A level Biology: Post your doubts here!

[Lola_sweet]

thanks.. what do you think about the other 2? they are really confusing me

ik the answers but my explanation will suck dnt wanna confuse u

 

[Abdul Hanan]

ik the answers but my explanation will suck dnt wanna confuse u

no problem

 

[qwertypoiu]

thanks.. what do you think about the other 2? they are really confusing me

Q5:
Enzymes are proteins. How are proteins produced?
Made in the ribosome, enter the endoplasmic reticulum, vesicle buds off, goes and joins Golgi apparatus!
It's C obviously

Q26: 2 and 4 are plasmolysed, they have low water potential... So C and D are negated. B is also negated because it mentions 1 to 3, which cannot be possible. Why not?
Because C has a much larger vacuole. Large vacuole = more water potential. So your answer is A!

Q29: Dilation and contraction of the arterioles are only done by the smooth muscle. Collagen is there for strength I think. Elastin is just for recoil to stabilize the pressure.
So D!

 

[princess Anu]

can somebody help with 33 2012 Oct nov/ 12
i don't get why C is not the answer but D is

 

[Abdul Hanan]

Q5:
Enzymes are proteins. How are proteins produced?
Made in the ribosome, enter the endoplasmic reticulum, vesicle buds off, goes and joins Golgi apparatus!
It's C obviously

Q26: 2 and 4 are plasmolysed, they have low water potential... So C and D are negated. B is also negated because it mentions 1 to 3, which cannot be possible. Why not?
Because C has a much larger vacuole. Large vacuole = more water potential. So your answer is A!

Q29: Dilation and contraction of the arterioles are only done by the smooth muscle. Collagen is there for strength I think. Elastin is just for recoil to stabilize the pressure.
So D!

Thanks so nice of you to help so many ppl here

 

[qwertypoiu]

can somebody help with 33 2012 Oct nov/ 12
i don't get why C is not the answer but D is

It seems you think this can cause heart failure:
"deposits of fatty material in arteries and veins"
From my book:
Heart failure happens due to the blockage of a main coronary artery and the resulting gradual damage to the heart muscle. The heart weakens and fails to pump efficiently.

As you can see, the main coronary artery has to be blocked for a heart failure. Even if we consider "arteries" to possibly refer to the coronary artery, the fact that "vein" has been included means this option is wrong.

 

[qwertypoiu]

Thanks so nice of you to help so many ppl here

Welcome

 

[Sadi66]

http://maxpapers.com/wp-content/uploads/2012/11/9700_w12_qp_13.pdf
Q39
____________________________________

http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_11.pdf
Q15: WHY OPTION A WRONG'
Q31
Q39 THE NITROGEN FIXING REQUIRE ANAEROBIC CONDITION FOR N FIXING?
__________________________________
http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_12.pdf
Q31 EXPLAIN ALL OPTIONS PLS
Q29
Q32
Q35 : PLS EXPLAIN THIS IN DETAIL LIKE WHATS INFLAMMATION AND SCARRED ?
Q40
___________________________________
http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_13.pdf
Q10; WHY D NOT
Q12
Q15
Q39

______________________________

 

[nehaoscar]

Please explain

 

[Sadi66]

View attachment 53194

Please explain

is the answer A?

 

[princess Anu]

sorry i quoted the wrong Que
it's oct 2012 / 11 Q33

It seems you think this can cause heart failure:
"deposits of fatty material in arteries and veins"
From my book:
Heart failure happens due to the blockage of a main coronary artery and the resulting gradual damage to the heart muscle. The heart weakens and fails to pump efficiently.

As you can see, the main coronary artery has to be blocked for a heart failure. Even if we consider "arteries" to possibly refer to the coronary artery, the fact that "vein" has been included means this option is wrong.

 

[qwertypoiu]

http://maxpapers.com/wp-content/uploads/2012/11/9700_w12_qp_13.pdf
Q39
____________________________________

http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_11.pdf
Q15: WHY OPTION A WRONG'
Q31
Q39 THE NITROGEN FIXING REQUIRE ANAEROBIC CONDITION FOR N FIXING?
__________________________________
http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_12.pdf
Q31 EXPLAIN ALL OPTIONS PLS
Q29
Q32
Q35 : PLS EXPLAIN THIS IN DETAIL LIKE WHATS INFLAMMATION AND SCARRED ?
Q40
___________________________________
http://maxpapers.com/wp-content/uploads/2012/11/9700_s13_qp_13.pdf
Q10; WHY D NOT
Q12
Q15
Q39

______________________________

Q30:

All energy made in the ecosystem comes from photosynthesis. The energy that the plant lost, kept, used, etc. ALL originally came from its photosynthesis. Therefore:
Energy from photosynthesis: 27,000 + 3000 = 30,000
Energy from Sun = 1,000,000
Percentage = 30,000/1,000,000*100%=3%

 

[princess Anu]

somebody plz!
Option D is correct.. but doesn't this imply secondary struc contains ionic bond

 

[qwertypoiu]

View attachment 53194

Please explain

A, because active transport is affected by the number of carrier proteins in the phospholipid bilayer.
The rest of them like diffusion and osmosis are affected by fluidity of the membrane, as this determines how well molecules can exit or enter. Endocytosis is also about entry of molecules through the bilayer, so is affected by fluidity.

 

[qwertypoiu]

My Name
Your immunity notes say:

Types of immunity ACTIVE and PASSIVE

Active natural- by antibodies passing through placenta

Active artificial- following injection of antibodies in serum

Passive natural- reaction in the body to infection

Passive artificial- reaction following vaccination

You mixed up the passive with active I think. Replace all active with passive and all active with passive and it should be correct

 

[qwertypoiu]

My Name
Also,

What is the sequence of events that describes the action of a phagocyte when a pathogen is encountered?

Endocytosis → digestion by lysosome enzymes → phagocytic vacuole formation →exocytosis

I think the phagocytic vacuole formation should be before digestion by lysosomal enzymes...

 

[qwertypoiu]

sorry i quoted the wrong Que
it's oct 2012 / 11 Q33

D. The graph shows percentage of smokers every year. However, every year population is also increasing. So if at beginning around 80% are smokers then later 32% are smokers it might seem okay to conclude that the number of men who were smokers decreased by 60%, but this cannot be true, since population has changed, option D actually states "number of men" so it cannot be true.

 

[nehaoscar]

is the answer A?

Yes!

 

[nehaoscar]

What's the difference between endocytosis and phagocytosis?
qwertypoiu

 

[nehaoscar]