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AS Biology P1 MCQs Preparation Thread

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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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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
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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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."

Sorry i didnt thank you before! BUT better late than never haha anyways THANKS:)
 
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Can anyone help me with this question 39 from 07 nov.
anyone Untitled 1.png Please explain!!!!!

the answer is supposed to be B

MY EXAM IS IN ONE HOUR PLEASE HELLLLLLP!!!!
 
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Can anyone help me with this question 39 from 07 nov.
anyone View attachment 12969 Please explain!!!!!

the answer is supposed to be B

MY EXAM IS IN ONE HOUR PLEASE HELLLLLLP!!!!
Due to increased amounts of dust, less sunlight reaches producers. Due to insufficient sunlight, the producers die. As the populations of producers decreases, the populations of the consumers will also decrease (food chain). As there are more dead organisms, there will be more decomposers (more proteins converted to ammonia) and hence, more nitrifying bacteria (which convert ammonia to nitrates). Hence, the correct option is B. :)
 
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Due to increased amounts of dust, less sunlight reaches producers. Due to insufficient sunlight, the producers die. As the populations of producers decreases, the populations of the consumers will also decrease (food chain). As there are more dead organisms, there will be more decomposers (more proteins converted to ammonia) and hence, more nitrifying bacteria (which convert ammonia to nitrates). Hence, the correct option is B. :)

THANKYOU SOOOO MUCH FOR THIS SIMPLE INTELLIGENT EXPLANATION!!!!!!!!!
I get it know thankssss!!
GODBLESS :)
 
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Q7 Turgid plant tissue is placed in a solution which has the same solute potential as the contents of
the cells. The diagram shows a cell after one hour.
Which equation describes the value of the pressure potential for this cell?
A pressure potential = solute potential of the cell
B pressure potential = solute potential of the external solution
C pressure potential = water potential of the cell
D pressure potential = zero

why is the answer D? its from winter 03
 
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Q13 How does increasing substrate concentration affect the rate of an enzyme-catalysed reaction in
the presence of a competitive inhibitor?
A) The rate of the reaction decreases.
B) The rate of the reaction decreases initially and then recovers.
C) The rate of the reaction increases.
D) The rate of the reaction is not affected.

why is the answer C? please help
 
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Can anyone please explain this one point?
I read in a book that the plasmodium which causes Malaria can pass form the mother to the fetus via the placenta. But in one question, the mark scheme said that malaria cannot pass directly from parents to child?
9700/11/M/J11 Q. 36.
Help me please!
 
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