VCE Biology Question Thread

[vox nihili]

Why is it that if mast cells are involved in both inflammation and allergic responses, the allergic responses swell up more??

The allergic response is inflammation

[cosine]

The allergic response is inflammation

Hi Mr T-Rav,

Saying that has confused me a little bit. Would it be possible if you could help me out, please?
If allergic responses involve specific IgE antibodies, which need to be produced by specific plasma B cells, then does this mean that allergic responses are specific immune responses? If so, then does this mean that allergic responses = inflammation, but inflammation in the non-specific immunity does not equal allergic response?

Sorry for the confusion, really appreciate yours and Biology 24123 help recently, learnt so much about immunity over the last week, took me soo long to understand it xD

[vox nihili]

Hi Mr T-Rav,

Saying that has confused me a little bit. Would it be possible if you could help me out, please?
If allergic responses involve specific IgE antibodies, which need to be produced by specific plasma B cells, then does this mean that allergic responses are specific immune responses? If so, then does this mean that allergic responses = inflammation, but inflammation in the non-specific immunity does not equal allergic response?

Sorry for the confusion, really appreciate yours and Biology 24123 help recently, learnt so much about immunity over the last week, took me soo long to understand it xD

Ah yes, I forgot that the VCE course treats them differently so no worries about the confusion, that's expected!

Inflammation is treated as something really particular in VCE, when it's not. In truth, inflammation is just an immune response, for all intents and purposes. In the context of VCE, the allergic response seems worse than inflammation because the allergic response is, really, inappropriate and hyperactive inflammation.

Just note that when you deal with questions on these in VCE exams that you really should pretend there is a difference between the two, when there's not really!

[cosine]

Ah yes, I forgot that the VCE course treats them differently so no worries about the confusion, that's expected!

Inflammation is treated as something really particular in VCE, when it's not. In truth, inflammation is just an immune response, for all intents and purposes. In the context of VCE, the allergic response seems worse than inflammation because the allergic response is, really, inappropriate and hyperactive inflammation.

Just note that when you deal with questions on these in VCE exams that you really should pretend there is a difference between the two, when there's not really!

Alright thanks for clearing that up for me

For the attached questions:

1. I have no idea for the F1 offspring are all Green and Spotted? I can deduce that the dominant colour is green, because if they are both pure breeding, they are homozygous for colour, and hence green is the dominant one. But if they are both homozygous for both gene loci, then how on earth does the F1 offspring have spotted skin? I can't make a correlation, I even assumed they were linked traits but realised it would not make a difference.

2. Stuck between B and D. Obviously lane 1 has a higher molecular weight because the fragment moved less as compared to the others, suggesting it is the largest DNA fragment = heavier. But, D could also be right because there are different amounts of fragments in the lane so does this not mean that two different people were used? Also just a side note, when using gel electrophoresis in human DNA, say lane 1 was the crime scene lane. The DNA from the crime scene would be obtained from the blood, and so do scientists have the complete genome of the suspect because of this blood cell? If so, do the scientists actually get DNA from a particular chromosome from both the crime scene cell AND the suspects? And then they compare the relative sizes of the gene from each suspect's chromosome?

3. Can this not be A or B?

[nhienhien852]

Few more questions:

2. When a macrophage engulfs a foreign pathogen, it digests and degrades it. Antigenic fragments are then presented on the MHC II markers. What happens now? Where does this macrophage go, or what comes to it?

3. Do we need to know about TCRs? If so, are they only found within the membranes of Cytotoxic T cells or all types of T cells? (T Helper cells)?

2. The activated macrophage will carry the antigen (on its MHC class II) to the lymph nodes, where T cells are accumulated, improving the chance of finding the matching helper T cell.
The macrophage then releases interleukin-1 to activate helper T cell.

3. What is TCR? Is that T cell receptor? If so, helper T cells and cytotoxic T cells both have their own TCRs. (noy sure about suppressor T and memory T cells though)

[sunshine98]

Alright thanks for clearing that up for me
3. Can this not be A or B?

Is the answer C? If not, ignore my explanation.
Then
-its dominant because all affected individuals have at least one affected parent.
-Its X linked because if only the father was affected (II-4) he passes it on , only to his daughters , and not his sons.
-Also , all affected mothers pass it on to both sons and daughters take I-2  and II-8 as an eg who have one son and daughter each affected.

