VCE Biology Question Thread

[colline]

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.

Do you want to do busman? I'm curious why your teacher would specifically suggest a subject especially when it's not a prereq for any uni courses.

I agree that only doing 4 subjects is very risky. It's not uncommon to do 5 in year 12. In fact, that's what most people do.

Which teacher are you talking to?? I don't believe a single teacher can actually have the power to force you to drop or not do a subject. Think about what subject/s you're actually interested in or would be good at. Your teacher's opinion should be suggestions only, you're the one making the decision in the end.

[Sine]

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?

I don't know if it is "worth" it but it would be possible to do bio 3/4 from scratch and still do well in it. The downside though is that school has already started so you miss out on 2 months you could've used to get yourself familiar with biology terminology.

[Mudasser.abb]

Post-transcriptional factors are a thing what about post-translational

[linesido]

Post-transcriptional factors are a thing what about post-translational

Do you mean Post transcriptional modification? If so, it is the 3 processes after a pre-mRNA is produced. In short, the introns are removed, a 5' cap is added and a poly A tail is added to 3'.

[Mudasser.abb]

Do you mean Post transcriptional modification? If so, it is the 3 processes after a pre-mRNA is produced. In short, the introns are removed, a 5' cap is added and a poly A tail is added to 3'.

I mean after translation occurs and the polypeptide chain is translated into a functional protein

[PhoenixxFire]

I mean after translation occurs and the polypeptide chain is translated into a functional protein

There are post translation modifications that occur but you don't need to know about them. The most you'll be taught in VCE is that changes happen to polypeptides in the ER.

[miyukiaura]

Do you need to restate/reword the question in a response e.g.
Q: Explain why it is important to place tissues or organs to be used in medical procedures in a solution with the same osmolarity as the cytoplasm.
A: It is important to place tissues or organs in a solution with the same osmolarity as the cytoplasm because...

Is this necessary or can you just jump straight to your explanation?

[PhoenixxFire]

Do you need to restate/reword the question in a response e.g.
Q: Explain why it is important to place tissues or organs to be used in medical procedures in a solution with the same osmolarity as the cytoplasm.
A: It is important to place tissues or organs in a solution with the same osmolarity as the cytoplasm because...

Is this necessary or can you just jump straight to your explanation?

Nope just go ahead with your answer. Be careful when answering comparison/differences questions though as you'll need to include more info so that it's clear what you're referring to with each part (e.g. if you're asked about differences between DNA and RNA and you want to talk about thymine/uracil you need to specify which has thymine and which has uracil which can feel a lot like restating the question but is necessary in this case).

[tigerclouds]

Hi guys, could someone please help me understand question 11 muilti-choice from the 2014 exam?
I get why it's D but I'm not exactly sure what the problem is with A.

I asked my teacher and they said it's because we're not concerned with the movement of the potassium ions, just the water molecules which move via osmosis. So from what I understood, that meant that the potassium ions weren't actually moving in and out of the motor cells, only the water was, which affected the concentration inside the cell BUT the question specifies that the "potassium ions stream out of the cell through ion channels" so doesn't that mean it's moving? So I also asked about this and she mentioned the potassium pump (which I'm so confused about) and how that means that it is active transport. HOWEVER (sorry), the question also states that when the cell is turgid, the concentration of potassium ions inside the cell is higher than outside the cell so wouldn't that mean that the ions would be moving along their concentration gradient when they move out, making it not active transport? Or is the definition of active transport not restricted to the concentration gradient?

I hope that makes sense! Sorry for the long read. I would be ETERNALLY grateful for any explanations (diagrams are also very very welcome because this question is so confusing)
Thank you in advance!

[Sine]

Hi guys, could someone please help me understand question 11 muilti-choice from the 2014 exam?
I get why it's D but I'm not exactly sure what the problem is with A.

I asked my teacher and they said it's because we're not concerned with the movement of the potassium ions, just the water molecules which move via osmosis. So from what I understood, that meant that the potassium ions weren't actually moving in and out of the motor cells, only the water was, which affected the concentration inside the cell BUT the question specifies that the "potassium ions stream out of the cell through ion channels" so doesn't that mean it's moving? So I also asked about this and she mentioned the potassium pump (which I'm so confused about) and how that means that it is active transport. HOWEVER (sorry), the question also states that when the cell is turgid, the concentration of potassium ions inside the cell is higher than outside the cell so wouldn't that mean that the ions would be moving along their concentration gradient when they move out, making it not active transport? Or is the definition of active transport not restricted to the concentration gradient?

I hope that makes sense! Sorry for the long read. I would be ETERNALLY grateful for any explanations (diagrams are also very very welcome because this question is so confusing)
Thank you in advance!

Definitely one of the harder VCAA questions. Has been asked on AN many times. The explanation I kind of went with was that potassium uses ion channels for the movement. I think this explanation is consistent with the venus fly trap although it wasn't named in the question.

[whys]

Hi guys, could someone please help me understand question 11 muilti-choice from the 2014 exam?
I get why it's D but I'm not exactly sure what the problem is with A.

I asked my teacher and they said it's because we're not concerned with the movement of the potassium ions, just the water molecules which move via osmosis. So from what I understood, that meant that the potassium ions weren't actually moving in and out of the motor cells, only the water was, which affected the concentration inside the cell BUT the question specifies that the "potassium ions stream out of the cell through ion channels" so doesn't that mean it's moving? So I also asked about this and she mentioned the potassium pump (which I'm so confused about) and how that means that it is active transport. HOWEVER (sorry), the question also states that when the cell is turgid, the concentration of potassium ions inside the cell is higher than outside the cell so wouldn't that mean that the ions would be moving along their concentration gradient when they move out, making it not active transport? Or is the definition of active transport not restricted to the concentration gradient?

