The table shows results from a laboratory investigation of blood flow through identical lengths of model blood vessel. A pump produced the same pressure in ...
Question 1 Report
The table shows results from a laboratory investigation of blood flow through identical lengths of model blood vessel. A pump produced the same pressure in each trial. The fluid had a similar viscosity to blood.
| Internal diameter of model vessel / mm | Volume of fluid collected in 30 s / cm3 |
|---|---|
| 1.0 | 12 |
| 2.0 | 43 |
| 3.0 | 88 |
| 4.0 | 151 |
(a) Describe the relationship between internal diameter and the volume of fluid collected. [2]
(b) Calculate the flow rate through the 3.0 mm model vessel in cm3 per second. Show your working. [2]
(c) Explain how narrowing of an artery by fatty deposits can reduce the delivery of oxygen to body cells. [3]
(d) State one variable, other than vessel diameter, that the scientist controlled in this investigation. [1]
(e) Suggest why the scientist used a fluid with a similar viscosity to blood. [2]
Answer Details
(a) As internal diameter increases, the volume collected increases. The increase is not constant: it becomes larger at greater diameters. [2]
(b)
\[\frac{88\text{ cm}^3}{30\text{ s}}=2.93\text{ cm}^3\text{ s}^{-1}\]
The flow rate is 2.93 cm3 s-1, or 2.9 cm3 s-1. [2]
(c) Fatty deposits reduce the lumen diameter of an artery. Less blood can flow through per unit time, so less oxygen reaches body cells for aerobic respiration. [3]
(d) The length of model vessel was controlled. Pumping pressure, collection time, or temperature are also acceptable. [1]
(e) Viscosity affects resistance to flow. A fluid with similar viscosity to blood makes the model more valid because it better represents blood flow in humans. [2]
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