Life Sciences/Grade 10 NCS1Assessmentexemplars forLife SciencesFET BandGrade 10January 2009DIRECTORATE:CURRICULUMDEVELOPMENT
Life Sciences/Grade 10 NCS2ContentsIntroduction 3Control Test (Term 1): Biosphere to Ecosystems 9Memorandum to Control Test: Biosphere to Ecosystems 15Research Project (Term 2): Mass extinctions 19Teacher Guidelines 19Research Task for learners 21Assessment Rubrics 22The Sixth Extinction article by Niles Eldridge 24Practical Task Exemplar (Term 3): Animal tissue 27Teacher Guidelines 27Practical Worksheets for learners 30Assessment Rubrics 32Control Test (Term 3): Molecules to organs 34Memorandum to Control Test: Molecules to organs 43Practical Task (Term 4): Anaerobic respiration 47Teacher Guidelines 47Practical Worksheet for learners 50
Life Sciences/Grade 10 NCS3IntroductionThis booklet contains exemplars for a Programme of Assessment in the LifeSciences for Grade 10, in accordance with the new Content Framework (January2009).The exemplars are arranged in the sequence they could reasonably be usedthrough the year. We have made some assumptions in deciding on thesequence.Firstly, we have assumed that the year plan for the grade will follow thesequence of topics as laid out in the new Content Framework document.Secondly, we have assumed that the two control tests will be written in aboutMarch and September and test the content covered during the first and thirdterms respectively, that the practical work will link to work done in the third andfourth terms and that the research project extends from work done in the secondterm.The Schools Development Unit at the University of Cape Town has preparedthese exemplars for the Western Cape Education Department. The Unit supportsschools in the effective delivery of the curriculum through its work in materialsdevelopment, courses, school-based work and research in language, life skills,mathematics and science education.The assessment purposes of these exemplarsThe assessment guidelines are quite intentional in their description of thepurpose of the assessment tasks. The exemplars are all to be used forcontinuous assessment, that is, assessment done during the learningexperience.The tests are summative and memos are provided. Total scores will provideteachers and learners with a measure of the extent to which the content hasbeen mastered (LO 2). Scores on certain items measure mastery of scientificprocess skills such as formulating hypotheses, interpreting graphs and drawingconclusions (LO 1). Some questions measure learner engagement with scienceand society (LO 3).
Life Sciences/Grade 10 NCS4The tests have been balanced in terms of the use of cognitive levels (e.g.Bloom’s taxonomy) and Learning Outcomes and Assessment Standards.QuestionnumberCognitive ability levels Learning OutcomesA B C D LO 1 LO 2 LO 3Total ofactualmarksNorm % 20 40 30 10 40 40 20NormmarksCognitive levels:A KnowledgeB ComprehensionC ApplicationD HOT* skills including Analysis, Synthesis and Evaluation* HOT = higher order thinkingThe practical tasks range in type from basic skills to investigations in support ofLOs 1 and 2. Criterion assessment of groups is usually by rubric, althoughanswers provided to questions could be scored. Assessment of practical workcan be more formative or more summative, depending on the placing of thepractical work in the learning programme relative to the learning of the theoreticalaspects of the topic.The research project is assessed using the criteria provided in the rubric, with anemphasis on LOs 2 and 3. Although meant to be summative, assessment of thistask can be made more formative by providing feedback on plans and drafts.Where learners are working in groups, the teacher could ask them to weight eachcontribution and distribute scores accordingly. There should be multiple chancesto formatively assess learners’ work throughout the project. Teachers coulddevelop rubrics for Process, Presentation, Criteria, Research, Teamwork,Persuasiveness, and Analysis and give them to learners.Rubrics help make your expectations clear to learners. They help the teacherassess a variety of qualities and behaviors by clearly defining or describing thelevels of skills from high to low.
Life Sciences/Grade 10 NCS5Preparing to use the research project exemplars1. General preparation• Contact your school/community library specialist for help locating relevantresources, scheduling time, and any other project assistance you feel youneed.• Gather books and other resources that will be used by learners in theirresearch activities.• Check all links for internet resources before beginning the project anddownload relevant resources and make them available to learners. Thosewho have access to the Internet can go directly to the website to do thesearch.• Create a checklist to track learner progress and completion of the projectelements. See the example below:Team Name Note Sheet Decision Sheet Process RubricTeam 1Team 22. Design StandardsA few points to consider when planning projects include• Focus on big ideas.• Frame the big idea around an essential question that provokes or sustainsinterest.• Use valid, reliable and sufficient measures of the desired results oroutcomes.• Select an effective and engaging problem or topic.• Ensure coherence, with outcomes, assessment and activities aligned.3. Thinking StrategiesInclude the following thinking strategies as a part of the lessons:• Scanning and looking for key words• Determining the importance of information• Determining into which category the information fits• Defining necessary vocabulary words• Attending to features like headings, sub-headings, table of contents,bibliography, index and glossary• Analysing, interpreting, synthesising information and ideas.
Life Sciences/Grade 10 NCS64. Technology TipsWork closely with the information technology teacher while doing the researchproject. They can schedule time where learners will work in the computer lab anddo their projectSkills: learners will need modeling, examples, and support to accomplish thegathering of information. They will need to know how to:• use the task bar at the bottom of the screen• minimise screens• navigate within a website• scroll down• copy and paste phrases and keywords (establish your rules aboutreferencing and plagiarism beforehand).Saving Work: learners may be asked to save their work on note pad or otherproject templates.Work with your IT teacher to formulate a plan for saving student documentsbefore you begin. You may need to create a folder on a common drive whereteams can save and access their files throughout the project. Demonstrate this tolearners.Classroom managementThe practical activities are written for group or pair work. Most of the learningrequires discussion and we are mindful that many schools will not have enoughequipment and other resources to keep groups very small. Suggestions forimprovised apparatus can be used to improve the situation.Some activities lend themselves to allocating roles to specific learners in thegroup. However, we have not been prescriptive in this area as different teachersdevelop different ways of doing group work in their classes.Assign 2-4 members to each team. Establish guidelines for teamwork throughdiscussion of the following:• Decide what jobs/tasks need to be done. (finding web sites, reading aloudfrom resources, typing and saving documents)• Decide how to share tasks (taking turns, how long does a turn last? doeseveryone have a task?)• What skills are needed to be successful? (good listener, patience, supportothers, how to help without doing someone else’s job)• How does a team come to agreement? Must everyone agree?• Who do the teams consult if they are having problems working together orfinding information?
