VCE Biology Exam - 01/11/19 - Discussion/Questions/Solutions

[dev_xy]

for 8a is PKU okay?

[Livcur16]

i think i forgot to state the temperatures at each stage of PCR, would i lose all 3 marks
Thanks

[PhoenixxFire]

Would heparin count for the chemical barrier question??

I don't know what heparin does and I can't seem to find much about it on google. What does it do?

for 8a is PKU okay?

Yeah that should be fine

i think i forgot to state the temperatures at each stage of PCR, would i lose all 3 marks
Thanks

depends how strictly your markers are following their marking guide. It'll probably say that to give one mark for each step, but if you're lucky they'll give you a mark or two for getting everything else right without the temp.

[tdowler100]

Heparin prevents blood clotting to the immediate infection area but clots the Blood around the broken skin. It prevents the spread of pathogen throughout blood

[Erutepa]

Would heparin count for the chemical barrier question??

I haven't heard of this before but I have done some reading and it seems that it is a chemical (anticoagulant) that does have innate immune fuctions, however, it is released by innate immune cells in response to the identification of a pathogen.
The question asked for chemical barriers that would stop a pathogen before immune cells are aware, so I would say this response is incorrect. It may depend on how strict the marking is though

[tubbc]

I haven't heard of this before but I have done some reading and it seems that it is a chemical (anticoagulant) that does have innate immune fuctions, however, it is released by innate immune cells in response to the identification of a pathogen.
The question asked for chemical barriers that would stop a pathogen before immune cells are aware, so I would say this response is incorrect.

For question 4)c. wouldn't a vaccine not be possible for pollen fragments? Because pollen fragments are allergens rather than pathogens, it is unlikely an immune response will be initiated against them in a normal individual as they will are ordinarily harmless molecules. Therefore, it no memory B cells or specific antibodies would be produced so long-term immunity could not be achieved?

[hearteyes4u]

hi for question 6c it gave us the mRNA sequence so i wrote out all the complementary bases for that mRNA sequence and then found the corresponding amino acid for each codon. were we supposed to do that or were we supposed to find the amino acids using the codons in the mRNA sequence given to us?

[amnawaseem19]

For the limitation questions, would the absence of a control group be a limitation?
(q11)

[3086]

would a systematic error be incorrect calibration of temp of test tubes and water bath therby affecting the whole lot of results

[hearteyes4u]

hi for the mc question about the bacteria that were modified to produce human insulin i chose GMO bc in the question it didnt specifially state that the bacteria had a gene from the human inserted into, it just stated that it was modified to produce human insulin so wouldnt GMO be more correct??

[Erutepa]

For question 4)c. wouldn't a vaccine not be possible for pollen fragments? Because pollen fragments are allergens rather than pathogens, it is unlikely an immune response will be initiated against them in a normal individual as they will are ordinarily harmless molecules. Therefore, it no memory B cells or specific antibodies would be produced so long-term immunity could not be achieved?

Allergens (such as pollen fragments) are just antigens. Ideally, people wouldn't mount an immune response to them as they would recognise them as benign antigens and thus an adaptive immune response would not be activated and IgE antibodies wouldn't be produced. However, this is not always the case, as the allergen antigens do illicit an adaptive immune response hence by IgE antibodies are produced and hence why people have allergic reactions to pollen and other allergens. As such, a vaccine can be made to allergens which operate as explained in the sample solution.

hi for question 6c it gave us the mRNA sequence so i wrote out all the complementary bases for that mRNA sequence and then found the corresponding amino acid for each codon. were we supposed to do that or were we supposed to find the amino acids using the codons in the mRNA sequence given to us?

Codons are the 3 base groups on the mRNA. By writing out the complimentary 3 base codes, you are finding the anticodons. The chart gave which codons correspond to each amino acid, thus you should be using the mRNA sequence

would a systematic error be incorrect calibration of temp of test tubes and water bath therby affecting the whole lot of results

Yes!

For the limitation questions, would the absence of a control group be a limitation?
(q11)

I don't think there is much use for a control group (such as one at room temperature) so I don't think that would improve the experimental design - I could be wrong though.

hi for the mc question about the bacteria that were modified to produce human insulin i chose GMO bc in the question it didnt specifially state that the bacteria had a gene from the human inserted into, it just stated that it was modified to produce human insulin so wouldnt GMO be more correct??

I think you are supposed to infer that the bacteria must have contained a human gene in order to produce human insulin

[Jashy]

Just a general question: How strict is the marking going to be.

What are peoples predictions??

[Sine]

Just a general question: How strict is the marking going to be.

What are peoples predictions??

Based on most people saying that the exam was relatively straightforward I am guessing the will be probably the usual strictness or maybe a bit more strict (although this will always be question/assesor dependent).

[Highway_end]

hi for the mc question about the bacteria that were modified to produce human insulin i chose GMO bc in the question it didnt specifially state that the bacteria had a gene from the human inserted into, it just stated that it was modified to produce human insulin so wouldnt GMO be more correct??

IIRC that option actually stated "genetically-mutated organism" so it would have been incorrect

[PhoenixxFire]

I wrote along the lines of...

The mutation of the gene BMP4 results in the changes in the intensity, duration and the times of the gene being expressed during embryonic development. And variation in these factors result in morphological changes, if there is a lot of variation it results in different phenotypic variation.

Phoenix is this right?

the question was question was quite stupid in my opinion.

You'd get some marks but I don't think you'd get all of them. And yeah, we hated it too.

Just a general question: How strict is the marking going to be.

What are peoples predictions??

I get the feeling that for a lot of the 3 and 4 mark questions, a lot of people are going to get at least 1 or 2 marks respectively, but not many people are going to get full marks. It did seem like a bit of a change from previous years where for some questions it was relatively easy to get all the marks and for others the average mark was very very low. I don't think there'll be too many questions with extremely low average marks this time around, but I also don't think there'll be too many of those questions that have an average mark 2.3/3 or higher either.