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Essay question - HSN forum

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Essay question


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#1 christine

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Posted 09 March 2006 - 10:34 PM

biggrin.gif hi

i'm doin higher biology this year biggrin.gif (love it) and we are on unit 3 just now, we are doing some practise essays on monday 13th of march and i was looking for some practice ones to do if anyone can help?

One on "genetic control" and one on "physiological homeostasis". sad.gif

I have been on the scholar site which is brilliant biggrin.gif if you havent been on, you have 2 be a registered user (our school does it for us in various subjects) and i have done both essays on there, 1 on "Jacob-Monod hypothesis of gene action" and the other on " give an account of how the glucose and water concentraions of the blood are controlled by negative feedback". rolleyes.gif

So basically I am wondering if any1 has any essay titles they can give me to do or reccomend any from the higher past papers to do with "genetic control" and "physiological homeostasis"??? unsure.gif

please help me !!!! blink.gif - i want to do well!!! cool.gif cool.gif cool.gif

Christine

#2 werlop

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Posted 10 March 2006 - 12:03 AM

Erm I'll just give you a couple of things to think about for homeostais.

I can't remember how much detail you do at higher, so I'll ramble lots and you can pick and choose.

The concept of homeostasis: the processes concerned with maintaining a stable internal environment. I.e. the physical and chemical stability of the internal environment in which cells live is the essential condition that makes possible the free, independent existence of the whole animal.

Under normal conditions and state of health, homeostasis depends on adaptive mechanisms in the body which range from control centres in the brain to hormones in the blood. Crucial homeostatic control is exerted over virtually all the properties of the blood. The most rapidly controlled of these are its pH and CO2 level.
The internal environment. This is not to be confused with the intracellular fluid, or cytoplasm. It is the fluid which bathes most cells in a complex animal, essentially an ultrafiltrate of blood.

As life evolved, cells stayed together to form multicellular organisms. Animals evolved a “skin” to allow control of the fluid their cells were bathed in. This fluid is the “internal environment".
Body Water: Note that in mammals typically 60% of body weight is water – and about 35% of body weight is intracellular water.
N.B. The steady state is not a fixed state.

The processes of homeostatic control almost all include the older (in evolution) parts of the brain; the brainstem and hypothalamus. Centres for control of respiration for example are found in the medulla, while osmoregulatory neurones are found in the supraoptic nucleus of the hypothalamus. The autonomic nervous system and endocrine system are both key parts of the homeostatic systems.

Control systems in both engineering and physiology usually involve a sensor, which measures the factor being controlled, an amplifier, which makes the signal larger, and a negative feedback system which applies the amplified error signal back to reduce the error. So the error signal is inverted, and fed-back the other way up. For example, suppose you are dehydrated. Your high blood osmolarity is then detected by osmoreceptors in the brain. The signal they produce is processed to produce (a) thirst (which drives you to drink, thereby diluting your blood and hence internal environment) and (b) the hormone ADH which minimises water loss in urine so you lose more salt than water – also diluting the blood.

So basically in an essay you want to explain all that and then mention some specific examples, eg glucose homeostasis, blood pressure, renin-angiotensin system, baroreceptors, chemoreceptors, temperature control, sympathetic/parasympathetic nervous system and their involvment in vasoconstriction/dilatation...

I honestly can't remember how much you cover of this in higher... A good reference book I use for physiology is Guyton and Hall: http://www.amazon.co.uk/exec/obidos/ASIN/0...8499573-0603832
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#3 christine

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Posted 10 March 2006 - 08:11 PM

smile.gif thanx - a lot of info there to read !!

Christine biggrin.gif

#4 Isla from Banff

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Posted 16 March 2006 - 08:35 PM

QUOTE(christine @ Mar 9 2006, 10:34 PM) View Post

biggrin.gif hi

i'm doin higher biology this year biggrin.gif (love it) and we are on unit 3 just now, we are doing some practise essays on monday 13th of march and i was looking for some practice ones to do if anyone can help?

One on "genetic control" and one on "physiological homeostasis". sad.gif

I have been on the scholar site which is brilliant biggrin.gif if you havent been on, you have 2 be a registered user (our school does it for us in various subjects) and i have done both essays on there, 1 on "Jacob-Monod hypothesis of gene action" and the other on " give an account of how the glucose and water concentraions of the blood are controlled by negative feedback". rolleyes.gif

So basically I am wondering if any1 has any essay titles they can give me to do or reccomend any from the higher past papers to do with "genetic control" and "physiological homeostasis"??? unsure.gif

please help me !!!! blink.gif - i want to do well!!! cool.gif cool.gif cool.gif

Christine


can you take the piss anymore?! scholar is too easily for a higher paper trust me i used it last year and got my MEGA SIMPLE 14 year old brother to do that practice questions and he managed it's a waste of time!!!

xx
I'm not a tease i'm just a reminder of what you can't please!!!!!





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