BIOL207 Athabasca University Assignment 1A PDF

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Assignment 1A (Evolution)For students with first names starting with the letters A to G. Assignments are graded out of a total of 100 points and are worth 10% of your total mark. Submit this assignment after you have completed Units 1 and 2 of the course and before you write the midterm exam. Before...

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Assignment 1A (Evolution) For students with first names starting with the letters A to G. Assignments are graded out of a total of 100 points and are worth 10% of your total mark. Submit this assignment after you have completed Units 1 and 2 of the course and before you write the midterm exam. Before you submit this assignment,make sure you have read the Assignmentssectionin your Course Orientation.

Part A: Short-answer questions Instructions: Answer each of the questions given below. You are not required to acknowledge any of the course material (eText, Study Guide). If, however, you use external resources (generally, this is not required), you will have to provide citations and references using CSE style in the name-year format.Use your own words. Don’t use direct quotes (see Orientation). Write in complete sentences. A complete answer requires on average one or two sentences per mark. Therefore, a three-mark question would be answered in three to six sentences. Part A is worth a total of 50 marks. EVOLUTION PAGES 391-408 MICROEVOLUTION PAGES 409-425 MACROEVOLUTION PAGES 426-444 CHEMICAL EVOLUTION PAGES 52-66 HISTORY OF LIFE PAGES 66-73, 445-480, 781783. 1. Briefly explain the differences between Lamarck’s and Darwin’s viewpoints concerning evolution. What do they have in common? (4) Lamarck’s theory of inheritance proposed a “perfecting principle”as a mechanism for evolutionary change, which would cause organisms to evolve into more complex versionsin order to become better suited to their environment. These changes were suggested to occur due to two evolutionary principles- “use and disuse,” and,“inheritance of acquired characteristics”. According to Lamarck, appendages would grow or shrink relative tothe amount of use they received, and adaptive changes acquired by an organism during its lifetime would be inherited by its offspring. While Lamarck theorized that an organism changed during its lifetime in accordance to its environment, Darwin proposed the theory of “descent with modification” by natural selection, which suggested that changes in populations over time were due to the selection of characteristics that provided individuals higher adaptative abilities to changing environmental forces.Darwin also described evolutionary change in terms of changes in populations rather than in individuals. This contrasted with Lamarck’s theory hypothesis in that the traits of an organism would be passed to its offspring without being revised by the life of the organism. While the evolutionary theories of Darwin and Lamarck differ in several aspects, they have some key elements in common. For example, both theories recognize that

Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Comment [AV1]: Hypothesized (see pages F-1 and F-4 through F-5 in Russell et al.)

Comment [AV2]: Explain this idea in terms of reproductive success

organisms? adapt in response to their environments, and characteristics are passed down through generations through specific mechanisms. 2. Name and explain in detail two ways of maintaining existing genetic variation in a population. (6) 3. Diploidy:Diploidic organisms contain two sets of chromosomes, each with a particular allele at a specific locus. Recessive alleles, which may be masked phenotypically, may become beneficial under changing environmental stresses and increase in expression as a result of natural selection. However, not all recessive alleles are beneficial, and could be expected to be removed from the gene pool of a population by natural selection. Diploidy protects the persistence of these masked alleles from natural selection via the phenotypic expression of the dominant allele. The property of diploidy maintains genetic variation by allowing two allelic variants of a gene. Balanced polymorphisms:Occur when different phenotypes are maintained at equilibrium in a population over many generations. This maintenance of genetic variability may occur due to a heterozygote advantage, where natural selection preserves the balanced polymorphismsince it produces a higher adaptive fitness. For example, in some areas where malaria is common, a heterozygote advantage is displayed in the genetic condition for sickle-cell anemia. When heterozygotes contract malaria, the infected cells begin to sickle and kill the parasites, allowing greater resistance to malaria.In addition, genetic variability may also be maintained when different alleles are advantageous in different environments. For example, selection for particular camouflage traits for corresponding habitats. Thus, preserving both alleles as opposed to only onemayproduce higher survival and reproductive success.  4.3.Irresponsible use of antibiotics as a routine preventive ingredient of animal feeds is a large contributing factor to the development of resistant bacterial strains (“superbugs”) that threaten animal and human well-being. Describe in detail all steps of the process that lead to bacterial resistance. Use all applicable microevolutionary terms. (6) Ingestion of antibiotics by animals, and subsequently humans, over time allows for the retention of resistant bacteria, which may begin to proliferate and be transmitted to others. The presence of the antibiotic action produces an environmental stressor for bacteria. Mutations of bacterial DNA can provide resistance to antibiotics, which allows the bacteria to exhibit higher survival and reproductive fitness in the Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Formatted: Indent: Left: 0.63 cm, No bullets or numbering

