nexttttt (4 Viewers)

[bekmay]

eww...designing experiments

ive been looking through the questions in the past papers
hsc success one textbook is very good!

alot of the same questions have been popping up constantly
i suggest everyone to go over:
the work of all the major figures: mendel, pasteur+koch, beadle+tatum, watson+crick, sutton+boveri, darwin+wallace
xylem/phloem
nephrons+kidney stuff
blood+ artificial blood
adh+aldosterone
antibiotics
vaccinations
meiosis/mitosis
all the quarantine stuff
immune system
know your pathogen types

for communication option topic i think you pretty much just have to know everything lol

^^^^ These are just some of the main stuff that i found that have been popping up alot.

I suggest you go over this stuff, but make sure you cover all dot points so you will not likely get a 'wtf question' =)

btw i posted like, two questions so far somewhere of the dot points im unsure about. can somebody help me? lol

can you post those questions you're unsure about again cos i can't be bothered going to find them... its likely i also don't know them, and i would like to find out LOL. and niiice suggestions thanks =]

 

[dolbinau]

Can anyone help me with Chromosomes?

2007 HSC question 22.

Now, can someone explain how the alleles are formed?

My understanding is elementary, I could only explain it by saying that genes on corresponding positions of the chromosomes come together (somehow?) But like, ae for example aren't between homologues chromosomes so yeah. I just don't understand. HELELLPPP .

Q: What are photoreceptors, and what role do they play in detecting stimuli?

(Communication Option Topic btw )

Rod/Cone cells found on Retina, detect light. (Is that enough for a two mark question, if it was one?)

 

[gloworm14]

can you post those questions you're unsure about again cos i can't be bothered going to find them... its likely i also don't know them, and i would like to find out LOL. and niiice suggestions thanks =]

already posted them on the previous page.
those are just points i havent got in my book that i forget or dont understand.
can anyone help?

 

[bekmay]

Here are the questions i dont get. Someone help me pretty please?

'process information to construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity'


'process information from secondary sources to construct a model that demonstrates meiosis and the processes of crossing over, segregation of chromosomes and the production of haploid gametes.'
( does it mean actual physical model we did... i remember we did one with pipeclearners. Or does it mean just draw the stages?)

from Blueprint of Life topic.


and here is my protein synthesis summary post

http://community.boredofstudies.org/showthread.php?t=188323

woops sorry found em. hmm well i have no idea for the 1st one...

and yeah i would say the pipe-cleaner model for the 2nd, it does say "... to construct a model..." sooo yeah. aha and i remember how confused my class was with that... the whole crossing over thing and people were cutting stuff and gosh it was all over the place. =D

 

[midifile]

Here are the questions i dont get. Someone help me pretty please?

'process information to construct a flow chart that shows that changes in DNA sequences can result in changes in cell activity'


'process information from secondary sources to construct a model that demonstrates meiosis and the processes of crossing over, segregation of chromosomes and the production of haploid gametes.'
( does it mean actual physical model we did... i remember we did one with pipeclearners. Or does it mean just draw the stages?)

from Blueprint of Life topic.


and here is my protein synthesis summary post

http://community.boredofstudies.org/showthread.php?t=188323

For the first one, if you just need a basic flowchart you can use:

Altered sequence of bases in DNA at the locus of a coding gene -->(transcription) --> Altererd sequences of bases in mRNA -->(translation)--> Altered sequence of amino acids in a polypeptide --> This polypeptide may fold in a different way to the normal polypeptide and as a result the protein will have a different structure and function to the normal protien, which may result in a change in cell activity

For the second dotpoint I think you can use either, but the pipecleaner one is probably better. If it came up in the exam the question would be "describe a procedure you used to model ..." and describing the procedure you used with pipecleaners is much better than saying "I drew a picture of a cell..."

 

[Takuto]

Rod/Cone cells found on Retina, detect light. (Is that enough for a two mark question, if it was one?)

I guess you could add that they produce signals or something? lol

Haha, just a random question, dunno how much it would be worth

 

[luucy]

Do we have to know the Phases of Meiosis ? ? ?

 

[gloworm14]

For the first one, if you just need a basic flowchart you can use:

Altered sequence of bases in DNA at the locus of a coding gene -->(transcription) --> Altererd sequences of bases in mRNA -->(translation)--> Altered sequence of amino acids in a polypeptide --> This polypeptide may fold in a different way to the normal polypeptide and as a result the protein will have a different structure and function to the normal protien, which may result in a change in cell activity

For the second dotpoint I think you can use either, but the pipecleaner one is probably better. If it came up in the exam the question would be "describe a procedure you used to model ..." and describing the procedure you used with pipecleaners is much better than saying "I drew a picture of a cell..."

thanks heaps.
yeh i would go for the pipecleaners, but thing is i totally forgot how we did it, all i remember is 2X 2 different colour pipecleaners, and alot of twisting and attaching, and might i add some cutting mistakes LOL... it confused me.
sooo does anyone have this procedure?

 

[jozza80]

The equine influenza.. again just apply your knowledge of vaccinations and/or medication that prevents the spread of the equine influenza virus, as well as quarantine measures.

Pretty straightforward IMO.

Don't forget all of the quarantine knowledge..

You would think after the epidemic earlier in the year, it will definately involve an effectiveness of quarantine question - and to be smart you would say it wasn't.

Talk of AQIS measures to prevent the spread of disease and how small things like washing clothing and shoes (to and from the Eastern Creek Quarantine Station for example) is highly important..