Life Sciences/Grade 10 NCS7Co-operative learning role functions for group tasks1. Principal Investigator (Initiator)Manages the task within the activity.Ensures that all the group members understand the goal and content of thetask or activity.Reads instructions and procedures.Checks results.Asks questions of the teacher to clarify tasks or points.Acts as facilitator during the group discussions.2. Materials ManagerResponsible for gathering, assembling and distributing materials andequipment needed.Responsible for assembling and operating the equipment as well as checkingthe results of the activity.Carries out the investigation or assigns members of the group to carry out theprocedure.Responsible for ensuring that all the equipment is cleaned and returned to itsproper place.3. Data Collector (Evaluator)Checks to see whether the group is focused on the task.Responsible for gathering, recording and organizing the data.Develops tables, charts and graphs where needed.Certifies the data amongst all group members.Reports the results of an Activity either in writing or orally to the class or to theteacher.4. Harmonizer/timekeeperResponsible for keeping track of time, safety and for monitoring noise level.Observes and records the group’s social interactions.Encourages group members to interact and to discuss the activity.Checks the results.
Life Sciences/Grade 10 NCS8AcknowledgementsAuthor: Andrew PetersenConsultant: Dr. Neil TeubesReader: Nomvuyo MgoqiEditor: Susan BrundritTranslation: Pauline HanekomArtwork: Natalie and Tamsin HinrichsonEnquiries to:Schools Development UnitSchool of EducationUniversity of Cape TownPrivate Bag7700 Rondeboschwww.sdu.uct.ac.zaTel: 021-650-3368/3276Fax: 021-650-5330January 2008Hierdie boek is ook in Afrikaans beskikbaar
Life Sciences/Grade 10 NCS9CONTROL TEST – GRADE 10LIFE SCIENCESCONTENT AREABIOSPHERE TO ECOSYSTEMSTotal: 60 marksTime: 1 HourINSTRUCTIONS AND INFORMATIONRead the following instructions carefully before answering the questions.1. Answer ALL the questions in this control test, writing the answers on thepaper provided.2. Number the answers correctly according to the numbering system used inthis question paper.3. If answers are not presented according to the instructions of eachquestion, you will lose marks.4. All drawings should be done in pencil and labeled in blue or black ink.5. Draw diagrams or flow charts ONLY when requested to do so.6 The diagrams in this question paper may NOT necessarily be drawn toscale.7. Non-programmable calculators, protractors and compasses MAY be used.
Life Sciences/Grade 10 NCS10SECTION AQUESTION 11.1 Various possible options are provided as answers to the followingquestions. Choose the correct answer and write only the letter (A –D) next to the question (1.1.1 – 1.1.5). For example 1.1.5 D.1.1.1 The basic functional unit of the environment is the…A. biosphere.B. ecosystem.C. population.D. lithosphere.1.1.2 All organisms around the world that live in the same climate share thesame…A. population.B. ecosystem.C. biome.D. community.1.1.3 Which of the following processes occur during the nitrogen cycle?(i) Consumption of plant protein by herbivores.(ii) The decay of dead organisms by decomposers.(iii) The conversion of nitrates to nitrites by bacteria.(iv) The absorption of nitrates by plants.A. (i), (ii) and (iii)B. (ii), (iii) and (iv)C. (i), and (iv)D. (i), (ii) and (iv)1.1.4 When a jackal kills and eats a rabbit, the jackal is the…A. Producer.B. Prey.C. Predator.D. Saprophyte.1.1.5 Which one of the following is not an abiotic factor?A. Height above sea level.B. Oxygen in the atmosphere.C. Water vapour in the atmosphere.D. Bacteria in the soil. (2 x 5) (10)
Life Sciences/Grade 10 NCS111.2 Each of the following statements can be replaced by a Biologicalterm. Write only the term beside the appropriate number on theanswer sheet.1.2.1 The place in which an organism lives.1.2.2 Species that is not indigenous to an area.1.2.3 Factors which include aspect, slope and altitude.1.2.4 The type of interaction among two or more organisms for limited resources.1.2.5 The variety of living organisms of various kinds of species on earth.(1 X 5) (5)1.3 Choose an item from COLUMN B that matches a description inCOLUMN A. Write only the letter (A – L) next to the question number(1.3.1 –1.3.10), for example 1.3.6 J.COLUMN A COLUMN B1.3.1 Recycle nutrients for a community.1.3.2 Humus, pH and water capacity.1.3.3 A product that causes acid rain.1.3.4 Species that no longer exist.1.3.5 Plants adapted to live in water.1.3.6 The gas released during combustion of fossilfuels.1.3.7 Rising carbon dioxide levels.1.3.8 Removes carbon dioxide from the atmosphere.1.3.9 Replaces nitrogen in the atmosphere.1.3.10 A by-product of photosynthesis.A. global warmingB. photosynthesisC. edaphic factorsD. decomposersE. carbon dioxideF. protozoaG. decompositionH. oxygenI. extinctJ. hydrophytesK. sulphur dioxideL. denitrifying bacteria(1 X 10) (10)
Life Sciences/Grade 10 NCS12SECTION BQUESTION 22.1 Study the map showing the Biomes of South Africa below and answer thequestions that follow:2.1.1 Explain the difference between the terms Biosphere and Biome. (2)2.1.2 You have been tasked to plan a 5-day Eco-tour for foreign visitors. Theywould like to visit 5 different Biomes on their trip. You have to supply themwith information, in tabular form, regarding the climate and flora(vegetation) of 5 different Biomes. Draw up the table that you will besupplying to your visitors on arrival.Climate = (1 X 5) (5)Flora = (1 X 5) (5)
Life Sciences/Grade 10 NCS13QUESTION 33.1 Study the diagram below and answer the questions that follow:3.1.1 Explain the difference between a food chain and a food web. (2)3.1.2 In a pyramid of numbers, there is an increase in numbers towards thebase of the pyramid. Explain the Biological importance of this concept. (2)3.1.3 Explain the impact of removal of all snakes from this food web. (2)
