VCE Biology Question Thread

[cosine]

For which of the following diseases would treatment with antibiotics be most appropriate?
A. Creutzfeldt -Jacob disease
B. Influenza
C. Ringworm
D. Foor poisoning

Answer: D

I understand that antibiotics provide passive immunity for people, so antibodies are injected into the bloodstream, but how we supposed to know which one is most appropriate?

[Jay.C]

For which of the following diseases would treatment with antibiotics be most appropriate?
A. Creutzfeldt -Jacob disease
B. Influenza
C. Ringworm
D. Foor poisoning

Answer: D

I understand that antibiotics provide passive immunity for people, so antibodies are injected into the bloodstream, but how we supposed to know which one is most appropriate?

Ok, so the question is asking which would be the most appropriate to treat with ANTIBIOTICS. Antibiotics are used to fight bacterial infections, thus we know it can not be Influenza due to it being a virus, it can not be Ringworm due to it being fungi and it cannot be CJD it is caused by a prion. Thus the answer is D due to food poising being caused by bacteria e.g. Salmonella.

[cosine]

Ok, so the question is asking which would be the most appropriate to treat with ANTIBIOTICS. Antibiotics are used to fight bacterial infections, thus we know it can not be Influenza due to it being a virus, it can not be Ringworm due to it being fungi and it cannot be CJD it is caused by a prion. Thus the answer is D due to food poising being caused by bacteria e.g. Salmonella.

Are we meant to know that antibiotics only work for bacterium? Are we required to know that CJD is a prion-related disease? Why do antibiotics not work with viruses?

Cheers

[pi]

In short, antibiotics target things that bacteria have, and viruses don't have these things. For example, your standard penicillin works by inhibiting the synthesis of the peptidoglycan layer of bacterial cell walls. Virsuses do not have cell walls and hence the drug won't be effective. Next time you have a bit of a cold, think twice whether your GP giving you an antibiotic is the responsible thing to do

I think it's a bit rough to know that CJD is a prion disease, although now you know There are only a handful of prion diseases anyway.

[Jay.C]

Hey guys just wondering, when DNA polymerase comes along to follow the RNA primer in DNA replication does it lay down DNA nucleotides or RNA nucleotides?

Also in the lagging strand does each okazaki fragment start with an RNA primer? If so, does that mean for each fragment DNA lygase must come along and change the RNA bases to DNA?

[Jay.C]

Are we meant to know that antibiotics only work for bacterium? Are we required to know that CJD is a prion-related disease? Why do antibiotics not work with viruses?

Cheers

Yes we are meant to know that antibiotics only work for bacterium.

No we don't have to know that CJD is a prion- related disease, however if you didn't know and the previous multiple choice question showed up on the exam you should know that food poising if often the result of bacteria.

Also as for why they don't work on viruses, I don't know and i'm pretty sure we don't have to know why in VCE. However im pretty sure Pi just explained it above.

[cosine]

Which of the following are products of BOTH aerobic and anaerobic cellular respiration in humans?
A. ATP and carbon dioxide
B. Pyruvate and ATP
C. Pyruvate and lactate
D. Lactate and carbon dioxide

Answer: A

I think the wording on this one is weird, because it says products of both, so what comes out of anaerobic respiration AND aerobic respiration. During glycolysis pyruvate is produced, and then if no oxygen is present then the pathway is anaerobic. So pyruvate is a product of anaerobic respiration. But how is it also a product of aerobic respiration? When we talk about aerobic respiration, do we consider all three steps (glycolysis, krebs cycle and ETC) as one, but in anaerobic respiration we only consider glycolysis by itself?

Anyone can help on this one?

Cheers for the help pi and Jay.C

[Yacoubb]

Anyone can help on this one?

Cheers for the help pi and Jay.C

Aerobic respiration involves three stages: glycolysis, Krebs cycle and the electron transport chain. So, when referring to aerobic respiration, always take these three into account. Anaerobic respiration is only glycolysis.

