Biology Unit 3 Questions Megathread

[HERculina]

let me attempt :

1)d (ive never heard of cholesterol doing a) )
2)c (adding more enzyme seems immediately more effective)
3)b (C3 because with C4 and CAM they grab C02 with a different enzyme i think that fixes it to a 4-carbon compund and not 3-carbon)
4)a (you either have steroid or protein hormones - lipid-soluble (travels straight into cell) or water-soluble (to surface of membrane) = peptide hormones would be water-soluble)
15) - havent covered this yet
20)d (all proteins can denature at high temperatures unless they already live in high temp. - i dont think prions can cause they enter our bodies)

wat are the answers
i havent tried tsfx yet, but it seems like you've gotten really good for MC with the other exams. have you done any VCAA ones yet? maybe then you can compare and see if these q.s are relevant.

[WhoTookMyUsername]

Thanks for the responses,

Hercules I'm doing VCAA 2009 in 20 minutes.

I haven't done that well in SA but i am improving

my scores in trial exams range from 60% - 90% so far which is alright as i haven't been taught and don't know half of the course that well

[HERculina]

I haven't done that well in SA but i am improving

me too. i just did the VCAA 2008 this morning, and i didnt do well in SA too. they are hard =(

[TrueLight]

What is the difference between Natural Killer Cells and Cytotoxic C Cells if they both kill virus infected cells?

just to add...
NK cells are part of the innate immune system (therefore can work early on in infection before CTL's get activated)
CTLs part of the adaptive immune system
NK cells work in a completely different way in terms of how they kill infected or abnormal cells (they have different receptors both inhibitory and activating receptors and can detect changes in MHC 1 levels) whereas CTL's have T cell receptor that is highly specific)
but they both kill with their cytotoxic granules (perforin, granzymes...)

[WhoTookMyUsername]

I haven't done that well in SA but i am improving

me too. i just did the VCAA 2008 this morning, and i didnt do well in SA too. they are hard =(

I did 2009 and yes, the MC is MUCH easier, i got 25/25 for MC and 40/50 for SA 87%

I'm quite happy with that, and i learnt a lot which was great.
Made a few silly mistakes, and didn't know some of the stuff

I do have a few concerns though

I can't seem to spend long enough on practice exams, i'm always finished within an hour even though i'm trying to slow myself down. Is this the same for everybody?


This was an MC Q that i'm confused about a bit

Q 11) Human and plant hormones are similar in that all are :

C) Signalling molecules that act on receptor molecules
D) Transported around the organism by a circulating fluid.

I know that C is correct, but why is D wrong, i was of the belief that hormones in plants were circulated in the phloem?

Also , when writing a scientific experiment, is your hypothesis taken directly from the question? Are you not allowed to extrapolate so that, instead of testing the effect of an enzyme or substance in an animal, you aren't able to take it out and place it in a test tube?

(that's what answers seemed to suggest)

[Russ]

Read every question carefully, the question states "all" and not all hormones will enter systemic circulation via some fluid

[Kaille]

how are chlororplasts involved in protein synthesis?

[Inside Out]

at the end of photosynthesis glucose can sometimes be converted to amino acids --> protein synthesis?
can someone correct me if im wrong :|

[WhoTookMyUsername]

Are neurimindase and hameuglutinin on influenza antigens (according to text) or enzyme (according to Insight 2009)

Also

Do gylcoproteins, lipoproteins, glycolipids all perform a role as antigens? Are antibodies just normal proteins?

[Russ]

Why can't they be both?
Conceivably, yes, anything specific to a pathogen can potentially serve as an antigen
Depends on the definition of "normal" but predominantly, yes.

[WhoTookMyUsername]

Thanks Russ
also

- Do amino acid derivates bind with receptors on the plasma membrane? Insight 2009 says they are hydrophobic and move through the plasma membrane while my textbook says otherwise.

Also , as neurons can recieve excitatory or inhibitarory charges, is an inhibitatory stimulus still considered a stimulus? (e.g. does -7 cause an action?) Thanks

[WhoTookMyUsername]

More questions

Is a G protien and secondary messenger or the instructor for precursor e.g. Cyclic AMP

What exactly is signal transduction?

One VCAA questions suggests neurotransmitters is a form of signal transduction ? or is it the signal is changed?

How are gene segments rearragend to form antibodies


Thanks!

[Russ]

Do amino acid derivates bind with receptors on the plasma membrane? Insight 2009 says they are hydrophobic and move through the plasma membrane while my textbook says otherwise.

Would depend on the structure of whatever the product was

Also , as neurons can recieve excitatory or inhibitarory charges, is an inhibitatory stimulus still considered a stimulus? (e.g. does -7 cause an action?) Thanks

Inhibiting a neuron to hyperpolarise it won't cause an action potential. But in order to do that, you need to send an AP via an inhibitory neuron that synapses with the target neuron and secretes an inhibitory neurotransmitter.

Is a G protien and secondary messenger or the instructor for precursor e.g. Cyclic AMP

Rephrase, this makes no sense.

What exactly is signal transduction?

If a signalling molecule (eg hormone) can't cross the membrane then it can't have an intracellular effect. So it binds something on the plasma membrane (ie receptor), which will transduce the message across the membrane into the cell. It's often coupled with amplification, so 1 signal molecule will cause (say) 10 effector molecules to be produced within the cell.

One VCAA questions suggests neurotransmitters is a form of signal transduction ? or is it the signal is changed?

Rephrase the second bit. I'm not an neuro expert but some neurotransmitters (Ach) will undergo signal transduction, yes.

How are gene segments rearragend to form antibodies

Very complicated answer, the further you go the more detail there is. Long story short, the gene has lots (100s) of different segments. You only need a few segments to make a functional antibody, so there is random rearrangement of the gene to transcribe only a few of them. Since it's random, we get different antibodies with every B cell.

[WhoTookMyUsername]

Is a G protien and secondary messenger or the instructor for precursor e.g. Cyclic AMP

Translation

Is a G protein a secondary messenger or simply another chemical that aids the transmission of a message from the receptor to a true secondary messenger such as Cyclic AMP.

One VCAA questions suggests neurotransmitters is a form of signal transduction ? or is it the signal is changed?

Translation - Can signal transduction refer to the changing of the signal - e.g. from electrical to chemical etc.

Thanks again Russ

After i finish my holiday's practice Q's today or tomorrow the influx of questions will cease

[Russ]

G proteins are membrane bound so they're not secondary messengers, they act to transduce signals.

Signal transduction refers to a signal being transduced across a membrane. This can be from electrical to chemical but you wouldn't use the term to refer specifically to that, it would refer to the overall process.