GRADE 8 NATURAL SCIENCES MEMORANDUM

1 GRADE 8 NATURAL SCIENCESMEMORANDUMMODULE 1: LIFE AND LIVINGLIFE AND LIVING 1 1 1 1 3 4 6 6 6

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3 19 20 21 22 22 23 24 26 26 Table of contentsGraphs IntroductionAnalysing graphsLine graph Line graphBar graphs (charts) and histogramsPie graphAssignment 1: graph exercisesLine graphBar graphPie graphPhotosynthesis and respirationIntroductionPhotosynthesisThe sun is the ultimate source of energyThe process of photosynthesisPlants convert glucose into other compoundsRespirationRespiration releases energy from foodRespiration and photosynthesis cycleConducting investigationsObservation and research questionIntroductionAimHypothesisMateria lsMethodsResults DiscussionConclusionReferencesAssignment 2.

4 Conducting investigationInteraction and interdependence within the environmentIntroductionEcologyInteractio ns between living thingsEcosystemsBiotic and abiotic factors 28 28 29 29 30 31 32 32 34 36 38 39 45 45 47 47 49

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6 69 69 70 71 Table of contentsThe size of an ecosystemSurvival in an ecosystemFeeding relationshipsProducersConsumersDecompose rsFood chains, food webs and energy pyramidsFood chainsFood websEnergy pyramidsBalance in an ecosystemHuman factors that disrupt ecosystem balanceAdaptationsDefining adaptationAssignment 3: adaptationChanging environmental conditions and adaptationsLack of adaptation causes extinctionAdaptations of plants Camouflage and mimicrySymbiosisConservation of the ecosystemWhy conserve species?Sustainable use of resourcesHow environmentalists conserve ecosystemsHow can I contribute to conservation?

7 MicroorganismsIntroductionTypes of microorganismsViruses BacteriaProtistsFungiPreventing infection with microorganismsCuring diseasePasteurisation VaccinesAntibioticsMicrographs and scalesHomework 1 GRADE 8 TERM 1 NATURAL SCIENCES MODULE 1 LIFE AND LIVING e-classroom 1 What does this graph show us? You may be asked to DESCRIBE the graph or to EXPLAIN the graph. When you are asked to describe the graph, you need to clarify what is happening on the graph. So, describe the graph above:The graph shows Jill s final maths score at every GRADE . We can see a general increase in scores from GRADE 7 to 12. GRAPHS Introduction We are going to learn how to analyse and draw four different types of graphs: line graphs, bar graphs, histograms and pie graphs. Graphs are an important tool in maths, science and biology to communicate information.

8 Analysing graphs Line graph 1 Line graph of Jill s maths scores from GRADE 7-12 GRADE 8 TERM 1 NATURAL SCIENCES MODULE 1 LIFE AND LIVING e-classroom 2In some instances, it will also be important to EXPLAIN the graph. When you are asked to explain the graph, you need to say WHY it is happening. This is not really relevant to the graph above, but we will look at another example below where it is relevant. In every graph that is drawn with an x-axis and a y-axis there is an independent variable and a dependent variable. The x-axis is horizontal and depicts the independent variable. The y-axis is vertical and depicts the dependent independent variable is the variable that the graph is showing that does not depend on anything else. The dependent variable is the variable that the graph is showing that depends on the independent the example above, what is the independent variable and what is the dependent variable?

9 The independent variable is the GRADE . The dependent variable is the maths score. The maths score DEPENDS on the GRADE , therefore it is the dependent variable. The GRADE that the learners are in DOES NOT DEPEND on the maths score, therefore it is the independent a graph that shows plant height over time in days, what is the independent variable and what is the dependent variable?Time in days is the independent variable. Plant height is the dependent variable. This is because time does not depend on the plants growing, and plant height will change with time, so it depends on a graph that shows how the density of water changes with temperature, what is the independent variable and what is the dependent variable?Temperature is the independent variable. Density is the dependent is because temperature does not depend on the density of the water, and the water density will change with temperature, so it depends on 8 TERM 1 NATURAL SCIENCES MODULE 1 LIFE AND LIVING e-classroom 3 Line graph 2Mr Smith recorded the temperature outside his classroom every hour during one school day.

10 His results are listed in the following table:Time090010001100120013001400150016 00 Temperature (OC)8911121213109He decided to plot a line graph to represent the data. Line graphs are useful for showing how things change over graph showing the temperature outside Mr Smith s class in a dayTime (hours)Temperature (OC)Describe the graph: In the morning the temperature outside is relatively cold and it warms up as the day progresses. After 14:00, it starts to cool down is the independent variable and what is the dependent variable? independent variable is time measured in hours. Time does not depend on temperature. The temperature changes with time, so it depends on time. GRADE 8 TERM 1 NATURAL SCIENCES MODULE 1 LIFE AND LIVING e-classroom 4 Based on the graph: What is the temperature outside the classroom at 10:30?