VCE Biology Question Thread

[Billuminati]

Thanks

A mutation occurs in the liver cell of a dog before the dog reproduces. When the dog reproduces, how many of the puppies are expected to have the mutation?
A all of the puppies will have the mutation
B it depends if the mutation is dominant or recessive
C none of the puppies will inherit the mutation
D half of the puppies will have the mutation

Would this be b

Sine beat me to it, the short answer is C. Note that if the parent dog inherited the mutation itself, it would also pass along the alleles to its offspring because inherited mutations affect every single cell of the body including the germline.

[Chocolatepistachio]

I was told most cellular reactions require a specific enzyme but don’t all??

[Sine]

I was told most cellular reactions require a specific enzyme but don’t all??

I think in general in biology it is rare to have anything where "All" applies since you can probably find an exception somewhere. Just from first principles, I would think maybe two different enzymes can catalyse 1 reaction but possibly 1 of those enzymes is really efficient whilst the other one isn't as efficient.

EDIT: An enzyme could be Hexokinase and Glucokinase which catalyse the same reaction but affinity differs on location

[Billuminati]

I was told most cellular reactions require a specific enzyme but don’t all??

The vast majority of reactions in the body require some kind of enzyme, but there are supposed to be exceptions. The only one I can think of off the top of my head is the dissociation of H2CO3 into H2O and CO2 in blood pH buffers, while the reverse reaction (ie CO2 + H2O --> H2CO3) requires an enzyme called carbonic anhydrase, the forward reaction is favoured and occurs pretty rapidly even in the absence of the enzyme eg when you dissolve a carbonate salt in HCl, which produces H2CO3 and quickly disintegrates to form CO2 and H2O.

[Chocolatepistachio]

In the amylase time course reaction HCl was added to the aliquots taken out of the master mix solution at various time intervals (t=0, 1,3,6,9, 12 mins). What was the purpose of adding HCl?
A HCl was added to increase the volume of the aliquots at different time intervals
B HCl acted as a buffer for amylase
C to stop the reaction between amylase and starch
D to speed up the reaction between amylase and starch

Would this be d

[Billuminati]

In the amylase time course reaction HCl was added to the aliquots taken out of the master mix solution at various time intervals (t=0, 1,3,6,9, 12 mins). What was the purpose of adding HCl?
A HCl was added to increase the volume of the aliquots at different time intervals
B HCl acted as a buffer for amylase
C to stop the reaction between amylase and starch
D to speed up the reaction between amylase and starch

Would this be d

It's actually C, amylase works best in neutral pH but is deactivated by low or high pHs. That's actually why starch digestion stops once food reaches the stomach and why it only recommences in the duodenum with pancreatic amylase mixing with bile (basic to neutralise stomach acid) to achieve its optimal functioning pH. You don't want the reaction to continue while you're measuring it.

[Chocolatepistachio]

Which of the following statements best describes how singer and Nicholson’s fluid mosaic model of the cell membrane differs from the Danielli/Davison model?
A proteins can span(cross) the lipid bilayer
B the lipid bilayer has a hydrophobic interior and hydrophilic exterior
C the lipid bilayer has a hydrophilic interior and hydrophobic exterior
D proteins can poke out of the internal and external surfaces of the membrane

Would this be a

[Billuminati]

Which of the following statements best describes how singer and Nicholson’s fluid mosaic model of the cell membrane differs from the Danielli/Davison model?
A proteins can span(cross) the lipid bilayer
B the lipid bilayer has a hydrophobic interior and hydrophilic exterior
C the lipid bilayer has a hydrophilic interior and hydrophobic exterior
D proteins can poke out of the internal and external surfaces of the membrane

Would this be a

I don't actually know this myself, this question may be worded poorly as there are 3 options that correctly describe the fluid mosaic model (options A, B and D) but from a quick consultation with my uni bio textbook on the DD model, it looks like A is the most relevant. Both models suggest hydrophilic exterior and hydrophobic interior (eliminating B) and both models can have membrane proteins with intra and extracellular domains (eliminating D). You're not expected to compare and contrast past models developed to explain the plasma membrane, you just need to know the fluid mosaic model.

[Chocolatepistachio]

if someone could help with this question

[Billuminati]

if someone could help with this question

It's W and Z. X is a negative control as adding iodine won't do anything if there is no starch, whereas Y is your intervention group

[Chocolatepistachio]

Thanks
For the electron transport chain why can’t 33 atp be produced only 32 or 34

In mice the expression of gene(Y) results in yellow coat colour and the expression of gene(y) results in black coat colour
“ the genotype of a true-breeding yellow coated mouse is Yy
Would this be false

[Billuminati]

Thanks
For the electron transport chain why can’t 33 atp be produced only 32 or 34

In mice the expression of gene(Y) results in yellow coat colour and the expression of gene(y) results in black coat colour
“ the genotype of a true-breeding yellow coated mouse is Yy
Would this be false

Remember all reactions aren't 100% efficient, while in theory NADH and FADH2 can make 3 and 2 ATP respectively, the experimental value is actually closer to 2.5 and 1.5 respectively.

My genetics knowledge is very bad so please take this with a grain of salt, but I'm pretty sure true breeding individuals must be homozygotes

[Chocolatepistachio]

What does this mean - olfactory neurons consist of an apical modified dendrite

[Billuminati]

What does this mean - olfactory neurons consist of an apical modified dendrite

I'm not 100% certain because this is going a bit beyond 2nd year uni anatomy, but I can infer that this refers to the thin olfactory fibres projecting through the cribiform plate that capture tiny particles in the olfactory epithelium. The word "apical" probably refers to how these receptors are located more towards the apical end of the surrounding olfactory epithelium, and as I said the other day, the olfactory nerve is considered a highly specialised, modified tract of the cerebrum

[Chocolatepistachio]

Nuclear pores permit the passage of all the following except:
A proteins: into and out of the nucleus
B RNA: only to the outside of the nucleus
C DNA: into and out of the nucleus
D enzymes: into and out of the nucleus


Would this be c