Expert answer:S104 Exploring science Tutor-marked assignment 05

  

Solved by a verified expert:S104 Exploring scienceTutor-marked assignment 05February 2011 presentationCovering:Book 5 LifeCut-off date:Thursday 14 July 2011IntroductionThis tutor-marked assignment (TMA) will contribute 12% towards your overallmodule score.Remember to show your working in all calculations.Information about how to submit your TMA is given in the Assessment Handbook(which you can access via StudentHome) and also on the Assessment page of theS104 website.You will receive feedback from your tutor on how well you have demonstratedthe learning outcomes listed for each question.Question 1We suggest that you tackle this question after you have studied Book 5,Chapters 1–3.This question carries 12% of the marks for this assignment. It will be markedaccording to how well you demonstrate in your answer the following learningoutcomes:Ky4use information technology to learn and communicate, in particular,access resources via the internet and contribute to electronic groupdiscussionsC2apply knowledge and understanding of scientific concepts to addressfamiliar and unfamiliar problems and their contribution to informeddebate about topical issuesIn Book 5, Activity 3.1 your tutor group collaborated to research several differentprimate families. Using the information gathered by your tutor group, decidewhich of the primate species investigated you would prioritise for conservationaction and explain why. (We expect you will be able to do this in 300–400words.)You will need to consider in your answer the combination of the factorsresearched in the tutor group forum, namely the phylogenetic importance of thespecies (and/or the primate family it belongs to), the geographical range andhabitat and any current specific or non specific threats your species is facing –which may or may not be reflected in the current International Union forConservation of Nature (IUCN) red list status.In Book 4, Activity 17.1 you accessed a journal article via the Open UniversityLibrary and were shown how to cite the source of journal references in the textand then give the full details in a list of references at the end. For your answer tothis TMA question it is important that you reference the sources of anyCopyright © 2011 The Open UniversityWEB 02098 47.1 information you use to help you come to your decision about conservation action.You should therefore use the following guidelines to help you reference any webdocuments or organisational websites that you accessed to help you answer thisquestion. Your reference should be explicit enough to allow your tutor to find thesame website and check your information.Referencing web documentsYou should use the following format when referencing documents from the web:Author’s surname and initials, year of publication (in brackets), title ofdocument, ‘available from’ information such as the web address, and the dateyou accessed the site. For example:Spitzer, K.L., Eisenberg, M.B. and Lowe, C.A. (1998) Information literacy:essential skills for the information age [online], Syracuse, NY: ERICClearinghouse on Information and Technology, Syracuse University (ED 427780), available from: http://ericit.org/toc/infoliteracytoc.shtml (Accessed 28October 2003).The text citation should be given as: (Spitzer et al., 1998) or Spitzer et al. (1998)state …Another example (which references an organisational website rather than aspecific author) is:Open University Library (January 2005) Welcome to the Open UniversityLibrary, available from: http://library.open.ac.uk/ (Accessed 2 February 2006).The text citation should be given as: (Open University Library, 2005) or OpenUniversity Library (2005) states …Question 2We suggest that you tackle this question after you have studied Book 5,Chapters 5 and 6.The question carries 28% of the marks for this assignment. It will be markedaccording to how well you demonstrate in your answer the following learningoutcomes:Kn1knowledge and understanding of the importance to the cell/organism ofmetabolic processesC1describe, analyse and interpret scientific information and data presentedin a variety of ways, including texts, tables, graphs, diagrams andfigures, numerical and mathematical descriptions, computer-based mediaKy2process and present data using appropriate qualitative and quantitativetechniques and methods of presentation (including graph plotting)(a) Figure 1 shows three graphs which individually illustrate the effect ofincreasing the temperature, substrate concentration or enzyme concentrationon the rate of hydrolysis of starch to maltose by the enzyme amylase.2 rate of reactionrate of reactionrate of reactionABCFigure 1 The effect of increasing temperature, substrate concentration, orenzyme concentration on the rate of hydrolysis of starch to maltose by theenzyme amylase.For each graph in Figure 1, describe how the rate of reaction changes in response tothe increase in the factor investigated and deduce which of the factors A, B and Care the most likely to represent:(i) temperature(ii) substrate concentration(iii) enzyme concentration (when the substrate is unlimited)Using your knowledge of how enzymes work, explain the reasoning behind eachof your answers. (We expect you will be able to do this in no more than 350words in total.)(b) Table 1 shows the results of an experiment looking at the effect oftemperature on:„the production of sugars as a result of photosynthesis andthe use of sugars in the process of respiration in the leaves of a plantgrowing in a constant high light intensity.