[Sine]

Alright thanks for clearing that up for me

For the attached questions:

What exams are these from I'm guessing engage education--->if so are they worth our time?

[cosine]

What exams are these from I'm guessing engage education--->if so are they worth our time?

Definitely not worth time, try answering the above questions?

Is the answer C? If not, ignore my explanation.
Then
-its dominant because all affected individuals have at least one affected parent.
-Its X linked because if only the father was affected (II-4) he passes it on , only to his daughters , and not his sons.
-Also , all affected mothers pass it on to both sons and daughters take I-2  and II-8 as an eg who have one son and daughter each affected.

I have not checked the answers, but why can't it be A or B? I mean yours makes sense yes, but also if it were autosomal rec/dominant would work out?

[vox nihili]

Alright thanks for clearing that up for me

For the attached questions:

1. I have no idea for the F1 offspring are all Green and Spotted? I can deduce that the dominant colour is green, because if they are both pure breeding, they are homozygous for colour, and hence green is the dominant one. But if they are both homozygous for both gene loci, then how on earth does the F1 offspring have spotted skin? I can't make a correlation, I even assumed they were linked traits but realised it would not make a difference.

2. Stuck between B and D. Obviously lane 1 has a higher molecular weight because the fragment moved less as compared to the others, suggesting it is the largest DNA fragment = heavier. But, D could also be right because there are different amounts of fragments in the lane so does this not mean that two different people were used? Also just a side note, when using gel electrophoresis in human DNA, say lane 1 was the crime scene lane. The DNA from the crime scene would be obtained from the blood, and so do scientists have the complete genome of the suspect because of this blood cell? If so, do the scientists actually get DNA from a particular chromosome from both the crime scene cell AND the suspects? And then they compare the relative sizes of the gene from each suspect's chromosome?

3. Can this not be A or B?

2. Is most definitely B. All a gel gives you is the size of fragments, not their identity so it can't be D. Interestingly, that gel doesn't have DNA in it, it's protein. Sneaky buggers!

3. Yes, you're right. There's no way to differentiate between the two based on this pedigree.

[cosine]

2. Is most definitely B. All a gel gives you is the size of fragments, not their identity so it can't be D. Interestingly, that gel doesn't have DNA in it, it's protein. Sneaky buggers!

Thank you so much:)

Can you answer my theory of gel electrophoresis please? What do you mean by the size of fragments and not their identity, because if two lanes has different sized fragments, then does that not imply that they were two different people because if it was the same person, it would obviously have the same sized fragments? o.o

Also for question 10 b (attached) the answer says that the woman would not be able to reproduce because her X chromosome would not be able to pair up with another sex chromosome. I dont really understand this, because can't meiosis occur even though there is a missing chromosome? I thought that because there is that one missing sex chromosome, then the baby has a higher chance of receiving a less chromosome (monosomy). 

[cosine]

I also apologise for asking so many questions

[Mishmosh]

Is it apoptosis when cytotoxic T cells kill infected cells?
If they ask for the inputs and outputs of the krebs cycle, do we write them per pyruvate or per glucose molecule?

[Bruzzix]

You're probably all aware of the new hominin species found a couple weeks ago, Homo naledi. I was reading up on its Wikipedia page and came across this:



So the bones were just loosely spread along the cave and weren't covered by sediment.. wouldn't they just have decayed over the long periods of time they were there for?

[cosine]

Is it apoptosis when cytotoxic T cells kill infected cells?
If they ask for the inputs and outputs of the krebs cycle, do we write them per pyruvate or per glucose molecule?

Yes, when a specific Cytotoxic T Cell recognises a foreign antigen presented on a MHC I marker of an infected cell (be it virally infected or tumour cell), the T Cell releases perforin which ruptures the membrane of the infected cell, and then it releases an enzyme known as granzymes that actually order the cell to undergo programmed cell death.

The entire worded/chemical equation of aerobic respiration involves one molecule of glucose, so I guess it would be safer to write them per molecule of glucose:

Inputs: 4ADP+Pi, 2 pyruvate, 8NAD+, 2FAD and 2 Coenzyme A
Outputs: 4ATP, 6CO2, 8NADH, 2FADH2

[BakedDwarf]

Can someone explain to me simply how apoptosis works? All i know is that it's a programmed cell death that removes cancer/old cells.

What's a transitional fossil?