Comment [AV3]: Do you mean in frequency?

presence of the environmental pressure. Since the mutation is advantageous and heritable, the process of evolution will select for the “superbug” and fully resistant generations may begin to emerge. The role of humans in the addition of antibioticsto animal feed is a display of artificial selection, where evolution was guided by direct human interference. 5.4.Which evolutionary mechanism would you suspect if males and females of an animal species look different? (1) When male and female animals of the same species contain particular exaggerated traits, they are referred to as dimorphic charactersand are formed as a result of sexual selection. 6.5.Among the five factors that cause microevolution, name the ones that may increase genetic variation in a population.(3) 

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Mutation: New alleles are most likely to arise from genetic mutations, which are heritable changes to DNA structure. Though rare, mutations alter the nucleotide sequence of an organism’s genome, and are therefore major sources of diversity over evolutionary time. However, only mutations on reproductive cells are heritable and increase the genetic variation of a population. √ Gene flow: If organisms or genetic material migrate from one population to another and reproduce, new alleles may be introduced to the population’s gene pool. The addition of new alleles shifts the genotype frequencies and may increase genetic variation. √ Natural selection:may increaseX (or decrease) genetic variation by shifting allele frequencies within a generation.

7.6.What are subspecies? How do they differ from species? (2) Subspecies are variants of a species, which may arisefrom the inhibition of gene flow within the population. Geographic separation can cause a subspecies to differ from the species genotypically and phenotypically, due to the differing habitats and patterns of selection. For example, marked phenotypic distinctions exist in the five rat snake subspecies in eastern North America, a ring species in which genetic material is exchanged between distant populations via intermediate ones. 8.7.Describe a scenario in which a new species can arise within one generation. Make sure to use all applicable terms. (3) Many sexually reproducing organisms are diploid, meaning they have two set of inherited chromosomes. Occasionally, errors during the meiosis can result in polyploidy, which is the condition in which an organism may have more than two Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Formatted: Highlight

sets of chromosomes. Although rare in the animal kingdom, hybridization and resulting polyploidy often occur in plant species. For example, a diploid plant may not undergo the cytokinesis phase of meiosis, resulting in unreduced gametes. Following fertilization with diploid gametes, the tetraploid offspring is able to selfpollinate or breed with other tetraploid individuals. In alloploidy, where an individual has more than two sets of chromosomes derived from a singleX species, the hybrid offspring may produce polyploid gametes if the chromosome number is doubled. Through fertilization with other doubled chromosome sets, or selffertilization, a new polyploid species may arise within one generation. 9.8.Outline the Linnaean system of classification with its hierarchies. (4) The Linnaean system refers to a taxonomic classification of all living things, consisting of a hierarchy of groupings called taxa. Taxa are organized in a linear fashion from the domain to the subspecies, with the domain taxa being the most inclusive, while the species and subspeciesare the smallest, with each tax on a becoming more exclusive as the list proceeds. For example, a beaver and a platypus would be categorized within the same domain, kingdom, phylum and class, and would diverge at the order, family, genus and species level. The formal categories of the taxonomic hierarchy include: Domain: ex- Archaea, Bacteria, Eukarya Kingdom: ex- plants or animals. Phylum:ex- animals with a backbone. Class: ex- mammals. Order: ex- primates. Family: ex- hominids. Genus: ex- Homo. Species: ex- Homo sapiens. Subspecies: ex- Bengal and Siberian tiger In addition to the hierarchies, the Linnaean system also comprises a method of naming species, called binomial nomenclature. Each species identified by this method are assigned a two-part Latin name, in which the first half identifies the genus, and the second represents the species. The combination of the binomial nomenclature provides a unique name for each identified species. 10.9. Mules are crosses between two species, female horses and male donkeys. They are bred as work animals because they ideally unite the most desirable properties of each parent species. Mules are viable but not fertile. Explain whether or not their existence poses a challenge to the biological species concept. (4) The biological species concept defines species as groups of interbreeding populations? which are reproductively isolated from other groups.In order to Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Comment [AV4]: Compare cytokinesis to telophase Comment [AV5]: Good. What is this phenomenon called?

