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Original post by Suzanna5678
I never seem to know whether to talk about horizontal or vertical gene transmission? For example looking at jan 2013 and the question says.... Using isoniazid to treat diseases caused by other species of bacteria could increase the chance of the bacterium that causes tuberculosis becoming resistant to isoniazid. Use your knowledge of gene transmission to explain how.


That would be horizontal gene transmission (describe conjugation) as it is between different species. Vertical green transmission is to direct offspring :smile:
Reply 1981
Original post by Simran Mars Foster
Thinking about it we made so many predictions for Unit 1 but hardly any of them came up! Gah.


****ing tuberculosis *shakes fists*
Feeling okay about biology (finally), I was getting C's earlier this week and atm getting 130UMS+ (got 140 twice), what I did was go through THIS THREAD and find all the answers for possible six markers people and gave and made my own revision cards by writing them down. I then last night identified topics I wasn't great at (water movement in plants etc) and spent 30 mins on each topic just reading notes and reading stuff online, recording myself saying notes and listening to them. After 30 mins, even if I wasn't 100% there I moved on to the next one. Good luck everyone!
Can someone give a 2 mark definition of biodiversity and tell me whether tissues are made up of similar cells or different cells? PLZ
Original post by Sapien
****ing tuberculosis *shakes fists*


EXACTLY!. :shakecane:
Are chromosome in an X shape or just in a shape of a single chromatid?
Original post by Suzanna5678
Can someone give a 2 mark definition of biodiversity and tell me whether tissues are made up of similar cells or different cells? PLZ


Biodiversity looks at the number of different species in an area and the number of individuals of each species.

Tissues are made up of similair cells.

Organs are made up of different tissues.
Original post by Hi, How are you ?
Are chromosome in an X shape or just in a shape of a single chromatid?


A chromosome is X shaped, made up of two identical chromatids (a chromatid is replicated to get two indentical chromatids, these are joined in the middle by a centromere to form a chromosome)
Reply 1988
Original post by Suzanna5678
Can someone give a 2 mark definition of biodiversity and tell me whether tissues are made up of similar cells or different cells? PLZ


Biodiversity -- The range and variety of genes, species and habititats within a particular region

And tissues are made out of similar cells that are organised into a structure that serves a specific function
Original post by alice.o123
ahhh thank you that did help :biggrin: also when so the sister chromatids get pulled apart, is it in anaphase?


Yeah. In metaphase chromosomes line up at the equator/middle/metaphase plate and spindle fibres form.
In anaphase sister chromatids are pulled towards opposite poles of the cell.

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image.jpgHow can you tell if the bars overlap or not from the graph?
guys what's independent segregation?
Original post by maryamnc
A chromosome is X shaped, made up of two identical chromatids (a chromatid is replicated to get two indentical chromatids, these are joined in the middle by a centromere to form a chromosome)


So are the chromosomes in a diploid cell in an X shape of just in a chromatid shape?
Original post by Suzanna5678
image.jpgHow can you tell if the bars overlap or not from the graph?


they dont
looking at the end of each tandard deviation they dont overlap
Could anyone quickly go through immunological comparisons? :smile:


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Reply 1995
Does anyone have the Letts - Revise AS & A2 AQA Biology revision guide?
If so, does anyone else think it's poop considering it doesn't even cover meiosis, gene transmission and all the nasty stuff?
Can someone tell me the grade boundaries? X


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Original post by anonymousecheese
they dont
looking at the end of each tandard deviation they dont overlap

Oh I see! I think I was over complicating it thank you !
Reply 1998
Original post by Sambird369
Can someone tell me the grade boundaries? X


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We won't know the official ones til everyone does the exam, but they're normally roughly 80% for an A, 70% for a B, 60% for a C and so on
Reply 1999
Could anyone who has the link for the Jan 2013 past paper Unit 2 please send me the link? I would be so grateful! :smile: x x

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