I hope that makes sense! Sorry for the long read. I would be ETERNALLY grateful for any explanations (diagrams are also very very welcome because this question is so confusing)
Thank you in advance!

Hello! The problem with option A is that the answer is stating potassium ions move into cells via diffusion. Diffusion is the net movement of a substance from a region of higher concentration to a region of lower concentration along the concentration gradient. The motor cells are turgid when the plant is in its resting state, and option A states that 'when the plant is opening...'. The plant, when opening, is in its resting state (when closing it is not). The question states that when turgid, the concentration of potassium ions inside cells is greater than the concentration of potassium in the extracellular environment. This involves the potassium ions moving against the concentration gradient as it is moving from an area of lower concentration to an area of higher concentration rather than the other way round. This requires energy (ATP) and thus can only occur through active transport, NOT diffusion. The answer option A would be correct if it replaced the word diffusion with 'active transport'.

EDIT; With what Sine said, Potassium ions use specific carrier proteins/ion channels when moving into the cell against the concentration gradient which is active transport. But the answer option states 'diffusion' so it can be eliminated as we know this is incorrect.

[tigerclouds]

Hello! The problem with option A is that the answer is stating potassium ions move into cells via diffusion. Diffusion is the net movement of a substance from a region of higher concentration to a region of lower concentration along the concentration gradient. The motor cells are turgid when the plant is in its resting state, and option A states that 'when the plant is opening...'. The plant, when opening, is in its resting state (when closing it is not). The question states that when turgid, the concentration of potassium ions inside cells is greater than the concentration of potassium in the extracellular environment. This involves the potassium ions moving against the concentration gradient as it is moving from an area of lower concentration to an area of higher concentration rather than the other way round. This requires energy (ATP) and thus can only occur through active transport, NOT diffusion. The answer option A would be correct if it replaced the word diffusion with 'active transport'.

EDIT; With what Sine said, Potassium ions use specific carrier proteins/ion channels when moving into the cell against the concentration gradient which is active transport. But the answer option states 'diffusion' so it can be eliminated as we know this is incorrect.

Thank you so much for your responses! I get what you're saying whys but if the potassium ions have moved out of the cell when they were closing, wouldn't that mean that the concentration of potassium ions is now greater outside the cell meaning that when it moves back into the cell as it's opening, it would just be moving along its concentration gradient?
EDIT: I was just thinking, when molecules move in and out of the cell in the most simple way (diffusion), they usually do so to reach equilibrium/ a balance between the concentration of the inside and outside of the cell. So is the reason that the potassium ions undergo active transport is because when the plant is opening, potassium ions move from higher to lower concentrations until the concentration on both sides equates, but rather than stopping there, the potassium ions keep moving into the cell, NOW making it active transport because the concentration of the outside is now less than the inside?

Definitely one of the harder VCAA questions. Has been asked on AN many times. The explanation I kind of went with was that potassium uses ion channels for the movement. I think this explanation is consistent with the venus fly trap although it wasn't named in the question.

Also with the potassium ion channels, is it inferred knowledge that they undergo active transport? My understanding is that channel proteins undergo facilitated diffusion meaning it's not active. Only carriers enable active transport. Is that correct? Are 'channels' and 'carrier' proteins used interchangeably? (because that's a common issue I'm encountering) Basically my question is, what is it about the question mentioning ion channels that alludes to the understanding that the potassium molecules undergo active transport?

[whys]

I don't think it matters. As the question states explicitly that there is a higher concentration inside cells when turgid and resting, it can be inferred that when opening it is resting and thus the above applies. The only time the plant isn't resting is when it is triggered and closes.

Are 'channels' and 'carrier' proteins used interchangeably? (because that's a common issue I'm encountering)

No. Carrier proteins bind the specific solute to be transported and undergo a series of conformational changes to transfer the bound solute across the membrane. Channel proteins interact with the solute to be transported much more weakly - form aqueous pores that extend across the lipid bilayer. Transport through channel proteins is faster than transport through carrier proteins.

EDIT: I was just thinking, when molecules move in and out of the cell in the most simple way (diffusion), they usually do so to reach equilibrium/ a balance between the concentration of the inside and outside of the cell. So is the reason that the potassium ions undergo active transport is because when the plant is opening, potassium ions move from higher to lower concentrations until the concentration on both sides equates, but rather than stopping there, the potassium ions keep moving into the cell, NOW making it active transport because the concentration of the outside is now less than the inside?

This could be true! I'm not sure, and VCAA hasn't given an explanation either. Now that I think about it, this explanation seems the most correct because when the traps are opening the cells are becoming turgid, so active transport is required if further movement of potassium ions into the cell is required.

[SS1314]

How much do we need to know about the structure of pathogens? Also do we need to know about Gram-positive and Gram negative bacteria?

Thanks

[Sine]

How much do we need to know about the structure of pathogens? Also do we need to know about Gram-positive and Gram negative bacteria?

Thanks

Have a definition for what is a pathogen - so know what they are in general but specifics are not too important. Having a look at virus structures could be useful.

Nah I don't think you need to know about gram neg/positive