Draw a large-scale diagram of the necklace starfish shown in Fig. 3.1.
Measure line PQ in Fig. 3.1. Then use the formula and your measurement to work out the actual diameter of the necklace starfish. $\text{magnification} = \frac{\text{length of line PQ in Fig. 3.1}}{\text{actual diameter of the necklace starfish}}$ Give the result to two significant figures.
State two features by which the spiny starfish in Fig. 3.2 differs from the necklace starfish in Fig. 3.3, and one feature they share. Do not refer to size in your response.
State two ways in which the scientists’ method made the counts of seven-armed starfish at different depths comparable.
Plot a histogram on the grid using the data in Table 3.1.
State the depth range in Table 3.1 where the greatest number of seven-armed starfish were found.
Calculate the total number of seven-armed starfish photographed at all depths, then use that total to calculate the percentage of starfish photographed in the 0.0-9.9 m range. Give the percentage as a whole number.