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Suggest how the environmental conditions have resulted in adaptations of systems using Model A rather than Model B - AQA - A-Level Biology - Question 2 - 2021 - Paper 1
Question 2
Suggest how the environmental conditions have resulted in adaptations of systems using Model A rather than Model B. A student studied Figure 3 and concluded that th... show full transcript
Worked Solution & Example Answer:Suggest how the environmental conditions have resulted in adaptations of systems using Model A rather than Model B - AQA - A-Level Biology - Question 2 - 2021 - Paper 1
Step 1
Suggest how the environmental conditions have resulted in adaptations of systems using Model A rather than Model B.
Answer
Larger organisms typically exhibit a smaller surface area to volume ratio, adapting their gas exchange systems to facilitate adequate diffusion. Smaller organisms, like those found in aquatic habitats, demonstrate a larger surface area relative to their volume, permitting faster diffusion rates.
Step 2
Use Figure 3 to justify this conclusion.
Answer
In Figure 3, fish exhibit a streamlined body shape and gills with extensive surface area, enhancing oxygen absorption from water. In contrast, humans have less surface area for gas exchange, resulting in less efficient oxygen uptake. The concentration gradient in fish is maintained more effectively due to the constant movement of water over the gills.
Step 3
Explain how the counter-current principle allows efficient oxygen uptake in the fish exchange system.
Answer
The counter-current principle involves blood flow in the opposite direction to water flow across fish gills, maintaining a concentration gradient for oxygen. This setup ensures that oxygen is constantly diffused from the water into the blood, optimizing gas exchange and allowing fish to extract more oxygen.
Step 4
Calculate how many times the lung volume per unit of body mass of the bat is greater than that of the shrew.
Answer
To find the lung volume per unit body mass, we compute the ratios for both mammals:
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Lung volume per kg for bat:
\text{Bat:} \frac{12.48}{0.096} = 130 \text{cm³/kg}
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Lung volume per kg for shrew:
\text{Shrew:} \frac{0.72}{0.024} = 30 \text{cm³/kg}
Now, the ratio of bat to shrew is:
\frac{130}{30} = 4.33
Thus, the lung volume per unit of body mass of the bat is approximately 4.33 times greater than that of the shrew.
Step 5
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