Life Sciences/Grade 10 NCS14QUESTION 44.1 Read the following extract from a case study on the critically endangeredBlue Crane species and answer the questions that follow:The Blue Crane lives in dry mountain grasslands. They make their nests on theground. They eat seeds, shoots and animals such as insects and reptiles, frogsand fish found in or near grasslands. In the winter, they move from the mountainsto the grasslands at lower altitudes where it is warmer. Grasslands are importantagricultural land. Grasslands are often replaced by crops, pastures or plantationsof trees. Grasslands are also popular for the development of small farms. The BlueCrane can no longer live and breed in the areas where people’s activities haveremoved its habitat.(www.ewt.org.za/cranes/)4.1.1 What is the most important part of the Blue Crane habitat? (1)4.1.2 Explain your answer in QUESTION 4.1.1. (1)4.1.3 List THREE ways in which the Blue Crane habitat is being lost orreduced. (3)4.1.4 Why is the Blue Crane listed as a critically endangered species? (1)4.1.5 Explain how habitat loss, and the reduction in the number of the BlueCranes can change the energy flow and energy relationships in theecosystem. (3)4.1.6 You have been tasked to come up with a strategy to save the Blue Cranefrom extinction? Outline two of your ideas. (2)4.1.7 Write a mini-essay outlining THREE reasons why we should conservebiodiversity in South Africa? (6)TOTAL 60 MARKS
Life Sciences/Grade 10 NCS15CONTROL TEST – GRADE 10LIFE SCIENCESCONTENT AREABIOSPHERE TO ECOSYSTEMSTotal: 60 marksTime: 1 HourMEMOQuestion 22.214.171.124 B√1.1.2 C√1.1.3 D√1.1.4 C√1.1.5 D√(2 X 5 = 10)Question 126.96.36.199 Habitat√1.2.2 Alien/exotic√1.2.3 Physiographic/Abiotic√1.2.4 Competition√1.2.5 Biodiversity√ (1 X 5 = 5)
Life Sciences/Grade 10 NCS16Question 188.8.131.52 D√1.3.2 C√1.3.3 K√1.3.4 I√1.3.5 J√1.3.6 E√1.3.7 A√1.3.8 B√1.3.9 L√1.3.10 H√ (1 X 10 = 10)SECTION BQuestion 22.1 Biosphere=the earths relatively thin zone of air, soil, and water that iscapable of supporting life, ranging from about 10 km into the atmosphereto the deepest ocean floor.√Biome= A biome is characterized by its plant life, the types of which aredetermined by a location’s climatic conditions, latitude, and altitude.√(2)
Life Sciences/Grade 10 NCS172.2CLIMATE FLORA (PLANTS)FORESTS Winter rainfall region. Coolmoist environment, goodrainfall. High transpirationrate. Microclimates exist. √Stratification of various treesincluding, yellow woods,stinkwood. Various fernspecies at ground level. √GRASSLANDS Summer rainfall region. Hailstorms and winter frost.Rainfall higher than Savannaand lower transpiration rateleads to higher moisturecontent. √Variety of grass species.Scarcity of tree species. Frostrestricts tree growth.√SAVANNA(Bushveld)Drier part – Kalahari. Moisteastern area. Summer rainfallregion. √Thorn trees and Boabab. √FYNBOS Winter rainfall, summers aredry with strong winds andwinters are cold with lots ofrain and snow. √Ericoids (small flowers),Restoids (reed species) andProteoids (protea species). √SUCCULENTKAROOWinter rainfall but scarce. Hotdry climate. √Acacia trees, Namaqualandspring flowers. Smallsucculent trees, Nama Karooplants. √NAMA KAROO Arid Hardy bushes and grasses.THICKET Low rainfall, previouslyforested areasLow impenetrable forest ofevergreen, succulent andspiny trees(10)Question 33.1.1 Food chain= Shows only a portion of a food web highlighting only oneexample at each trophic level.√Food web= A series of linked food chains showing the inter-connectivity. √(2)3.1.2 Energy is lost as one move up the pyramid. √ The trophic level below mustbe large enough to sustain the level above it. √ (2)3.1.3 The primary consumer numbers (herbivores) will increase, which in turn willresult in exploitaion of the primary producers (i.e the plants will beeradicated). √ The tertiary consumers numbers may reduce as a foodsource is removed. √ (2)
Life Sciences/Grade 10 NCS18Question 44.1.1 Grasslands√ (1)4.1.2 They live in the grassland region in both winter and summer. √ (1)4.1.3 For agricultural land, √ replaced by crops, √ pastures/plantations of trees√,development of small farms. √ (any three) (3)4.1.4 Only very few are alive. √ (1)4.1.5 Insects, reptiles, frogs and fish are eaten by the Blue Crane.√ They wouldtherefore increase in numbers√because there are fewer Blue Cranesfeeding onthem. √ (3)4.1.6 Place them in a protected environment where they are allowed to breed. √Highlight the plight of the Blue Crane through a public awarenesscampaign. √ (2)4.1.7 Maintenance of ecological processes: √ oxygen we breathe, the food weeat, decomposition, recycling of nutrients that we obtain from thebiodiversity in balanced ecosystems√Medical resources: √ medical researchers regularly discover new plantsources to cure diseases. √Economic resources: √ making products for the tourist market, such asgrass mats, baskets, shells, wood, and so on. √orEthical reasons: √ do we have the right to overexploit to the point ofextinction?Humans, with their superior brain capacity, are considered custodians ofremainingliving organisms. √(6)TOTAL 60 MARKS
Life Sciences/Grade 10 NCS19Learning Outcomes and Assessment StandardsLO1: AS 2, AS 3; LO 2: AS 1, AS 2 & AS 3; LO 3: AS 1, AS2 & AS3AimThe aim of the research project is for learners to investigate mass extinctions andthe history of life on Earth.Prior learningIt would be useful if learners have been introduced to the History of life on Earthand the main eras over the past 4.5 billion yearsInstructions for teacherLearners should read the article on their own. Each learner will also need a copyof the questions and rubrics. All the tasks are suitable for group work, but Task 3should be completed individually following group discussion. The group orindividual’s work on the Tasks needs to be submitted to the teacher in the form ofa project. In addition, groups are asked to present their work to the class in theform of a PowerPoint presentation.Article Source: http://www.actionbioscience.org/newfrontiers/eldredge2.htmlConditions of LearningThis activity is suitable for individuals or groups of 2-3 learners.Language for learningThrough the activities in this task, learners will be able to understand, use andspell correctly the following terms: species; extinctions; biotic; dinosaurs andmammals; fossil record; geological-time scale and bolide impact;GRADE 10 Life SciencesResearch Project ExemplarTopic: Mass ExtinctionsTeacher guidelines
Life Sciences/Grade 10 NCS20Resources and out of school learningContact your school/community librarian for help locating relevant resources.Work closely with the information technology teacher to schedule time for thelearners to be in the computer lab to do their project. Check internet links beforebeginning the project and download relevant resources and make them availableto learners.Project AssessmentThe project will be assessed according to the rubrics at the end of the learnerworksheet. It would be useful to prepare a timeline for learners with deadlines tocomplete at different stages of the project.
