorphy | An ancestral character state that is shared by two or more groups, but is inherited from ancestors older than the last common ancestor |
| Sister Taxa | 2 lineages that stem from the same branch point |
| Node | Point where 2 lineages diverge |
| Clade | A group that includes a common ancestor and all its living/extinct descendants |
| Ancestor | Indicator of a phylo's lineage |
| Analogous Trait | Structures modified for similar functions w/in unrelated species (no common ancestry) |
| Convergent Evolution | Evolution from natural selection that acted in the same way from the same conditions for 2+ unrelated species |
| Monophyletic, paraphyletic, and polyphyletic clades | Mono: a group that includes a common ancestor and all its living/extinct descendants Para: a group that includes a common ancestor and and some, but not all, of its descendants Poly: a group w/o a common ancestral species |
| What is the importance of having an outgroup on a cladogram/phylogeny? What about on a character matrix? | An outgroup is used to determine which character state is ancestral/primitive (0), and which traits are derived/advanced (1) |
| How can you tell when a trait is a synapomorphy versus when it is an analogous trait? | A trait is a synapomorphy when it's shared & derived from a common ancestor w/in the ingroup, while an analogous trait is a similar trait that evolved independently in a different lineage. (evolutionary relation vs. convergent evolution) |
| Explain the principle of parsimony. | When presented with multiple explanations for a phenomenon, the simplest explanation is usually the best. In phylogeny, it meaning the tree w/ the fewest changes/branches is most likely to be correct. |
| Know the basics of skull morphology. Which skull characteristics were most useful in classifying these organisms? | The most useful traits are autapomorphic or synapomorphic (i.e. peg teeth, diastema, extended rostrum, large braincase, occipital crest) |
| Understand what the “0” and “1” represent on a character matrix. Why does the outgroup get all “0”s even if it has a trait present? | The 0's indicate a group's evolutionary common traits. The outgroup is the closest ancestor for the ingroup, so it has every common trait (therefore all 0's). The 1's indicate the advancement/adaptation of an og trait. |
| Why is the generally-accepted consensus tree thought to be more accurate than a tree based on 1 or 2 genes? | Different genes can evolve at different rates and in different unrelated species (convergent evolution), leading to potentially conflicting evolutionary histories in single-gene trees. |
| What does the y-axis (x-axis for computer-generated phylogenetic trees) represent? | Y-axis of the tree represents the degree of relatedness btw different species thru passage of time w/ evolutionary changes (branch lengths usually prop. to the time elapsed since the split from a common ancestor) |
| describe the basic characteristics of the three Domains of living organisms, as well as their unique characteristics. | |
| identify the three morphological forms (shapes) of bacteria. | |
| what horizontal gene transfer is and why it is sometimes difficult to determine the phylogeny of single-celled organisms. | |
| Aerobic, anaerobic, and facultative anaerobic bacteria. | |
| Why are cyanobacteria ecologically important? | |
| What is the theory of endosymbiosis? What is secondary endosymbiosis? | |
| akinete | |
| heterocyst | |
| Oogonium vs. isogonium | |
| Which generation is diploid? | |
| Which generation is haploid? | |
| Which generation produces spores and by what process? | |
| Which generation produces gametes and by what process? | |
| two main groups of Angiosperms (Monocot and Eudicot) and the characteristics we use to identify them. | |
| What are the two types of vascular tissue and their functions? | |
| Distinguish between Monocot and Eudicot Flower anatomy | |
| What is a fruit? | |
| What is the difference between simple, aggregate and multiple fruit and know some examples? | |
| How would the Eudicot stem differ if it were a woody stem? What other types of plants besides Eudicots can also have woody stems? | |
| What is secondary growth? What two layers of tissue on a woody stem are responsible for secondary growth? What is the area in the center of the woody stem called? |
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