SAC 3 - What's It all About?!

[drcrowthorne]

Hey guys,

I've just received 20, and 18 for my first two SACs, and I guess this is a two part question:

1. It it still possible for me to get like, over a 45 for Bio, or is that just out of my reach? :S

2. Our second SAC at MHS is thermoregulation with regard to excercise. We essentially have to formulate a hypothesis ourselves, and i've got a couple of questions about this.

My first question is:
 - What do i say in my hypothesis? Like, what does excercise do to CO2 concentration in the exhaled breath? I'm pretty sure that they hypothalmus causes vasodilation in the capillaries and arteries closest to the epidermis to cool the body most effectively. Is this right?

my second question is
 - If you guys did this SAC, are there any tips to get marks? Cause I really want to ace this SAC, otherwise i reckon i'll screw up my study score :S

Cheers,

drcrowthorne.

[LOLs99]

The third sac will most likely on plant growth and hormones.

[drcrowthorne]

Heay,'thatt is what a lot of people have been saying, but i know for a fact that SAC 3 will be on thermoregulatory action in terms of homeostasis, cause our teacher told us about the sac

[yellowsone31]

Last year, my third SAC was on tropisms

[Shenz0r]

It's still possible to get a 50 if you smash the exam, but that's going to be very tough. One of the 50s in Biology came from someone who got B+ SACs. And the dux (99.95) last year got B+ on his first English SAC.

Honestly, while SACs are important, you don't have to full-mark each one. All you need to do is maintain good grades. As my chem teacher says, "it's only 1 mark out of 200 out of 33%..."...which is less than 1% of your study score.

Your hypothesis is your educated guess. And it has to be falsifiable. That is, it can be proven to be incorrect. Your hypothesis can never be proved, only supported, but it can always be disproved.

The thing about your hypothesis, is that how are you going to test if the hypothalamus really does cause vasodilation in the arteries? How will you test that the arteries cool the body most effectively? There are other systems at play here too; decreased thyroxine production, decreased metabolism, decreased muscle movement...

For me my hypothesis would be that "The skin temperature will be lower immediately after the exercise than before, due to negative feedback. The temperature will then be elevated significantly by the removal of excess heat after exercise. As time progresses, the skin temperature will decrease gradually to its original temperature. The breath rate and CO₂ levels will rise immediately after the exercise but it will slowly decrease to normal levels."

If you've read over homeostasis you should know that the graph for body temperature sort of resembles a sine graph.

When you finish with your hypothesis, check: can it be falsified? We can measure heat, using a thermometer (or whatever we are really using). We can count the number of breaths per minute. The teacher is giving us something to measure CO₂ levels. So yes.

For getting the marks, make sure you know the topic well enough. It's all about applying, not memorising.

[drcrowthorne]

Thanks guys, that answered my question really well Thanks again

Drcrowthorne

[LOLs99]

It's still possible to get a 50 if you smash the exam, but that's going to be very tough. One of the 50s in Biology came from someone who got B+ SACs. And the dux (99.95) last year got B+ on his first English SAC.

Honestly, while SACs are important, you don't have to full-mark each one. All you need to do is maintain good grades. As my chem teacher says, "it's only 1 mark out of 200 out of 33%..."...which is less than 1% of your study score.

Your hypothesis is your educated guess. And it has to be falsifiable. That is, it can be proven to be incorrect. Your hypothesis can never be proved, only supported, but it can always be disproved.

The thing about your hypothesis, is that how are you going to test if the hypothalamus really does cause vasodilation in the arteries? How will you test that the arteries cool the body most effectively? There are other systems at play here too; decreased thyroxine production, decreased metabolism, decreased muscle movement...

For me my hypothesis would be that "The skin temperature will be lower immediately after the exercise than before, due to negative feedback. The temperature will then be elevated significantly by the removal of excess heat after exercise. As time progresses, the skin temperature will decrease gradually to its original temperature. The breath rate and CO₂ levels will rise immediately after the exercise but it will slowly decrease to normal levels."

If you've read over homeostasis you should know that the graph for body temperature sort of resembles a sine graph.

When you finish with your hypothesis, check: can it be falsified? We can measure heat, using a thermometer (or whatever we are really using). We can count the number of breaths per minute. The teacher is giving us something to measure CO₂ levels. So yes.

For getting the marks, make sure you know the topic well enough. It's all about applying, not memorising.

That makes me feel better because my first sac is B+.

[Shenz0r]

But remember if you get B+ for your SAC, look over what went wrong, what gaps in your knowledge there are, if you're getting B+ for your SACs, you need to put in heaps of work to pull of the high A+ in the exam.

SACs are just the school's way to getting you to study consistently instead of leaving everything up to the last minute before exams, in my opinion... (can't say the same for Chemistry @ MHS though - 3 SACs in May :O)

[Russ]

Your hypothesis doesn't need the negative feedback bit, but other than that you're set

[drcrowthorne]

I think a lot of people have been correcting my hypothesis, but I was sort of asking what i should write in the hypothesis. But, thankfully, i've actually managed to make one, so is this hypothesis alright, or should I adjust it?

That carbon dioxide (CO2) levels and surface or skin temperature of the individual will increase rapidly as a result of exercise, and decrease less after exercise has ceased, at a slower rate. That the breathing rate of the individual will increase as a result of exercise, and decrease at an equal rate after exercise has ceased.

I mean, personally, I thought that it might be a little generalized. But if it isn't, that's fine too.

Cheers guys

Drcrowthorne

[Shenz0r]

I would leave out the stuff on rates (i.e rapidly, or slowly - I'm aware I wrote it in mine though) but yeah that hypothesis is fine.

Your hypothesis states what you expect to happen. For example, for enzymes, "that the activity of enzymes will be affected by varying the temperature". Or, for the Beetroot SAC, that the "structural integrity of cell membranes may be affected by certain chemicals". It's an educated guess.

So say for example you wanted to test the effect of Manganese Dioxide as a co-factor in the breakdown of Hydrogen peroxide. Your hypothesis would be "That manganese dioxide affects enzyme activity in the breakdown of hydrogen peroxide".