VCE Biology Question Thread

[vox nihili]

Hey All! I'm having a little bit trouble with these questions. If any of you guys would like to help me that would be great thanks! sorry it's lenthy

Exactly how much ATP molecules are produced in the ETC? Which is better to write- 32 ATP molecules or 36-38? I'm super confused

If we do not simplify ratio's when writing the phenotypic or genotypic ratio, will we be deducted?! For eg, if it's • 2 females with white eyes: 2 males with brown eyes or do we have to write 1 female with white eyes: 1 male with brown eyes?

Lactose attaches to repressor proteins which this change its shape causing it to detach from the operator region right?


What are the temperatures that are used in PCR? Every book is telling me different, is it 94•C/93C then 55 or 50C then 72C? Btw is the DNA strands denatured? Can we use the word denatured or dissociated?

Can we say that
ATP is formed when ADP is phosphorylated? Or
ATP is formed when ADP + Pi is phosphorylated?! Which one?

Does light energy split water molecules into hydrogen ions and oxygen?

Is NADPH and NADP considered as molecules? (2015 vcaa paper only included water, oxygen, ATP as molecules?)

Are igE antibodies produced during an allergic reaction? Can we say that when an allergen is encountered, your B cells produce the antibody igE which later bind to mast cells etc?

Are nerves electrical and chemical? Whereas hormones are just chemical?

What are some immune cells? I know mast cells are but what else?

Okay, for fatty acids/lipids, is it attached to a glycerol head? I'm so confused... where does the phosphate head come into place? Is it glycerol or phosphate?

Do we have to draw glycoprotein as a alpha helix shape? BTW is carbohydrate attached to the glycoprotein?

Lastly, can someone please explain to me everything we need to know about booster injections? I actually have no clue

1. 32-34, the other four come from glycolysis and Krebs

2. Nope, you don't have to simplify

3. Correct

4. They're not exact. It actually depends on what primers you're using, hence the slight differences. You only need to know them roughly

5. ADP is phosphorylated to form ATP. Phosphorylation is the addition of Pi to something.

6-10. Yes

11. This link is helpful

12. Fatty acids are attached to glycerol, so is the phosphate



13. No, glycoprotein's don't have to have alpha-helices. They're just protein and carbohydrate stuck together in the one molecule

14. After a time, memory cells start to die off. So you give a booster to create more.

Explain the role of lipids in the plasma membrane. List 2 other functions of lipids
   • In the plasma membrane, the membrane itself is made of phospholipids which are orientated in a bilayer to regulate the input/outputs of a cell
          In addition, cholesterol are also lipids in the plasma membrane that maintains structure and fluidity for the membrane
         

           Fat storage and insulation


Would this be an acceptable answer? I actually do not know the real answer for the question

Yep, that'd get full marks

[HasibA]

can a nerve impulse travel across a myelinated sheath in multiple directions? i always thought it was a one-way directional impulse.. ?

editL can someone explain why the attached question is not 'B' ?
http://imgur.com/7QjltGu

[plsbegentle]

can a nerve impulse travel across a myelinated sheath in multiple directions? i always thought it was a one-way directional impulse.. ?

editL can someone explain why the attached question is not 'B' ?
http://imgur.com/7QjltGu

What do you mean multiple directions?  But yes, nerve impulses move in a one way direction, from dendrite to axon to axon terminal and so on.

I got B as well!

[HasibA]

What do you mean multiple directions?  But yes, nerve impulses move in a one way direction, from dendrite to axon to axon terminal and so on.

I got B as well!

i'll upload the question as well ! http://imgur.com/a/ZgCyR

answer was 'A' apparently, dont know why it was wrong

[sweetcheeks]

@Hasiba
I went through this exam, there appears to be no correct answer for the question. It should be 2/3 light green and 1/3 dark green.

[AhNeon]

i'll upload the question as well ! http://imgur.com/a/ZgCyR

answer was 'A' apparently, dont know why it was wrong

Notice how the question asks for the phenotypic ratio of 'mature' soybeans. As yellow leaves do not absorb enough light for the soybeans to survive and mature, you don't include them in the ratio. Thus the ratio should be 2/3 light green:1/3 dark green, not sure if thats a typo but the answer is definitely not B

[plsbegentle]

@Hasiba
I went through this exam, there appears to be no correct answer for the question. It should be 2/3 light green and 1/3 dark green.

Welp, lethal genes...

i'll upload the question as well ! http://imgur.com/a/ZgCyR

answer was 'A' apparently, dont know why it was wrong

Well myelin sheath don't direct nerve impulses, rather they insulate the neuron ( protection) and speed up the impluse across the axon.

[HasibA]

thanks guys! i originally thought what y'all said, but i second guessed myself and chose an answer -_-
@sweetcheeks- what'd you think of the paper? t'was quite good, but the pregnancy immunity question was difficult imo

@plsbegentle- hmm i agree, and bc its a multiple choice, i'd defs agree, but again i've seen some whack as short answer questions stating that nerve impulses can go in any direction, but i think they mean that they can go in any direction to any neuron? idk

thanks guys!

[plsbegentle]

What exam paper is this lol? And very curious how many papers have people done already? o.O

[sweetcheeks]

@Hasiba I quite liked the paper. I liked the pregnancy question, it did require a fair amount of thought to understand and come up with a viable answer. Almost 2/3 of my class got 0 marks on the tRNA question, which I thought was really easy.

@plsbegentle; The exam is the STAV 2015. I have completed about 3 full practice exams, I find myself stopping towards the end and moving on to other exams (usually for other subjects).

[HasibA]

ive done sections of like 5 exams. im yr 12 so not too much time, but yeah bits and pices here to 'fill the gaps in my knowledge bucket' rather than just continue to 'fill a bucket with holes' [if u get this analogy LOL]

hmm , same for my class @sweetcheeks. i think i only missed out on 1 mark for it? my class and i are doing the 2016 STAV exam tmr for practice, i'll defs see how it goes haha

[hodang]

Thankyou so much Vox nihilli! Just one more question, for PCR the DNA strands are denatured right? We can use that word or dissociated right? And is it okay if we get the temperatures not exactly the same? Like write 50C when it's supposed to be 55C for example?

[Gogo14]

Thankyou so much Vox nihilli! Just one more question, for PCR the DNA strands are denatured right? We can use that word or dissociated right? And is it okay if we get the temperatures not exactly the same? Like write 50C when it's supposed to be 55C for example?

Yep they are denatured. I don't think they will get you recite the exact temperatures because the temperatures vary from each DNA strand, but as long as you are fairly close it shuld be fine

[hodang]

Thanks so much Gogo14!!

[HasibA]

anyone done the 2016 STAV exam units3/4? found it really good bar a one/two questions. I still believe nearly every company exam i do 'appears' to be harder than VCAA, but i think it's moreso VCAA is written far better :p

quick q-> do we have to know pretty much all the types of mutations, and their categories. eg missense, nonsense, and then specifically point, substitution etc. i've seen concept maps on the interwebz that are dense with info so idk :/ i know study design mentions it but yeahh ty!