AS Biology P1 MCQs Preparation Thread

[HuN3yy !!]

A specimen is viewed under a microscope using green light with a wavelength of 510nm.
If the same specimen is viewed under the same conditions, but using red light with a wavelength
of 650 nm instead, what effect will this have on the magnification and on the resolution of the
microscope?
http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w07_qp_1.pdf
itx qst no. 3 ..As resolution is half of the wavelength, according to this fact the answer should hav been C ,But it is D whyyy ?? Help !!

 

[rogue94]

A specimen is viewed under a microscope using green light with a wavelength of 510nm.
If the same specimen is viewed under the same conditions, but using red light with a wavelength
of 650 nm instead, what effect will this have on the magnification and on the resolution of the
microscope?
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_qp_1.pdf
itx qst no. 3 ..As resolution is half of the wavelength, according to this fact the answer should hav been C ,But it is D whyyy ?? Help !!

Basically the numerical value of resolution increases, but resolution itself decreases. Light microscope has a resolution of 200nm while electron microscope has a higher resolution of 0.5 nm, However the numerical value is higher for light microscope (200). Basically the numerical value tells us the minimum distance between two points on the image that can be seen as separate. For this particular question using green light the resolution is 255 nm, so 2 points on the image closer to each other than 255nm will not be seen (clearly). Using red light the resolution is 325 nm (the numerical value is higher), but it means that 2 points closer than 325 nm will not be seen. Hence, the resolution is lower for red light.
Resolution is always inversely proportional to the wavelength of the radiation being used to view the specimen.

 

[Ahmed Ali Akbar]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_13.pdf
How do we do 38? and for 40, isnt the right answer C??

good questions...me too looking forward to an explanations......

 

[HuN3yy !!]

Basically the numerical value of resolution increases, but resolution itself decreases. Light microscope has a resolution of 200nm while electron microscope has a higher resolution of 0.5 nm, However the numerical value is higher for light microscope (200). Basically the numerical value tells us the minimum distance between two points on the image that can be seen as separate. For this particular question using green light the resolution is 255 nm, so 2 points on the image closer to each other than 255nm will not be seen (clearly). Using red light the resolution is 325 nm (the numerical value is higher), but it means that 2 points closer than 325 nm will not be seen. Hence, the resolution is lower for red light.
Resolution is always inversely proportional to the wavelength of the radiation being used to view the specimen.

Yess i got that ...THANKS A LOT !!

 

[HuN3yy !!]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w07_qp_1.pdf
Plz help me out in qst no 15 and 24 !!!

 

[HuN3yy !!]

good questions...me too looking forward to an explanations......

Em also confused about qst 38 ...buh as far qst 40 is concerned, multiply the biomass of one individual by number of individuals ..Then compare the answers with energy value per unit mass ..or multiply the answers with energy value per unit mass ..This will give u answer D ..And datx the correct answer !! Hope u understand

 

[rogue94]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_qp_1.pdf
Plz help me out in qst no 15 and 24 !!!

For no. 15 the correct answer is B, because as sucrose concentration increases water potential decreases and becomes more negative. As the water potential decreases less water moves into the plant tissue via osmosis, so there is less turgidity.
For no. 24 movement of sucrose from leaf cell to sieve tube element is active transport since it involves pumping out protons by companion cells followed by cotransport of sucrose, which is against the concentration gradient. Although sucrose diffuses down the conc. gradient from companion cell to sieve tube element, but movement from leaf cell (1) to sieve tube element (2) also involves active transport. As sucrose enters sieve tube element (2), the sucrose concentration increases, leading to a decrease in water potential, so water potential is more negative (higher water potential is less negative and lower water potential is more negative.)

 

[HuN3yy !!]

For no. 15 the correct answer is B, because as sucrose concentration increases water potential decreases and becomes more negative. As the water potential decreases less water moves into the plant tissue via osmosis, so there is less turgidity.
For no. 24 movement of sucrose from leaf cell to sieve tube element is active transport since it involves pumping out protons by companion cells followed by cotransport of sucrose, which is against the concentration gradient. Although sucrose diffuses down the conc. gradient from companion cell to sieve tube element, but movement from leaf cell (1) to sieve tube element (2) also involves active transport. As sucrose enters sieve tube element (2), the sucrose concentration increases, leading to a decrease in water potential, so water potential is more negative (higher water potential is less negative and lower water potential is more negative.)

