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Question 13

In a study on kidney function, researchers measured the concentrations of two biomarkers, Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin C, in various bodily fluids of patients.

The results are represented in the bar chart below:

A bar graph showing the concentration of two biomarkers, NGAL and Cystatin C, in different body fluids: plasma, saliva, urine, and sweat. The y-axis is on a logarithmic scale showing concentration in pg/cm³, ranging from 10^1 to 10^10 in steps of powers of 10. For each fluid, there are two bars: a white bar for NGAL and a shaded bar for Cystatin C. In plasma: NGAL is at 10^8, Cystatin C is at 10^4. In saliva: NGAL is at 10^2, Cystatin C is at 10^3. In urine: NGAL is at 10^1, Cystatin C is at 10^7. In sweat: NGAL is at 10^3, Cystatin C is at 10^5.

a.

Calculate the order of magnitude by which the concentration of Cystatin C in the urine is higher than the concentration of NGAL in the saliva. Show your working.

[3]
b.

An electron micrograph of a spherical macrophage cell from a kidney tissue sample is also analyzed. In the image:

  • The scale bar represents 4 μm4\ \mu\text{m}4 μm and has a measured length of 1.2 cm1.2\text{ cm}1.2 cm on paper.
  • The diameter of the spherical macrophage cell has a measured length of 7.2 cm7.2\text{ cm}7.2 cm on paper.

Calculate the actual volume of this macrophage cell. Assuming it is perfectly spherical, use the formula for the volume of a sphere:

V=43πr3 V = \frac{4}{3}\pi r^3 V=34​πr3

Give your answer to four significant figures. Show your working.

[4]

Analysis Questions

  1. A Level
  2. /Biology
  3. /Analysis