Life Sciences/Grade 10 NCS21Aim: The aim of the research project is to research mass extinction and toevaluate the evidence for the various proposed hypotheses about what causedthe mass extinctions.Task 1 Extinction ChartNiles Eldredge describes the five major extinctions of the past in his article titled“The Sixth Extinction”. Create a visual representation such as a chart, mindmapor learning diagram, to represent the information in the article, using a geological-time scale.Task 2 A closer ExaminationSelect one of the past five major extinctions and describe the suggested causesand evidence scientists have gathered.Task 3 Content questions you should cover in your research1. Describe the pattern of causes for earlier mass extinctions.2. Which mass extinction was the most devastating?3. Which mass extinction is the most famous and why?4. What is the possible cause of dinosaur extinction?6. Why is the current extinction different from other major extinctions?7. How did humans cause large animals to go extinct?Your final presentation should take the form of a power point presentationand include the answers to the tasks above.Research task for learners
Life Sciences/Grade 10 NCS22Assessment rubrics1. Research project rubricThe project is assessed according to the criteria below and points are awardedas follows:2 points if the criteria are fully met.1 point is awarded for partial fulfilment.0 points awarded if criteria are not met.Criteria for project evaluation Pointsawarded2 1 0Title page and organisation1 Project is well organised with correct headings. Project titleand names of the author and a contents page are provided.Introduction2. The introduction includes a statement that makes thepurpose of the project clear and background.Presentation3. A detailed time line with the five extinctions clearlyindicated.4. Project outlines one of the extinctions in detail.5. Content questions answeredResearch and report writing6. Evidence of research7. Demonstrates clear, logical thinking and is insightful.8. Project is written in clear legible sentences and includes avalid conclusion.9. There was evidence of effort and there was evidence thatthe authors used insight when writing it up. The project wasalso handed in on time.Bibliography10.Is there evidence of literature research?Comments :________________________________________________________________________________________________________________________________
Life Sciences/Grade 10 NCS232. Presentation rubric1 2 3 4OrganisationPresentationis notorganised.Presentsfindings andconclusionswith someorganization.Presentsfindings andrecommend-ations in anorganisedmanner.Uses supportto presentsfindings,conclusions,andrecommend-ationsconvincingly.Persuasive-nessIs notpersuasive inpresentation.Shows littleevidence ofpersuasionArgumentshowsevidence ofpersuasion.Makes adramatic andcompellingargument.TeamworkDoes notwork togetherto makepresentation.Workstogether tomake thepresentation.Works as agroup tomake thepresentation.Works as acohesive unitto make thepresentation.Use oftechnologyDoes not usethetechnologyeffectively topresent themessage.Moreemphasis onuse ofgraphics andanimationthan onpresenting themessage.Use oftechnologyenhances themessage.Usestechnology asa highlyeffective tool.Graphics givestrength to apowerfullypresentedmessage.
Life Sciences/Grade 10 NCS24The Sixth ExtinctionBased on the article by Niles EldredgeThere is little doubt left in the minds of professional biologists that Earth iscurrently faced with a mounting loss of species that threatens to rival the fivegreat mass extinctions of the geological past. In 1993, it was estimated that Earthis currently losing around 30,000 species per year. Some biologists have begunto feel that this biodiversity crisis — this “Sixth Extinction” — is even moresevere.Extinction in the pastThe major global extinctions were all caused by physical events that lay outsidethe normal climatic and other physical disturbances which species, and entireecosystems, experience and survive. What caused them?The previous mass extinctions were due to natural causes.• First major extinction (c. 440 mya): Climate change (relatively severeand sudden global cooling) seems to have been at work at the first of these-theend-Ordovician mass extinction that caused such pronounced change in marinelife (little or no life existed on land at that time). 25% of families lost (a familymay consist of a few to thousands of species).• Second major extinction (c. 370 mya): The next such event, near theend of the Devonian Period, may or may not have been the result of globalclimate change. 19% of families lost.• Third major Extinction (c. 245 mya): Scenarios explaining whathappened at the greatest mass extinction event of them all (so far, at least!) atthe end of the Permian Period have been complex amalgams of climate changeperhaps rooted in plate tectonics movements. Very recently, however, evidencesuggests that a bolide impact similar to the end-Cretaceous event may havebeen the cause. 54% of families lost.• Fourth major extinction (c. 210 mya): The event at the end of theTriassic Period, shortly after dinosaurs and mammals had first evolved, alsoremains difficult to pin down in terms of precise causes. 23% of families lost.
Life Sciences/Grade 10 NCS25• Fifth major extinction (c. 65 mya): Most famous, perhaps, was the mostrecent of these events at the end-Cretaceous. It wiped out the remainingterrestrial dinosaurs and marine ammonites, as well as many other speciesacross the phylogenetic spectrum, in all habitats sampled from the fossil record.Consensus has emerged in the past decade that this event was caused by one(possibly multiple) collisions between Earth and an extraterrestrial bolide(probably cometary). Some geologists, however, point to a great volcanic event,17% of families lost.How is the Sixth Extinction different from previous events?At first glance, the physically caused extinction events of the past might seem tohave little or nothing to tell us about the current Sixth Extinction, which is apatently human-caused event through such activities as:• transformation of the landscape• overexploitation of species• pollution• the introduction of alien speciesHowever, the results of these activities are to cause vast physical changes to theplanet, as with the other extinctions.Only 10% of the world’s species survived the third mass extinction. Willany survive this one?What is the Sixth Extinction?We can divide the Sixth Extinction into two discrete phases:• Phase One began when the first modern humans began to disperse outof Africa to different parts of the world about 100,000 years ago.• Phase Two began about 10,000 years ago when humans turned toagriculture.Everywhere, shortly after modern humans arrived, many native species typicallybecame extinct. The fossil record attests to human destruction of ecosystems.
