The Biological Question Thread

[onerealsmartass]

It cuts the phosphodiester bond, so yes.

so what would be the best answer if they ask what is the name of the bond between the sugar and phospahte?
would it be covalent bond or phosphodiester?

Covalent is just a type of bond, if they specifically ask for the name then I would put phospodiester

cheers, my teacher mentioned it to us in class, but i didnt realy take notes of it cos in most prac exams the answers are usually covalent bonds.

[akira88]

Another question, do we need to know about promoters for the unit 4 exam? If so, what are they and what is their role? There's nothing about them in my textbook but I've came across them in a few practise exams...

[Russ]

I would know what they are, it's not exactly hard: a region of DNA that regulates transcription of another region of DNA. They're typically immediately prior to whatever gene(s) they regulate but they don't have to be (they can be on other chromosomes)

[onerealsmartass]

Does crossing over occur during meiosis: prophase 1 or metaphase 1??? ive gotten those two answers from different teachers...

[akira88]

Does crossing over occur during meiosis: prophase 1 or metaphase 1??? ive gotten those two answers from different teachers...

Yes I would like to know this as well.... I swear my teachers and textbook say metaphase, but somewhere else I heard/saw it was propase? Sometimes I wish that VCAA wrote the damn textbooks so we would know what to learn for the exams

[thushan]

Prophase 1 - the actual crossing over occurs
Metaphase 1 - the chiasmata are still joined

[matt123]

Prophase 1 - the actual crossing over occurs
Metaphase 1 - the chiasmata are still joined

Agreed
its actually in the notes book.

[simpak]

Prophase is pretty pro.

[Russ]

Prometaphase is even more pro

[stonecold]

Gotta love questions like in VCAA 2006 about why the shrimp are the same species and then the answer is the are not the same species.  VCAA are so lame.

Anyway, I don't really get how they arrived at the answer for this question.  If the male bee produces haploid gametes by mitosis, and the female produces haploid gametes by meiosis, then how do you end up with males?  :S

[Russ]

It's a different sex determination system, males can be produced without fertilization of the oocyte (so they're still haploid)

That's specific knowledge though, you can't infer it from the question.

[stonecold]

And we are supposed to know this?

[Russ]

Can't hurt, but I doubt it.

[stonecold]

This came from a VCAA exam though, and from the current study design.

[thushan]

Gotta love questions like in VCAA 2006 about why the shrimp are the same species and then the answer is the are not the same species.  VCAA are so lame.

Actually, I think that VCAA have simply mis-worded their answer on the assessment report. The question was

"Why is the inability to mate sufficient evidence to call the two groups two different species?"

I think that VCAA meant that many students came up with the following response:

'because they cannot mate' --> 0/1

I think VCAA wanted the following answer:

'inability to mate implies inability to produce viable and fertile offspring, which is the criterion for calling two groups different species' --> 1/1