A level Biology: Post your doubts here!

[kareem22010]

What mark scheme says is that the doubling of the chromosome number is inevitable since the homologus chromosomes have to pair so if the the chromosome number has not doubled during the interphase it would have been possible to get a sterile hybrid just by the combination of two which itself is impossible under normal circumstances. I hope I didn't commplicate this further for you.

but i don't get it, why if the chromosome number didn't double during interphase , the hybrid would be sterile?

 

[leenz98]

but i don't get it, why if the chromosome number didn't double during interphase , the hybrid would be sterile?

Yeah see the last two boxes one species has 28 chromosomes and other and 14 chromosomes, each of them gives one chromosome from every pair means the one with 28 gives 14 and the one with 14 gives 7 so both chromosomes combine and make 21 that is the haploid number so the diploid number is 42 (21*2) which is sterile as shown in the box.. <-- This was if the doubling of chromosomes didnt occur in the beginning had it occured then the chromsome number would have doubled as from the two boxes (28*2= 56 and 14*2 =28) and then the halving would have occured and this is what normally happens.

 

[kareem22010]

Yeah see the last two boxes one species has 28 chromosomes and other and 14 chromosomes, each of them gives one chromosome from every pair means the one with 28 gives 14 and the one with 14 gives 7 so both chromosomes combine and make 21 that is the haploid number so the diploid number is 42 (21*2) which is sterile as shown in the box.. <-- This was if the doubling of chromosomes didnt occur in the beginning had it occured then the chromsome number would have doubled as from the two boxes (28*2= 56 and 14*2 =28) and then the halving would have occured and this is what normally happens.

oh, i get it now, thank you so much. by the way, is this question compatible with the new 2016 syllabus?:

 

[leenz98]

oh, i get it now, thank you so much. by the way, is this question compatible with the new 2016 syllabus?:
View attachment 59598

Not sure about that but this question can be a part of hormonal control etc since the answer is somewhere along those lines and that's very much in the syllabus.

 

[kareem22010]

Not sure about that but this question can be a part of hormonal control etc since the answer is somewhere along those lines and that's very much in the syllabus.

yeah, what confuses is me is that some of the answers are present in the content of the book and while some others have not even been given as a cue by my book. the only i thing i know is that they reduced the content of human reproduction in 2016 syllabus.

 

[My Name]

Thanks

welcome

 

[kareem22010]

Hello guys, can anybody answer this question that I found in the new syllabus document?:
Outline how mutation may affect phenotype?

 

[angelica007]

Hey guys!!! I am completely new here and just got to know about this forum from a friend. Well I found an awesome resource that I think I should share. And it is:

Hodder Cambridge as/a level biology revision guide 2nd edition (2015 edition)

Here's the link: www.fileml.com/file/0573aM

Note : Problem here is that you have to complete an offer to download!! I know it sucks... But the revision guide is really awesome... And anyway it just 5 minutes to complete the offer..I am not able to upload here as it is a big file and my internet is smaller

 

[My Name]

Hey guys!!! I am completely new here and just got to know about this forum from a friend. Well I found an awesome resource that I think I should share. And it is:

Cambridge as/a level biology revision guide 2nd edition (2015 edition)

Here's the link: www.fileml.com/file/0573aM

Note : Problem here is that you have to complete an offer to download!! I know it sucks... But the revision guide is really awesome... And anyway it just 5 minutes to complete the offer..I am not able to upload here as it is a big file and my internet is smaller

I don't get it.It asks for your phone number.

 

[Rizwan Javed]

Hey guys!!! I am completely new here and just got to know about this forum from a friend. Well I found an awesome resource that I think I should share. And it is:

Hodder Cambridge as/a level biology revision guide 2nd edition (2015 edition)

Here's the link: www.fileml.com/file/0573aM

Note : Problem here is that you have to complete an offer to download!! I know it sucks... But the revision guide is really awesome... And anyway it just 5 minutes to complete the offer..I am not able to upload here as it is a big file and my internet is smaller

Surveys are always fake, lol

 

[My Name]

Surveys are always fake, lol

So the book isn't there? :/
I haven't seen any revision guide except for the blue fishes one. :/

 

[angelica007]

Hey.. Just try it and you will see it is there..

 

[My Name]

Hey.. Just try it and you will see it is there..

You want me to click:

Play games right now.
Play new games.

to get Biology AL revision guide?

You can post it here if you have it.

 

[Rizwan Javed]

So the book isn't there? :/
I haven't seen any revision guide except for the blue fishes one. :/

Nope. There's no book. I tried and nothing happened.

Hey.. Just try it and you will see it is there..

If you have it, then why don't you just share it here. Upload it on mediafire, and share the link. It's only 40MB file

 

[angelica007]

Okay I will be truthful here.. I have the file because I bought the hard copy... So there is a cost... Every time someone fills up the survey.. I will get paid.. Yeah paid!! By sharecash which is a PPD network... So isn't it a good deal? ... You would get the scanned book for free and I would get some cash to cover up the cost of buying the book... So one last time... It is there bro... And that is why I am not uploading the actual file....

 

[Lola_sweet]

Okay I will be truthful here.. I have the file because I bought the hard copy... So there is a cost... Every time someone fills up the survey.. I will get paid.. Yeah paid!! By sharecash which is a PPD network... So isn't it a good deal? ... You would get the scanned book for free and I would get some cash to cover up the cost of buying the book... So one last time... It is there bro... And that is why I am not uploading the actual file....

we dont get survey
it asks for a mobile number and operator to play some game .-.
and what if we dont have a mobile number?

 

[mohmed ahmed soliman]

can anybody help me with this question?
View attachment 59594 View attachment 59595 View attachment 59596
I don't understand what the makscheme is saying, can anybody explain how to get to the answer of this question?

any clear explanation would be very helpful

which year

 

[mohmed ahmed soliman]

can anybody help me with this question?
View attachment 59594 View attachment 59595 View attachment 59596
I don't understand what the makscheme is saying, can anybody explain how to get to the answer of this question?

any clear explanation would be very helpful

which year

 

[Akshajistari]

Guys just go to GCE guide. It's there, no need to fill in these fake surveys.

And this is the link http://www.gceguide.com/e-books/

 

[My Name]

Guys just go to GCE guide. It's there, no need to fill in these fake surveys.

And this is the link http://www.gceguide.com/e-books/

That is a great site.
But a newer version of revision guide isnt there.