VCE Biology Question Thread

[Biology24123]

Very well explained. I have the exampro but I haven't started it yet. Have you?

Also what is the main difference between gene flow and genetic drift? I know that gene flow involves the allele frequencies of a population sort of flowing, in a sense that new immigrants come in and attribute to the allele frequencies, and then emigrants leave a population and take with them the alleles, whereas genetic drift is the drifting of alleles in a population due to non-selective events.

Is gene flow constant? So the alleles are changing but the population remains constant, right? Like there is no significant drop in population size?

Yes that's the main difference. Although "drifting of alleles" is really unclear, change in allele frequencies is better. Gene flow doesn't require a drop in population

[Biology24123]

Why is it that Meiosis does not occur when the chromosomes are not in homologous pairs?

It still occurs but it produces non viable gametes. Homologous chromosomes won't pair up in prophase I

[Sine]

Very well explained. I have the exampro but I haven't started it yet. Have you?

I've done all the practice SACs but I haven't started or done any of the exams.

I don't want to leave those exams too late as they have a reputation of being quite difficult comparable to the very top end of VCAA exams whilst not going beyond the syllabus. I'm expecting Exam 3 to be only challenging questions which may be tough to get through in 2.5 hours.

Also anyone got NEAP smart study exams a book with 4 exams with 110marks?

[vox nihili]

Very well explained. I have the exampro but I haven't started it yet. Have you?

Also what is the main difference between gene flow and genetic drift? I know that gene flow involves the allele frequencies of a population sort of flowing, in a sense that new immigrants come in and attribute to the allele frequencies, and then emigrants leave a population and take with them the alleles, whereas genetic drift is the drifting of alleles in a population due to non-selective events.

Is gene flow constant? So the alleles are changing but the population remains constant, right? Like there is no significant drop in population size?

Gene flow, as you've correctly asserted, is about migration between populations. By definition, it does change the size of the population because the loss or gain of (im)migrants will change population size. It doesn't really have to change the size of the population in a qualitative sense though, no.

Genetic drift describes random changes in allele frequencies.

[Biology24123]

Can someone explain the answer?

[Jay.C]

Can someone explain the answer?

Ill take a guess with this question and say that because oxygen is required for cellular respiration and enzymes are essential for cellular respiration, as the temperature drops below optimum for these animals enzymes, oxygen consumption would decrease due to a decrease in enzyme activity. Can someone confirm or know otherwise??   

[vox nihili]

Can someone explain the answer?

There are a few possible answers. The most obvious is that it decreased for the mouse and increased for the crayfish.

A mouse is a mammal, therefore its enzymes are most likely to work best at warmer temperatures. Crayfish are not. They live in water and that constitutes a relatively cold environment. Therefore, it's reasonable to suspect that the optimum temperature of their enzymes is lower than 20. Therefore, trending towards ten is likely to make them work better.

Of course, the answer isn't complete without the requisite acknowledgement of the fact that oxygen consumption is tied to the work of enzymes that catalyse metabolic reactions.

[Biology24123]

And one more. Thanks

[StupidProdigy]

And one more. Thanks

Is it D? I'll share my reasoning if it is

[Biology24123]

Is it D? I'll share my reasoning if it is

Not D. Want to see what Mr T Rav thinks

[cosine]

And one more. Thanks

Is the answer B?

[cosine]

Is it D? I'll share my reasoning if it is

Why do you think its D? Share your answer anyway and we can share our knowledge of it, not sure if im correct though too but I have a theory for why D is incorrect

[Biology24123]

Is the answer B?

Nope. That's what I had. It's a tough one.

Spoiler

It's C

[cosine]

Nope. That's what I had. It's a tough one.

Spoiler

It's C

Is this from VCAA?
Because the thymus does not produce T cells - bone marrow does?

I think I know why it's C but we'll wait for an expert. My theory is that, because the thymus is decreasing in volume, less and less T cells are being matured. However, there still exists a little amount of T cells and if a viral infection occurs, a specific T helper cell will bind with a phagocyte to proliferate and memory cells are produced as per usual. Not sure if this is right though hopefully someone can confirm

[vox nihili]

Not D. Want to see what Mr T Rav thinks

In all honesty, I wasn't exactly sure about this one so I've asked an immunology major to come in and save us. Hopefully will post soon

Needless to say, when I thought of posting I did bullshit an answer. That answer turned out to be the right one. Moral of the story: when stuck, bullshit.