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March 29, 2024, 09:28:20 am

Author Topic: VCE Biology Question Thread  (Read 3571008 times)  Share 

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yeshelly

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Re: VCE Biology Question Thread
« Reply #12285 on: January 23, 2020, 12:50:03 pm »
+1
Help please! From chapter review and I am so confused with this question :/

20.   A culture of living cells (A) is placed in a solution of high concentration of sodium ions. A second culture of living cells (B) is exposed to temperatures high enough to denature the proteins in their membranes and then placed in the concentration sodium ion solution.
a.   predict the relative concentration of sodium ions in their internal cellular environments of both cultures.
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SmartWorker

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Re: VCE Biology Question Thread
« Reply #12286 on: January 23, 2020, 02:42:10 pm »
+3
Help please! From chapter review and I am so confused with this question :/

20.   A culture of living cells (A) is placed in a solution of high concentration of sodium ions. A second culture of living cells (B) is exposed to temperatures high enough to denature the proteins in their membranes and then placed in the concentration sodium ion solution.
a.   predict the relative concentration of sodium ions in their internal cellular environments of both cultures.

Hey Yeshelly,

So for A: If there is a higher concentration of sodium ions outside the cell (extracellular fluid), then when compared to the cell contents, the solution is said to be hypertonic.

Therefore, sodium ions will move down its concentration gradient into the cell via facilitated diffusion, till the point of equilibrium is reached (between intracellular and extracellular environment)

Short answer: It is predicted that there is an equal concentration of sodium ions in the internal cellular environment and external cellular environment.

For B: High temperatures = enzymes which are proteins and other proteins are denatured. (meaning that they change shape and no longer functional). First we recognise that the plasma membrane is made of proteins and a phospholipid bi-layer. Therefore, if the proteins involved in transport such as the channel or carrier proteins are denatured, the plasma membrane is no longer an effective semi-permeable barrier. Thus, water in the cell will flow out via osmosis (high--->low conc. of water molecules or low-->high conc. of solutes)

I believe in both solutions the cells will end with equal concentrations of sodium ions, but someone please check.

Thinking about it, just about made me as confused.
« Last Edit: January 23, 2020, 02:50:04 pm by SmartWorker »
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yeshelly

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Re: VCE Biology Question Thread
« Reply #12287 on: January 23, 2020, 03:08:00 pm »
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Hey Yeshelly,

So for A: If there is a higher concentration of sodium ions outside the cell (extracellular fluid), then when compared to the cell contents, the solution is said to be hypertonic.

Therefore, sodium ions will move down its concentration gradient into the cell via facilitated diffusion, till the point of equilibrium is reached (between intracellular and extracellular environment)

Short answer: It is predicted that there is an equal concentration of sodium ions in the internal cellular environment and external cellular environment.

For B: High temperatures = enzymes which are proteins and other proteins are denatured. (meaning that they change shape and no longer functional). First we recognise that the plasma membrane is made of proteins and a phospholipid bi-layer. Therefore, if the proteins involved in transport such as the channel or carrier proteins are denatured, the plasma membrane is no longer an effective semi-permeable barrier. Thus, water in the cell will flow out via osmosis (high--->low conc. of water molecules or low-->high conc. of solutes)

I believe in both solutions the cells will end with equal concentrations of sodium ions, but someone please check.

Thinking about it, just about made me as confused.

Thank you so much!
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Ionic Doc

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Re: VCE Biology Question Thread
« Reply #12288 on: January 25, 2020, 12:50:25 pm »
0
Hey, everyone, I'm really struggling with this question.
I sorta get what it's asking but I really don't know how to refer to the graph.




thanks in advance
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vox nihili

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Re: VCE Biology Question Thread
« Reply #12289 on: January 25, 2020, 01:23:32 pm »
+5
Hey, everyone, I'm really struggling with this question.
I sorta get what it's asking but I really don't know how to refer to the graph.

(Image removed from quote.)


thanks in advance

What you've drawn on the graph is correct. Can you work us through how you've got to 1? YOu're very close!!
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Ionic Doc

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Re: VCE Biology Question Thread
« Reply #12290 on: January 25, 2020, 01:49:21 pm »
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What you've drawn on the graph is correct. Can you work us through how you've got to 1? YOu're very close!!

Ah sorry, that's my teachers working out.

I'll still go through what I have figured out.

The formula for RF(resistance factor) is Test Population LT90/Control Population LT90

For insectitide B, the control population LT90 value is 12 minutes.

Ok, so now all I need to figure out is the Test Population LT90 value...? (is this correct so far thnx)

Referring to my teachers working out ( I don't get where she got 24 from or neither what the lines she's drawn imply  :-\ )

Edit: So from looking at the graph again I can see that my teacher has drawn a line from 90% on the mortality axis and from 24 minutes on the time axis. I don't really understand the purpose of that. . . I'm guessing those two numerical values will help lead me to the Control Population value.

