VCE Biology Question Thread

[Yacoubb]

In reference to chromosome numbers for a particular species, what does the 'n' represent?

Would it just be representing the haploid number of chromosomes for that species?

And any number in front of that for eg: '2n' would just represent how many full sets of chromosomes that species has?

I miss this board! Bio <3

Okay, so 'n' represents a haploid number of chromosomes, such as those in a sex cell (gamete). '2n' represents the full set of chromosomes (i.e. one set inherited maternally, the other paternally), such as those found in somatic cells.

[vox nihili]

Thanks...i was just intrigued tro find out the answer so if anyone know's please tell me

It's pretty cool. It's a sex determination system essentially. I've had a bit of a refresher. The basic idea is that male bees are derived directly from the queen bee and they're haploid. They create sperm via mitosis, which fuses with the queen's gametes to make female bees (workers).

http://en.wikipedia.org/wiki/Haplodiploidy

[grannysmith]

Meiosis I results in two HAPLOID daughter cells that are genetically different, NOT diploid. Right?

[alchemy]

Meiosis I results in two HAPLOID daughter cells that are genetically different, NOT diploid. Right?

Yup, as each has half the number of chromosomes as the parent cell and crossing over makes them genetically different.

[Rishi97]

It's pretty cool. It's a sex determination system essentially. I've had a bit of a refresher. The basic idea is that male bees are derived directly from the queen bee and they're haploid. They create sperm via mitosis, which fuses with the queen's gametes to make female bees (workers).

http://en.wikipedia.org/wiki/Haplodiploidy

Oh wow that is soo cool. Thanks heaps Mr T-Rav

[grannysmith]

How should I structure/include in experimental design questions?

[nhmn0301]

How should I structure/include in experimental design questions?

You mean those experimental design on the VCAA exams? I usually do it in this form:
 hypothesis
 2/3 groups depending on the question (ensure you have 1 group of control)
 explain the control (name possible control variables like water, food, genetics, height, weight etc)
 mention multiple subjects ( you can have 100 subjects in 1 group etc)
track changes over a reasonable amount of time
compare/record results with other groups
if hypothesis is  supported, what will happen?
Repeat the experiment
(n.b ensure that you mention everything pretty specific in each step)

[vox nihili]

Meiosis I results in two HAPLOID daughter cells that are genetically different, NOT diploid. Right?

That's right. Meiosis I is the reductive division.

[nerdmmb]

Is it true to say that in prophase, there are 92 chromosomes present as DNA undergoes replication in interphase?

[grannysmith]

Is it true to say that in prophase, there are 92 chromosomes present as DNA undergoes replication in interphase?

Assuming this is mitosis, no; there are 46 chromosomes but 92 chromatids.

[grannysmith]

Yup, as each has half the number of chromosomes as the parent cell and crossing over makes them genetically different.

That's right. Meiosis I is the reductive division.

Cheers. It's just that some resources I've read say that the cell is temporarily 4n after DNA replication, and the first nuclear division results in two diploid daughter cells that are genetically different.

[vox nihili]

Cheers. It's just that some resources I've read say that the cell is temporarily 4n after DNA replication, and the first nuclear division results in two diploid daughter cells that are genetically different.

Those resources, I'm afraid, are a load of toss. It's not the most important point to remember in VCE, I must admit, but it's certainly worthwhile knowing if you're aiming high.

[grannysmith]

The compensation point is the point at which the uptake of carbon dioxide of a photosynthesising plant is equal to the release of carbon dioxide through respiration?

[Rishi97]

The compensation point is the point at which the uptake of carbon dioxide of a photosynthesising plant is equal to the release of carbon dioxide through respiration?

Yes in other words, the compensation point is when the production of oxygen by the plant is equal to the uptake of carbon dioxide. There is no "net" production or usage

[RazzMeTazz]

Why is it that if alleles for a particular genes are further apart on a chromosomes the more likely they are to be swapped in the "crossing over" process of meiosis?