Biology; Chemistry; Physics: Post your doubts here!

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s13_qp_12.pdf
Question 3?
And in question 4 why does the iodine test give black colour when we have BOILED amylase which means that the enzyme got denatured. Thus the enzyme wont act on it and the colour should be yellow.No?

Look at the chloride ion uptake. It is irrespective of the oxygen conc. whatsoever. Thus it is not move by active transport. Nitrate ions do however

4. Bioled amylase will mean no reducing sugars will be present (ie. starch will be there), and thus there is a postive test for starch

 

[Mahnoorfatima]

Look at the chloride ion uptake. It is irrespective of the oxygen conc. whatsoever. Thus it is not move by active transport. Nitrate ions do however

4. Bioled amylase will mean no reducing sugars will be present (ie. starch will be there), and thus there is a postive test for starch

Oh righttt. You mean that active transport needs oxygen as for active transport to take place, energy is required and which is obtained in the presence of oxygen. (Aerobic respiration) Its needed for active transport.
Right?

 

[Nisa Mirza]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s13_qp_12.pdf
Question 3?

I'd go with C. Uptake if nitrate increases with oxygen [], so that means its an energy-dependent process (active transport). Chloride ions aren't affected by the O2 [] so its reasonable to assume that its plain old diffusion.

 

[DaniyalK]

Can someone please explain questions 1 and 24?

 

[funky brat]

Can someone please explain questions 1 and 24?

Rinsing with distilled water removes all impurities making it suitable for re-use so B.
In 24th the test tube initially contains air which has almost 21% oxygen in it. So the oxygen in the air reacts with the steel forming rust. Water level at the beginning of experiment is at D so it will reach C approximately when 21% of the tube contents have reacted.

 

[funky brat]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s13_qp_12.pdf
Question 3?
And in question 4 why does the iodine test give black colour when we have BOILED amylase which means that the enzyme got denatured. Thus the enzyme wont act on it and the colour should be yellow.No?

For chloride ions see the graph is constant. The uptake occurs even when the oxygen from respiration is zero. Though the rate of uptake of nitrate ions increases with oxygen showing that it is an energy dependent process.

 

[Dark Destination]

Can someone please explain questions 1 and 24?

Q1. B, because all the other options are weird. They involve acid and alkalis.

Q24. C? Because oxygen will get used up, i think. And the water level will rise.

 

[funky brat]

Q1. B, because all the other options are weird. They involve acid and alkalis.

Q24. C? Because oxygen will get used up, i think. And the water level will rise.

Exactly. Chemistry Master.

 

[Dark Destination]

I've forgotten everything about Chemistry, even. What the hell!

 

[Dark Destination]

Exactly. Chemistry Master.

Lol, okay. Distilled water. Food samples.
Biology-master. xD

 

[funky brat]

I've forgotten everything about Chemistry, even. What the hell!

Same here. :O
I just picked up a paper and could not remember anything so placed it back. It would be done easily in 3 days.

 

[Dark Destination]

Same here. :O
I just picked up a paper and could not remember anything so placed it back. It would be done easily in 3 days.

Those two questions i solved? Do you get them? :/
Why C?

 

[funky brat]

Somebody posted a link to study Nitrogen cycle. I think Awesome12 can you re-post please?

 

[funky brat]

Those two questions i solved? Do you get them? :/
Why C?

Yeah because it has 21% oxygen in it which reacts with steel and the air is now almost 79% in the test tube. The empty space which was initially occupied by oxygen is filled with water.

 

[Dark Destination]

Yeah because it has 21% oxygen in it which reacts with steel and the air is now almost 79% in the test tube. The empty space which was initially occupied by oxygen is filled with water.

Oh.. So that's the actual explanation! I didn't know this. .-.

 

[funky brat]

Oh.. So that's the actual explanation! I didn't know this. .-.

You get 39/40. Still not bad.

 

[funky brat]

Oh.. So that's the actual explanation! I didn't know this. .-.

You ALWAYS get the right answers. Mostly you know the reason and even if you don't you make perfect tukkas.

 

[Faizan Muhammmad]

Hey guys how about we go specific?
Like Bio Phy ATPs coming up, so start discussing them?

 

[Faizan Muhammmad]

You ALWAYS get the right answers. Mostly you know the reason and even if you don't you make perfect tukkas.

you are ALWAYS flattering other people while never talking about yourself

 

[funky brat]

you are ALWAYS flattering other people while never talking about yourself

So you think I should become a mian mithu praising myself. That's what I've seen. Why would I even flatter?