Percentage Error from equiptment used.

*An error is half the smallest possible reading.*

The errors can come from:

• Thermometer: reads to nearest degree celcius, half = +/- 0.5 degrees celcius error.
  
• Balance: Reads to two decimal places, so the error is half of 0.01, therefore, +/-0.005g

Working out errors:
Balance error- We weighed on the balance twice, therefore, times eror by two = 0.01, then:
0.01/mass weighed (calculated). You then multiply this by 100 to get the percentage error.

So:

1. Multiply error by how many times used. (I.e., two readings = multiply by two.)
2. Divide this by the mass weighed, which you should have calculated.
   
3. Multiply by 100 to reach the % error. (:
   

Thermometer Error-

1. Times the error by how many times used read off the thermometer. (So, two, would be 0.5 x 2 = 1) :D
   
2. Then you divide this by the difference in tempereature, which you should have calculated, or been given.
   
3. Multiply by 100 to get the % error.
   

Thereeeyougooo. All done for today, more tomorrow possibly, or friday. (:

Measuring energy changes.

If the energy given out is bigger then the energy put in, it's exothermic, if the energy put in is bigger then the energy given out, it;s endothermic.

q=mc(delta)T

q is the heat/enegry given out in joules.
m is the mass of the substance heated.
delta T is the rise in temperature in celcious or kelvin.
c is the specific heat capacity, usually 4.18 J/g/k

To get from equation to answer in KJmol-1, there are 3 basic steps:
1) Calculate Q from the info given, using q=mc(delta)T
2)Calculate moles of fuel from the mass of fuel burnt.
3) Divide 'q' by the moles to get the answer in joules, and then divide this by 1000 to get the answer in kJ

Insects :D

Key terms:

• Spiracles
• Trachae
• Tracheoles.
  

Some insects will have a high metabolic rate from springing, jumping, flying, etc. Need a lot of food for respiration to provide ATP for muscle contraction, in which case, they wouldwould need oxygen and some sort of system.

They are small, and therefore have a large SA/V ratio.

Exoskelton- skeleton on the outside. Hard, rigid and waxxy. Subject to dehydration,exo skeleton is waterproff to prevent this, and therefore, gases cannot be exchanged through the surface.

Tracheal System:

---------
| head |----------|-----------------)
---------| thorax |____abdomen_)
|_______|

Okay, yeah. I just drew a diagram of bug anatomy with my keyboard. Swish, eh?

Anywhoz...

Air enters the insect's body through valve like openings (spiracles) in the exoskeleton. These are located laterally along the thorax and abdomen of most insects.
Air flow is regulated by small muscles that operate one of two flap like valves within each spiracle -contracting to close the spiracle, or relaxing to open it.

Trachae are tubes that carry air directly to cells for gas exchange. They penetrate between cells and muscle fibres. After passing through a spiracle, air enters a longitudial tracheal trunk, eventually diffusing throughout a complex branching network of trachael tubes that divide smaller and smaller to recah every part of it's body.
At the end of each trachael branch, a specialised cell (tracheole) provides a thin, moist surface for the exchange of gases between atospheric air and a living cells.
Oxygen in the tracheal tube frist dissolves in the liquid of the tracheole and then diffuses into the cytoplasmof an adjacent cell. At the same time, carbon dioxide, produced as a waste product of cellular respiration, diffuses out of the cell and eventually out of the body through the tracheal system.

The muscle contracts using ATP from aerobic respiration, and then uses anerobic respiration, which produces lactic aicd, which is soluble in water, this lowers the water pressure in the muscle, and water then moves in by osmosis from the tracheole. Since the oxygen is dissolved, this makes a faster rate of movement of oxygen to muscles.

-Thoughts?

Nin. (:

SA/V ratio and temperatures. :D

What causes the higher body temperature of birds?
A high metabolic rate, so, when glucose is broken down, some is converted into heat energy, which maintains heat.

What is the relationship between bodymass and time spent feeding?
The greater the amount of time spent feeding, the lower the body mass, as, as the body mass increases the surface area to volume ratio decreases, therefore, there is less surface area to unit of body volume to loose heat through, so the rate of heat loss is slower, and hterefore, less energy is needed to maintain body temperatures (and also, food.)

Low raio of SA/V helps maintain a body temperature:
Large volume mean there are lots of cells repiring and producing heat energy. Also, surface area is relative to volume, and if it is very small there is less for heat to escape from, so rate of heat loss is slower.

How does the given trend: 'The greater body mass and length, relies on a higher latitude, and lower winter temperature', explain how possums adapt to where they live:
An increase in size means a reduction in SA/V ratio, meaning the area through which heat can be lost can be reduced, compared with the size of the posum. The conserves heat, and lowers the amount of energy required to maintain body temperature.

Suggest a reason for no adaptation in size in cooler climates:
SA/V is only one thing that can be adapted, other things like insulating fur can make a difference. As can higher metabolic rates, as more energy could be generated to compesate for heat loss. There are also behavioural habits like migrating and hibernating that could affect it.

(: That's alllll... :D

Fish and Counter Current Flow and that. (:

I have a feeling I've missed a little from what we studied, so I'll find my old notebook later and get it from there, but alas, fish: :P

Counter-current flow = Constant concentration gradient.

The water, and the blood in the blood vessels are flowing in opposite directions. Oxygen diffueses from the water into the blood, which causes the oxygen concentration in the water to fall. The concentration of oxygen in the blood, subsequently, rises. However, concentration of oxygen in water is always higher then in blood, therefore, a constant concentration gradient is maintained.

In the gills, the flow of water is in the opposite direction to the flow of blood, therefore, the concentration gradient is maintained. This means the blood is continually meeting fresh water with a higher percentage concentration of oxygen.
The concentration gradient is maintained across the gill lamellae and oxygen continues to diffuse into the blood. The same would not happen if they flowed in the same direction, as diffusion would only occur until equilibrium is reached, which is less effcient.
When in counter current flow, 90% of the oxygen the water contains if difused, whereas if it was parallel flow, only 70% would.


Thoughts?
-Nin.