Biology; Chemistry; Physics: Post your doubts here!

[Manobilly]

W-O-W that was the best explanation thankyou!..

Your welcome! My dad helped me remember it by this way! Good Luck

 

[convent2012]

what the difference b/w mitosis and meiosis ??

 

[ashiqbal]

Next question
Dilute sulphuric acid reacts copper2oxide to form copper2sulphate and water
What would not alter the rate of this reaction?
A.the concentrationof the sulphuric acid
B. The pressure at which the reaction takes place
C. The size of the particles of copper2oxide
D.the temperature of the reacting mixture
Ps.I think all of them alter the rate of reaction!

ITs B, thus proving my theory of surface area affecting rate of reaction correcT
Thank You! Thank You!

 

[Rimsa]

what the difference b/w mitosis and meiosis ??

meisos occurs when the number of chromosomes if halved. mitsos occurs when genetically identical daughter cells are produced.

 

[luckywang]

Next question
Dilute sulphuric acid reacts copper2oxide to form copper2sulphate and water
What would not alter the rate of this reaction?
A.the concentrationof the sulphuric acid
B. The pressure at which the reaction takes place
C. The size of the particles of copper2oxide
D.the temperature of the reacting mixture
Ps.I think all of them alter the rate of reaction!

Pressure only alter the rate of reaction of gases?

 

[luckywang]

Now here is chemistry question
how to solve it
the fertilizer ammonium nitrate (NH4NO3, Mr. = 80 ) is manufactured from ammonia (Mr.= 17) by a two stage process :
STAGE 1= NH3 +2O2-----> HNO3 + H2O
STAGE 2= HNO3+ NH3 -----> NH4NO3
what is the maximum mass of the fertilizer that can be made if only 17
tonnes of ammonia is availaible?
A.34 tonnes
B. 40 tonnes
C. 80 tonnes
D. 97 tonnes

Answer is c? One mole produce one mole of fertilizer so is 80 tones?

 

[ashiqbal]

Pressure only alter the rate of reaction of gases?

only rate of reaction when the reaction is reversible.

 

[luckywang]

only rate of reaction when the reaction is reversible.

that is favour the forward reaction of reversible reaction?

 

[Rimi]

i have a question.. are the Basic units of DNA (Guanine, thymine etc) included in the syllabus? And what about teh whole process of protein synthesis? ( the transcription and translation thing)?

 

[luckywang]

i have a question.. are the Basic units of DNA (Guanine, thymine etc) included in the syllabus? And what about teh whole process of protein synthesis? ( the transcription and translation thing)?

transcription and translation is not included in the syllabus but dont know the basic unit...

 

[beeloooo]

Answer is c? One mole produce one mole of fertilizer so is 80 tones?

its B

 

[luckywang]

its B

can you explain why answer is B? because he ammonia is split to half so that it can be use in both process? so the actual mole is 0.5 mol and not 1 mol?

 

[ashiqbal]

that is favour the forward reaction of reversible reaction?

no that is favour of the reaction from more moles to less moles, eg:
N2 + 3H2 <--> 2NH3
4 moles of reactant and 2 moles of products
so if pressure increased, the forward reaction is favourable.

can you explain why answer is B? because he ammonia is split to half so that it can be use in both process? so the actual mole is 0.5 mol and not 1 mol?

yes exactly, there is only limited ammonia. if we use all of it in first process, we wont have any for second, so we have to utilise it carefully!

 

[luckywang]

no that is favour of the reaction from more moles to less moles, eg:
N2 + 3H2 <--> 2NH3
4 moles of reactant and 2 moles of products
so if pressure increased, the forward reaction is favourable.



yes exactly, there is only limited ammonia. if we use all of it in first process, we wont have any for second, so we have to utilise it carefully!

oh... thx!

 

[luckywang]

and... i wan ask... is the electron micrograph of animal cell and plant cell included in our syllabus? or just simple structure like cell membrane, cytoplasm and nucleus? mitochondria, ribosome, SER, RER, centriole and some others is not included in our syllabus right?

 

[ashiqbal]

and... i wan ask... is the electron micrograph of animal cell and plant cell included in our syllabus? or just simple structure like cell membrane, cytoplasm and nucleus? mitochondria, ribosome, SER, RER, centriole and some others is not included in our syllabus right?

electron micrograph usually comes in ATP, though u cant blame me if CIE decide otherwise!
and about those extra structures, no i dont think they are included, as i have solved about 10 years pst papers, didnt see them once, so you are good to go!

 

[luckywang]

electron micrograph usually comes in ATP, though u cant blame me if CIE decide otherwise!
and about those extra structures, no i dont think they are included, as i have solved about 10 years pst papers, didnt see them once, so you are good to go!

YES! can u tell me which structure is included in our syllabus? i hate memorise those freaky name....

 

[ashiqbal]

Where can find past papers of chemistry,physics,and biology of years
1998 till 2003

redspot, of course

 

[ashiqbal]

YES! can u tell me which structure is included in our syllabus? i hate memorise those freaky name....

the basic structures are included, cell wall, membrane, nucleus, cytoplasm, vacuoles, chloroplasts, and chromosomes(chromatids), DNA, nuclear envelope,
also for viruses, bacteria, fungi and sperms, you must know : flagella, DNA thread, hyphae, mycelium, chitin, protein coat, acrosome.

 

[luckywang]

the basic structures are included, cell wall, membrane, nucleus, cytoplasm, vacuoles, chloroplasts, and chromosomes(chromatids), DNA, nuclear envelope,
also for viruses, bacteria, fungi and sperms, you must know : flagella, DNA thread, hyphae, mycelium, chitin, protein coat, acrosome.

what is chitin and acrosoe?