„Table 1Effect of temperature on the rate of sugar production or use.Rate of sugar production or use /arbitrary units*Temperature/°CSugar production inphotosynthesis (highlight intensity)Sugar use inrespiration002536410425157262080825481630123035020400Net gain of sugar(negative valueshows net loss)16* Arbitrary unit: a relative unit of measurement which allows comparison ofexperimental results.3 (i) Using the data given in Table 1 calculate the net gain or loss of sugar ateach temperature and enter your data into Table 1 under the appropriateheading. You may do this either by copying the completed Table 1 intoyour TMA or by completing the electronic version of Table 1 availableon the Assessment page of the S104 website and including this withyour TMA.(ii) Plot the data from Table 1, by hand, on to a single graph to show theeffect of temperature on:„sugar production during photosynthesis„sugar use during respiration andthe net gain or loss at each temperature.(You should submit your graph as part of your assignment. For advice onhow to submit a hand-drawn graph via the eTMA system please consultthe S104 website. If you will have difficulty producing a graph by handplease contact your tutor for advice.)(iii) Describe and explain the effect of temperature on the net gain or loss ofsugar in this plant as shown on the graph you have plotted. From yourgraph, estimate the temperatures at which the rate of sugar productionand use are equal and include this in your answer. (We expect you will beable to do this in 150–200 words in total.)(iv) Using your understanding of photosynthesis and respiration explain howand why the net gain and loss of sugar differs between the day and nighthours in a plant growing in a greenhouse kept at a constant temperatureof 20 °C. Your explanation should include references to ATP andNADP.2H. (We expect you will be able to do this in 120–150 words.)„Question 3We suggest that you tackle this question after you have studied Book 5, Chapter 7.The question carries 20% of the marks for this assignment. It will be markedaccording to how well you demonstrate in your answer the following learningoutcomes:Kn1knowledge and understanding of food webs and energy flow throughecosystemsC1describe, analyse and interpret scientific information and data presentedin a variety of ways, including texts, tables, graphs, diagrams andfigures, numerical and mathematical descriptions, computer-based mediaKy1use mathematical skills appropriate to the study of science at this level(algebra and arithmetic)Ky2process and present data using appropriate qualitative and quantitativetechniques and methods of presentationThroughout the calculation in this question you should show all of yourworkings, including any equations and rearrangement of equations you use, andthe correct scientific units.An ecological investigation of an area of European grassland found that theamount of solar energy reaching the grassland was 1.85 × 106 kJ m−2 y−1. Thegrasses of the area used 3.3 × 103 kJ m−2 y−1 in respiration and showed a netprimary productivity (NPP) of 2.07 × 104 kJ m−2 y−1.4 (a) What is the gross primary productivity (GPP) for this area of grassland?(b) Calculate the photosynthetic efficiency, i.e. the percentage of solar energyreaching the vegetation that is converted to GPP.(c) The biomass consumption of the three main groups of animals feeding on thegrassland is shown in Table 2. Use the information in the table to calculatethe total increase in biomass of all three primary consumers in this foodchain.Table 2 Biomass consumption and loss of energy through faeces andrespiration.Grass biomassconsumed/kJ m−2 y−1Energy used inrespiration/kJ m−2 y−1Energy lost asfaeces/kJ m−2 y−1Field mice1052664Grasshoppers440109.5264.8601632Small birds(d) 0.8 kJ m−2 y−1 is the total energy value of the grasshopper biomass that isconsumed by their major predator, spiders. If 60% of the energy consumedby spiders is unassimilated and 15% of it is converted to biomass, calculatethe energy lost to respiration by spiders.(e) Calculate the percentage of the total grasshopper biomass increase, ascalculated in (c) that is lost over a year by pathways other than spiderpredation (e.g. death, other predators).(f) Some important groups of organisms that should be included in this food webhave been omitted from this account. Name one of them and state its role inthe ecosystem. (One or two sentences)Question 4We suggest that you tackle this question after you have studied Book 5,Chapters 8, 9, 10, 13 and 14.The question carries 40% of the marks for this assignment. It will be markedaccording to how well you demonstrate in your answer the following learningoutcomes:Kn1knowledge and understanding of the gene as a unit of inheritance, sexlinked characters, genetic variation and natural selectionKn3the role of science in the world around us and in everyday lifeC2apply knowledge and understanding of scientific concepts to addressfamiliar and unfamiliar problems and their contribution to informeddebate about topical issuesKy1use mathematical skills appropriate to the study of science at this level(probability)Ky3communicate scientific topics clearly and concisely, using methods andscientific language appropriate to your purpose and audience5 A poultry farmer hopes to profit from the current craze for keeping egg layingchickens as pets and wishes to increase his stock of interesting and unusualbreeds.(a) The farmer crossed a pure-breeding white chicken with a pure-breeding blackchicken and found that 100% of their offspring (the F1 generation) were anattractive blue colour. Hoping to get more of these blue chickens he crossedseveral of the F1 offspring, but found that he had the following numbers ofchickens in the F2 generation:„Black, 28„White, 30„Blue, 60.Assign symbols to the alleles controlling these colour characters and drawgenetic cross diagrams illustrating both crosses (details of crosses may be laidout as in Book 5, Figure 8.10, using lines or, as in the alternate way shown inBook 5, Figure 8.11, using squares). Explain why the mode of inheritance offeather colour in this case means that the farmer will never be able to developpure-breeding blue chickens. Use the hints for tackling genetic problems inBook 5, Box 8.1, p. 172, to help you with these questions. (We expect youwill be able to do this in up to 120 words, excluding diagrams.)