Life Sciences/Grade 10 NCS27GRADE 10 Life SciencesExemplar of a Practical TaskTopic : Animal TissueTeacher guidelinesLearning Outcomes and assessment standardsActivity 1: Dissection of a Chicken wing (LO 1: AS 1; AS 2; AS 3)Activity 2: Identify and label the different muscles of the forelimb of a chicken.(LO1: AS 2, AS 3; LO 2: AS 1, AS 2 & AS 3).Extension Activity: Research topic on Salmoneliosis(LO 2: AS 1, AS 2 & AS 3; LO 3: AS 1, AS2 & AS3)Prior LearningIt is helpful if learners can:1. recognize and label the front limb2. recognize different tissue types.3. have had some background to microorganisms and diseaseHealth and SafetyRisk assessments are required for any hazardous activity. In this practicallearners dissect and explore the wings of a chicken.• Instruct learners to take care when using a scalpel or sharp knife and whenhandling raw poultry meat.• Ensure that appropriate cleaning materials are provided in order to clean upspills, including paper towelling, plastic bags and disinfectant solution anddisposable gloves.• Cleaning staff should be alerted to the type of waste material that has beenadded to the waste bin and the need for appropriate disposal.• A First Aid kit should be readily available.Conditions of LearningThis activity is suitable for group-work or as a demonstration. Refer to theguidelines about co-operative learning and classroom management.
Life Sciences/Grade 10 NCS28Language for learningThrough the activities in this task learners will be able to:• identify and describe different tissue types including muscles and connectivetissue (including adipose tissue, cartilage, bone ,tendons and ligaments),nerves and blood vessels and their functions• discuss disease causing microbesResources• Secondary sources providing data about different tissues types (e.g. a tableshowing the different tissues types and their constituents)• Newspaper or other articles about salmoneliosis• The following websites my be useful:http://www.cdc.gov/nczved/dfbmd/disease_listing/salmonellosis_gi.htmlhttp://www.capetown.gov.za/en/CityHealth/EnviroHealth/Extension ActivityLearners could use leaflets, newspapers, books and the internet to find out aboutSalmonella food poisoning and other diseasesAnswers to questions and additional info for the teacherActivity 1:Pulling on the triceps group of muscles causes the wing to extend. Pulling on thebiceps causes the wing to flex.Tendons are made of very strong but flexible connectivetissue and attach muscle to bone. Tendons cannot stretch.Ligaments are more elastic than tendons and are able to stretch.Note: Emphasis should be placed on the structural suitability of the skeletalcomponent for the function it carries out.Memo for Activity 2:Award marks for neatness and labelling. The drawing should clearly show theinsertion of the biceps and triceps tendons on the humerus, radius and/or ulnaand shoulder .
Life Sciences/Grade 10 NCS29Memo for Extension Activity: Refer to the website:http://www.cdc.gov/nczved/dfbmd/disease_listing/salmonellosis_gi.html
Life Sciences/Grade 10 NCS30Practical Worksheet for LearnersActivity 1: Dissection of a chicken wingAim: The aim of this activity is to dissect a chicken wing and to investigate theexternal and internal tissue structure.Materials requiredPaper plateSharp knife or 1 small pair of scissors1 chicken wingDisposable glovesSafety precautionsPlease observe the laboratory rules and take care when using a sharp knife orscissors.Conditions of LearningIf you are working in groups you will be assigned tasks as per your role in thegroup. However, you will each need to complete the worksheet independently inyour books.Instructions1. Study the diagram of a chicken wing. Use the diagram to help you locatecertain bones and muscles.2. Put on protective gloves if possible.
Life Sciences/Grade 10 NCS313. Your teacher will give you a chicken wing. Rinse it well with cool water, dry itwith paper towels, and place it in a dissecting tray.4. Carefully extend the wing to find out how many major parts it has. Using thescissors, cut the skin from the wing tip to the shoulder joint. Try not to cutthrough the muscles below the skin. Do this by piercing the skin and thenslipping the scissors between the skin layer and the muscle.CAUTION: Cut away from your body and your classmates.5. Take your time peeling the skin back so as not to damage the tissuesunderlying it. The thin membrane that holds the muscles together is areolar(loose) connective tissue.6. Look for yellowish tissue that is clumped together beneath the skin. This tissuefeels greasy and is adipose tissue, made of fat cells.7. Examine the bundles of pink skeletal muscle tissue around the bones. Findthe two groups of muscles in the upper arm. Hold the arm down at the shoulder,and alternately pull on each muscle group. Observe what happens.Show the teacher that you did this. Teacher initials: _____________8. Find the two groups of muscles in the lower arm. Hold down the arm at theelbow, and alternately pull on each muscle group.9. Find the tendons--shiny white tissue at the ends of the muscles. Notice whichparts are connected by the tendons. Gently pull on a tendon. Can you stretch it?Show the teacher that you did this. Teacher initials: _____________10. Remove the muscles and tendons. Find the ligaments, the whitish ribbon-like structures between bones at the joint of the wing. They are strong, whitebands of connective tissue that connect bones.Pull gently on a ligament. Does it stretch?11. Look for cartilage. It is white in colour, and is found at the end of long bones.Describe how the cartilage feels. Is it flexible (i.e. can you bend it)?12. Cut away the membrane (connective tissue) around the muscle. The muscleis made up of many bundles of muscle fibres. Use the tip of your scissors or aneedle to separate the bundles of fibres.13. Look for nerves, which are very thin, white threads. They are often found nextto blood vessels but may be difficult to see.CLEAN UP: Dispose the chicken parts according to your teachers instructions.To prevent salmonella contamination, wash your hands and instruments well withsoap and water.
