VCE Biology Question Thread

[Biology24123]

So do we need to know they exist or not ? Like after a specific Cytotoxic T Cell is activated, it proliferates into effector and memory T cells. Do we need to know this? If not, what can be said instead, for example when we are asked to describe the cell mediated immunity ?

My mistake. I thought you were talking about memory cells in general

[matchabubble312]

Hey I watched McGrawHill animation and it seems that the activated helper T cell releases cytokines to stimulate the B cells to poliferate and differentiate into plasma B cells and B memory cells.
But the T helper cell has to be activated by both the MHC-II-antigen complex on the macrophage and the B cell in order to be activate the B cell....?

[vox nihili]

Hey I watched McGrawHill animation and it seems that the activated helper T cell releases cytokines to stimulate the B cells to poliferate and differentiate into plasma B cells and B memory cells.
But the T helper cell has to be activated by both the MHC-II-antigen complex on the macrophage and the B cell in order to be activate the B cell....?

It doesn't. It only need be activated by a MHC class II antigen complex on an APC, not the B-cell. I think it binds to the B-cell via that complex on the B-cell though, not entirely sure. But it's already activated by this point. The rest of what you say is correct though.

[grindr]

I have a question regarding phylogenetic trees. What is the difference between the first two types of diagrams?



When asked in a  question to draw a phylogenetic tree, which one do I use?

[mahler004]

I have a question regarding phylogenetic trees. What is the difference between the first two types of diagrams?

(Image removed from quote.)

When asked in a  question to draw a phylogenetic tree, which one do I use?

The trees are the same, just drawn differently. The last one is in polar coordinates.

[vox nihili]

I have a question regarding phylogenetic trees. What is the difference between the first two types of diagrams?

(Image removed from quote.)

When asked in a  question to draw a phylogenetic tree, which one do I use?

All the same as mahler said, but just use the first because it's the easiest to draw quickly.

[grindr]

The trees are the same, just drawn differently. The last one is in polar coordinates.

All the same as mahler said, but just use the first because it's the easiest to draw quickly.

Okay, thanks!

[Marmalade]

How would you do this question?
I attached the answer as well but I don't understand how they got to it. Why can't you have the translocated chromosome and the other longer chromosome in the same gamete?

[Biology24123]

How would you do this question?
I attached the answer as well but I don't understand how they got to it. Why can't you have the translocated chromosome and the other longer chromosome in the same gamete?

They can't be in the same gamete since they will pair up and separate into different gametes during meiosis (unless non-disjunction occurs). The small chromosome can't pair up with the translocated chromosome. But I don't get how the small chromosome can be by itself

[Maca 13]

How would you do this question?
I attached the answer as well but I don't understand how they got to it. Why can't you have the translocated chromosome and the other longer chromosome in the same gamete?

I think it's because technically the translocated chromosome is two different chromosomes (14 and 21), therefore the gamete already has the two chromosomes, one of each from 14 and 21? I'm not too sure

[jyodesh.com]

I think it's because technically the translocated chromosome is two different chromosomes (14 and 21), therefore the gamete already has the two chromosomes, one of each from 14 and 21? I'm not too sure

I dont know what VCAA's thinking but attachment is from Mastering Genetics

[cosine]

Is it true that meiosis II can work if a chromosome is missing because there is no homologous line up in the middle, but meiosis I, if there is a chromosome missing then meiosis I cannot occur?

[Sine]

can someone explain question 6(b) http://www.vcaa.vic.edu.au/Documents/exams/biology/2003_biol2.pdf

[vox nihili]

can someone explain question 6(b) http://www.vcaa.vic.edu.au/Documents/exams/biology/2003_biol2.pdf

Because the same nucleotide could be mutated more than once. In other words, you may have started off with T, mutated to C, and then mutated to G. This would mean 2 base substitutions, but you can only observe the T-G

[tashhhaaa]

for photosynthesis, do we need to know about the details of and differences between cyclic and non-cyclic phosphorylation?

also, since the study design only states for the main inputs and outputs of each phase, does this mean that we do not need to learn the actual steps of photosynthesis?