VCE Biology Question Thread

[vox nihili]

Hi! I was just wondering,
What is the difference between Myosin and Myoglobin?
they're both proteins right?

Myosin is a key component of the contractile apparatus. In less wanky words, it helps muscles move.

Myoglobin, on the other hand, is an oxygen carrying protein found in muscles, effectively analogous to haemoglobin but, unlike haemolgobin, without a quarternary structure.

[Gogo14]

Just some clarification:

Why does a graph showing enzyme concentration plateau?

I know that with substrate concentration, it plateaus since the enzymes are saturated with substrate and the rate can't go faster, but why does enzyme concentration plateau?

Because there is a finite amount of substrates. Hence it will eventually reach a point when there is more enzymes than the amount of substrates, and the rate will not increase because all teh substrates are being used by already present enzymes. The excess enzymes cannot increase the reaction as there is no substrates to bind to.

[Gogo14]

Which sacs did you guys have for the enzyme sac, and what were the questions?

[pi]

Which sacs did you guys have for the enzyme sac, and what were the questions?

Sharing of SAC questions probably falls within the umbrella of "cheating". We don't condone cheating on AN, take it elsewhere (or better still, don't do it at all!)

[Gogo14]

Sharing of SAC questions probably falls within the umbrella of "cheating". We don't condone cheating on AN, take it elsewhere (or better still, don't do it at all!)

Oh what, I didnt mean it like that. Yea, maybe not the questions, but the general structure of the experiment.

[vox nihili]

Oh what, I didnt mean it like that. Yea, maybe not the questions, but the general structure of the experiment.

As an ever better exercise (and one that served me really well) try to guess what questions you might get asked

[geminii]

As an ever better exercise (and one that served me really well) try to guess what questions you might get asked

Yeah we did that at school! It definitely helped!

[she0071]

Myosin is a key component of the contractile apparatus. In less wanky words, it helps muscles move.

Myoglobin, on the other hand, is an oxygen carrying protein found in muscles, effectively analogous to haemoglobin but, unlike haemolgobin, without a quarternary structure.

Thanks!

[Arithmetic]

HI,
can anyone please answer this question.

Which of the following is an example of chemosynthesis?
-Glucose production by plants.
-Methane production by methanogens.
-Carbon Dioxide production by organisms.
-Conversion of nitrites into nitrates by prokaryotes.

Thank you I can't seem to find an answer any where. 

[vox nihili]

HI,
can anyone please answer this question.

Which of the following is an example of chemosynthesis?
-Glucose production by plants.
-Methane production by methanogens.
-Carbon Dioxide production by organisms.
-Conversion of nitrites into nitrates by prokaryotes.

Thank you I can't seem to find an answer any where. 

Glucose production by plants. Basically just means making a bigger molecule. All the others are examples of catabolic processes.

[Photon]

How does starch pass through a membrane?

Thanks

[cosine]

How does starch pass through a membrane?

Thanks

Think about this one. Starch is a polysaccharide composed of glucose monomers. Although glucose is soluble in water, starch is a polymer and because of its relatively huge size, it remains insoluble. So, we now know that its a  large, non-polar molecule. Typically, small non-polar molecules can simply diffuse through membranes, but large ones cannot otherwise they will puncture the membrane. So, starch will undergo exocytosis/endocytosis to exit/enter cells.

[vox nihili]

How does starch pass through a membrane?

Thanks

The other answer too, though, is that it just doesn't. The enzymes to make starch (or glycogen in animals) are abundant, so glucose gets transported around and starch is just rebuilt basically.

[qwertyqwerty]

In my previous SAC, the effect of alcohol (of different concentrations) on beetroot cell membranes was determined by recording the colour of the alcohol solution with the beetroot. This colour was recorded in a table, by writing 0-5 (0 meaning clear, 5 meaning red solution).

If a question asks you to describe the effect of alcohol on the beetroot membranes using your results, can I say something like:
"From the results, it is clear that a strong alcohol solution damaged the membrane and affected its permebility. This occurs because ... (reason why alcohol disrupts the membrane)"

OR do I have to say:
The 40% alcohol solution scored a 5, meaning a lot of pigment leaked out of the cell. On the other hand, the 1% alcohol solution scored a 1, meaning a little (or none) of the pigment leaked out of the cell. Therefore, it is clear that a strong alcohol solution damaged the membrane and affected its permebility.  This occurs because ... (reason why alcohol disrupts the membrane)"

In other words, when a question asks you to use your results to answer a question, can you sum up the results or do you have to use the "raw" data?

[Photon]

The other answer too, though, is that it just doesn't. The enzymes to make starch (or glycogen in animals) are abundant, so glucose gets transported around and starch is just rebuilt basically.

Wow, I did not expect this to happen. The truth is that I had a multiple choice question asking how starch passes through the membrane and I answered endocytosis when some other classmates answered channel proteins. We still don't know who's right and I was hoping I could resolve it by asking here but I got both answers. :l

My guess is that it gets broken down via hydrolysis reactions into glucose and then transported only to be 'rebuilt' on the the other side of the membrane.