« Last Edit: January 25, 2020, 01:57:56 pm by Ionic Doc »
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12291 on: January 25, 2020, 01:59:27 pm »
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Looks like you're just having trouble reading the graph. The LT90 value is when the mortality rate is 90%. The mortality rate is on the Y axis here - that line horizontal near the top is indicating where 90% mortality is. You want to find the time when insecticide B is at 90% mortality so you need to find where the line for insecticide B meets that horizontal line your teacher has drawn. The vertical line they've drawn is where the line for insecticide B is at 90% mortality, the location of this on the X axis indicates the time at which this occurs - this is about halfway between 20 and 30 minutes.

The time when insecticide B is at 90% mortality is the LT90 value - your teacher has approximated 25. To work out the RF you put those values into the formula. So it would be 25/12 which is approximately 2.
« Last Edit: January 25, 2020, 02:01:32 pm by PhoenixxFire »
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thenuttyprofessor

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Re: VCE Biology Question Thread
« Reply #12292 on: January 29, 2020, 02:53:43 pm »
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do we need to know about type 2 3 4 hypersensitivity or just immediate (type 1) hypersensitivity reactions.

Sine

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Re: VCE Biology Question Thread
« Reply #12293 on: January 29, 2020, 02:56:44 pm »
+4
do we need to know about type 2 3 4 hypersensitivity or just immediate (type 1) hypersensitivity reactions.
VCE biology really only covers type 1 hypersensitivity reactions (allergic reactions as a result of re exposure)

thenuttyprofessor

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Re: VCE Biology Question Thread
« Reply #12294 on: January 29, 2020, 03:02:28 pm »
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VCE biology really only covers type 1 hypersensitivity reactions (allergic reactions as a result of re exposure)
perfect thanks

mion

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Re: VCE Biology Question Thread
« Reply #12295 on: February 06, 2020, 10:41:17 am »
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Hey guys,

I'm currently doing specialist 3/4, methods 3/4, english 3/4 and chemistry 3/4. I did further in year 11 and got 33, which I was very unhappy with. I was also failing my other classes due to specialist taking up too much time last year. Although I'm only doing 4 subjects this year, I find specialist challenging since starting 3/4. Is it worth it dropping specialist and picking up 3/4 bio without doing 1/2?

linesido

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Re: VCE Biology Question Thread
« Reply #12296 on: February 06, 2020, 11:09:53 am »
+5
Hey guys,

I'm currently doing specialist 3/4, methods 3/4, english 3/4 and chemistry 3/4. I did further in year 11 and got 33, which I was very unhappy with. I was also failing my other classes due to specialist taking up too much time last year. Although I'm only doing 4 subjects this year, I find specialist challenging since starting 3/4. Is it worth it dropping specialist and picking up 3/4 bio without doing 1/2?

1/2 bio doesn't really relate to 3/4 (except a couple topics plasma membrane and cellular respiration) so it can definitely be a smooth transition. Bio also requires less time compared to Spesh and IMO way easier overall even though they are two very different subjects. 

ajka0002

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Re: VCE Biology Question Thread
« Reply #12297 on: February 06, 2020, 08:29:51 pm »
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Hello all!!
I am wondering if anyone knows about the Units 3&4 study design and requirements... Do I need to know the entire structure and order of bases in the structure of tRNA, or just the basic shape and details about the anti-codons and amino acids?
Thanks :)

darkz

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Re: VCE Biology Question Thread
« Reply #12298 on: February 06, 2020, 09:55:27 pm »
+2
Hello all!!
I am wondering if anyone knows about the Units 3&4 study design and requirements... Do I need to know the entire structure and order of bases in the structure of tRNA, or just the basic shape and details about the anti-codons and amino acids?
Thanks :)

You do not need to know the entire structure or order of bases. You just need to know the function, anti-codon being complementary to the codon, and that it brings amino acids to the ribosome.
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mion

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Re: VCE Biology Question Thread
« Reply #12299 on: February 06, 2020, 10:52:56 pm »
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So I talked to my teacher today and she told me to not pick up Bio 3/4 but still drop Spesh 3/4. She told me my options were:
1. Only do 4 subjects - repeat further again and get a score in the 40's but I don't like the risk that comes with it.
2. Pick up BusMan - our schools average is 37 for the study score but then the teacher that I will have for it won't be great.
3. I want to ask her if I could do both further and busman but I don't know if she will allow it or that I can do well with 5 subjects this year.
« Last Edit: February 06, 2020, 11:13:47 pm by mion »