A level Biology: Post your doubts here!

[SalmaXXXX]

Could someone please explain to me these graphs? Q 14
and also how it would look if the amount of product formed on Y-axis and time on X-axis. It was a question in June 2002 but I can't find it here.

http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w07_qp_1.pdf

 

[magnesium]

phloem sieve tube cells mein lignification to nhi hoti na?

nope

 

[Student12]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
Q5(B), 20(C) , 23(C)

Someone helppp ! Yaar koi help karoooo !

 

[Student12]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s12_qp_11.pdf
Q16(C), 39(C) HELPP ! Could someone explain?

 

[Kinki Tiffany 12]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w10_qp_12.pdf

qns 12

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s11_qp_11.pdf
qns 13

 

[daredevil]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
Q5(B), 20(C) , 23(C)

Someone helppp ! Yaar koi help karoooo !

5) find out how many division of the eye piece make up one on the stage micrometer
in this diagram there are 40 divisions of eyepiece for 1 division of micrometr
now the chloroplast in the plant cell is 5 divisions of eye piece...
1 of eyepipece = 1/40 of stage micrometer
so 5 of eyepice make 4/40 of stage micrometer.
1 of stage micrometer = .1 mm

so ur answer will be (5/40) * 0.1

 

[SalmaXXXX]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s12_qp_11.pdf
Q16(C), 39(C) HELPP ! Could someone explain?

When air was bubbled in the medium, thus oxygen was bubbled too and respiration took place, both carbon sugars were uptaken so so far we can't decide which one requires energy (uptaken by active transport) and which is passive. However, when nitrogen was bubbled, the cell could not make respiration thus couldn't generate ATP for active uptake of 6 carbon sugar. As the 3 carbon sugar is a passive process, it doesn't require ATP thus even when cell couldn't make respiration or generate ATP, it was not affected.

 

[daredevil]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_12.pdf

qns 12

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s11_qp_11.pdf
qns 13

12) its tertiary for both bcz only the most complex of structure is altered and that too just a bit... the basic structure of the protein remains unchanged. just the shape changes (tertiary structure) so that it does not fit.

 

[Kinki Tiffany 12]

12) its tertiary for both bcz only the most complex of structure is altered and that too just a bit... the basic structure of the protein remains unchanged. just the shape changes (tertiary structure) so that it does not fit.

i don't get you.

 

[daredevil]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
Q5(B), 20(C) , 23(C)

Someone helppp ! Yaar koi help karoooo !

39)
first calculate the mass of the given no. of inviduals of a specie and then find their total energy by multiplying the answer with energy value. i.e.
(no. of species)*(mass)*(energy)
the largest value will be for the first trophic level as they have the highest amount of energy. as we move up the food chain the amount of energy for each level starts decreasin...
best approach is to first write the energy values infront of each option respectively and then arange them in descending order in the options.

 

[daredevil]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
Q5(B), 20(C) , 23(C)

Someone helppp ! Yaar koi help karoooo !

20)
look there is a double stranded DNA which has 12000 bases. if we take one strand - bcz one strand is needed to make a polypeptide - it means 6000 bases are present. then divide the 6000 by 3 bcz every 3 bases for one amino acid. as a result we get 2000 amino acids for that polypeptide.

 

[raamish]

does tb have a vaccine?

 

[ahmed abdulla]

39)
first calculate the mass of the given no. of inviduals of a specie and then find their total energy by multiplying the answer with energy value. i.e.
(no. of species)*(mass)*(energy)
the largest value will be for the first trophic level as they have the highest amount of energy. as we move up the food chain the amount of energy for each level starts decreasin...
best approach is to first write the energy values infront of each option respectively and then arange them in descending order in the options.

can u solve it plz

 

[daredevil]

can u solve it plz

R = 1000 (just multiply all the three values)
S = 100
T = 1.8
U = 450 000

from largest to smallest energy values: -
U > R > S > T

 

[Irfan1995]

does tb have a vaccine?

There's the BCG vaccine. Although it's not 100% effective, it's the best we've got so far.

 

[daredevil]

There's the BCG vaccine. Although it's not 100% effective, it's the best we've got so far.

so TB is a viral disease and vaccine is used to combat it??

 

[daredevil]

http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_s08_qp_1.pdf

Q37

 

[SalmaXXXX]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s08_qp_1.pdf

Q37

One of the reasons of failure of Measles Eradication programme was that the vaccine needed several boosters. This is a developing country and the idea of several boosters is hard to be applied there. We don't need a combined vaccine for other diseases, the question states for eradication of Measles. A vaccine containing only live measles, I think that this virus is strong so it has to be taken dead. Option D, genetic engineering is expensive and this is a developing country

 

[MaxStudentALevel]

MaxStudentALevel said: ↑
Hey can anyone explain ON 2008 p1 Q3???
raamish daredevil Irfan1995 ?

 

[SalmaXXXX]

Mit

MaxStudentALevel said: ↑
Hey can anyone explain ON 2008 p1 Q3???
raamish daredevil Irfan1995 ?

Mitochondria has ribosomes 70 s and circular DNA as a prokaryote so it didn't lose this feature. A prokaryotic cell doesn't even have ER ( no membrane bound organelles are present) However, a prokaryotic cell has a cell wall and mitochondria doesn't have one so it's the right answer.