Biology; Chemistry; Physics: Post your doubts here!

[***amd***]

I tended to give further details but none of it is necessary in O Levels, so i didn't. But still you need to know this concept about proteins, can be asked in paper 1.

then tell us man!!! what are u waiting for

 

[black widow]

then tell us man!!! what are u waiting for

tell us what?

 

[***amd***]

de

tell us what?

tails

 

[LioxMessi]

then tell us man!!! what are u waiting for

I told you just enough, you don't need to know more than this, solve past papers and bring your quarries

 

[***amd***]

I told you just enough, you don't need to know more than this, solve past papers and bring your quarries

umm... plz?

 

[black widow]

umm... plz?

y do u want to know things that are not included in the syllabus
CIE CANNOT ask things not included in the syllabus

 

[***amd***]

y do u want to know things that are not included in the syllabus
CIE CANNOT ask things not included in the syllabus

it did -.-
about the structure and functioning of nephron <---- its just what my teacher told me .-.

 

[funky brat]

Are Auxins (growth hormone in plants) included in our syllabus? I've seen questions related to this in ATP.

 

[black widow]

Are Auxins (growth hormone in plants) included in our syllabus? I've seen questions related to this in ATP.

no they are not

 

[Izhaan]

Regarding std's, in how much detail do we have to go ? & someone please tell the name of the std's included in our syllabus

 

[asadalam]

Only Syphillis and HIV are included in our syllabus.Detail depends wholly on the question and its marks.

 

[black widow]

in question 4 (b), the marking scheme says that
water present in soil;
absorbed by root;

y is it absorbed?
doesn't water move in to the root hair cells by osmosis
if i wrote water moves in to the root hair cell by osmosis, will my statement be wrong?

 

[asadalam]

in question 4 (b), the marking scheme says that
water present in soil;
absorbed by root;

y is it absorbed?
doesn't water move in to the root hair cells by osmosis
if i wrote water moves in to the root hair cell by osmosis, will my statement be wrong?

No it wont as far as i know..its basically the same thing a bit more elaborated.PS.where did you get these papers?

 

[black widow]

No it wont as far as i know..its basically the same thing a bit more elaborated.PS.where did you get these papers?

i got them from here
https://www.xtremepapers.com/community/threads/cie-oct-nov-2013-papers-with-marking-schemes.31471/

cud u also explain question 4 (c)

 

[asadalam]

Well,the cow returns nitrates to the soil via egestion,urination.By the deamination of amino acids urea is formed and when it is passed out it is present in the soil where the freely present nitrifying bacteria act up on the matter and decompose it to form Nitrate(NO3-) ions,which enter the soil.
The factory on the other hand burns the fuel which contains nitrogen so oxides of nitrogen are emitted as exhaust(you may have read this in chemistry).They are then dissolved in rain to make acid rain,which falls on the soil and the nitrates are returned to soil.Any problem?

 

[Nabeel.Ahmad]

What is Galvanizing and Sacrificial Protection? [Chemistry] :/

 

[black widow]

Well,the cow returns nitrates to the soil via egestion,urination.By the deamination of amino acids urea is formed and when it is passed out it is present in the soil where the freely present nitrifying bacteria act up on the matter and decompose it to form Nitrate(NO3-) ions,which enter the soil.
The factory on the other hand burns the fuel which contains nitrogen so oxides of nitrogen are emitted as exhaust(you may have read this in chemistry).They are then dissolved in rain to make acid rain,which falls on the soil and the nitrates are returned to soil.Any problem?

thnx bro

 

[♣♠ MagneD ♣♠]

Are u asking for difference ???

 

[♣♠ MagneD ♣♠]

Galvanizing iron means coating it with zinc. Zinc is much more corrosion-resistant than iron (despite being a more active metal) because its oxide, ZnO, adheres to the surface of the metal rather than spalling off to expose more zinc to the atmosphere. In other words, the iron is covered by a metal which does not corrode.
Sacrificial protection, on the other hand, entails protecting the iron with a sacrificial anode made of a more active metal such as magnesium, which will oxidize preferentially to the iron. The iron cannot be oxidized because the iron cations will be reduced by the more active metal anode. When the sacrificial anode is depleted, the iron will begin to corrode.
I HOPE IT HELPS....

 

[black widow]

What is Galvanizing and Sacrificial Protection? [Chemistry] :/

both galvanizing and sacrificial protection are methods of preventing rusting

in galvanizing, a layer of zinc is electroplated on iron to prevent air and water from coming in contact with the iron
it is done on dustbins mostly

in sacrificial protection, magnesium is connected to the iron. Mg being more reactive reacts with the water and air instead of the iron. therefore no water or air comes in contact with the iron and the iron does not rust. this method is used in ships mostly