Mr Rayon

Methane (CH4), ammonia (NH3), water (H2O), hydrogen chloride (HCl), butane (C4H10), phosphine (PH3), oxygen (O2), carbon dioxide (CO2), ethene (C2H4), nitrogen (N2), ethyne (C2H2).

And how do you know?

Please someone respond in less than an hour!

It really depends on what kind of stem cell research you are talking about. There will be different issues associated with embryonic stem cells compared to adult stem cells, etc.

Could you list the differences?

What are the pros and cons of stem cell research? I am supposed to form an argument about it tomorrow for an oral presentation for English. I am supposed to convince my class that I am right by using many persuasive techniques (e.g. bias). The oral is supposed to be 5 minutes long.

What are the ethical issues of stem cell research?

Thanks

What's everybody worried about?

Is it more correct to say the HIV or the HIV virus?

...

What is common to all proteins?

All proteins contain carbon, hydrogen, oxygen and nitrogen. In addition to these, some also contain sulfur and phosphorus.

How much of it would be found in a protein (at minimum)?

I'm still not sure. I guess, C, H, O and N. But that still leaves B and D.

The formula that represents a protein is compound

A. C18H32O2

B. C58H114PNO8

C. C600H1000O500

D. C708H1130N180O224S4

The answer is D. Please explain why B is not a good answer.

The drift velocity is directly proportional to the current in the conductor. If electrons have a drift velocity of 1.6*10^-4 m s^-1 for a current of 10 A in a certain conductor, what would be their velocity if the current was 5.0 A?

What is drift velocity by the way? Any help on the above will be appreciated!

Introduction

Any organism whose temperature alters very little, despite variations in the surrounding temperature, must have mechanisms that are regulating its body temperature. Under normal circumstances, humans maintain a body core temperature in the range of 36.1°C to 37.8°C. When the core temperature is in this range, it provides the optimum conditions for the body to functions. External factors, infection or exercise can cause the body to make changes to regulate its core temperature. And these responses may be physiological or behavioural.

Purpose

To investigate the responses of the human body to extremes of ambient temperature.

Materials

Each group will require:

-oral thermometer

-skin thermometer

-alcohol swabs

-buckets/tubs

-hot and cold water

-ice cubes

-spray bottle

-stopwatch

-electric fan

-heater

-sleeping bag

-bathing suit

-hat, scarf and gloves

Procedure

-Read the procedure and formulate an hypothesis about the effect that extremes in ambient temperature (after 20-minute exposure) will have on core temperature (as measured by an oral thermometer) and skin temperature in humans. Complete this section of data sheet 1.

-Identify the variable, control and the factors that will be kept constant. The experimental procedure whould take no longer than 30 minutes.

-Work in groups of 3 or 4. Stop if the subject/s feel unwell at any time.

Cold subjects:

-Record skin and core temperatures of the subject before you begin (Table 4.1).

-Make the subeject/s as cold as possible by:

-wearing bathers

-placing in a cold breezeway

-placing feet in buckets of icy water

-exposing the body to ice from a spray bottle containing icy water

Hot subjects:

-Record skin and core temperatures of the subject before you begin (Table 4.1).

-Make the subject/s as hot as possible by:

-wrapping in a sleeping bag

-wearing a hat, scarf and gloves

-sitting in front of a heater

-For both cold and hot subjects, record the core and skin temperature every 2 minutes, as well as any other observations (Table 4.1)

-Record the class results

Results

Data Sheet 1

2) Identify the:

a) variable: I'm guessing this would be temperature.b) control (explain how it will be used): I'm not sure what the control is here. We had only two groups. Two people from each group were put into conditions of extreme cold or warm external environment.

c) constants:

__________________________________________________________________________________________________

Well, the above is what's written in the sheet of the practical part of a SAC that my school did for biology. I have used the red colour to indicate the parts that are not typed in my practical sheet, and are just my thoughts. Any way in the above what would be the control and constants? Can someone clarify if temperature would be the variable? I think we were suppose to go through this in class but my teacher forgot. What's typed here as well as the next page (not shown here) will be brought to school as reference material for my SAC on Monday. We are also allowed to bring one A4 sheet of notes as a cheat sheet.

