Year 8 Science · Unit 4 · Lesson 10
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Learning Goals
Read the graph
Study the line graph below showing dissolving time (s) vs temperature (°C). Answer the three questions.
Data: simulated salt-dissolving investigation, HSCScience Lab.
(a) Describe the trend shown in the graph. Use at least two specific values in your answer.
(b) Use interpolation to estimate the dissolving time at 35°C. Show your reasoning.
(c) Would it be reliable to extrapolate this graph to predict the dissolving time at 90°C? Explain why or why not.
Enzyme investigation
Two students measured enzyme activity at pH values from 4 to 10. Student A's enzyme peaked at pH 7 with an activity of 95 units. Student B's enzyme peaked at pH 8 with an activity of 87 units. Both enzymes showed low activity below pH 5 and above pH 9.
(a) What does the graph tell us about the optimal pH for each enzyme? State the value for each student.
(b) What conclusion can you draw about how pH affects enzyme activity? Use evidence from both students.
(c) Why can't we conclude which enzyme is "better" from this data alone? What additional information would be needed?
1. A graph shows a line that rises steeply at first, then levels off into a plateau. What does the plateau tell us about the relationship between the two variables at that point?
2. A student says "the graph shows the experiment worked." Explain why this is a weak interpretation and how it could be improved.
Wrap Up
In one sentence, what was the main idea of this lesson?