To observe a human blood smear using an optical microscope, a student used two different stains. The first stain binds to DNA; the second stain binds to red blood cells.
Explain why the first stain (which binds to DNA) would not stain mature human red blood cells. Suggest which protein the second stain could bind to in the red blood cells.
The student also investigated alveoli in healthy lungs and lungs damaged by emphysema. They calculated the surface area to volume ratios for these alveoli. Some of their results are shown in the table below:
| Alveolar condition | Surface area / μm2\mu\text{m}^2μm2 | Volume / μm3\mu\text{m}^3μm3 | Surface area:volume ratio |
|---|---|---|---|
| Healthy | 1.2×1051.2 \times 10^51.2×105 | 4.5×1054.5 \times 10^54.5×105 | __________ |
| Damaged (Emphysema) | 3.2×1043.2 \times 10^43.2×104 | __________ | 0.058:10.058:10.058:1 |
Complete the table. State your calculated volume and surface area:volume ratio to 2 significant figures.
Emphysema causes the alveolar walls to break down, merge, and develop fibrous scar tissue. Other than surface area:volume ratio, describe one way this physical change affects the alveoli. Explain how this difference would affect gas exchange.