Life Sciences/Grade 10 NCS32Activity 2:Draw and label the bicep and tricep muscles showing where they attach (tobones) with the tendons. Draw tendons in red, muscles in grey.Out of School Extension Activity: Research Task on SalmoneliosisUse information from leaflets, newspapers, books and the internet to find out thefollowing:• What is salmoneliosis?• How do people catch Salmonella?• What can a person do to prevent this illness?Assessment rubricsActivity 1: Assessment Rubric for group workCRITERIA PERFORMANCE LEVELS0 1 2 COMMENTS1. Ability tofollowinstructionsUnable tofollowInstructionseven withhelp.Instructionsfollowed withregularsupervision.Able to workcompletely ontheir own.2. Ability toobserve safetyprecautionsUnable toobservesafetyprecautionsmore thantwice.Observe safetyprecautions butmade one error.Follows safetyprecautionscompletely.3. Group work Were unableto work as agroup.Attempted towork as a groupbut were unableto deal withconflict and/ordid not sharetasks in thegroup.Cooperated wellas a group – eachmember of thegroup knows theirroles.4. Ability towork tidily,organised andused timeefficientlyActivity failsbecause ofdisorganisation.Work at timestidily/organisedbut dissectionrushed.Works tidily andorganisedthroughout andcompleted task ingood time.TOTAL: 10
Life Sciences/Grade 10 NCS33Activity 2: Assessment Rubric for drawingCRITERIA PERFORMANCE LEVELS0 1 2 COMMENTS1. Layout No headingprovided anddrawing toosmall.Headingprovided but notat top of pageand/or drawingtoo small.Drawingprovided witha clear neatheading andsize at leastone third ofthe page.2. Accuracy Inaccuratesketch.Partially correctbut lacks detail.A detailedaccuratebiologicaldrawing.3. Labelling No labelsprovided.Labels untidyand or somelabels areincorrect.Labels correctand label linesare evenlyspaced, drawnclearly and donot cross.4. Use of line Untidysketch.Goodresemblance toactual structurebut used a bluntpencil and/orused excessiveshading.Used a sharppencil and didnot useexcessiveshading.TOTAL: 10
Life Sciences/Grade 10 NCS34CONTROL TEST – GRADE 10LIFE SCIENCESCONTENT AREAMOLECULES TO ORGANSTotal: 60 marksTime: 1 HourINSTRUCTIONS AND INFORMATIONRead the following instructions carefully before answering the questions.1. Answer ALL the questions in this control test, writing the answerson the paper provided.2. Number the answers correctly according to the numbering systemused in this question paper.3. If answers are not presented according to the instructions of eachquestion, you will lose marks.4. All drawings should be done in pencil and labeled in blue or blackink.5. Draw diagrams or flow charts ONLY when requested to do so.6 The diagrams in this question paper may NOT necessarily bedrawn to scale.7. Non-programmable calculators, protractors and compasses MAYbe used.
Life Sciences/Grade 10 NCS35SECTION AQUESTION 11.1 Various possible options are provided as answers to the followingquestions. Choose the correct answer and write only the letter (A –D) next to the question (1.1.1 – 1.1.5). For example 1.1.5 D.1.1.1 The part of a microscope that controls the amount of light from the lightsource is the …A. diaphragm.B. objective.C. occular.D. condensor.1.1.2 Replication of chromosomes occurs during …A. metaphase.B. anaphase.C. fertilisation.D. interphase.1.1.3 To obtain food from a plant, an aphid would pierce into which of thefollowing tissues?A. Phloem.B. Xylem.C. Schlerenchyma.D. Meristematic.1.1.4 Which of the following is not needed for photosynthesis to take place?A. Water.B. Oxygen.C. Chlorophyll.D. Carbon Dioxide.1.1.5 Which of the following is not a by-product of cellular respiration in plants?A. Oxygen.B. Water.C. Ethanol.D. Carbon dioxide.(2 x 5) (10)
Life Sciences/Grade 10 NCS361.2 Each of the following statements can be replaced by a Biologicalterm. Write only the term beside the appropriate number on theanswer sheet.1.2.1. The monomers (building blocks) of protein.1.2.2. Organelles primarly involved in protein synthesis.1.2.3. The cell cycle during which the cytoplasm is split.1.2.4. The waxy layer covering the epidermis of a leaf.1.2.5. Microscopic, finger-like projections found in the small intestine.(1 x 5) (5)1.3 State whether the following statements are True or False.1.3.1 Glucose made during photosynthesis in plants, is converted and stored asstarch, because starch is osmotically inactive.1.3.2 Fibre stimulates the digestive tract to perform peristalsis.1.3.3 Aerobic respiration in plants results in alcoholic fermentation.1.3.4 Deamination of excess amino acids is performed by the pancreas.1.3.5 A leaf that turns blue-black during a starch test is regarded as a positiveindicator for the presence of starch.(1 x 5) (5)
Life Sciences/Grade 10 NCS371.4 Choose a description from COLUMN B that matches an item inCOLUMN A. Write only the letter (A – P) next to the question number(1.4.1 – 1.4.10), for example 1.4.6 J.COLUMN A COLUMN B1.4.1 Glucagon A. Produced during anaerobicconditions in muscles.1.4.2 Cardiac sphincter B. Dependant on green plants forenergy needs.1.4.3 Lactic acid C. A hormone that converts glycogenback into glucose.1.4.4 Heterotrophic organisms D. The sphincter that controls theentrance into the stomach.1.4.5 Cambium E. Produced during aerobic conditionsin muscles.1.4.6 Mitosis F. Produce organic food from inorganiccomponents.1.4.7 Mitochondria G. Region with the greatest number ofchloroplasts.1.4.8 Fluid mosaic model H. Meristem resulting in secondarygrowth that increases the girth ofstems and roots.1.4.9 Disaccharides I. Results in the formation of twoidentical daughter cells.1.4.10 Palisade parenchyma J. Organelles responsible for cellularrespiration and production of ATP.K. Sucrose and maltose.L. The sphincter that controls theenterance into the small intestine.M. A hormone that converts glucoseinto glycogen.N. Explains the structure of the cellmembrane.O. Results in sexual reduction division.P. Glucose and fructose.(10)
Life Sciences/Grade 10 NCS38SECTION BQUESTION 22.1 Study the micrograph below and answer the questions that follow.2.1.1 Identify the biological process occuring in the cells. (1)2.1.2 State three reasons why this process is important to living organisms. (3)2.1.3 The image was captured with an electron-microscope. State two ways inwhich improvement in microscope technology has been beneficial to man. (2)2.2 Advances in Biotechnology have stimulated debate on ethical issuesregarding cloning. Read the extract from an article below:Before cloning is considered permissible medicine for human infertility, society needs toresolve many questions, including:• Is cloning unnatural self-engineering?• Will failures, such as deformed offspring, be acceptable?• Will cloning lead to designer babies who are denied an open future?• Who is socially responsible for cloned humans?• Do clones have rights and legal protection?Glenn McGee An article in ActionBioscience.org
Life Sciences/Grade 10 NCS392.2.1 Explain how cloning could be a solution to human infertility. (1)2.2.2 A number of questions are raised in the article. Write a paragraph outliningyour OWN thoughts whether cloning is a solution to human infertility. (3)2.3 Read the article below and then answer the questions that follow:2.3.1 Supply your own definition for cancer. Use your own words. (1)2.3.2 List two of the main side-effects of cancer treatment. (2)2.3.3 Cancer also affects family members. Explain the role that family memberscould play to help the cancer patient. (2)CANCER AS A DISABILITYCancer is often called uncontrolled cell growth and results when atumour arises as a result of abnormal growth of tissue. Cancer can occur inall different parts of the body and there are many different kinds of cancercells. But luckily there are ways of treating cancer nowadays. If cancer isfound early, it can often be cured completely. If however, cancer is notfound early enough; the cancer can only be slowed down, so patients livemuch longer than they would have without treatment.Cancer is a long term illness which can be seen as a ‘disability’. Theperson has to have regular treatments, and the treatments have side effectsthat make people tired and sick and may cause their hair to fall out.Patients with cancer are often anxious and afraid about whether theywill live or die. They often become depressed. Families of patients withcancer need to be understanding and supportive towards people who havecancer.Adapted from Life Sciences for all, J. de Fontaine et al.
