A level Biology: Post your doubts here!

[Hisham Khan]

Cool down bro

I WAS NEVER angry THOOOO xD

 

[A*****]

I WAS NEVER angry THOOOO xD

It seemed so

 

[innovative_1]

It seemed so

He is not angry bird he was just proving himself to be Mr. RIGHT right hisham?

 

[A*****]

He is not angry bird he was just proving himself to be Mr. RIGHT right hisham?

Hahahaha

 

[Hisham Khan]

Hahahaha

Stop bullying me or ill 360 degree no scope u guys :/

 

[A*****]

Stop bullying me or ill 360 degree no scope u guys :/

We're not bullying but you're being kinda rude :/

 

[Hisham Khan]

I was joing haha lmfao.I don't think you get the joke in it so I will stop then.

 

[blymphocytes]

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

No, none of those came.
We had food tests involving milk and there was serial dilution and plant cell microscopy.

 

[blymphocytes]

Idk how there is absence of non-reducing sugars here :-/
Could anyone explain why C is the answer ad not A?

A student carried out four tests for biological molecules on a sample of milk.
The tests and their results were as follows.

● Heating to 80 °C with Benedict’s solution gave a brick red colour.
● Adding Biuret solution gave a purple colour. ● Adding iodine solution gave an orange colour.
● Boiling with acid, followed by neutralisation, then heating to 80 °C with Benedict’s solution gave a brick red colour.

Which biological molecules must be present in the milk?
1 non-reducing sugars
2 protein
3 reducing sugars
4 starch


A 1, 2 and 3
B 1 and 2 only
C 2 and 3 only
D 3 and 4

 

[A*****]

Idk how there is absence of non-reducing sugars here :-/
Could anyone explain why C is the answer ad not A?

A student carried out four tests for biological molecules on a sample of milk.
The tests and their results were as follows.

● Heating to 80 °C with Benedict’s solution gave a brick red colour.
● Adding Biuret solution gave a purple colour. ● Adding iodine solution gave an orange colour.
● Boiling with acid, followed by neutralisation, then heating to 80 °C with Benedict’s solution gave a brick red colour.

Which biological molecules must be present in the milk?
1 non-reducing sugars
2 protein
3 reducing sugars
4 starch


A 1, 2 and 3
B 1 and 2 only
C 2 and 3 only
D 3 and 4

Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present

 

[blymphocytes]

Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present

Ohww nktt...........thanks

 

[Hisham Khan]

Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present

You saw the examiner report right ......

 

[Kanekii]

Guys does Carbon dioxide combine with haem group of a haemoglobin molecule?

 

[A*****]

You saw the examiner report right ......

NO

 

[A*****]

Guys does Carbon dioxide combine with haem group of a haemoglobin molecule?

No it combines with amine group to form carbaminohaemoglobin

 

[Hisham Khan]

Guys does Carbon dioxide combine with haem group of a haemoglobin molecule?

I think it binds to amine (NH2) group of haemoglobin

 

[Kanekii]

oh i see thanks
apparently i confused the Haem group to nitrogen but is actually iron xD

 

[Kanekii]

Bio Bombs Away!!! I understand that the objective lens should be x10 but why must the eyepiece lens be x5?

 

[A*****]

Bio View attachment 63761 View attachment 63762 Bombs Away!!!View attachment 63760 I understand that the objective lens should be x10 but why must the eyepiece lens be x5?

The anticodon for serine is UCA so the codon is AGU and hence the DNA triplet is TCA
Tip: the DNA triplet and anticodon are the same except for U and T

 

[A*****]

I understand that the objective lens should be x10 but why must the eyepiece lens be x5?

The TOTAL magnification must be calculated...so for the largest number of cells, the total magnification must be lowest which is x50 for A