GCSE Edexcel Biology Magnification: Figure 9 shows the structure and

Figure 9 shows the structure and actual size of red blood cells (erythrocytes) - Edexcel - GCSE Biology - Question 5 - 2021 - Paper 1

Question 5

Figure 9 shows the structure and actual size of red blood cells (erythrocytes). (a) (i) Calculate the image size of the top view of this red blood cell if this cell... show full transcript

Worked Solution & Example Answer:Figure 9 shows the structure and actual size of red blood cells (erythrocytes) - Edexcel - GCSE Biology - Question 5 - 2021 - Paper 1

Step 1

Calculate the image size of the top view of this red blood cell if this cell is magnified 400×.

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Answer

To calculate the image size, we use the formula:

$ext{Image Size} = ext{Actual Size} imes ext{Magnification}$

The actual size of the top view of the red blood cell is 2.5 µm. Given that the magnification is 400×:

$ext{Image Size} = 2.5 ext{ µm} imes 400 = 1000 ext{ µm}$

To convert micrometers to millimeters:

$1000 ext{ µm} = 1 ext{ mm}$

Thus, the image size is 1 mm.

Step 2

Explain how the shape of a red blood cell is related to its function.

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Answer

The shape of a red blood cell (erythrocyte) is critical for its function of transporting oxygen throughout the body. The following points highlight the relationship between its shape and function:

Biconcave Structure

The red blood cell has a biconcave shape, which increases its surface area relative to its volume. This allows for more hemoglobin to be exposed to incoming oxygen, facilitating efficient gas exchange.

Flexibility

The flexible shape enables red blood cells to deform as they pass through narrow capillaries, ensuring that they can navigate the microcirculation effectively.

Short Diffusion Path

The thinness at the center of the biconcave design minimizes the distance that oxygen must diffuse, enhancing the speed of oxygen uptake and carbon dioxide release.

In summary, the red blood cell's unique shape contributes significantly to its ability to efficiently transport oxygen and carbon dioxide in the bloodstream.