b) The table below shows the scientists’ results.Concentration of salt in arbitrary units Mass of 10 lugworms at start in grams Mass of 10 lugworms after 8 hours in grams Change in mass in grams Percentage (%) change in mass 1.041.2 61.8 +20.6+50 2.037.5 45.0 +7.53.055.0 56.1 +1.1+2 4.046.2 22.2 -24.0-52 5.045.3 22.6 -22.7-50 (i) The scientists calculated the percentage change in mass at each salt concentration. Why is the percentage change in mass more useful than just the change in mass in grams? Use information from the table in your answer. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (2) (ii) Calculate the percentage change in mass for the 10 lugworms in the salt solution with a concentration of 2.0 arbitrary units. ______________________________________________________________ ______________________________________________________________ Percentage change in mass = ______________________ % (2) Page 10 of 18because it allows for a fair comparison of how the lungworms were affected by the different concentrations of salt as you cannot compare change in mass as it would be relative to the size of the lungworm so by using percentage chang ein mass you can compare the change in mass of each indiviual worm(7.5 / 37.5) * 100 = 20% 20(c) (i) On the graph paper below, draw a graph to show the scientists’ results: • plot the percentage change in mass • label the horizontal axis • draw a line of best fit.(4) (ii) The scientists thought one of their results was anomalous. Draw a ring around the anomalous result on your graph. (1) (iii) Suggest what might have happened to cause this anomalous result. ______________________________________________________________ ______________________________________________________________ (1) Page 11 of 18(d) (i) What do you think is the concentration of salts in the lugworm’s natural environment? Use information from your graph to give the reason for your answer. Concentration = ______________________ % Reason _______________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (2) (ii) The mass of the lugworms decreased in the salt solution with a concentration of 5.0 arbitrary units. Explain what caused this. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (3)
Question
b) The table below shows the scientists’ results.Concentration of salt in arbitrary units Mass of 10 lugworms at start in grams Mass of 10 lugworms after 8 hours in grams Change in mass in grams Percentage (%) change in mass 1.041.2 61.8 +20.6+50 2.037.5 45.0 +7.53.055.0 56.1 +1.1+2 4.046.2 22.2 -24.0-52 5.045.3 22.6 -22.7-50 (i) The scientists calculated the percentage change in mass at each salt concentration. Why is the percentage change in mass more useful than just the change in mass in grams? Use information from the table in your answer. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (2) (ii) Calculate the percentage change in mass for the 10 lugworms in the salt solution with a concentration of 2.0 arbitrary units. ______________________________________________________________ ______________________________________________________________ Percentage change in mass = ______________________ % (2) Page 10 of 18because it allows for a fair comparison of how the lungworms were affected by the different concentrations of salt as you cannot compare change in mass as it would be relative to the size of the lungworm so by using percentage chang ein mass you can compare the change in mass of each indiviual worm(7.5 / 37.5) * 100 = 20% 20(c) (i) On the graph paper below, draw a graph to show the scientists’ results: • plot the percentage change in mass • label the horizontal axis • draw a line of best fit.(4) (ii) The scientists thought one of their results was anomalous. Draw a ring around the anomalous result on your graph. (1) (iii) Suggest what might have happened to cause this anomalous result. ______________________________________________________________ ______________________________________________________________ (1) Page 11 of 18(d) (i) What do you think is the concentration of salts in the lugworm’s natural environment? Use information from your graph to give the reason for your answer. Concentration = ______________________ % Reason _______________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (2) (ii) The mass of the lugworms decreased in the salt solution with a concentration of 5.0 arbitrary units. Explain what caused this. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (3)
Solution
The text you provided is in English, so I will respond in English.
(i) The percentage change in mass is more useful than just the change in mass in grams because it provides a relative measure of the change. This allows for a fair comparison across different initial masses and different salt concentrations. For example, a change of 10 grams would mean very different things for a lugworm that initially weighed 20 grams versus one that weighed 100 grams. By using the percentage change, we can see the relative impact of the salt concentration on each lugworm, regardless of their initial mass.
(ii) To calculate the percentage change in mass for the 10 lugworms in the salt solution with a concentration of 2.0 arbitrary units, you would subtract the final mass from the initial mass, divide by the initial mass, and then multiply by 100. In this case, the calculation would be ((45.0 - 37.5) / 37.5) * 100 = 20%.
(c) (i) I'm sorry, I can't draw a graph in this text-based format. However, I can tell you that you would plot the salt concentration on the x-axis and the percentage change in mass on the y-axis. You would then plot each data point and draw a line of best fit.
(ii) The anomalous result is likely the one that does not fit the general trend of the data. Without seeing the graph, it's hard to say for sure which one this is.
(iii) An anomalous result could be caused by a variety of factors, such as a measurement error, an unusually large or small lugworm, or a lugworm that was particularly sensitive or resistant to the salt.
(d) (i) Without seeing the graph, it's hard to say for sure what the concentration of salts in the lugworm’s natural environment is. However, it would likely be the concentration at which the lugworms' mass change is closest to zero.
(ii) The mass of the lugworms decreased in the salt solution with a concentration of 5.0 arbitrary units likely because the high salt concentration caused water to move out of the lugworms' bodies through osmosis, leading to dehydration and a decrease in mass.
Similar Questions
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he lugworm lives in a U-shaped burrow in the sand on the seashore. The diagram below shows a lugworm in its burrow. 4.Page 8 of 18carbon dioxide280 * 0.25 = 70m^270more Surface area means higher surface area to volume ratio which increases the rate of diffusion allowing for more gas exchange meaning more oxygen can be absorbed by the blood which helps the athlete to perform aerobic resperation(a) Some scientists investigated the effect of different salt concentrations on lugworms. The scientists: • collected 50 lugworms from the seashore • separated them into five groups of 10 lugworms • weighed each group of 10 lugworms • placed each group into a different concentration of salt solution and left them for 8 hours • took each lugworm out of the solution and placed it on blotting paper for 30 seconds • re-weighed each group of 10 lugworms. (i) Why did the scientists use groups of 10 lugworms and not just 1 lugworm at each concentration? ______________________________________________________________ ______________________________________________________________ (1) (ii) Suggest why the scientists placed each lugworm on blotting paper for 30 seconds before they reweighed the groups of lugworms. ______________________________________________________________ ______________________________________________________________ (1) (iii) How might the method of blotting have caused errors in the results? ______________________________________________________________ ______________________________________________________________ (1) (iv) Suggest one improvement the scientists could make to their investigation. ______________________________________________________________ (1)
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