Analysis, Conclusions and Evaluation

Suggest why two strips were used, rather than one, in each solution.

______

Explain how your observations do, or do not, support this suggestion.

______

Complete Table 1.1.

Table 1.1

Using the information in Table 1.1 draw a graph, on the axes provided, of mean change in length against concentration of solution.

From your graph, determine the concentration of the solution at which there would be no change in mean length of potato strip.

______

Explain the significance of this concentration.

______

Suggest three ways in which this investigation could be improved.

1. ______
2. ______
3. ______

Calculate the mean diameter of the clear areas around the discs with antibiotic H. Enter the value in the table rounded to one decimal place.

______

Construct a bar chart of the four mean diameters in Table 2.1 on the grid.

State which antibiotic was most effective at preventing growth of the bacteria.

______

The student realised that one of their results was anomalous.

State which measurement was an anomalous result and suggest what the student could have done about it.

______

Describe how your results could be made more reliable.

______

On the grid below and using one set of axes, construct a graph with two lines to show the relationship between time and temperature of the water in the two test-tubes.

Join your points with ruled, straight lines.

Use your graph to determine the temperature of the water in the large test-tube at 3 minutes.

Show your working on your graph.

______

Describe what you can conclude about heat loss in large and small animals from your results.

______

what difference there may be in the size of the penguins found in these two areas,

size = ______
explanation = ______

why penguins stand very close together in groups when external temperatures are very low.

______

Describe how your results could be made more reliable.

On the grid below and using one set of axes, construct a graph with two lines to show the relationship between time and temperature of the water in the two test-tubes.

Join your points with ruled, straight lines.

Use your graph to determine the temperature of the water in the large test-tube at 3 minutes.

Show your working on your graph.

______

Describe what you can conclude about heat loss in large and small animals from your results.

what difference there may be in the size of the penguins found in these two areas,

size = ______
explanation = ______

why penguins stand very close together in groups when external temperatures are very low.

The whole field measured $10\,\text{m} \times 20\,\text{m}$.

Use the sample in Fig. 2.1 to estimate the number of plants of species E in the whole field and record this value in Table 2.1.

Show your working.

Explain why the student counted the numbers of plants in samples of the field instead of counting the number of plants in the whole field.

______

Suggest two reasons why taking several samples would improve the accuracy of the estimate for the number of plants in the whole field.

1. ______
2. ______

Use the data in Table 2.1 to construct a bar chart to show the estimated number of plants of species C, D and E in the whole field.

Enter the times taken for the discs to reach the surface and the mean time in the table below.

• Repeat this full procedure with three freshly cut $1\text{ mm}$ discs of potato in $2\%$ hydrogen peroxide solution, recording your results and the mean in the table.

• Repeat this full procedure with three freshly cut $1\text{ mm}$ discs of potato in $3\%$ hydrogen peroxide solution, recording your results and the mean in the table.

Describe the effect of increasing the concentration of hydrogen peroxide solution on the time taken for the potato discs to reach the surface.

______

Explain what you would do to make the mean results more reliable.

______

Suggest two possible sources of error in the method used in this experiment. Explain why each could have affected the results.

source of error 1 = ______

explanation = ______

source of error 2 = ______

explanation = ______

Observe the potato disc in the test-tube labelled $0\%$.

start time ______

end time ______

Calculate how long the potato disc has been in the solution.

______ $\text{minutes}$

State and explain the position of the potato disc in the test-tube.

position = ______

explanation = ______

Construct a line graph of the data in the table on the grid below. Draw a smooth curve through your points.

Describe the effect of increasing enzyme concentration on the rate of the reaction.

Suggest an explanation for the shape of the line between 4 and 5 discs of potato.

Construct a line graph of the data in the table on the grid below. Plot the data as two lines on the same axes. Join your points with ruled, straight lines.

Use the data to describe and compare the effect of still air and moving air on the rate of transpiration.

The area of the cross-section of the hollow glass tube containing the air bubble was $0.785\text{ mm}^2$.

Use the data to calculate the volume of water that was transpired by the plant between four and five minutes in moving air. Give your answer to 2 decimal places.

______ $\text{mm}^3$

Another student repeated this investigation a week later, but her results were different.

Suggest two reasons why her results were different.

1. ______
2. ______

Complete the table including the appropriate temperature for each test-tube.

State one possible source of error in the method used. Explain how the method could be improved.

source of error = ______
improvement = ______

Explain how repeating the experiment makes the observations of colour more reliable.

______

Calculate the average reading for each temperature and complete the table.

On the grid construct a line graph to show the relationship between temperature and average colorimeter readings. Join your points with ruled, straight lines.

Use your graph to determine the average colorimeter reading for $55\,^\circ\text{C}$.

Show your working on your graph.

______ $\text{arbitrary units}$

On the grid provided, plot a line graph of the data in the table. Join the points with ruled lines.

Use the results to state the time period during which catalase activity was the greatest.

______

Describe the shape of the graph.

Suggest a source of inaccuracy in the method for this experiment.

______

Design an experiment based on the method already described (see page 2) to investigate the effect of increasing temperature on the activity of catalase. Give full experimental details.

On the grid below construct a line graph of the heart rate against time. Join the points with ruled straight lines.

Identify the period of exercise on your graph by drawing two lines.

• Draw one beginning from the point at which exercise started and finishing at the axis. Label this line S.
• Draw one beginning from the point at which exercise ended and finishing at the axis. Label this line E.

Suggest why it would not be valid to use the graph to determine the heart rate at 5 minutes.

Describe any changes in heart rate and the percentage of oxygen in the blood during the investigation, using the data in your graph and Table 2.1.

heart rate = ______

percentage oxygen = ______