VCE Biology Question Thread

[anat0my]

I might added the two different protein receptors on the membrane as well.

Would adding an envelope be okay for a typical virus?

[Vicbelgaus]

Would adding an envelope be okay for a typical virus?

I bet they would have no problem with it, however envelopes are not found in all viruses.

Plus i doubt we will need to go so much in detail about viruses

[anat0my]

What is the structure of DNA in chloroplasts and mitochondria?

[AllG_]

Should I do the Unit 3 VCAA exams from 2002 - 2005? A lot of their questions seem to be from the previous study designs and a lot of it is not related to the current study design. Idk for those who have done them are they worth doing?

[millie96]

how do you figure this out?

[Reus]

What is the structure of DNA in chloroplasts and mitochondria?

They are circular in structure. This is because according to the endosymbiotic theory they must possess DNA similar to those of bacteria.

Should I do the Unit 3 VCAA exams from 2002 - 2005? A lot of their questions seem to be from the previous study designs and a lot of it is not related to the current study design. Idk for those who have done them are they worth doing?

Just skip those that are not relevant. You never know, they might pull one out of there on this years as those haven't been asked in a while

[Reus]

how do you figure this out?

20 chromosomes in the sperm cell and egg cell respectively. This is because the diploid number is 40 and they are gametes. Hope this helps

Edit; ooooo wait I just noticed that the egg is fertilised meaning it would have 40.

[katiesaliba]

HELP!
http://www.vcaa.vic.edu.au/Documents/exams/biology/2007biol2.pdf
Q4 b)
Can someone please explain to me how the hell rabbit I-1 would have a genotype that's 'impossible to tell'??
If the rabbit was affected, then her offspring would also be affected....it's X-linked dominant? So rabbit I-1 must be unaffected because II-1 is unaffected?? Very confused and stressing out ahaha.

[millie96]

Are Homo neanderthals the most common ancestor to homo sapiens? Do they share the most common characteristics?

[Reus]

Are Homo neanderthals the most common ancestor to homo sapiens? Do they share the most common characteristics?

It's Homo erectus if I am not mistaken? (still haven't studied this independently myself yet)

[Vicbelgaus]

HELP!
http://www.vcaa.vic.edu.au/Documents/exams/biology/2007biol2.pdf
Q4 b)
Can someone please explain to me how the hell rabbit I-1 would have a genotype that's 'impossible to tell'??
If the rabbit was affected, then her offspring would also be affected....it's X-linked dominant? So rabbit I-1 must be unaffected because II-1 is unaffected?? Very confused and stressing out ahaha.
+ Attachments and other options

Okay first thing nothing to be stress about,  Well considering Rabbit I1 Is a female she has two X's and can only pass on one of her X's to her Daughter,  And her daughter is unaffected this leaves us with the mother having two possible genotypes.

A) She is hetrozygous with two different alleles on her two X chromosomes, and because because she can only pass on one of her x chromosomes, in this case she passed on her unaffected chromosome X to her daughter.

B) she is homozygous recessive on her XX explaining why she had an unaffected offspring. as she can only give her offspring X chromosomes with the unaffected allele

so because she can have to possible genotypes, we cannot determine her genotype.

I hope this makes sense, its a little bit of a jumble

[dankfrank420]

@Katie

Firstly, we know her possible genotypes but not her phenotype. You've read the answer wrong.

Since it's X-linked dominant, it means that the father passed on an x^d chromosome to her offspring. And since we know that II 1 does not show the trait, her genotype is x^d x^d. This means that she must have received an x^d chromosome from her mother. However, the mother can pass on an x^d chromosome if she is heterozygous or homozygous recessive. There is no extra information to choose between one of these two permutations, hence it is "impossible to tell" her phenotype.

@millie

Neanderthals are our cousins, not our ancestors. We share a direct common ancestor.

[katiesaliba]

Okay first thing nothing to be stress about,  Well considering Rabbit I1 Is a female she has two X's and can only pass on one of her X's to her Daughter,  And her daughter is unaffected this leaves us with the mother having two possible genotypes.

A) She is hetrozygous with two different alleles on her two X chromosomes, and because because she can only pass on one of her x chromosomes, in this case she passed on her unaffected chromosome X to her daughter.

B) she is homozygous recessive on her XX explaining why she had an unaffected offspring. as she can only give her offspring X chromosomes with the unaffected allele

so because she can have to possible genotypes, we cannot determine her genotype.

I hope this makes sense, its a little bit of a jumble

@Katie

Firstly, we know her possible genotypes but not her phenotype. You've read the answer wrong.

Since it's X-linked dominant, it means that the father passed on an x^d chromosome to her offspring. And since we know that II 1 does not show the trait, her genotype is x^d x^d. This means that she must have received an x^d chromosome from her mother. However, the mother can pass on an x^d chromosome if she is heterozygous or homozygous recessive. There is no extra information to choose between one of these two permutations, hence it is "impossible to tell" her phenotype.

Oh my god, ahah wow  . Thanks guys! I think bio has turned my brain into mush.

[katiesaliba]

Actually for the same exam, (http://www.vcaa.vic.edu.au/Documents/exams/biology/2007biol2.pdf) question 5c has annoyed me because the question explicitly asks to use evidence from the results in your answer, and yet the VCAA answer doesn't really...

[Damo23]

Quick questions, whats a transitional fossil and what and how does an actional potential work?( is it something like the K+ions in and Na+ out)

 Thanks