VCE Biology Question Thread

[BakedDwarf]

Can somebody explain this to me? I know A or C cannot be the answer, so it's either B or D.

[grindr]

The answer is B, since is has identical combining sites.
Why is this a better option than C?

[Mieow]

The answer is B, since is has identical combining sites.
Why is this a better option than C?

Can antibodies have different variable regions?
Love the u/name btw xP

[BakedDwarf]

The answer is B, since is has identical combining sites.
Why is this a better option than C?

The variable regions (antigen binding spots) must be the same on an antibody. Hence, because they're different, that type of antibody does not occur naturally.

[grindr]

Can somebody explain this to me? I know A or C cannot be the answer, so it's either B or D.

It's asking about signal transduction, which is a set of chemical reactions/cascade of events that occur through the binding of a molecule to it's receptor so it wouldn't be B, as there is no binding of molecules involved. Leaves us with D, with the binding of the signalling molecule to its receptors on the post synaptic membrane.

[grindr]

Can antibodies have different variable regions?
Love the u/name btw xP

I don't know.. can they?

Thank you, I'm glad to have found someone to appreciate it.

The variable regions (antigen binding spots) must be the same on an antibody. Hence, because they're different, that type of antibody does not occur naturally.

Okay that makes sense,
Thanks!

[grindr]

This question, I don't get..
Answer is D.

Has this got to do with dihybrid crosses (heterozygousxheterozygous)?
Why isn't B a valid answer?

On the same topic, in a dihybrid cross that was linked, would the ratio be anything that is not 9:3:3:1 ?

[warya]

This question, I don't get..
Answer is D.

Has this got to do with dihybrid crosses (heterozygousxheterozygous)?
Why isn't B a valid answer?

On the same topic, in a dihybrid cross that was linked, would the ratio be anything that is not 9:3:3:1 ?

Not sure but a test cross would indicate a lots-lots-little-little ratio rather than 1:1:1;1 which is how you differentiate linked vs unlinked

[warya]

This is m understanding of block mutatiions:

Duplications - a part of the chromosome is copied, resulting in duplicate segments (potentially increasing gene expression)
Inversions - a segment of a chromosome is removed and then replaced in reverse order
Deletions - a portion of a chromosome is lost (along with any genes contained within this segment)
Insertions - a part of one chromosome is removed and added to another chromosome (may interrupt gene sequences)
Translocations - segments of two chromosomes are exchanged (may interrupt gene sequences)

Do we need to know the implications further than this (e.g. with inversions?)

[katiesaliba]

This question, I don't get..
Answer is D.

Has this got to do with dihybrid crosses (heterozygousxheterozygous)?
Why isn't B a valid answer?

On the same topic, in a dihybrid cross that was linked, would the ratio be anything that is not 9:3:3:1 ?

Just a few things to remember when doing these genetics problems:
-hetero x hetero, then the phenotypes of the progeny should be in a 9:3:3:1 ratio, assuming complete dominance.
-a test cross (pure-breeding homozygous recessive individual) is used to decipher whether or not two gene loci sort independently (hence 1:1:1:1 ratio of phenotypes observed in progeny), or if they are linked (deviance from the 1:1:1:1 phenotypic ratio, with non-recombinants (I.e. Parental phenotypes) having a higher prevalence within the progeny.
-if two genes are more than 50 mu apart on a single chromosome, then they will assort independently as crossing over is more likely to occur.

Hope this helps to clarify things somewhat :p

[grindr]

Just a few things to remember when doing these genetics problems:
-hetero x hetero, then the phenotypes of the progeny should be in a 9:3:3:1 ratio, assuming complete dominance.
-a test cross (pure-breeding homozygous recessive individual) is used to decipher whether or not two gene loci sort independently (hence 1:1:1:1 ratio of phenotypes observed in progeny), or if they are linked (deviance from the 1:1:1:1 phenotypic ratio, with non-recombinants (I.e. Parental phenotypes) having a higher prevalence within the progeny.
-if two genes are more than 50 mu apart on a single chromosome, then they will assort independently as crossing over is more likely to occur.

Hope this helps to clarify things somewhat :p

Thank you for replying, but I still don't understand the solution to the question.

[CarterGray12]

When writing chemical or even word equations for either photosynthesis or any respiration, do we include ATP or any of the carrier molecules?

[sunshine98]

Probs a stupid q but whenever I do prac exams , I notice that I write O2 instead of oxygen and H2O etc . Ofcourse I do not intend to do this  in the exams , but would this result in lost marks?

[cosine]

Probs a stupid q but whenever I do prac exams , I notice that I write O2 instead of oxygen and H2O etc . Ofcourse I do not intend to do this  in the exams , but would this result in lost marks?

No because they are elemental symbols, but something like ER instead of endoplasmic reticulum would lose marks.

When writing chemical or even word equations for either photosynthesis or any respiration, do we include ATP or any of the carrier molecules?

Include ATP in the cellular respiration, because that's the main output anyway, right? But you do not include the carrier molecules because they are simply reused in the reactions, and so are not necessarily that important in the equation.

[heids]

This question, I don't get..
Answer is D.

Has this got to do with dihybrid crosses (heterozygousxheterozygous)?
Why isn't B a valid answer?

On the same topic, in a dihybrid cross that was linked, would the ratio be anything that is not 9:3:3:1 ?

So, the offspring are SsWw - as the SW came from one parent, and the sw from another, these offspring have SW on one chromosome and sw on the other.  So, unless crossing over occurs between gene 1 and gene 2, then offspring of the test cross (SsWw x ssww) will be passed either SW or sw - they'll only get sW or Sw if crossing over happens, which is unlikely as these genes are close together.  So there'll be lots of SW or sw (long and straight/short and wavy), but very few sW or Sw (long and wavy, short and straight), so approx equal SW and sw --> D.