2009 Biology Unit 3 Exam Suggested Solutions

[n.f]

Thyroxin, although an amino acid hormone, can pass through the phospholipid cell membrane and its receptors are located in the cytoplasm so I'm pretty sure that model S is the correct one here.

The question was referring to TSH. I assume it is not under the same exception as thyroxine?

[Pumpkinator]

yeh this is what i first though but

TSH and thyroxine are totally different things

TSH - pepdtide hormone they can travel through the bloodstream but cant pass the cell membrane

Thyroxine - amino acid derivative that is however lipid -soulble they pass through the cell membrane

HOWEVER , the question is asking for TSH not thyroxine.

I know what u mean, i screwed up this question as well

[shinny]

Thyroxin, although an amino acid hormone, can pass through the phospholipid cell membrane and its receptors are located in the cytoplasm so I'm pretty sure that model S is the correct one here.

True, but as people were saying, it's asking for TSH. I typo'd in the amino-acid part so sorry for that. As for what you said though, it's true. Amino-acid derived hormones can go to the nucleus as they are small enough to fit through the pores.

[Pumpkinator]

is there such things as consequential marks in biology?

[shinny]

By the way, feel free to post your answers for the questions I haven't done as they're mostly the really wordy ones which I'm not too sure of how to write, or that I don't know it. If its a good answer, I'll chuck it up and give credit.

[scocliffe09]

6a2) should be afferent (sensory) neuron I think?

[shinny]

6a2) should be afferent (sensory) neuron I think?

Refer to here. If you've got a good argument against that though, go for it. I still don't really understand the diagram all too well.

EDIT: Actually I think I might still change my answer to sensory, gimme a sec.

[Greggler]

its in the spinal chord tho. it must be interneurone?why wouldnt it be?

[shinny]

It's quite debatable IMO. I'll just list the for and against and make your own conclusions on this.
Interneuron
1. It connects to a motor neurone
2. It's in the brain tissue

Sensory Neuron
3. It's continuous with the cell body of the sensory neuron which connects to the retina (which proves its a sensory neuron), and an interneurone needs to have its own cell body.
4. In relation to 1, it's not actually connecting to the motor neuron. It's connecting to the brain tissue in the background, and then to the motor neuron, with the brain tissue being representative of interneurons as a whole.
5. In relation to 2, it's just a horribly drawn diagram and it's actually connecting to the brain tissue; not within it.

EDIT: Just to add my own opinion, I think I'd be more inclined towards sensory neuron rather than interneuron as it doesn't depend on the fact that the diagram is incorrectly drawn, but rather, just drawn really badly and ambiguously. I don't think VCAA would let mistakes like missing an entire cell body pass through (or at least I hope not).

[Greggler]

that is so ghey if the actual brain tissue represents the interneuron
i had afferent, coz of the presence of the cell body. but then changed it when i saw that the arrow was pointint a a part withihn the brain tissue

[shinny]

that is so ghey if the actual brain tissue represents the interneuron
i had afferent, coz of the presence of the cell body. but then changed it when i saw that the arrow was pointint a a part withihn the brain tissue

It's a horrible diagram all-round =\ I really don't know what to make of it unless some of my assumptions above are wrong.

Also, that's probably all I'll do for tonight so no need to stick around. If you've got anything to add, then go for it and I'll chuck it in.

[Greggler]

thanks mate, this has truly relieved me so much
with your answers im pretty much looking at a 23/25 for MC and 45/50 which gives me a very pleasing 68
hopefully VCAA can keep it at around that lmao

[Pinkerbell]

For the centrifuge question, doesn't the nucleus sink first because it's the largest therefore heaviest organelle in the cell. Then, the answer's either C or D. Then because ribosomes are smaller than the other organelles, it's lighter as well therefore it would sink last. Hence the answer would be C.
At least, that's what I thought when I was doing the exam.

[Pinkerbell]

Hey, I'm just curious as to if you put more in your answer than was expected, but the information you provide is still right, would you get penalised for that? Because I think i elaborated on a few of the answers, but I hope that's okay. Oh and good luck to everyone!

[polky]

Hey, I'm just curious as to if you put more in your answer than was expected, but the information you provide is still right, would you get penalised for that? Because I think i elaborated on a few of the answers, but I hope that's okay. Oh and good luck to everyone!

Nothing wrong with elaboration, as long as it is relevant and accurate. (and as long as you finished the exam!)