A level Biology: Post your doubts here!

[princeali97]

Carrier proteins simply 'carry' the molecules across the membrane and the process may be active or passive. It is important to note here that it is just not the 'type of molecule' that influences what membrane protein is used by a molecule for transport. Other factors such as temperature, electrochemical gradient etc. also influence what molecules go through which protein.
Channel proteins however are distinguished for actively transporting a specific type of 'ion' across them.

You're sayying exactly the opposite thing bro :/ In the book its written clearly that facilitated diffusion takes place across channel proteins and active transport thru carrier proteins.:/

 

[princeali97]

this is a very good question..can sum1 explain pls...q20... http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s11_qp_13.pdf

 

[Mohammed salik]

this is a very good question..can sum1 explain pls...q20... http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_13.pdf

Q20:-(D)
It says Used in Photosynthesis (used by Plants)
The first three are Not Used By plants.. SO just add them up and Substract From total.! Which ends up to Be 23 500J!
If u Need Detailed Explanation do Tell Me!

 

[princeali97]

Q20:-(D)
It says Used in Photosynthesis (used by Plants)
The first three are Not Used By plants.. SO just add them up and Substract From total.! Which ends up to Be 23 500J!
If u Need Detailed Explanation do Tell Me!

Wait but you're getting the answer only by adding the last 3 values in the table.You dont need to add the first 3 and subtract from the total

 

[Mohammed salik]

Wait but you're getting the answer only by adding the last 3 values in the table.You dont need to add the first 3 and subtract from the total

Wait but you're getting the answer only by adding the last 3 values in the table.You dont need to add the first 3 and subtract from the total

Okay.. I wanted to Look More logical !!

 

[Mohammed salik]

Hello can someone please explain the following :
How to solve q 24 and 40 !
And why q38 ans should be A not B ?!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_13.pdf

Q24: 40 Units on Eyepeice cover 1 unit on Micrometer which is equal to 0.1mm or 100 micrometer.
Not it asks for 10 micrometer.. simply use ratios..
40 : 100
X : 10
X= 4 (ans is B).

Q40: Multiply all Three Values for Given Specie... Then You end up With B !

Q38) So You understand Sun to Plants is Least.. so ans is A or B
In A it says Decomposers would get 2nd Least amount of energy which is True
Because There is Too Much energy lost in respiration of Producer+Primary+Secondary consumer.
Hence Least Energy remains For Decomposers..!
Hope I Helped

 

[princeali97]

Okay.. I wanted to Look More logical !!

Yeh theres logic in adding the bottom 3 too.Photosynthesis is the process whereby light energy is converted to chemical energy.so u can see that the bottom 3 processes are converting chemical energy to other forms.So youll add them up to get the chemical energy.

 

[Mohammed salik]

Yeh theres logic in adding the bottom 3 too.Photosynthesis is the process whereby light energy is converted to chemical energy.so u can see that the bottom 3 processes are converting chemical energy to other forms.So youll add them up to get the chemical energy.

Why didnt You Think of This Before Asking the Question !

 

[joanna omar]

someone please explain me this!
what would be exact answer of Q6 (C) ?


http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w13_qp_21.pdf

 

[princeali97]

Why didnt You Think of This Before Asking the Question !

Acha tell me how does the casparian strip help with generation of root pressure ?

 

[princeali97]

someone please explain me this!
what would be exact answer of Q6 (C) ?


http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w13_qp_21.pdf

Look.First the total energy content of Kelp consumed i.e by all organisms will be determined.And then the energy content of Kelp consumed only by sea urchins will be determined.So the Percentage of energy transfer can be calculated by (Energy content of kelps consumed by urchins/energy content of kelp consumed by all organisms) multiplied by 100%.I hope you understand

 

[Mohammed salik]

Is this From Past paper?

Acha tell me how does the casparian strip help with generation of root pressure ?

 

[Snowysangel]

Acha tell me how does the casparian strip help with generation of root pressure ?

Root pressure is built up due to osmosis s dthe difference in water potential. So you basically explain how water moves through the symbolist route in the endodermis and how it leaves the previous cells it moved through(including the root hair cells) having a lower water potential, so water moves from the soil into the root because of the difference in root pressure

 

[Gehad Mohamed]

Q24: 40 Units on Eyepeice cover 1 unit on Micrometer which is equal to 0.1mm or 100 micrometer.
Not it asks for 10 micrometer.. simply use ratios..
40 : 100
X : 10
X= 4 (ans is B).

Q40: Multiply all Three Values for Given Specie... Then You end up With B !

Q38) So You understand Sun to Plants is Least.. so ans is A or B
In A it says Decomposers would get 2nd Least amount of energy which is True
Because There is Too Much energy lost in respiration of Producer+Primary+Secondary consumer.
Hence Least Energy remains For Decomposers..!
Hope I Helped

Thank you soooooo much

 

[joanna omar]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w13_qp_12.pdf

Explain me please Q14 , Q20 and Q30 ?

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w13_qp_12.pdf

Explain me please Q14 , Q20 and Q30 ?

q14 1 is correct as you will be able to thee the tail and Head
2 the arrangement can be seen (its like you cut a human body in half you will be able to see where the stomach is just an example)
3 length :/ it doesn't show anything about strength 'you can't see strength'
q20 whats the confusion here? can you let me know so i can explain better
q30 there is no Hemoglobin in plasma its only present in RBC so no carbaminohaemoglobin

 

[joanna omar]

q14 1 is correct as you will be able to thee the tail and Head
2 the arrangement can be seen (its like you cut a human body in half you will be able to see where the stomach is just an example)
3 length :/ it doesn't show anything about strength 'you can't see strength'
q20 whats the confusion here? can you let me know so i can explain better
q30 there is no Hemoglobin in plasma its only present in RBC so no carbaminohaemoglobin

Thanks a lot
In Q20.....I believe that 2 is not correct as complementary base pairing doesn't occur in TRANSLATION ! that is way my answer was only 1,3and 4
soo ? how they say its correct ?

 

[princeali97]

Root pressure is built up due to osmosis s dthe difference in water potential. So you basically explain how water moves through the symbolist route in the endodermis and how it leaves the previous cells it moved through(including the root hair cells) having a lower water potential, so water moves from the soil into the root because of the difference in root pressure

what? i dint get it :/

 

[thats_me]

Can you help with q38 & 40 of the same paper?

q14 1 is correct as you will be able to thee the tail and Head
2 the arrangement can be seen (its like you cut a human body in half you will be able to see where the stomach is just an example)
3 length :/ it doesn't show anything about strength 'you can't see strength'
q20 whats the confusion here? can you let me know so i can explain better
q30 there is no Hemoglobin in plasma its only present in RBC so no carbaminohaemoglobin [/quoteCPU

 

[joanna omar]

Can you help with q38 & 40 of the same paper?

Q38)
Since the sun is more intense during the summer than the winter, this must be
curve B. During the winter most plant and animal life will be very limited as many have died and therefore
the nutrients are more in winter than summer, curve A. This leaves curves C and D. Since primary
consumers feed on producers, there should be more producers than consumers, hence curve C is correct.

Q40 )
Statement A is valid since in ecosystem Y the dominant
producer is large and woody, so would not be easily consumed. Statement B is valid since there is a smaller
fluctuation of temperature in marine aquatic ecosystems and also there is less oxygen. Statement C is also
valid, since with lower energy losses between trophic levels the ecosystem X can support more trophic
levels. Therefore the answer is statement D.