Also hypothesise (maybe?):
- Airborne spread from Sydney Airport
- Contaminated people, equipment, vehicles associated with movement of such horses from airpot
- Airborne spread from Eastern Creek...

This is just my random thought, so feel free to critisise it/me?



EDIT: YOU DID SAY QUARANTINE....Sorry....

 

[gloworm14]

Do we have to know the Phases of Meiosis ? ? ?

from all the questions ive seen with meiosis they never really ask you for them.
i think you just need to know when it duplicates, crosses over, replicates, separates and what it produces.
make sure u know that it has a 1st cell devision and a 2nd cell devision stage.

 

[bekmay]

Can anyone help me with Chromosomes?

2007 HSC question 22.

Now, can someone explain how the alleles are formed?

My understanding is elementary, I could only explain it by saying that genes on corresponding positions of the chromosomes come together (somehow?) But like, ae for example aren't between homologues chromosomes so yeah. I just don't understand. HELELLPPP .



Rod/Cone cells found on Retina, detect light. (Is that enough for a two mark question, if it was one?)

This is crossing over...
crossing over occurs during prophase 1 of meiosis. the chromosomes may be closely aligned at this stage, and sometimes even touching so parts of the chromosomes may break off and "swap". i.e the chromosome in the top in the cell on the right (this is metaphase 1) were close togetherbefore, so their alleles b and B swapped.

hmm sorry i'm not a very good explainer. do you get it?

 

[Takuto]

from all the questions ive seen with meiosis they never really ask you for them.
i think you just need to know when it duplicates, crosses over, replicates, separates and what it produces.
make sure u know that it has a 1st cell devision and a 2nd cell devision stage.

haha can someone explain this process?

im STILL confused about what is happening during meiosis and what it produces

 

[dolbinau]

This is crossing over...
crossing over occurs during prophase 1 of meiosis. the chromosomes may be closely aligned at this stage, and sometimes even touching so parts of the chromosomes may break off and "swap". i.e the chromosome in the top in the cell on the right (this is metaphase 1) were close togetherbefore, so their alleles b and B swapped.

hmm sorry i'm not a very good explainer. do you get it?

I get crossing over from those diagrams, the homologues chromosomes align and swap genes in the second circle (unknown) to produce the final circle. (Well, I guess its meant to be a cell lol).

BUT. From the 3rd cell, how can I know what the 'possible combinations of alleles" are?

Also, can you explain random segregation quickly ? Is that just the chromosomes align/split into daughter cells randomly?

m STILL confused about what is happening during meiosis and what it produces

All I know is. Chromosomes replicate. Then they divide twice. SO you're left with four haploid daughter cells. I have no idea how i'll remember all the phases

 

[gloworm14]

haha can someone explain this process?

im STILL confused about what is happening during meiosis and what it produces

meiosis gets me all the time.

here is what i have in my book:

1st cell division
1. genetic material is duplicated.
2. homologous chromosome pair with each other crossing over.
3. replication (chromatids become visible).
4. Homologous pairs separate.

2nd cell division
5. two daughter cells formed. each contain one chromosome of homo pair.
6. chromosomes align at equatorial plate.
7. centromeres divide.
8. cell division complete- 4 haploid daughter cells obtained.

 

[homijoe]

guys just a quick question does both active and passive transport occur in the phloem or just active?

 

[gloworm14]

guys just a quick question does both active and passive transport occur in the phloem or just active?

xylem= passive
phloem= active


however im not sure if phloem does both. i just learnt phloem uses active.

 

[imqt]

xylem= passive
phloem= active


however im not sure if phloem does both. i just learnt phloem uses active.

in phloem both passive and active...water, which contains dissolves sugars enters tthe phloam via osmosis, however the rest is active as sugars are deposited at source sinks against diffusion gradient

 

[imqt]

btw i hope there are no questions of meiosis...possible my weakest area

 

[gloworm14]

ok here is a random question:
firstly, define what a transgenic speices is.

then

outline the process used to produce transgenic species. include an example and reason for its use.

now gogogogogo!

 

[bekmay]

I get crossing over from those diagrams, the homologues chromosomes align and swap genes in the second circle (unknown) to produce the final circle. (Well, I guess its meant to be a cell lol).

BUT. From the 3rd cell, how can I know what the 'possible combinations of alleles" are?

Also, can you explain random segregation quickly ? Is that just the chromosomes align/split into daughter cells randomly?



All I know is. Chromosomes replicate. Then they divide twice. SO you're left with four haploid daughter cells. I have no idea how i'll remember all the phases

remember all the phases PMAT. lol. and then i have little ways to remember each but i won't embarass myself on here.

ok lets see. well seeing as in the 2nd 'circle' (LOL), crossing over has occured, we'll use just those alleles and not ones that would have happened in it didn't happen in one of the pairs...

ok in anaphase, one member of each pair moves to opposite ends of the cell right. and then we have blah blah blah 1st and second stage. then YAY four daughter cells.
in each cell we could (COULD... independent assortment) have:
1. AB, ED
2. Ab, ED
3. aB, ed
4. ab, ed

i'm guessing you have the paper with you?
just cut each chromosome into halfs vertically. then the left two get dragged to the left hand side, and the right two get dragged to the right hand side.

i'm so sorry but i'm a really shit explainer.
LOL.
what textbook do you have? mine has a pretty good explaination in it about this...