Okayyyy i got it ....thankyouu soo much

 

[HuN3yy !!]

http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_s09_qp_1.pdf
Need help in qst 22 and 26 !!! For no. 22 why the answer is not B as replication is semi-conservative ,so the % of cells containing N15 should be 50 %..no ??

 

[zainabk]

Can anyone please upload papers of 2001 and 2000 and the paper of m/j 2002?

 

[zainabk]

Q.Which disease is least likely to be passed from parent to child? The options are cholera,HIV/AIDS,malaria and sickle cell anaemia.The answer is malaria.Can anyone please explain why it is malaria and not cholera? :/ And can anyone please tell that what would have been the answer if they had asked 'most likely' instead of 'least likely?

 

[zainabk]

And can anyone please explain question.20 of M/J 03 paper?

 

[confused123]

good questions...me too looking forward to an explanations......

for 40 you should see that in order to know how much total energy is given by total number of one specie say P we need to multiply first number of individuals with biomass of one individual. this will give us total mass of all the species of one type. we need to multiply this result with energy value per unit mass for that specific specie.

P = 10,000 into 0.100 = 1000 , multiply this mass with energy value per unit mass, 1000 into 1 = 1000
follow this method for other species and you will get B. The point is we need to find total energy given by all species of one type, for that we need to first calculate total mass...

38) IDK!

 

[confused123]

And can anyone please explain question.20 of M/J 03 paper?

Link plz

 

[confused123]

Q.Which disease is least likely to be passed from parent to child? The options are cholera,HIV/AIDS,malaria and sickle cell anaemia.The answer is malaria.Can anyone please explain why it is malaria and not cholera? :/ And can anyone please tell that what would have been the answer if they had asked 'most likely' instead of 'least likely?

malaria as it is passed by vector anopheles mosquito, fetul blood is seperate from mother's blood so plasmodium will not be able to pass. :/
cholera bacterium breeds inside small intestine. so no chance of bacteria passing to child as the mode of transmission for this is poor sewage handling, unwashed hands etc..

HIV/Aids would be most likely to be passed on due to the transfer of virus. breast feeding, blood transfusion or accidental mixing could cause it..fluids exchange can occur so there are more ways for this disease to be transferred

 

[confused123]

Em also confused about qst 38 ...buh as far qst 40 is concerned, multiply the biomass of one individual by number of individuals ..Then compare the answers with energy value per unit mass ..or multiply the answers with energy value per unit mass ..This will give u answer D ..And datx the correct answer !! Hope u understand

Its B the correct answer for 40th mcq.

 

[zainabk]

Can't sickle cell anaemia pass from parent to child as it is also a hereditary disease? ;/

 

[confused123]

Can't sickle cell anaemia pass from parent to child as it is also a hereditary disease? ;/

u said it is also a hereditary disease which suggest that you might have thought Hiv aids or any other disease to be hereditary from the given options. if that is so then you are wrong. no other disease has a hereditary link.

sickle cell anaemia is a hereditary disease and can pass from parent to child. but these sort of errors are very rare when genetic material passes from parent to child. this will be second least likely after malaria.

 

[00tanveer]

Which agricultural practice will not provide an alternative to the use of ammonium nitrate as a
fertiliser to increase the productivity of wheat?

A. growing wheat and another cereal crop in the same field in alternate years

B. growing wheat and beans in the same field in alternate years

C. ploughing animal waste such as dung into the soil

D. using synthetic urea as a fertiliser

 

[confused123]

Which agricultural practice will not provide an alternative to the use of ammonium nitrate as a
fertiliser to increase the productivity of wheat?

A. growing wheat and another cereal crop in the same field in alternate years

B. growing wheat and beans in the same field in alternate years

C. ploughing animal waste such as dung into the soil

D. using synthetic urea as a fertiliser

Its B i think. if it its right then i can make some solid explanation for that. in short i think this practice will not replenish the soil fertility as plant seeds are grown on the same soil. A option will provide the alternative to fertilizer as the previous crop waste material will act as fertiliser.