breed successfully, the offspring must be produced under natural conditions and be fertile. The existence of mules therefore does not pose a challenge to the biological species concept because the offspring are infertile. Hybrid sterility is indicative of thereproductive isolation experienced byhorses and donkeys because they are different species. 11.10. The Canadian flora and fauna west of the Rocky Mountains is quite distinct from those east of the range. Which evolutionary term best describes (one of) the reasons for the difference? Briefly explain the process. (2) Allopatric speciation may describe the reason for the distinction between the flora, as the Rocky Mountains pose a physical barrier to subdivide the population. Following geographic separation, gene flow between the flora would be inhibited, while different patterns of natural selection and genetic drift would cause genetic differences. Over evolutionary time, these differences would have accumulated as each population adapted to different environments, resulting in marked genetic differentiation. 12.11. Explain the theory of endosymbiosis. Provide two lines of evidence in its support. (4) The model of endosymbiosis theorizes that the modern chloroplast and mitochondrion are descendants of prokaryotic cells, which were engulfed by eukaryotic cells. Over time, the cells would lose their independence,becoming a joint organism as a result of symbiosis. In support of this theory, mitochondria and chloroplasts share a number of similar features with prokaryotic cells. For example, these organelles cannot be synthesized by cellular machinery, but rather are formed via binary fission, analogous to the reproduction of bacteria and archaea. In addition, mitochondria and chloroplasts both contain their own circular DNA, which is consistent with the theory of having prokaryotic ancestors, since independent prokaryotes would have had their original DNA before assimilating. Sequencing of ribosomal RNA of chloroplasts and mitochondria has also determinedthem to be of bacterial origins, with chloroplasts being most similar to cyanobacteria. The evolution of plants and algae may have begun following the incorporation of these photosynthetic cyanobacteria into eukaryotic cells. 13.12. Explain the multiregional hypothesis for the origin of humans. (3) The multiregional hypothesis for the origin of humans suggests that modern humans evolved approximately 0.5 million years ago from Homo erectus populations, which had migrated from Africa into various parts of Eurasia. Despite geographical separation, it is hypothesized that gene flow between the populations prevented reproductive isolation, resulting in the evolution and maintenance of the Homo sapiens species across a large area. Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Comment [AV6]: Yes—what kind?

By contrast, the African emergence theory argues that H. sapiens emerged from H. erectus populations in Africa approximately 100,000 years ago, and subsequently migrated into other continents, with modern humans being descendants of these migrations. The main differences between the two theories are the location and timing of the evolution of the H. erectus species into H. sapiens. 14.13. Are prokaryotes a monophyletic group? Use Fig. 3.20 in the textbook to find the answer. Use all applicable terms. (3) The three domains of life include bacteria, archaea and eukarya, which are hypothesized to have descended from a common ancestor. Prokaryotes include the bacteria and archaea taxa because they are single-celled organisms which lack a nucleus. A monophyletic taxon or group includes an ancestral species and all of its descendants, therefore, prokaryotes are not a monophyletic group because they exclude the eukaryote taxa. Prokaryotes would be considered a paraphyletic group, which include a common ancestor and only some of its descendants. 15.14. Explain the term RNA world. (2) RNA world refers to an evolutionary hypothesis which describes the potential origin of the central dogma, a process where information stored in DNA is transferred to an RNA intermediate to instruct the production of proteins. The discovery of ribozymes, single-stranded molecules capable of folding into specific shapes, introduced the idea of a system where an RNA molecule could be capable of serving as both a carrier of genetic material as well as a catalyst for chemical reactions. Evolutionary advantages for organisms encouraged the use of DNA and enzymes for protein synthesis, as these molecules improved storage and catalysis in comparison to precursor RNA. 16.15. Are gibbons closer related to humans than to orangutans? Explain your answer using the tree in Fig. 20.13 of the eText. (3) Phylogenetic trees use nodes (points of branching) and clades (biological taxa including all descendants of a common ancestor) to hypothesize the relatedness of species. The nodes represent how recently clades diverged in evolutionary time. Due to their relative position on the phylogenetic tree, gibbons are not more closely related to humans than orangutans,√ since orangutans share a more recent ancestor with humans√ and are therefore one node closer than gibbons.

Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

Comment [AV7]: Pre-mRNA has a different meaning than what I think you are intending

Comment [AV8]: What does this say about their clade?

Part B: Multiple-choice questions Instructions: Select the single best answer to each of the questions given below. Each question is worth one mark, for a total of 50 marks. 1. Which scientist first brought forward the idea of biological evolution? a. Lyell b. Darwin c. Wallace d. Hutton e. Lamarck 2. Which term from geology fits best with our ideas of how life evolved? a. genetic drift b. gradualism c. catastrophism d. erosion e. natural theology 3. Which scientist developed the idea of uniformitarianism? a. Cuvier b. Lamarck c. Darwin d. Lyell e. Wallace 4. Which term best describes Darwin’s “descent with modification”? a. evolution b. natural selection c. artificial selection d. sexual selection e. inheritance x 5. Which of the following statements was not a part of Darwin’s concept of evolution? a. Individuals of a population have variations of characters. b. Some individuals in a population reproduce more than others. c. Some recessive alleles may “hide” in a population and become more frequent when the environment changes. d. Some inherited variations may have a higher survival rate than others. e. Populations may change as a result of natural selection. 6. Darwin integrated the observation that many individuals of a species die without reproduction into his concept of evolution. Who influenced Darwin’s thoughts on this observation? a. Wallace b. Lamarck c. Cuvier d. Hutton e. Malthus Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

7. Which of the following is one of the requirements for a Hardy-Weinberg equilibrium? a. random mating b. mutations c. small populations d. natural selection e. none of the above 8. Humans have a coccyx (tailbone) that serves no particular function. This is an example of a. natural selection b. artificial selection c. a vestigial structure d. convergent evolution e. a polymorphism 9. You measure the leaf length of a population of dandelion leaves and find that they range between 1.9 cm and 35.8 cm. What is this an example of? a. microevolution b. directive selection c. qualitative variation d. quantitative variation e. stabilizing selection 10. Grasses are wind-pollinated. When pollen lands on the stigma of a flower, what is it an example of? a. non-random mating b. genetic variation c. genetic drift d. natural selection e. gene flow 11. You study a population of a butterfly species over several generations. You observe that its average wing size is steadily increasing and is significantly higher in the more recent generations. What is this most likely an example of? a. genetic drift b. sexual selection c. disruptive selection d. genetic variation e. directional selection 12. The genetic variation of the human population in Iceland was found to be low compared to that of other populations in mainland Europe. Which term best describes the likely cause of this observation? a. sexual selection b. directional selection c. disruptive selection d. bottleneck effect Biology 207: Principles of Biology II (Rev. C3)

Assignment 1A

e. founder effect 13. What is the best term to describe the existence of blood groups in humans? a. polymorphism b. balanced polymorphism c. quantitative variation d. directional selection e. inbreeding 14. If a Drosophila fly female has a preference for mating with large males, what term would you use? a. inbreeding b. random mating c. non-random mating d. genetic drift e. artificial selection 15. What is the founder effect an example of? a. non-random mating b. genetic drift c. genetic variation d. natural selection e. directional selection 16. Which of the following terms would you associate with genetic drift? a. mutations b. natural selection c. disruptive selection d. small populations e. non-random matings 17. What is heterozygote advantage an example of? a. inbreeding b. a balanced polymorp...