VCE Biology Question Thread

[blacksanta62]

Of course *facepalm* didn't see the link at all  
Makes sense

[solution]

Can someone explain this question please?

[Apink!]

Not relevant to VCE, so just skip it.


Basically all it's telling you is that because there are two X chromosomes and we only need one, in each cell, one X chromosome is randomly turned off, so it basically sits there and does nothing. So the particular colour fur you get depends on which X chromosome is turned off in the cells producing that fur.

That's an over-simplification, and there's a lot of nuance here that we could go into, but it's all completely irrelevant to the VCE course so I'd just move on

Thanks vox nihili 

[grannysmith]

Can someone explain this question please?

C is incorrect because frankly, it doesn't make sense It's saying that the plants themselves are haploid, which is nonsense. Even if we take it as meaning that the cells with an odd number of chromosomes are haploid, this is only possible in the case of sex cells. The question stem states that these are of root tip cells, which are somatic cells and hence are not involved in reproduction.

B is correct since an even number of chromosomes is necessary for meiosis.

[solution]

Sorry for the question spam, I have a SAC tomorrow...
Is this correct?

* I assume when they mean a crossover occurs at X, the whole chromosome from X downwards gets switched with the corresponding part of chromosome from the other strand. Is this correct?

[solution]

C is incorrect because frankly, it doesn't make sense It's saying that the plants themselves are haploid, which is nonsense. Even if we take it as meaning that the cells with an odd number of chromosomes are haploid, this is only possible in the case of sex cells. The question stem states that these are of root tip cells, which are somatic cells and hence are not involved in reproduction.

B is correct since an even number of chromosomes is necessary for meiosis.

Are seeds gametes of a plant?

[plsbegentle]

Sorry for the question spam, I have a SAC tomorrow...
Is this correct?

* I assume when they mean a crossover occurs at X, the whole chromosome from X downwards gets switched with the corresponding part of chromosome from the other strand. Is this correct?

Wow, you guys get to bring the sac home . But for Q18, ur answer is wrong. This is because the question states that there is no crossing over occurring and since the genes are on the same chromosome, they are not independently assorted. The answer would be AB and ab.
Q19. The answer is actually the same as Q18, have a look at the point bellow X, crossing over at strand 2,3 would produce a  outcome of AB and ab.
Q20. Your answer is fine
Q21. Your answer is also correct, but i think your missing key words, my answer would be something along these lines: AB and ab would occur more frequently compared to the other gamete possibilities because these are parental genes while the others are recombinant which occur in lesser percentages.

EDIT: remember to label the chromosome in the figure, i loss easy marks just like that !!!!

[grannysmith]

Are seeds gametes of a plant?

A seed contains an embryo capable of developing into a plant. So no, it's not a gamete. However, seed production is possible because of sexual reproduction.

[Apink!]

Hi all,

I'm getting really confused with haploid and diploid numbers. For example, in this question, I know that in Telophase 1, it will have two 'x' shaped chromosomes but in Telophase II, it will  have two 'I' shaped chromosomes. But I'm not sure whether in Telophase 1:
I should say having a diploid number of 2, or 4 or whether I should say diploid or haploid number (because it's a gamete?). I'm just confused. Please help!

[plsbegentle]

Hi all,

I'm getting really confused with haploid and diploid numbers. For example, in this question, I know that in Telophase 1, it will have two 'x' shaped chromosomes but in Telophase II, it will  have two 'I' shaped chromosomes. But I'm not sure whether in Telophase 1:
I should say having a diploid number of 2, or 4 or whether I should say diploid or haploid number (because it's a gamete?). I'm just confused. Please help!

I'm gonna say the answer is D. Haploid is half of the chromosomes and diploid is the full set. So in humans, the haploid number would be 23 and diploid would be 46. Meiosis is reduction division, from knowledge, A and C. should already be eliminated because after telophase 1, there should be half the amount of chromosomes. Now we are left with B and D. B is incorrect because the haploid number in telophase should be 2 but DOUBLE STRANDED.  So i think the answer is D.

[solution]

Wow, you guys get to bring the sac home . But for Q18, ur answer is wrong. This is because the question states that there is no crossing over occurring and since the genes are on the same chromosome, they are not independently assorted. The answer would be AB and ab.
Q19. The answer is actually the same as Q18, have a look at the point bellow X, crossing over at strand 2,3 would produce a  outcome of AB and ab.
Q20. Your answer is fine
Q21. Your answer is also correct, but i think your missing key words, my answer would be something along these lines: AB and ab would occur more frequently compared to the other gamete possibilities because these are parental genes while the others are recombinant which occur in lesser percentages.

EDIT: remember to label the chromosome in the figure, i loss easy marks just like that !!!!

Thanks for replying. Isn't my Q18 answer the same as yours? (I just wrote it twice, which I probably should not have done)

[Gogo14]

Thanks for replying. Isn't my Q18 answer the same as yours? (I just wrote it twice, which I probably should not have done)

Just wondering for the q you asked, should you write out the combinations as AABB instead of AB since they are two different genes? Asking anyone in general.

[Apink!]

I'm gonna say the answer is D. Haploid is half of the chromosomes and diploid is the full set. So in humans, the haploid number would be 23 and diploid would be 46. Meiosis is reduction division, from knowledge, A and C. should already be eliminated because after telophase 1, there should be half the amount of chromosomes. Now we are left with B and D. B is incorrect because the haploid number in telophase should be 2 but DOUBLE STRANDED.  So i think the answer is D.

Thank you plsbegentle!
Why is Bio so confusing *sigh...

Hi all,

I attach two more questions. Help will be greatly appreciated

[Callum@1373]

Thank you plsbegentle!
Why is Bio so confusing *sigh...

Hi all,

I attach two more questions. Help will be greatly appreciated

Waddup D.O

For question 4, I'd say the answer is D because the chromosomes aren't double stranded in anaphase so it's kinda doubled the number of chromosomes if that makes sense.

For question 5, I'd say the answer is B. Crossing over and independent assortment are really important, and fertilisation is a random process so i'd cancel those options out which leaves B

[Apink!]

Waddup D.O

For question 4, I'd say the answer is D because the chromosomes aren't double stranded in anaphase so it's kinda doubled the number of chromosomes if that makes sense.

For question 5, I'd say the answer is B. Crossing over and independent assortment are really important, and fertilisation is a random process so i'd cancel those options out which leaves B

Callum, you legend! Thanks for helping me with Bio XD