The answer is A, but I'm curious to know where this question is from. Human cells would respire anaerobically if necessary and produce lactic acid + 2 ATP molecules. From my understanding, CO2 is only produced in ethanol fermentation in plant/yeast/some bacterial cells.

[cosine]

Aerobic respiration involves three stages: glycolysis, Krebs cycle and the electron transport chain. So, when referring to aerobic respiration, always take these three into account. Anaerobic respiration is only glycolysis.

The answer is A, but I'm curious to know where this question is from. Human cells would respire anaerobically if necessary and produce lactic acid + 2 ATP molecules. From my understanding, CO2 is only produced in ethanol fermentation in plant/yeast/some bacterial cells.

This is from chemology 2011
Sorry the answer is actually B for pyruvate is produced in both aerobic and anaerobic, and, of course ATP too.

But as you say it, A can also be correct right?

[Yacoubb]

This is from chemology 2011
Sorry the answer is actually B for pyruvate is produced in both aerobic and anaerobic, and, of course ATP too.

But as you say it, A can also be correct right?

It would have been A without a doubt if they hadn't specified human. But because they did, it technically isn't correct. It can be B but the question is misleading due to the fact that it actually isn't the final product of aerobic respiration; pyruvate is converted to CO2 in the Krebs cycle.

[cosine]

Assistance on the attached image, please.

I can cancel out all of them besides D, and that is the answer. But I do not understand how it is correct. I mean the question says that potassium ions stream out of the cell when it is stimulated, so that means they're diffusing into the surrounding fluid via facilitated diffusion. But when/where does water come into play?

[cosine]

It would have been A without a doubt if they hadn't specified human. But because they did, it technically isn't correct. It can be B but the question is misleading due to the fact that it actually isn't the final product of aerobic respiration; pyruvate is converted to CO2 in the Krebs cycle.

So are you saying that in humans, CO2 is not produced in anaerobic respiration?

[Yacoubb]

Assistance on the attached image, please.

I can cancel out all of them besides D, and that is the answer. But I do not understand how it is correct. I mean the question says that potassium ions stream out of the cell when it is stimulated, so that means they're diffusing into the surrounding fluid via facilitated diffusion. But when/where does water come into play?

As the K+ ions move out of the motor cells of the mid-rib, they make the cells adjacent to the motor cells more concentrated. We know that osmosis is the movement of water from a region of low to high solute concentration, and so water follows as K+ moves OUT of the motor cells in the mid-rib. Does that make sense?

So are you saying that in humans, CO2 is not produced in anaerobic respiration?

Correct. The products of lactic acid fermentation (i.e. anaerobic respiration in animals) is lactic acid + net production of 2 ATP molecules.

[cosine]

As the K+ ions move out of the motor cells of the mid-rib, they make the cells adjacent to the motor cells more concentrated. We know that osmosis is the movement of water from a region of low to high solute concentration, and so water follows as K+ moves OUT of the motor cells in the mid-rib. Does that make sense?

Correct. The products of lactic acid fermentation (i.e. anaerobic respiration in animals) is lactic acid + net production of 2 ATP molecules.

no that does not really make sense to me

[Yacoubb]

no that does not really make sense to me

Okay so think about it this way. When the trap is open, the motor cells in the mid-rib are highly concentrated in K+ ions. Because of this, the water will be highly concentrated in the motor cells in the mid-rib. Water always wants to be in the regions where solute concentration is highest (attempting to balance the concentrations). When the trap is closing though, the surrounding cells need to become turgid (they literally become heavier which induces the trap to close). So the only way that water can move out of the motor cells in the mid-rib and into the surrounding cells is by the facilitated diffusion of K+ions into those surrounding cells. Given that water moves from regions of low to high SOLUTE concentration to establish some sort of equilibrium in concentrations, water will move OUT of the motor cells, because now the surrounding cells are concentrated with K+, more so than the motor cells of the mid-rib. If you still have confusion let me know