Any thoughts on the questions above will be appreciated!

i use the nature of biology books book 2 third edition... btw, sorry if u had your sac today and got no further help. I was busy all day yesterday with paretn teacher interviews (yawn), so i couldnt even og on to this.

Oh no it's postponed. It will be tomorrow or Monday I think.

EDIT: So if you really want to help you still can!

Hi there! I have a SAC tomorrow on thermoregulation (the practical). Would anyone would be able to answer a few questions that I might think of in preparation for the written work that is to be done during class time (day after tomorrow)? For SACs we usually just get a series of questions instead of doing practical reports.

Basically, the SAC will be on the effects of the human body to a range of different temperatures, with strong emphasis in the extremes. i.e. how the body responds to really cold and really hot environments.

So far I've done a bit of researching and reading on the topic and found little things like: vasoconstriction or vasodilation of arterioles and capillaries.

However, does anyone know if there is more that I can do? How can I prepare for this oncoming SAC? What sorts of questions should I expect in the SAC (question sheet)? We are usually allowed one sheet of A4 paper as a cheat sheet so it would not have questions as simple as, "...how does shivering generate heat? Explain".

Anyway...feel free to ask me any questions on the topic as I need all the help I need!

let me guess... Voltman, you have a SAC. I know this because the last time i came on this forum, for sac help, you had one too and asked me what school i went to. Guess what... i have a Blood glucose sac now as well.

I do have a SAC tomorrow, but it's on the nervous and hormonal system (thermoregulation). It will demonstrate how the human body responds to different temperatures. For example, the contraction of errector pili muscles (think I spelt that right) to pull hair up and trap heat, when external conditions are cold. I have gone through everything and memorised the common responses made by the body to extremely hot and cold external environments. But I am not sure what to do next. Any ideas on how I can prepare for this?

Maybe we can helop each other out, along with the fellow helpful contributers.

Yes, that would be great!

I agree with all but the first two posts. I also heard that glucagon inhibits production of insulin as one of its many effectts, and visa versa for insulin. Is this right?

Well, that's what I heard. I asked a tutor at yourtutor.com.au also and essentially they said that it is sort of true. I think there is a period where they are both secreted, before the inhibition of one starts to effect the secretion of the other. Can anyone confirm?

However, I'm not quite sure because I have a diagram of all this in my textbook and it does not mention this. It sort of contradicts my above theory. But it's definitely worth looking into.

Also, what kind of questions will they have on it. Mine cant just be abiut insuling and glucagon, rioght?

Well, I wouldn't know, every school does these things a little bit different. Have you been to this site: http://www.vcenotes.com ?

There are lots of VCE students online that may be able to help you with that over there.

BTW, what textbook/s do you use to study biology?

Merged post follows:

I'm not sure which is right?

When I said the above quote, I meant if there was a high blood glucose level, would only insulin be produced? i.e. the secretion of insulin would inhibit that of glucagon. Or is glucagon still produced but in lesser quantities along with more insulin? I know it's not something big to worry about, but I have to get the wording right. In an exam, it could be this knowledge that seperates me from a point or two.

Where did you hear that? .

I got it from here:

http://www.biologymad.com/resources/A2%20Homeostasis.pdf

Check out the last sentence of page 4.

Merged post follows:

They counter each other constantly to maintain proper blood glucose levels.

Okay, so let me just ask you this question. If blood glucose levels were to go above the normal range, would alpha cells in the pancreas produce less glucagon and beta cells in the pancreas produce more insulin?

Well, that's what my textbook says. But apparently, there is more to it then that. I'm not sure which is right?

Is it true that insulin and glucagon can never both be produced at the same time? If so, why? I find this pretty interesting...

Hi everybody! I'm interested in hearing how the body responds when it is faced by conditions of freezing and hot climate. For example, vasodilation of arterioles and capillaries occur when the body is faced by extremes in heat. However it does the opposite when conditions are cold. Does anyone know where I can possibly get a list of all these different responses to different external temperatures faced by the body? Or if this is not possible, if anyone could tell me some interesting reponses made by the body to different temperatures.

