VCE Biology Question Thread

[Gogo14]

Hello Would anyone be able to help me with this? Thank you so much!

The magpie moth, Abraxas grossulariata, can have either pale wings (p) or dark wings (P). Scientists experimenting with these flies accidentally broke vials containing the F1 generation. Some of the captured moths had black phenotypes that the scientists needed to establish the parental genotypes of.

Using a cross how could you successfully determine the parental genotype of these black F1 moths? (Show all working)

Because the question mentions some, you know that the magpies are pp and Pp or PP.  Therefore from the phenotypes of the magpies(pale and black) you can infer that the parents must be 1. Pp and pp or 2. Pp and Pp. (these are the only combinations that result in both pale and black offspring)

Hence to find out the parental genome, you can run a test cross with the F1 generation. If the results of the test cross have only black wings for one offspring(over a large sample), then the genotype of that offspring must be PP becuase that is the only genotype that gives all black offspring. Therefore, the parents must be Pp and Pp(see above). Otherwise if not then it must be Pp and pp.

Plz tell me if I confused you

[neurons]

Because the question mentions some, you know that the magpies are pp and Pp or PP.  Therefore from the phenotypes of the magpies(pale and black) you can infer that the parents must be 1. Pp and pp or 2. Pp and Pp. (these are the only combinations that result in both pale and black offspring)

Hence to find out the parental genome, you can run a test cross with the F1 generation. If the results of the test cross have only black wings for one offspring(over a large sample), then the genotype of that offspring must be PP becuase that is the only genotype that gives all black offspring. Therefore, the parents must be Pp and Pp(see above). Otherwise if not then it must be Pp and pp.

Plz tell me if I confused you

Thank you Gogo14! Your explanation was very clear and made complete sense

[instax101]

Just a quick question: what's the difference between comparative anatomy and comparative morphology?

[vox nihili]

Just a quick question: what's the difference between comparative anatomy and comparative morphology?

Nothing really

[QueenSmarty]

Hey everyone! I'm currently doing Chapter 10 from the Nelson textbook and I came across this question which I have no idea how to answer. Would someone please be able to help me out?

Question: Chicken-sized dinosaurs with very large optic lobes have been found on the southern coast of Australia. What does this tell us about conditions in this location at the time that these animals were alive?

Thank you in advance!

[solution]

As a result of DNA sequencing, an electropherogram is produced. Is this sequence of the template strand (the strand being sequenced) or is it a sequence that is complementary to the template strand?

Experimental design questions are worth 3 marks. What are those marks allocated to? Is it:
1. Hypothesis
2. Sensible method (control, controlled variables)
3. "Repeat experiment"

Also, is there any way to concisely write these? I tend to write too much (over the provided lines)

Bump please! Would especially like an answer for the DNA sequencing question as I have a SAC soon.

[Gogo14]

"When chromosomes sort independently during meiosis, the possible number of gametes is 2^n, where n is the haploid number of the organism"
I dont understand this, can someone plz explain why?thnx
p.s. soz solution, can't help you

[zsteve]

"When chromosomes sort independently during meiosis, the possible number of gametes is 2^n, where n is the haploid number of the organism"
I dont understand this, can someone plz explain why?
p.s. soz solution, can't help you

Of course, chromosome sorting is only concerned for diploid organisms.
So for a diploid organism with diploid number 2N (and hence haploid number N), at meiosis I, we need to go through each pair of homologous chromosomes and choose one to put in two of our gametes (and thus automatically put the other in the other two of our four gametes produced by meiosis).

For one pair of chromosome, there are 2 choices.
For two pairs of chromosomes, there are 2*2 choices.
For 3 chromosomes, 2*2*2 choices

and so on. Hence, for N homologous pairs of chromosomes, we need to make 2^N choices.
Hence there are 2^N possibilities for gametes.

[Gogo14]

Of course, chromosome sorting is only concerned for diploid organisms.
So for a diploid organism with diploid number 2N (and hence haploid number N), at meiosis I, we need to go through each pair of homologous chromosomes and choose one to put in two of our gametes (and thus automatically put the other in the other two of our four gametes produced by meiosis).

For one pair of chromosome, there are 2 choices.
For two pairs of chromosomes, there are 2*2 choices.
For 3 chromosomes, 2*2*2 choices

and so on. Hence, for N homologous pairs of chromosomes, we need to make 2^N choices.
Hence there are 2^N possibilities for gametes.

Ah I see. This reminds me of independent probability in methods....so is this the concept of independent assortment?Chromosomes arranging randomly to result in a large range of gamete possibilities?

[blacksanta62]

Does PCR result in the production of semi-conservative DNA (like DNA replication) or is it called something else?
Thank you

[vox nihili]

Does PCR result in the production of semi-conservative DNA (like DNA replication) or is it called something else?
Thank you

The DNA itself isn't semi-conservative, the replication is. In PCR, it's the same—it's a type of semi-conservative replication.

[blacksanta62]

The DNA itself isn't semi-conservative, the replication is. In PCR, it's the same—it's a type of semi-conservative replication.

Thank you for clearing that all up nihili, saved me from using the word wrong

[vox nihili]

Thank you for clearing that all up nihili, saved me from using the word wrong

You'd probably have been ok either way, they're not usually that nit-picky

Just make sure you know how PCR works properly and understand how it can be used. It's a tricky area that often gets looked over

[solution]

Does the Kreb's cycle require oxygen? I thought it doesn't, but my notes say it is part of an aerobic pathway.

[HasibA]

Does the Kreb's cycle require oxygen? I thought it doesn't, but my notes say it is part of an aerobic pathway.

Krebs cycle is indirectly dependent on the oxygen. The process doesn't consume oxygen but is dependent on oxygen to proceed, because its products NADH and FADH2 are utlilized in the ETC. If there is no oxygen, its means that ETC won't be there, so the krebs cycle's product will go in vain, hence it functions in presence of oxygen. Moreover the process occurs inside the matrix.

ETC requires oxygen directly and is dependent on it, as oxygen functions as the electron acceptor.

*excerpt from some notes, should be right tho*