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Carbon dioxide is one of the substances carried in mammalian blood - HSC - SSCE Biology - Question 21 - 2005 - Paper 1
Question 21
Carbon dioxide is one of the substances carried in mammalian blood. (a) Why is it necessary for excess carbon dioxide to be removed from blood? (b) In what forms i... show full transcript
Worked Solution & Example Answer:Carbon dioxide is one of the substances carried in mammalian blood - HSC - SSCE Biology - Question 21 - 2005 - Paper 1
Step 1
Why is it necessary for excess carbon dioxide to be removed from blood?
Answer
Excess carbon dioxide must be removed from the blood to maintain acid-base balance and prevent respiratory acidosis. If carbon dioxide accumulates, it can lower the pH of the blood, leading to potential harm to bodily functions. Thus, the regulation of carbon dioxide levels is crucial for homeostasis.
Step 2
In what forms is carbon dioxide transported in blood?
Answer
Carbon dioxide is transported in blood primarily in two forms:
- As bicarbonate ions (HCO3^-), which constitute about 70% of carbon dioxide transport.
- Bound to hemoglobin as carbamino compounds, which accounts for approximately 20-23% of transport. A small percentage (about 7-10%) is dissolved directly in the plasma.
Step 3
Outline your method, identifying the variables AND account for how you ensured the reliability of your data.
Answer
To investigate the effect of dissolved carbon dioxide on the pH of water, I followed these steps:
- Preparation: I set up three beakers containing equal volumes of distilled water.
- Variable Control: I ensured that only the amount of carbon dioxide varied, while keeping temperature and volume of water constant.
- Carbon Dioxide Addition: I bubbled carbon dioxide into the first beaker for a specific duration, while the second received CO2 for half that time and the third remained untreated as a control.
- pH Measurement: After treatment, I measured the pH of each sample using a calibrated pH meter.
- Reliability Assurance: I performed the experiment in replicates and averaged the pH readings for each beaker. Additionally, I rinsed the pH meter thoroughly between measurements to prevent cross-contamination. This ensured consistent and reliable data.