8.2. Transport of oxygen and carbon dioxide
A subsection of Biology, 9700, through 8. Transport in mammals
Listing 10 of 241 questions
As blood passes through the capillaries in the lungs it becomes oxygenated. Explain how the structure of haemoglobin aids the uptake of oxygen in the lungs. shows the dissociation curve of adult haemoglobin. Use partial pressure of oxygen / kPa Percentage saturation of haemoglobin with oxygen [T Use the information given in to complete the table below. During exercise the concentration of carbon dioxide in muscle tissue increases. This stimulates an increase in the release of oxygen from the blood. Explain how carbon dioxide stimulates the release of oxygen from the blood. part of the circulation partial pressure of percentage saturation oxygen / kPa of haemoglobin capillaries in the lungs capillaries in muscle tissue at rest capillaries in muscle tissue during 2.0 strenuous exercise
9700_s05_qp_2
THEORY
2005
Paper 2, Variant 0
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Scientists at the Tibet Institute of Medical Sciences in Lhasa investigated differences between adult Tibetans who had lived in Lhasa (altitude 3658 m) all their lives and adult Han Chinese residents who had lived there for about 8 years. The Tibetans and the Han Chinese exercised at maximum effort and various aspects of their breathing were measured. Some of the results are shown in Table 4.1. Table 4.1 feature Tibetans Han Chinese minute volume / dm3 min–1 oxygen uptake / cm3 kg–1 min–1 51.0 46.0 • Minute volume. This is the volume of air breathed in during one minute. • Oxygen uptake. This is the volume of oxygen absorbed into the blood during one minute. It is expressed per kg of body mass. The researchers observed that • the greater minute volume of the native Tibetans resulted from a greater tidal volume • the tidal volumes of the Tibetans showed a positive correlation with their vital capacity measurements • the Han Chinese had lower values for both tidal volume and vital capacity. State what is meant by the term tidal volume. Suggest why the researchers also measured the vital capacity of the people in the study. Explain how the minute volume at rest would be determined. Suggest two differences in the structure of the lungs that may account for the greater oxygen uptake by the Tibetans shown in Table 4.1. When people who have lived all their lives at low altitude go to a place at high altitude, such as Lhasa, they are often breathless, lack energy and suffer from altitude sickness. However, with time, they often acclimatise to the high altitude. In another study, researchers found that the red blood cell count increases in such people by about 30% over several weeks. Explain why the red blood cell count increases so much when people visit places at high altitude.
9700_s08_qp_2
THEORY
2008
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Carbon dioxide is transported in the blood in various forms. Describe how carbon dioxide molecules reach red blood cells from respiring cells. shows part of a capillary network and some cells of the surrounding tissue. X Y venule end arteriole end State three ways in which the blood at Y differs from the blood at X other than in the concentration of carbon dioxide. 1. 2. 3. An enzyme in red blood cells catalyses the reaction between carbon dioxide and water as blood flows through respiring tissues. CO2 + H2O H2CO3 enzyme H+ + HCO3 – Name the enzyme that catalyses this reaction. Explain the significance of this reaction in the transport of carbon dioxide. shows the effect of increasing the carbon dioxide concentration on the oxygen haemoglobin dissociation curve. partial pressure of oxygen / kPa percentage saturation of haemoglobin with oxygen partial pressure CO2 1.0 kPa partial pressure CO2 1.5 kPa State the percentage saturation of haemoglobin with oxygen at a partial pressure of 5 kPa of oxygen when the partial pressure of carbon dioxide is: 1.0 kPa 1.5 kPa The percentage saturation of haemoglobin with oxygen decreases as the partial pressure of carbon dioxide increases. Explain how this happens. Name the effect of increasing carbon dioxide concentration on the oxygen dissociation curve. Explain the importance of the effect of carbon dioxide on haemoglobin as shown in .
9700_s11_qp_21
THEORY
2011
Paper 2, Variant 1
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Questions Discovered
241