Anything relevant said of the above will be appreciated!

...

Shouldn't this be in "homework help"?

Oh yes, I guess so. When I go on here my mind always tell me to go the biology section instead. Woops...do I have the power to move a thread? I wonder...

The Gila monster is a venomous lizard, native to several south-western US states. This lizard eats only four times a year. It has the ability to activate its pancreas at these times, whereas at other times the pancreas is inactive. The saliva of this lizard has a hormone, exendine-4. This a 39-amino acid peptide that is secreted when the lizard eats. The effect of exenrine-4 is to stimulate insulin production, inhibit glucagon secretion and slow down the rate of the stomach emptying.

a) Name the cells in the pancreas that produce insulin.

b) Why is it necessary for the lizard to produce insulin at a meal?

c) Explain the significance of the action of exendin-4 in inhibiting glucagon production.

Synthetic exendin-4 is currently being trialled as a drug teatment for people with type 2 diabetes. Excess glucagon production is a major factor in their heperglycaemia. Synthetic exendin-4 has all the properties of the naturally occurring exendin-4,

d) How does slowing down the emptying of the stomach help people suffering from type 2 diabetes?

The drug, exendin-4, stimulates insulin secretion in the presence of elevated glucose concentrations, but not when blood glucose levels are low.

e) Explain how this property of exendin-4 gives an advantage over insulin injections for diabetics.

f) Exendin-4 has the disadvantage that it needs to be injected. Give one possible reason why it needs to be injected rather than taken orally.

_______________________________________________________________________________________

Are these reponses right? Well, any help, clarification or/and confirmation on the above will be appreciated.

6a) Beta cells of the pancreas

b) The insulin production would decrease the blood-glucose levels after the lizard has finish eating its meal.

c) If glucagon production production were to take place (as is the case in the absence of exendin-4) the blood-glucose levels would skyrocket after the meal. This would lose the lizard lots of energy, and make it harder for it to survive if it only eats four times a year.

d) Slowing down the emptying of the stomach helps people suffering from type 2 diabetes by making them feel fuller, longer.

e) Not sure

f) Not sure

it`s called the "two-point threshold test"

As usual you haven't been a dissapointment. Your contributions to this forum continue to impress many.

What's the difference between a synapse and a synaptic cleft? I've looked at the definition that my textbook gives me but they seem sort of similar. So, are these synonyms or are they supposed to be different? If they are different when would it be appropriate to use one of them as opposed to the other? If anyone could show two different sentences where it would be most appropriate to use the two terms, it would be greatly appreciated!

one that I find interesting is to get 2 sharp pencils of equal length (not sharp enough to cause skin injury), and put them side by side, with your victim blindfolded, put the 2 pencil points to their skin to that both tips touch at exactly the same time, then ask if they can feel 1 or 2 points.

try this in various places on the skin.

Then increase the distance between the 2 pencils and do it again, record your results.

what it will show is nerve density for a given area, some not so hot zones you can have a nerve servicing a patch of skin over an inch sqr (they will only feel One pencil even though there is 2).

Okay...this one seems interesting. Do you know where I can out more about this experiment (I assume it is well known)?

...specifically involving the pressure receptors under the skin.

After a heart attack, people often have small amounts of lactate in the blood, which comes from the injured heart muscle. Suggest an explanation for this observation.

Well, I know that during anaerobic respiration lactic acid or lactate (for what I presume is the same thing) is produced as a by-product of respiration. However I fail to see the connection here? I don't really want to assume things which I am not sure of.

Any help will be appreciated!

Enzymes are responsible for both sperm and male sex hormone production in the testicles of human males. Some of these enzymes have an optimal termperature of 33°C, which is about 4°C lower than body temperature. If this termperature is increased or lowered, sperm and testosterone production is adversely effected?

b) What anatomical feature helps the testicles to maintain a lower temperature?

I'm not sure on what this question means by anatomical feature... the testicles are located below the core of the body? Would that be a sufficient answer?