Life Sciences/Grade 10 NCS40QUESTION 33.1 A researcher carried out an experiment to determine the effect of theconcentration of carbon dioxide on food production. The researcher plantedthe same number of bean seedlings in seven different greenhouses. Thebean seedlings were similar in age and size. Watering, temperature and thetype of soil was standardized. The researcher varied the amount of carbondioxide in the air in each greenhouse. After 30 days the bean seedlingswere collected, dried and weighed. The results are represented in the graphbelow.Graph showing the dry mass of beanseedlings grown in different carbondioxide concentrations05101520250 0.03 0.06 0.09 0.12 0.15 0.18 0.21Percentage of carbon dioxide in theair (%)Drymass(kg)3.1.1 Formulate a hypothesis for the researcher’s investigation. (1)3.1.2 Identify the following:(a) Dependent variable(b) Independent variable (2)3.1.3 At what concentration of carbon dioxide was food production the best? (1)3.1.4 Why did the learner measure the dry mass of the bean seedlings? (1)3.1.5 Explain from the graph, the relationship between the percentages ofcarbon dioxide in the air and the dry mass of the bean seedlings. (2)3.1.6 Explain how the results of such an investigation are of value to society. (1)
Life Sciences/Grade 10 NCS413.1.7 Technologically advanced nations are able to produce more food thanthey need. Suggest what could be done with the excess food produced. (2)
Life Sciences/Grade 10 NCS423.2 Malnutrition is a world-wide phenomenon. The Progress of Nations (1996)published a League Table for Malnutrition. Study an extract thereof belowand answer the questions that follow:League Table of MalnutritionPercentage of under-fives malnourishedSUB-SAHARANAFRICAMIDDLE EAST andNORTH AFRICAASIA ANDPACIFICAMERICASSouth Africa 9 Algeria 9 Mongolia 12 Chile 1Cameroon 14 Egypt 9 China 16 Paraguay 4Zimbabwe* 16 Jordan 9 Malaysia 23 Panama 7Senegal 20 Morocco 9 Philippines 30 DominicanRep.10Lesotho 21 Turkey 10 Myanmar 31 Jamaica 10Kenya 23 Iraq 12 Sri Lanka 38 El Salvador 11Zambia 25 Oman 12 Cambodia 40 Peru 11Namibia 26 Syria 12 Lao Rep. 40 Nicaragua 12Ghana* 27 Iran 16 Pakistan 40 Bolivia* 16Malawi 27 Yemen 30 Viet Nam 45 Honduras 18Rwanda 29 Sudan 34 Nepal* 49 Haiti 27Sierra Leone 29 India 53Tanzania 29 Bangladesh 67Ethiopia 48Mauritania 48
Life Sciences/Grade 10 NCS433.2.1 Which of the four areas have the highest average malnutrition statistics? (1)3.2.2 Name the country with the greatest percentage of under-fives that sufferfrom malnutrition? (1)3.2.3 State a medical condition that infants may suffer from due to a lack ofprotein in their diet. (1)3.2.4 Suggest a suitable strategy that your school could adopt in order tomake a meaningfull contribution to the fight against malnutrition. (2)TOTAL 60 MARKS
Life Sciences/Grade 10 NCS44CONTROL TEST – GRADE 10LIFE SCIENCESCONTENT AREAMOLECULES TO ORGANSTotal: 60 marksTime: 1 HourMEMOQuestion 184.108.40.206 A√1.1.2 D√1.1.3 A√1.1.4 B√1.1.5 A√(2 X 5 = 10)Question 220.127.116.11 Amino acids√1.2.2 Ribosomes√1.2.3 Cytokinesis√1.2.4 Cuticle√1.2.5 Villi√ (1 X 5 = 5)Question 18.104.22.168 True√1.3.2 True√1.3.3 False√1.3.4 False√1.3.5 True √ (1 X 5 = 5)
Life Sciences/Grade 10 NCS45Question 22.214.171.124 C√1.4.2 D√1.4.3 A√1.4.4 B√1.4.5 H√1.4.6 I√1.4.7 J√1.4.8 N√1.4.9 K√1.4.10 G√(1 X 10 = 10)SECTION BQUESTION 22.1.1 Mitosis.√ (1)2.1.2 Growth√ Repair√ Replacement of cells.√ (3)2.1.3 Specimens can be examined in great detail to make identificationpossible. Based on identification a variety of applications are possible,e.g. a medical condition can be diagnosed and treated. √It also allows for work to be done in genetic engineering.√ (2)2.2.1 Infertile parents could become parents by cloning their own DNA. Theiroffspring will thus be an exact replica of themselves. (1)2.2.2 It could be regarded as a solution to infertility, as the parents hadpreviously been unable to conceive naturally. √It makes use of advances in the medical field and is thus progressive. √It allows for ‘manipulation’ of both pheno-and genotypic traits. √or
Life Sciences/Grade 10 NCS46It is an unnatural process; it is playing ‘God’. √It may lead to abuse of the advances made in the medical field. √It may lead to exploitation by large medical firms. √ (3)(Use your own discretion and award marks if argument is well motivated.)2.3.1 When normal cell division is disrupted. The cell division becomesuncontrolled and no longer result in duplicate copies of the original mothercell. √ (1)2.3.2 Tiredness,√ nausea (vomitting) √ and/or hair-loss. √ (2)2.3.3 Family members must be supportive, understanding and informed. √ Thefamily must show empathy and provide guidance. √ (2)QUESTION 33.1.1 The higher the carbon dioxide concentration in the air, the higher the foodproduction/the lower the food production. √orThe lower the carbon dioxide concentration in the air the lower the foodproduction/the higher the food production. √ (1)3.1.2 a) Dry mass of the seedlings/food production. √b) Amount of carbon dioxide in the air in the greenhouse. √ (2)3.1.3 0.12%√ (1)3.1.4 Dry mass excludes water, therfore it shows the actual amount of foodproduced by the plant. It is more accurate. √ (1)3.1.5 As the amount of carbon dioxide increases, the dry mass/ food productionalso increases up to a certain point. √After which further increase in the carbon dioxide concentration no longerincreases the food production. √ (2)3.1.6 Such information is useful in large scale crop production to improveyield.√ (1)3.1.7 - Donated to poorer nations that cannot afford to feed their populations. √- Used to make other non - perishable products that can last longer. √ (2)
