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AS Biology P1 MCQs Preparation Thread

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rogue94

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sarasousou1996 said:
does haemoglobin have a higher affinity for oxygen or carbon dioxide?
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This is what Wikipedia says about HbCO2: When carbon dioxide binds to hemoglobin, carbaminohemoglobin is formed, lowering hemoglobin's affinity for oxygen via the Bohr effect Therefore, at low oxygen partial pressures and hight CO2 partial pressures, CO2 combines with Hb to give HbCO2 and this lowers Hb's affinity for O2. I guess CO2 does not directly have higher affinity for Hb, but it reduces Hb's affinity for O2.
 
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The King XII

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rogue94 said:
This is what Wikipedia says about HbCO2: When carbon dioxide binds to hemoglobin, carbaminohemoglobin is formed, lowering hemoglobin's affinity for oxygen via the Bohr effect Therefore, at low oxygen partial pressures and hight CO2 partial pressures, CO2 combines with Hb to give HbCO2 and this lowers Hb's affinity for O2. I guess CO2 does not directly have higher affinity for Hb, but it reduces Hb's affinity for O2.
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yeah and remember CO2 combined with Hb gives carbo-amino heamoglobin which is only 5 % transmitted in this form and most of the time heamoglobin is transporting oxygen so yeah answer was CO-->O2-->CO2
 
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The King XII

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Hemoglobin, the main oxygen-carrying molecule in red blood cells, carries both oxygen and carbon dioxide. However, the CO2 bound to hemoglobin does not bind to the same site as oxygen. Instead, it combines with the N-terminal groups on the four globin chains. However, because of allosteric effects on the hemoglobin molecule, the binding of CO2 decreases the amount of oxygen that is bound for a given partial pressure of oxygen. The decreased binding to carbon dioxide in the blood due to increased oxygen levels is known as the Haldane Effect, and is important in the transport of carbon dioxide from the tissues to the lungs. Conversely, a rise in the partial pressure of CO2 or a lower pH will cause offloading of oxygen from hemoglobin, which is known as the Bohr Effect
 
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rogue94

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The King XII said:
yeah and remember CO2 combined with Hb gives carbo-amino heamoglobin which is only 5 % transmitted in this form and most of the time heamoglobin is transporting oxygen so yeah answer was CO-->O2-->CO2
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Oh, was this a question in another variant paper? 11? Cause i gave paper 12, i did not realize that this was a question from a paper when i was answering it :p
 
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shivana

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Jaf said:
I don't see what is confusing you. They are also saying that the cell wall is present. What is confusing me is that they are saying there are no centrioles???? During metaphase, the centrioles are the one which produce the spindle fibres, no?



It's HIV. Mary Jones give an example of Zidovudine and says, "(e.g. zidovudine is similar to the nucleotide that contains the base thymine). Zidovudine binds to the viral enzyme reverse transcriptase and blocks its action. This stops the replication of the viral genetic material and leads to an increase in some of the body's lymphocytes."
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Sorry i didnt thank you before! BUT better late than never haha anyways THANKS:)
 
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