biology paper 1 doubts

[Irfan1995]

hmmm.. x400 means using the x40 lense on the microscope right? because x10 is the fixed magnification of the ocular. Am i right?

Anyway, lets just stick to mitochondria not being visible with a light microscope... ?

Yes, that would be right.
Maybe the Cambridge examiners are a bit too old and need to get their eyes fixed to see more clearly.

 

[♥Яαηõõşḧ♥]

hmmm.. x400 means using the x40 lense on the microscope right? because x10 is the fixed magnification of the ocular. Am i right?

Anyway, lets just stick to mitochondria not being visible with a light microscope... ?

exactly, i think so too !!
yeah good idea

 

[xtremeforums]

Yes, that would be right.
Maybe the Cambridge examiners are a bit too old and need to get their eyes fixed to see more clearly.

lol or maybe the blurry structures you saw using the microscope were just specks of dust?
But jokes apart! If this question does come up... what would u all choose??

 

[Irfan1995]

lol or maybe the blurry structures you saw using the microscope were just specks of dust?
But jokes apart! If this question does come up... what would u all choose??

Well, if they previously mentioned that it wasn't visible, then I would say it's not visible. But if they asked me to draw a cell in a practical exam, I'd draw the mitochondria.

 

[♥Яαηõõşḧ♥]

lol or maybe the blurry structures you saw using the microscope were just specks of dust?
But jokes apart! If this question does come up... what would u all choose??

hahahahaha... i would choose that mitochondria are not visible

 

[Taci12]

lol or maybe the blurry structures you saw using the microscope were just specks of dust?
But jokes apart! If this question does come up... what would u all choose??

I'd go for no mitochondria, hoping Cambridge remains consistent

 

[xtremeforums]

ok so lets just all stick to what Ranoosh said:

At low power, u can see the cytoplasm with many dense granular bodies (refer to june 2012 question 2.)
At high power u can see, chloroplasts, nucleus, starch grains, vacuoles. u cant see the ER, ribosomes, mitochondria, lysosomes or cell membrane​

 

[♥Яαηõõşḧ♥]

ok so lets just all stick to what Ranoosh said:

At low power, u can see the cytoplasm with many dense granular bodies (refer to june 2012 question 2.) ​

At high power u can see, chloroplasts, nucleus, starch grains, vacuoles. u cant see the ER, ribosomes, mitochondria, lysosomes or cell membrane​

i totally agree

 

[Irfan1995]

ok so lets just all stick to what Ranoosh said:

At low power, u can see the cytoplasm with many dense granular bodies (refer to june 2012 question 2.) ​

At high power u can see, chloroplasts, nucleus, starch grains, vacuoles. u cant see the ER, ribosomes, mitochondria, lysosomes or cell membrane​

Oh come on, you MUST see mitochondria at high power. I mean, mitochondria are 500 nm long, and the minimum visible length is 200 nm.
I agree with everything else.

That's all I have time for today. Good night everyone, and good luck tomorrow! I hope that I've at least helped some people with their questions.

 

[♥Яαηõõşḧ♥]

Oh come on, you MUST see mitochondria at high power. I mean, mitochondria are 500 nm long, and the minimum visible length is 200 nm.
I agree with everything else.

That's all I have time for today. Good night everyone, and good luck tomorrow! I hope that I've at least helped some people with their questions.

well thats what cambridge think so imma stick with them....
yeah u rlly helped alooot thanks soo much, gd night and isa we'll all rock the exam tomorrow!!!

 

[xtremeforums]

Oh come on, you MUST see mitochondria at high power. I mean, mitochondria are 500 nm long, and the minimum visible length is 200 nm.
I agree with everything else.

That's all I have time for today. Good night everyone, and good luck tomorrow! I hope that I've at least helped some people with their questions.

U helped alot, thanks! and good luck to u too...

And what ur saying makes sense, thats why i was confused.. Oh well, ive a strong feeling that it wont come in the exam tomorrow...

 

[xtremeforums]

well thats what cambridge think so imma stick with them....
yeah u rlly helped alooot thanks soo much, gd night and isa we'll all rock the exam tomorrow!!!

InshAllah!

 

[Taci12]

Oh come on, you MUST see mitochondria at high power. I mean, mitochondria are 500 nm long, and the minimum visible length is 200 nm.
I agree with everything else.

That's all I have time for today. Good night everyone, and good luck tomorrow! I hope that I've at least helped some people with their questions.

Thanks for your help! You're really good at biology All the best everyone!

 

[Kumkum]

http://www.xtremepapers.com/papers/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
please help with question 23

 

[♥Яαηõõşḧ♥]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf
please help with question 23

ok in this question, at first all bacteria contain N15
After one generation of being grown with N14, about 100% of the bacteria have hybrid DNA ( N14 and N15) which is graph A
After the second generation, 50% have N14 and 50 % have hybrid DNA ( as shown in the question)
After the third generation ( which is being asked about in the question), 75% have N14 and 25% have hybrid DNA so the answer is C
After the fourth generation, about 100% of the bacteria have N14 which is graph D
hope i could help u out

 

[Kumkum]

ok in this question, at first all bacteria contain N15
After one generation of being grown with N14, about 100% of the bacteria have hybrid DNA ( N14 and N15) which is graph A
After the second generation, 50% have N14 and 50 % have hybrid DNA ( as shown in the question)
After the third generation ( which is being asked about in the question), 75% have N14 and 25% have hybrid DNA so the answer is C
After the fourth generation, about 100% of the bacteria have N14 which is graph D
hope i could help u out

ok i understand now thnx!

 

[railey]

Walaikum salaam! The question asks for the proportion of net productivity passing on from the producers to the primary consumers.
Hence you can ignore the 4.0% from the producer as it represents the gross productivity. Likewise, the 2.3 % is irrelevant .The value of the net productivity passing from producers to primary consumers is 0.75%.
Moreover, 1.8% is the total energy passing from the producers. So the proportion is 0.75/1.8.
You can think of the net productivity as the effective or net energy transfer and the gross productivity as the total amount of energy passing from one trophic level to the next.
Hope I helped!

Thank you!

 

[nelly trich]

Guys did anyone solve nov 2011 varient 2 and marked from the markscheme ? if yes did you find the markschem having mistakes ???

 

[angelic crystal]

hye can anyone please upload all the variants of M/J 2012 with their mark schemes please?