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A level Biology: Post your doubts here!

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mynameisnotneeded

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roxylara said:
If anyone can please explain all the answers for these questions properly I'd be really greatful
Click to expand...
19 is C as during the first generation, due to semi conservative replication, half the nucleotides are made using 14-N.
Thus the new bacteria contain half 14-N and half 15-N.
The second gen, the bacteria contain 50% 14N and 50% 15N before replication, and when it replicates, it becomes 75% 14n and 25% 15N
This goes on until the nth generation but u can easily eliminate D coz it doesn't make any sense. Where did all the 15N go???
 
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Zain Javaid said:
Ca

Can i pleasehav a detailed info on this note ?
Click to expand...
Um so u knw the blood that enters the ventricle during diastole is what is pumped up through the aorta or pulmonary artery right?
That blood is called the ventricular end diastolic volume.

Now the stoke volume is the blood that is pumped by the ventricle out of the heart (like into the aorta)

The more blood there is in the ventricle during diastole, the more blood is pumped out during systole.

HOWEVER, all pumps have a limit as to how much they can pump right? Thus, beyond a certain point the stoke volume becomes level as the heart has reached the maximum amt of blood it can pump in one contraction....

Hope I helped!
 
♣♠ Magnanimous ♣♠

♣♠ Magnanimous ♣♠

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Zain Javaid said:
Can i pleasehav a detailed info on this note ?
Click to expand...
listen, in the ques it is written that stroke volume is of contaction of ventricles which directly says that volume of blood will be high... next see
ventricular end diastole is the volume of blood in ventricles that is just before systole which means that blood is entering the ventricles from atruim so he volume of blood varies and it is D
i hope you will not mess up in my answer.
 
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mynameisnotneeded

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roxylara said:
If anyone can please explain all the answers for these questions properly I'd be really greatful
Click to expand...
18 - Ah I remember this one... cheeky one. Question says FOUR KINDS OF Amino Acids, thus maybe the same tRNA can bring them back and forth? Four different AAs need only four types of tRNA, and maybe a few tRNA molecules make more than one trips...
Answer - 4

16 - Google tells me that pairing up happens only in meiosis, and mitosis does not involve reduction of chromosome number
Answer - A (not sure can u check marking scheme and let me know???)

7 - measurement question. I can't do now but I can tell you that the minimum distance is where the rbc touches the capillary wall to the alveolar wall. And then u divide by 5000 to get the answer.

4 - when the cell and the solution have the same water potential, there is no movement of water. Thus the length of the cell does not increase or decrease. Thus the initial/final length value should be 1
Use the graph, and read off the corresponding concentration value...
Answer - C (0.45 moldm-3)
 
Zain Javaid

Zain Javaid

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thnkx
♣♠ Magnanimous ♣♠ said:
listen, in the ques it is written that stroke volume is of contaction of ventricles which directly says that volume of blood will be high... next see
ventricular end diastole is the volume of blood in ventricles that is just before systole which means that blood is entering the ventricles from atruim so he volume of blood varies and it is D
i hope you will not mess up in my answer.
Click to expand...
thnksss
 
Zain Javaid

Zain Javaid

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mynameisnotneeded said:
Um so u knw the blood that enters the ventricle during diastole is what is pumped up through the aorta or pulmonary artery right?
That blood is called the ventricular end diastolic volume.

Now the stoke volume is the blood that is pumped by the ventricle out of the heart (like into the aorta)

The more blood there is in the ventricle during diastole, the more blood is pumped out during systole.

HOWEVER, all pumps have a limit as to how much they can pump right? Thus, beyond a certain point the stoke volume becomes level as the heart has reached the maximum amt of blood it can pump in one contraction....

Hope I helped!
Click to expand...
thnks aloot
 
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