A level Biology: Post your doubts here!

[ShahdNaasan]

Each time he repeats the procedure,he gets a 'new' pellet with a 'single' organelle,indicating previous organelles were digested.

How were they digested ? They sank to the bottom after centrifuging

 

[Hisham Khan]

How were they digested ? They sank to the bottom after centrifuging

If they had sank to the bottom,why would their be only a single organelle present?

 

[Hisham Khan]

I'm so scared .In some papers I get over 35 and in some hard ones 26 etc lol in p1

 

[ShahdNaasan]

If they had sank to the bottom,why would their be only a single organelle present?

They said in the question that they sank to the bottom, the reason it would be a single organelle is because when they are spun in the centrifuge the heaviest one is removed first

 

[Kanekii]

Guys is it necessary to draw double line to show cell wall in cell drawings or is one line okay?

 

[ShahdNaasan]

Guys is it necessary to draw double line to show cell wall in cell drawings or is one line okay?

No you must draw the cell wall as double lines very close to each other and make sure that it is at constant thickness. Like this :

 

[A*****]

If they had sank to the bottom,why would their be only a single organelle present?

The question says that after centrifugation, the tube is filtered

 

[A*****]

Did onion epidermis or yeast come in P33?
If not then what experiment was it?

No none of them came...I think it was a non-reducing sugar test

 

[A*****]

I'm so scared .In some papers I get over 35 and in some hard ones 26 etc lol in p1

Bio P1 has lame logics that's why

 

[innovative_1]

Guys pls help!!!!

 

[Kanekii]

No you must draw the cell wall as double lines very close to each other and make sure that it is at constant thickness. Like this :

Thanks really useful
but are cells supposed to share their cell walls with other cells like this one?

 

[A*****]

Guys pls help!!!!

This is the dipeptide...
Add the diameter of 1 Nitrogen and 2 Carbon atoms (single bonded) to 0.7

 

[A*****]

Thanks really useful
but are cells supposed to share their cell walls with other cells like this one?

Maybe that is overlapping of cells but we are supposed to draw them like that ONLY IF THEY APPEAR to be like that

 

[ShahdNaasan]

How is it 0.07 seconds ? Isnt it the time between 3 and 4 ?

 

[innovative_1]

This is the dipeptide...
Add the diameter of 1 Nitrogen and 2 Carbon atoms (single bonded) to 0.7

Thanks

 

[innovative_1]

Guys don't u think so this statement is wrong? Like N14 to be transferred to N15.

 

[A*****]

Guys don't u think so this statement is wrong? Like N14 to be transferred to N15.

No it's fine

 

[innovative_1]

No it's fine

Yeah ur right actually i was sleepy so might be out of senses

 

[innovative_1]

Can someone pls clarify me what is the min n max number of hydrogen bonds in a length of DNA containing 700 base pairs? It's really confusing sometimes they say min 1400 or 700

 

[Hisham Khan]

Can someone pls clarify me what is the min n max number of hydrogen bonds in a length of DNA containing 700 base pairs? It's really confusing sometimes they say min 1400 or 700

Hmm what??.
1 base pair means A-T or C-G.A-T base pair have 2 hydrogen bonds and C-G base pair have 3 hydrogen bonds.

You want minimum number of hydrogen bonds?.So 700 base pairs into 2 (considering all base pairs are A-T)=1400.This answer is confirmed from the mark scheme..
And max 700 into 3 =2100