(b) In chickens, males have two Z sex chromosomes (ZZ) and females have oneZ and one W sex chromosome (ZW). The mechanism for inheritance of thesex chromosomes is exactly the same as for X and Y sex chromosomes inother species. In chickens the character of ‘barred’ or striped feathers is Z­chromosome linked. The barred feather allele ZB is dominant to the non­barred feather allele Zb. Write down the genotype that would result in a non­barred male and a barred female and explain why these are the onlygenotypes that could result in these phenotypes. (We expect you will be ableto do this in up to 100 words.)(c) In a cross between the chickens in part (b), what are all of the possibleoffspring in terms of sex and feather barring of the F1 offspring? Include agenetic cross scheme showing how you reached your answer.(d) Some combinations of alleles are actually lethal. In chickens an autosomalallele called ‘creeper’ results in short legs when it is heterozygous, but chickshomozygous for the allele die inside the egg. If the farmer crossed twocreeper heterozygotes what is the probability that an offspring that hatchedand survived would be a short-legged creeper? Assign symbols for the allelesand draw a genetic cross scheme to demonstrate how you reached youranswer.(e) Read the following edited extract from a news article, published in 2008,which discusses a recent study of genetic diversity in commercial chickensraised for the egg and meat industry, then write an account of no more than750 words entitled ‘Genetic variation is important for both wild chickens andcaptive commercially bred chickens’.You should use examples and information from the extract and S104materials. Your account should be written for a student of S104, so you mayuse scientific terminology if its meaning is clear in the context in which it isused. You are advised not to use material outside the provided extract orS104 materials, but if you do use such material, you must cite and reference itcorrectly as described in Question 1 of this TMA. It is not necessary toreference the S104 materials or the extract.6 In the introduction to your account you should include a brief explanation ofwhat is meant by genetic variation within a population. Then write youraccount using the following list as a guide to the points you should discuss inyour answer.Briefly outline the cellular processes that result in a huge range of geneticvariation in wild populations of a sexually reproducing species such as thechicken.„What are the conditions that are necessary for natural selection to act ongenetic diversity in the wild to allow species to adapt?„Which of these conditions is not fulfilled during selective breeding ofchickens in captivity?„How does selective breeding in captivity result in a reduction in geneticdiversity?„What are some of the disadvantages of losing genetic diversity and howcould the problem be overcome?„Is it important to improve genetic diversity in commercial chickenstocks?„Finally, conclude with a brief summary that relates to the content and title ofyour account.Note: Your account should be written as continuous prose (not bullet points) andyou should not use headings. Use correct sentence construction and paragraphslinked coherently and logically together. Take care that you do not exceed theword limit, and give the number of words you use at the end of your account.Edited abstract: Commercial Poultry Lack Genetic DiversityAs concerns such as avian flu, animal welfare and consumer preferencesimpact upon the poultry industry, the reduced genetic diversity ofcommercial bird breeds increases their vulnerability and the industry’sability to adapt. Researchers have found that commercial birds aremissing more than half of the genetic diversity native to the species,possibly leaving them vulnerable to new diseases and raising questionsabout their long-term sustainability.The research, led by Hans Cheng of the U.S. Department of Agriculture,is the first study to investigate the genetic diversity of basically an entireagricultural commodity. Historically, chicken producers selected birdsfor breeding based on certain desirable traits. Size was important forbroilers, while egg production was critical for layers. Despite the fact thathundreds of chicken breeds exist, today’s commercial broilers aredescended from about three lines of chickens, and poultry used in eggproduction come from only one specialised line.The research team included government, university and industrialscientists who conducted the study using the recently sequenced chickengenome. Obtaining DNA from commercial birds, they identified thenumber of different alleles found throughout the genome. By comparingthe commercial breeds with native and non-commercial birds, they foundthat commercial lines had lost up to 90 percent of alleles in some cases.Poultry is the leading meat consumed in the United States and in mostother countries, with chicken meat production increasing by 436 percentsince 1970, so maintaining a healthy genetic reservoir in food-producinganimals is crucial in order to protect the nutritional demands of a growing7 global society. Recent concerns over avian flu point to the need to ensurethat even rare traits, such as those associated with disease resistance arenot totally missing in commercial flocks. It’s also important to preservenon-commercial breeds and wild birds for the purpose of safeguardinggenetic diversity and interbreeding additional species with commerciallines might help protect the industry.8