VCE Biology Question Thread

[PhoenixxFire]

I would say If Elodea Canadensis is exposed to 5 different light colours then the highest rate of reaction would occur under the blue light and the lowest rate of reaction would occur under the green light. You could list all five colours in brackets as well if you wanted.

Edit: Or you could say the highest rate of reaction will occur under blue, then X, then Y, then Z and the least will occur under green. Or words to that effect.

[Scribe]

If the experimental question was "Do different wavelengths of light equally affect the rate of photosynthesis and cellular respiration in aquatic plants?", would your hypothesis be okay?

If Elodea Canadensis is exposed to five different colours of light (purple, red, yellow, blue, green), then the rate of photosynthesis will be highest under the blue light while the rate of photosynthesis will be lowest under the green light.

[PhoenixxFire]

If the experimental question talks about wavelengths then you should say wavelengths (despite your equipment not being good enough to measure it-you can talk about that in your discussion) otherwise yes the one you have there is good.


Are you supposed to be measuring cellular respiration as well or is that seperate?

[Scribe]

Thank you very much for the help PhoenixxFire! 

I believe we are supposed to be measure cellular respiration as well. By measuring the pH of the pond water in the beakers, we indirectly determine the relative rates of photosynthesis and cellular respiration.

Does this need to be mentioned in the hypothesis as well?

[FabAsianZung]

"the sources and mode of transmission of various signalling molecules to their target cell, including plant and
animal hormones, neurotransmitters, cytokines and pheromones"

I'm confused about this study design dot point. What do we need to know in regard to this study design dot point?

[darkz]

"the sources and mode of transmission of various signalling molecules to their target cell, including plant and
animal hormones, neurotransmitters, cytokines and pheromones"

I'm confused about this study design dot point. What do we need to know in regard to this study design dot point?

Well you basically need to know the general idea behind each signalling molecule. For the source, its just the place that produces it, e.g. for neurotransmitters, they're produced in the axon terminal or just neuron. And the mode of transmission refers to endocrine/paracrine etc. So for neurotransmitters it's paracrine, as they diffuse across the synaptic cleft

[juntyhee]

I understand that enzymes have an optimum temperature as it is an optimal condition for energetic collisions and function.

Does the same apply to pH? Why do enzymes have an optimum pH?

To ensure the shape of the enzyme's active site is most specific and complementary to its substrate. I believe extreme pH levels alter ionic interactions in the enzyme's tertiary structure.

[darkz]

I understand that enzymes have an optimum temperature as it is an optimal condition for energetic collisions and function.

Does the same apply to pH? Why do enzymes have an optimum pH?

Enzymes have an optimum pH level because different levels of pH can affect the bonding in the enzyme. If the enzyme is placed in just slightly more acidic or basic, then it'll just loosen the bonds lowering the efficiency. However, if it's placed in a solution which is extremely acidic or basic, then it can cause the denaturation of the enzyme

[PopcornTime]

Glucose syrup is used as an alternative sweetening agent. Why is it important to ensure enzymes do not contaminate this syrup?
- ensure substrates in the syrup are not broken down

[vox nihili]

Enzymes have an optimum pH level because different levels of pH can affect the bonding in the enzyme. If the enzyme is placed in just slightly more acidic or basic, then it'll just loosen the bonds lowering the efficiency. However, if it's placed in a solution which is extremely acidic or basic, then it can cause the denaturation of the enzyme

It also has an impact on the way the substrate(s) bind to the enzyme itself. So, although it is absolutely true that different pH will see the enzyme take different structures (the details of this are waaaaaay beyond VCE), also worth considering the other end

Glucose syrup is used as an alternative sweetening agent. Why is it important to ensure enzymes do not contaminate this syrup?
- ensure substrates in the syrup are not broken down

Sounds reasonable to me

[juntyhee]

is there a functional difference between coenzymes and cofactors?

[darkz]

is there a functional difference between coenzymes and cofactors?

I don't believe that there are really any significant functional differences that you need to know for VCE, after all, coenzymes are a subset of cofactors - they're just organic. So any function of a coenzyme would ultimately come under a function of a cofactor. But I suppose that one off the top of my head would be that coenzymes can act as carrier molecules i.e. they can carry electrons/protons between reactions etc, and other cofactors just increase the rate of a reaction - they increase the affinity of the enzyme for its substrate (the ease with which the enzyme binds to the substrate)

[vox nihili]

I don't believe that there are really any significant functional differences that you need to know for VCE, after all, coenzymes are a subset of cofactors - they're just organic. So any function of a coenzyme would ultimately come under a function of a cofactor. But I suppose that one off the top of my head would be that coenzymes can act as carrier molecules i.e. they can carry electrons/protons between reactions etc, and other cofactors just increase the rate of a reaction - they increase the affinity of the enzyme for its substrate (the ease with which the enzyme binds to the substrate)

Your first sentence in this is really excellent, capturing the meaning of both really well.

Just for interest, cofactors don't actually just increase the affinity for a substrate. Indeed, this is not usually how they function. They actually tend to act as temporary electron donors and acceptors (hence the reason they're metals!)

[Mr West]

Your first sentence in this is really excellent, capturing the meaning of both really well.

Just for interest, cofactors don't actually just increase the affinity for a substrate. Indeed, this is not usually how they function. They actually tend to act as temporary electron donors and acceptors (hence the reason they're metals!)

is water an output of glycolysis or not?

different sources say different things.

thanks

[darkz]

is water an output of glycolysis or not?

different sources say different things.

thanks

While I'm not sure 100% if or not water is produced in glycolysis maybe in one of the 10 steps, however, I know that for a VCE standard, we don't need to say that water is an output of glycolysis. The only outputs we really need to know are the pyruvates, NADH and ATP