A level Biology: Post your doubts here!

[Shemyaa]

I now understand why A, B and C are wrong. Can you please once more explain why D js correct? Shouldnt the option say "form strands that fold and twist together to from a chromosome"? Or is their wording the same? Are chromosomes and chromatids the same thing? Individual chromatids are coiled and thick too?

watch this and you'll understand what I meant might be easier to visualize while explaining.

 

[Shemyaa]

Need help understanding this one too. Stuck between option A and C.

Again, let me break this down for you. As I explain all the options you'll understand the answer.
Why it's not A: When we say "contain something" that means that we're trying to modify something in order to be able to store it in. So, for example, we know the DNA is coiled around nucleosomes (8 histone proteins) in order to avoid DNA knotting AND to actually fit the DNA because DNA is about 2 m long while the nucleus is 6 micrometers! so it makes sense to say the DNA is folded to bla bla bla but talking about option A , they attach to spindle fibers to be arranged in the equator and to be pulled to opposite poles, as simple as that, they are already fit into the nucleus so it makes no sense to say that these chromosomes have already been in the cell during interphase and were even longer yet they fit perfectly in the cell, that's why when you go through option C you'll understand what I'm saying. Sometimes in such cases when you're really confused don't rely only on your theory, imagine the processes it'll turn out more logical.
Why its not B: First, its definitely right that they condense because they don't want to express any genes or activities, and more precisely they don't want to undergo transcription, so them saying that "translating genes", PLUS we don't translate genes we translate mRNA so the sentence structure is wrong.
Why its C: That's true, during telophase they move to opposite poles, recoil, become longer, thinner and that's why they become no more visible under a light microscope.
Why it's not D: The sentence is hilarious, it's not the chromosomes that replicate to produce DNA, and "sufficient" basically isn't the right word to use here at all
I hope I made enough sense

 

[mn096261]

any expectations for p32?

 

[blymphocytes]

Hey ....can someone plzz explain this to me
thank you!

 

[Shemyaa]

Hey ....can someone plzz explain this to me
thank you!

View attachment 64757

Is it D?
Whatever is on the tRNA is the anticodon, and they gave you the list of codons,
to make it really easy for you, under each tRNA molecule, write the codon, so i'll write this in a sequence from left to right,
GUA,GAA,ACU,ACG
(Incase you don't know anticodons and condons have complementary base pairs,
now that you have all the list of codons written, just compare with the codons they gave you, you do have GUA,GAA,ACU but you don't have ACG this means that this is a codon that codes for another aminoacid other than thr-pro-val-glu

 

[blymphocytes]

Is it D?
Whatever is on the tRNA is the anticodon, and they gave you the list of codons,
to make it really easy for you, under each tRNA molecule, write the codon, so i'll write this in a sequence from left to right,
GUA,GAA,ACU,ACG
(Incase you don't know anticodons and condons have complementary base pairs,
now that you have all the list of codons written, just compare with the codons they gave you, you do have GUA,GAA,ACU but you don't have ACG this means that this is a codon that codes for another aminoacid other than thr-pro-val-glu

Yes it is.......ohh that's such a convenient method
tysm <3

 

[Shemyaa]

Yes it is.......ohh that's such a convenient method
tysm <3

Any time

 

[Kelly W]

You got anymore exams? BTW what does IA stand for? Anyway, I wish you all the best in your exams !

anyone know somewhere I can get IAL biology or chemistry book2answers?

 

[HoneyBunny1864]

Xylem is made up of lignin so water can pass through it

Can u give a little explaination for this

 

[bibek234]

You can go through this link to get answers to some of your doubts in A Levels Biology. There are some completely solved (handwritten) past-papers, too. You can get an idea of how to write answers in the real exam. Link: https://biologyref.blogspot.com/

 

[Rain0.0]

hi i have a question regarding O/N 2015 p11
in question 39, why is the answer A?
and in question 17,why is the answer b?

 

[Maida Qazi]

1. This is a vacuole. Plants cells have vacuoles, and animal cells don't
At this point, the only possible option is B. Therefore I'd just choose B and continue with other questions. But just for benefit:

2. This is a lysosome.
3. Mitochondria
4. Endoplasmic Reticulum
5. Ribosomes

3,4,5 all exist in both animal and plant cells.
As for lysosomes this is debatable, it depends on your definition for lysosomes. If you're interested have a look here

But animals do have vacuoles isn't it???

 

[Amjad Ahmed]

Can anyone explain this question

 

[sampada]

Hey, would anyone be kind enough to help me with this problem?
(9700/13/o/n/17 question no 9