Life Sciences/Grade 10 NCS473.2.1. Asia and the Pacific.√ (1)3.2.2. Bangladesh. √ (1)3.2.3 Kwashiorkor√ or Marasmus. √ (1)3.2.4 Supporting a school feeding programme in your area. √Start an awareness campaign, highligting the plight of those in need. √.orStart sandwich-collection days at school; proceeds to go to a needyschool. √Donation of tuckshop profits could go towards a feeding programme. √ (2)(Use your own discretion and award marks if argument is well motivated.)TOTAL 60 MARKS
Life Sciences/Grade 10 NCS48Learning Outcomes and Assessment StandardsTask 1: To investigate how different temperatures affect the rising of bread(LO 1: AS 1, 2, 3)Task 2: The use of microorganisms in industry(LO 2: AS 1, AS 2 & AS 3; LO 3: AS 1, AS2 & AS3)Prior LearningDuring aerobic respiration, glucose is completely broken down to produceenergy. In the absence of oxygen, glucose is partially broken down into carbondioxide and ethanol. Since alcohol is produced, this process is also known asalcoholic fermentation. In humans the end product of the anaerobic respirationprocess (that occurs in the cytoplasm of cells) is lactic acid, often associated withcramping in muscles.It is helpful if learners know the equation:C6 H12O6 2C2H5OH + 2CO2 + EnergyGlucose Ethanol Carbon dioxideLearners should also be familiar with the following ideas:• Where and how glucose is broken down in the cell,• Basic structure of organic moleculesConditions of learningThese activities are suitable for group-work.Language for learningThrough the activities in this task, learners will be able to:• describe anaerobic respiration as a chemical reaction• identify the effects of variables like temperature and moisture on enzymeaction• identify the effect of excess temperature on enzyme activity (denaturation)GRADE 10 Life SciencesPractical Task ExemplarTopic: Anaerobic RespirationTeacher guidelines
Life Sciences/Grade 10 NCS49Classroom management• Learners should be assigned to clear roles within groups.• After conducting their experiment and recording the results, each groupwill need time to discuss and draw conclusions.Extension ActivityLearners can also experiment by putting samples in boiling water, in an oven or afreezer.Out of school learningThe following support activities are suggested:• Complete the questions to consolidate knowledge• Visit websites that will provide additional information and interactiveexercises on cellular respiration. Here is a useful website:http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/enzymes/enzymes1.shtmlTask 1: MemoThe following marks can be awarded for the graph:• Complete heading 1 mark• Correct dependent variable (height of dough in mm) 2 marks• Correct independent variable (sample A, B and C) 2 marks• Accurate line graphs plotted 2 marksAnswers to questions1. The dough mixture used, the measuring cylinder or jar size.2. The dough kept in a cool place may bit rise at all. The dough kept at roomtemperature may rise.3. Clearly since all the other variables were kept constant the only possibleexplanation is that the warmer temperature was more suitable for yeaststo be activated and produce carbon dioxide.Note : The enzymes will be denatured at very high temperature (e.g. boilingwater @ 100°C or an oven which is at 180 °C) but inactivated at very lowtemperature (e.g. in a fridge at -15 °C).
Life Sciences/Grade 10 NCS50Task 2: Research TaskThe use of microorganisms in industryResearch the use of yeast and other organisms in industry. Various industriesmake use of the process of anaerobic respiration. Learners can investigate theuse of bacteria in the production of yoghurt and in biogas production. Yeasts arealso used extensively in the wine and beer industry and to make bread andcheese.Traditional beer brewingThis is a great opportunity to include Indigenous Knowledge Systems as part ofan LO3 investigation. Learners can investigate the history of traditional beerbrewing, how the beer is brewed and how it was stored.Extension ActivityDesign an investigation to determine the effect of yeast on a dough mixture.
Life Sciences/Grade 10 NCS51Task 1: To investigate how different temperatures affect the rising of breadMaterial required for each experiment• 3 equally sized measuring cylinders or glass jars• marking pen• safety goggles• A dough mixture needs to be prepared: Mix 3 ½ cups flour with 2teaspoons of instant active dry yeast, then add 1 ¼ cups warm (not hot)water and knead.Method1. Press down equal amounts of dough into the bottom of three measuringcylinders or jars to a height of about 5 cm and label the containers A, Band C.2. The level of the dough must be marked on the side of each cylinder or jar.3 Put cylinder or jar A in a cool place, keep B at room temperature, andplace C in a warm place.4 Write down the level of the dough in each cylinder or jar immediately andnote the time on the clock and record these readings.5. At 5 minute intervals over the next 30 minutes, measure the levels of thedough for A, B and C. Record the heights and times in a suitable table onthe results sheet below.Practical worksheet for learners
Life Sciences/Grade 10 NCS52Results sheetName: _______________________________Names of others in group: ________________________________________Results of experiment:Draw a table of your resultsOn the grid below, plot the data recorded for samples A, B and C as threecurves on one set of axes.
Life Sciences/Grade 10 NCS53Questions1 Give one controlled variable …………………………………… (1)2. Compare the heights of dough samples A and B. Suggest an explanationfor this difference.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (2)3. Compare the volume of the test tubes from sample A and sample C.Suggest an explanation for this difference.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (2)