A level Biology: Post your doubts here!

[RoOkaYya G]

These 15 divisions and 10 division are 15 and 10 EYEPIECE UNITS!

its NOT 10 EPG!! it cannot be!!
its 10 div stage i.e the growth!! see the quest again!!
10 EPG is too much!! think of it logically also -_______-

 

[♣♠ Magnanimous ♣♠]

its NOT 10 EPG!! it cannot be!!
its 10 div stage i.e the growth!! see the quest again!!
10 EPG is too much!! think of it logically also -_______-

Just see PAge 7 of Biology coursebook third edition and see those words EYE PIECE UNITS!

 

[RoOkaYya G]

Just see PAge 7 of Biology coursebook third edition and see those words EYE PIECE UNITS!

eye piece is the big scale. anyway -____- my answer was better above so leave it

 

[♣♠ Magnanimous ♣♠]

eye piece is the big scale. anyway -____- my answer was better above so leave it

 

[***amd***]

this is misleading!
this is how we do it :

2 eye piece graticule (EPG) scale= 100 division on stage micrometer
100 div on stage = 2 EPG scale
on fig 1 :
5 div on stage= (2/100) * 5
=0.1 EPG = 0.01 mm = 10micrometer

on fig 2 :
15 div on stage = (2/100) *15
= 0.3 EPG scale =0.03 mm = 30 micrometer

increase in size (growth) = 30 micrometer - 10 micrometer = 20 micrometer

rate of growth = 20/4 = 5 micrometer per hour <---------

u could work out 10 div for growth directly like :

10 div on stage = (2/100)*10 =0.2 EPG scale = 0.02 mm= 20 micrometer
then rate= 20/4 = 5micrometer per hour

actually, my method was just to make her understand what exactly was going on. otherwise we both are correct and it is acceptable both ways.

 

[RoOkaYya G]

actually, my method was just to make her understand what exactly was going on. otherwise we both are correct and it is acceptable both ways.

ur method is right. just that theres difference in EPG n stage micrometer thts wht i was sayin

 

[Daniel Lim]

To all those who are taking A Level,

Here are the full tips on how to score every subject in AS and A2, which includes the tips on studying and the answering techniques.

http://daniellimjj.blogspot.com/2014/09/complete-tips-for-cie-as-and-level.html

 

[princess Anu]

Q What causes the cellulose molecule to straighten?
Q why can cellulose molecules make hydrogen bonds but starch cannot?

 

[Yogita.T]

Could someone please help me ASAP? It would be much appreciated if someone could tell exactly how to get the correct volumes etc for the simple dilution in Q1 a, as i didnt understand what was given in the mark scheme. The main issue is how to obtain a difference of 0.02% in the concentrations.
I have included files of the paper as well as its respective mark scheme
thanks so much in advance!

 

[Yogita.T]

HERE it is
Hope it helps
and BTW u tell me how to prepare the other 2 concentrations of S so that u test ur understanding
DONT hesitate to ask if u need more explination
View attachment 44031

Can you please help me with a similar question?? would be much aprreciated. its Q1 from w13 qp31
Thanks so much! )))

 

[Bba321]

Is anyone giving biology p34 this Tusday?

 

[Yogita.T]

Is anyone giving biology p34 this Tusday?

I am!

 

[DeViL gURl B)]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_21.pdf

Guys can anyone please explain me Question 3 (b) .. I don't get it ..
Thank you

 

[Yogita.T]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_21.pdf

Guys can anyone please explain me Question 3 (b) .. I don't get it ..
Thank you

Stem cells are our back up cells basically, the most simple kind with no specific function
they're always in our body, ready to differentiate into cells we may need
thats why you always hear about cancer patients needing stem cells right? because their own cells are being destroyed and they need new ones that help their body. So, in the same way, as and when our body needs RBC's, as we mature, the stem cells can differentiate into them, hence obtaining a specific function. This is just a broad outline, but i hope it helps
also, it develops into an RBC by losing its cell contents, hence creating the indented cell we know to be an RBC
I hope this helped you could also google stem cells for any further info or doubts you may have

 

[Yogita.T]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w09_qp_22.pdf

Hi Can someone please explain Q6, part (iii). The markscheme isnt very clear, unfortunately

Thanks

 

[♣♠ Magnanimous ♣♠]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w12_qp_21.pdf

Guys can anyone please explain me Question 3 (b) .. I don't get it ..
Thank you

As you know that WBC and RBC both are made in "Bone Marrow" and in bone marrow they are produced by some specialised cells called "stem cells"
Stem cells --->

1. an undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.

 

[♣♠ Magnanimous ♣♠]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w09_qp_22.pdf

Hi Can someone please explain Q6, part (iii). The mark schemeisnt very clear, unfortunately

Thanks

Can you see in energy flow diagram that from secondary consumers one thick arrow comes TOWARDS SECONDARY CONSUMERS and TWO ARROW GOES FROM SECONDARY CONSUMERS which shows energy is available for them as well as released.

The total energy got to secondary consumers is 13 right? And 8 is released in respiration and 3 to decomposes so now if you sum up the energy released is 8+3 equals 11 and now available energy for tertiary consumers is very less i.e. 2 so due to less amount of energy available for them there are no tertiary consumers in energy flow diagram

This is bit confusing but if you understand than it's easy

 

[Yogita.T]

Can you see in energy flow diagram that from secondary consumers one thick arrow comes TOWARDS SECONDARY CONSUMERS and TWO ARROW GOES FROM SECONDARY CONSUMERS which shows energy is available for them as well as released.

The total energy got to secondary consumers is 13 right? And 8 is released in respiration and 3 to decomposes so now if you sum up the energy released is 8+3 equals 11 and now available energy for tertiary consumers is very less i.e. 2 so due to less amount of energy available for them there are no tertiary consumers in energy flow diagram

This is bit confusing but if you understand than it's easy

Hi there thanks for the explanation, but i was actually asking about part 3, (iii)
The question asking about the leaf litter. If you could explain that, it would be great thanks

 

[♣♠ Magnanimous ♣♠]

Hi there thanks for the explanation, but i was actually asking about part 3, (iii)
The question asking about the leaf litter. If you could explain that, it would be great thanks

really sorry
let me see

 

[Yogita.T]

really sorry
let me see

No problem at all