VCE Biology Question Thread

[vox nihili]

Damn it I wasted my time then -.-

You'll have to learn it 40000 times again in your Uni career, so don't worry, you've made the right choice :p

[dankfrank420]

Is anything wrong with my description of the following processes?

Light-dependant Photosynthesis

- Chlorophyll absorbs light, energising the electrons so they move down the Electron Transport Chain and produce ATP
- Water is split into Hydrogen ions and oxygen
- Hydrogen ions are taken up by the NADPH acceptor molecule
- Oxygen gas is produced as a byproduct

Light-independent photosynthesis

- Hydrogen ions from NADPH react with carbon dioxide to produce glucose, ATP (produced in LD photosynthesis) is used as an energy source for this reaction
- Water is produced as a byproduct

Electron transport chain

- Loaded acceptor molecules NADH and FADH2 pump electrons into the cristae, releasing energy when the electrons move from one molecule to the other
- This energy is used for the phosphorylation of ADP to convert it to ATP
- Hydrogen ions are also released by the acceptor molecules, which combine with oxygen to produced water as a byproduct

Passing an impulse from one neuron to another

- Impulse reaches the axon terminal
- Neurotransmitter is secreted and travels across the synapse to bind the the receptors on the dendrites of the next neurone
- The reaction between the neurotransmitter and the receptors generate and impulse

An impulse travelling along an axon

- Threshold reached
- Sodium enters the neurone through sodium channels, making the inside of the cell positive (depolarising it)
- This propagates the impulse
- To correct this, Potassium ions leave the neurone through channels, restoring the inside of the cell as negative (re-polarising it)

Bringing this over the page.

[RazzMeTazz]

In genetics do we simplify the genotype and phenotype ratios?
so instead of writing 2:2 would be write 1:1?

[anat0my]

Bringing this over the page.

For the E.T.C, state the amount of ATP formed.

When describing the impulse that is propagated chemically, probably use the terms 'diffuse' when describing how the neurotransmitter travels and refer to the receptors as 'specific receptors'.
There's nothing wrong with your descriptions but if you want to appease the pedantic examiners, it's a good idea to be specific haha

[vox nihili]

In genetics do we simplify the genotype and phenotype ratios?
so instead of writing 2:2 would be write 1:1?

You don't have to, but you can.

[anat0my]

How to distinguish between co-dominance and incomplete dominance? I think incomplete dominance (?) was omitted from the study design but it may appear in a multiple choice.

[RazzMeTazz]

do we have to know about x-inactivation/lyonization?

[dankfrank420]

How to distinguish between co-dominance and incomplete dominance? I think incomplete dominance (?) was omitted from the study design but it may appear in a multiple choice.

Codominant is both expressed (eg. roan cows have white and brown spots), whereas incomplete is a mixture of the two (eg. snapdragon flower is pink when it has red and white alleles).

For the E.T.C, state the amount of ATP formed.

When describing the impulse that is propagated chemically, probably use the terms 'diffuse' when describing how the neurotransmitter travels and refer to the receptors as 'specific receptors'.
There's nothing wrong with your descriptions but if you want to appease the pedantic examiners, it's a good idea to be specific haha

Cheers man

[vox nihili]

do we have to know about x-inactivation/lyonization?

Absolutely not; though it is interesting.

[RazzMeTazz]

In the secondary antibody response why does the level of antibodies in the bodily fluids remain higher for a longer period of time than in the primary antibody response?

[Reus]

In the secondary antibody response why does the level of antibodies in the bodily fluids remain higher for a longer period of time than in the primary antibody response?

Well in Humoral immunity, T helper cells initiate the differentiation of B cells when exposed to a non self cell. The B cells become either memory or plasma cells, the memory cells remain in the body for a longer period of time, providing a rapid immune response (the secondary response). This is achieved by developing plasma cells much quicker than previously, destroying the pathogen before it can affect the host. Also known as the immunological memory.

[RazzMeTazz]

Thanks! :)
Also when looking at a graph representing the phenotypes of individuals how do you know if it's discontinuous variation or continuous variation?

I thought discontinuous variation was represented by a bar graph but sometimes continuous variation seems to be as well?

[melons]

Thanks!
Also when looking at a graph representing the phenotypes of individuals how do you know if it's discontinuous variation or continuous variation?

I thought discontinuous variation was represented by a bar graph but sometimes continuous variation seems to be as well?

Discontinuous is always made up of distinctively separate bars in a graph. When continuous is given as a bar graph, the bars are always drawn really close together and a curve can be drawn to join the bars.
If the trait is given, that alone may be able to give you the answer.

[RazzMeTazz]

Does it make sense to say that the immune system recognizes a virus as a non-self antigen
or it recognizes the molecules on the surface of the virus as non-self antigens?

Thanks!

[nerdmmb]

Does it make sense to say that the immune system recognizes a virus as a non-self antigen
or it recognizes the molecules on the surface of the virus as non-self antigens?

Thanks!

I don't think this is always the case. Sometimes, viruses are recognised as non-self because of their surface antigens but for viruses that enter a cell and "steal" it's membrane, then the virus is recognised as self.