[填空题]
In an investigation into the effects of artery occl+. x7kopww kes qe (v0c506requzk ;3 u 8j/*y;seue;yc e(arqusion on blood pressure, students set up a simple experiment. A rigid, hard, plastic tube, representing an artery, was fixed to an electric water pump, and the end was sealed with a rubber stopper. A suysyr; u;j8ee u;a(zce /q3*kingle hole was drilled into the plastic tube and the electric pump was turned on. Students measured the distance the water stream travelled.
In subsequent trials, students added increasing numbers of equally sized and shaped clay-like masses to the inside of the plastic tube and the distance the water stream travelled was measured again.
Results are shown below.
1.1.Identify the independent variable in this experiment.
1.2.State two control variables, not mentioned in the question, that must be kept constant in order to achieve valid results.
2.1.Outline the relationship between the number of clay-like masses and the distance travelled by the water stream.
2.2.Explain how the results of this experiment can be used to understand artery occlusion.
3.Based on the results, predict the distance travelled by the water stream if there were no clay-like masses present.
Distance travelled by water for 0 clay masses= cm
4.1.Using your knowledge of coronary heart disease, suggest a reason for the anomalous result seen when 5 clay-like masses were present.
4.2.State a risk factor associated with coronary heart disease.
5.Identify a limitation of using the plastic tube to represent an artery in this experiment.
