CHEM AND BIO HELP AND TIPS HERE

[K_M]

 
I have a small doubt, i think i misunderstood the concept or this is an exception but can someone please clear it for me!
Active uptake is the movement of molecules of a substance from low concentration to high concentration against the concentration gradient. Then how is mineral ions absorbed by the roots of a plant? Doesnt the soil have a higher concentration of mineral ions than the plants?

[rhea]

have a question:

In which change is the nitrogen reduced?

A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2

PLLZZ HELLP OOUUTT!!

i have NO idea of how to do this question!

[Vin]

have a question:

In which change is the nitrogen reduced?

A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2

PLLZZ HELLP OOUUTT!!

i have NO idea of how to do this question!

it should be 'D' .. check the ans n tell .. i'll giv u an explanation if its right ..

[ambitious94]

I have a small doubt, i think i misunderstood the concept or this is an exception but can someone please clear it for me!
Active uptake is the movement of molecules of a substance from low concentration to high concentration against the concentration gradient. Then how is mineral ions absorbed by the roots of a plant? Doesnt the soil have a higher concentration of mineral ions than the plants?

I answered that in the other thread (IGCSE BIOLOGY------>TRANSPORT IN PLANTS)...didn't u read it? Or do I suck at explaining stuff?   LOL

[Baladya]

http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf

6)a) Both ovums... can u make a small drawing or smth Thanks

[rhea]

it should be 'D' .. check the ans n tell .. i'll giv u an explanation if its right ..

nope, its C.

[K_M]

I answered that in the other thread (IGCSE BIOLOGY------>TRANSPORT IN PLANTS)...didn't u read it? Or do I suck at explaining stuff?   LOL

oh crap i didnt see it! thanks will check it now!

[Helium]

Can someone explain why it's C i thought it's D

[Vin]

http://www.freeexampapers.us/IGCSE/Biology/CIE/2006%20Nov/0610_w06_qp_3.pdf

6)a) Both ovums... can u make a small drawing or smth Thanks

here ..

[NidZ- Hero]

can any1 explain wata  a negative feedback wid sum defination thnaku  

[Baladya]

here ..

Thx man u look like u studied this chapter very well jk xD

[nid404]

have a question:

In which change is the nitrogen reduced?

A. NH3 to NO
B.NH3 to NO-3
C.N2 to NH3
D. N3- to N2

PLLZZ HELLP OOUUTT!!

i have NO idea of how to do this question!

C. ox state of N2 gas is always 0. it goes from 0 to -3 in NH3

[rhea]

C. ox state of N2 gas is always 0. it goes from 0 to -3 in NH3

hey can u explain this?

how does one know the oxidation state and how its change is calculated

[the_grim_reaper]

I really don't think its oxidation state has changed to -3 here. It hasn't exacly gained 3 electrons. Ammonia is a covalent compound.

THe reason this question is tough is that there are 3 definitions of reduction.
1) Gain of electrons
2) Loss of oxygen
3) Gain of hydrogen (No oxygen must be involved)

As far your question is concerned, it is reduction since the N2 has gained hydrogen to form NH3.
Please correct me if I am wrong...

[J.Darren]

H - Oxidation number : 1
O - Oxidation number : -2
N - Oxidation number : -3

In A and B, as Nitrogen forms a covalent bond with Hydrogen (Ammonia) and Oxygen (Nitrate, Nitrogen Oxide), the oxidation number will remain as -3.

In C, we know that the valency of Nitrogen molecule is zero, and we know that when Nitrogen forms a covalent bond with Hydrogen (Ammonia), the oxidation number will be -3, since its oxidation number has decreased, we can tell that a reduction has taken place.

In D, we know that the valency of Nitrogen molecule is zero, and we know that when Nitrogen forms a covalent bond with Hydrogen (Ammonia), the oxidation number will be -3, since its oxidation number has increased, we can tell that a oxidation has taken place.