Biology P5

[angel eyez]

I MEANT ANYONE WHO HAS GOT AN ANS TO THIS QS???

 

[ParanoidAleveler]

Alright, let me give an entirely exam-oriented perspective at these statistical tests:

1) It is just math
2) They give you the formula, there is no memorisation required
3) It assumes you have knowledge on elementary statistics (i.e. mean, standard deviation)
4) It also assumes that you have brought a reasonably functional calculator with you
5) It is an excuse you can use when you are asked to suggest to what extent a given hypothesis is supported by the student's results (trust me, it's always the student that gets the results, they always use the term student in this type of thing, coincidence or lack of originality in CIE's part?)
6) They will give you this table for both tests with "degrees of freedom" and the "probability is greater than". These terms are unnaturally fancy for something this basic and so are the names "chi-squared" and "t-test". What're you trying to do, scare us teens from our pursuit of a career in science?
7) Degrees of freedom means the amount of freedom the data has when we are comparing them. This "freedom" is not the same as the "get out of jail" freedom. Don't think about it too much, it just means, in our sample of data, there is this amount of randomness due to the large/small number of data which we need to keep in consideration when calculating the values for the chi-squared and t probability. (In other words: the more the data, the more we need to consider the spread of it, hence we need to alter the testing values to suit the different numbers of data that may be presented to us) Mathematically, it is just n -1 where n = number of data.
8) Calculate --> Compare --> Reject (and by reject I mean reject the null hypothesis) What a null hypothesis basically is, is the exact opposite statement of what we are testing. If we are testing the difference between to sets of values, we say they are not different, so the tests let us prove ourselves wrong (scientists are so crazy that they love being proven wrong! What a hobby! :no: ). So, we calculate the t and chi-squared values using the formula that is given to us. Compare it with the respective value with the same degrees of freedom in the provided table (if your degree of freedom is not in the table, just find the values it lies between and find the mean of the respective probabilities of the two values, i.e. your degrees of freedom ins 29 but the table only lists values for 28 and 30. Now if the values at 28 and 30 are 2.1 and 2.2, respectively, then the value you're looking for is 2.15! Get it?) I don't remember how the value relates to the rejection or acceptance of the hypothesis but you have Pranav (AKA Zeebu) for that.
9) STAY CALM! This is just a small city of the big country we know as Biology P5, so please, if you don't understand it, stop wasting your time, move on and concentrate on better and more important things!
10) Good day!

You are freaking hilarious, man :lol:

thankyouuu for this! =)

 

[zeebujha]

Light independent process involves enzymes. At low temperatures the enzyme activity is low but it is not zero. So, we start the graph with a y-intercept. As the temperature increases, we begin to approach the optimum temperature of the enzymes. So, the rate increases. However, as we overshoot the optimum temperature, we begin to denature the enzymes involved in the process and thus the rate dips.

 

[angel eyez]

BTW THE QS IN ABT LIGHT DEPENDENT STAGE NOT INDEPENDENT STAGE...
WILL UR ANS B STILL THE SAME???

 

[angel eyez]

BTW THE QS IS ABT LIGHT DEPENDENT STAGE NOT INDEPENDENT STAGE...
WILL UR ANS B STILL THE SAME???

 

[princesszahra]

BTW THE QS IS ABT LIGHT DEPENDENT STAGE NOT INDEPENDENT STAGE...
WILL UR ANS B STILL THE SAME???

No it cannot be the same!

 

[angel eyez]

DO U NOE THE ANS??
ANYONE??

 

[princesszahra]

read from here
http://chemistry.about.com/od/lectureno ... esis_2.htm

 

[angel eyez]

N ONE MORE QS IN J/10/51 QS 1
Y IS LIGHT INTENSITY THE INDEPENDENT VARIABLE WHY NOT THE TYPE OF LEAF I.E.SHADE N SUN LEAF?????
PLZ ANYONE....

 

[honeycoveredcookie]

In Oct / 2007, question 3 a ii.
Why do they divide the value of X^2 by 58.42 ?
The mark scheme says 39.9/58.42; I can't understand why though.

 

[MukeshG93]

RESPIROMETER

- When using it to compare the rate of respiration of two different species, make sure the same mass of each species is used in the test.
- When testing the rate of respiration of seedlings, make sure they have not sprouted green shoots yet (as they will photosynthesize and give back the oxygen it takes and cheat us of our readings). Nevertheless, if you HAVE to use green sprouts, conduct the experiment in a dark room or in a container deprived of light)
- Soda lime and Potassium Hydroxide are two of the best carbon dioxide absorbents but always make sure to separate them from the individuals of the species using a wire mesh (keeping in mind the carbon dioxide has to make through from the organisms to the absorbent but the absorbents should not be able to come in contact with the organisms as they can be corrosive, poisonous, etc.
- Closing the clip on the respirometer to disallow the escape of air and opening it to reset the apparatus, blah blah, the basic workings will give you marks to write home about
- The use of a manometer or a gas syringe to measure the decrease in the volume of air inside the container is a staple to the answer
- Make sure the gas syringe is completely pulled so that a rather large decrease in volume can be measured for more accurate results
- You're supposed to time how long it takes for a particular decrease in volume to be indicated by the gas syringe or you can also measure how much of the volume decreases in a particular interval of time (for example: 2 to 3 minutes, more if you're measuring the rate for something really small or sluggish)
- Also, EQUILIBRATION TIME. You should allow time for the species to adapt to the environment of the respirometer.
- Temperature should be controlled.
- CLICHE: repeat procedure multiple times and take mean
- Rate of respiration = decrease in volume/time taken
- If you are planning to calculate the respiratory coefficient, remove the carbon dioxide absorbent (if the total volume INCREASES then the RQ is greater than one but if it DECREASES it is probably less than one)
- add more here

 

[angel eyez]

WELL M GETTING 39.9 AS THA ANS...
I THINK THEY HAV NOT DIVIDED....

 

[beacon_of_light]

THANKU....
I REALLY APPRECIATE...

HAS ANY1 DONE N/09/51??
THERE'S A QS ASKING TO MAKE A GRAPH OF TEMP V/S LIGHT DEPENDENT STAGE...
I CAN NOT UNDERSTAND WHY IS THERE A HORIZONTAL LINE N THEN DECREASING....???
ISNT IT SUPPOSE TO B INCREASING INITIALLY...???

M REALLY CONFUSED...

ANYONE WHO HAS THE QS TO THIS QS??? :Search:

well we know that light dependent reactions are light dependent not temperature dependent... so the rate remains constant initially ...but as the temperature increases and exceeds the optimum level, the membrane systems within the chloroplasts are damaged, hence, decreasing rate of light dependent reactions...
hope that helps

 

[angel eyez]

YEAH..
THNX ALOT

 

[beacon_of_light]

In Oct / 2007, question 3 a ii.
Why do they divide the value of X^2 by 58.42 ?
The mark scheme says 39.9/58.42; I can't understand why though.

No it's not that you have to divide the two values... the chi-squared value will be either 39.9 or 58.42 ... 39.9 when "E" is taken as 80 and 58.42 when "E" is taken as 58.42...

 

[MukeshG93]

N ONE MORE QS IN J/10/51 QS 1
Y IS LIGHT INTENSITY THE INDEPENDENT VARIABLE WHY NOT THE TYPE OF LEAF I.E.SHADE N SUN LEAF?????
PLZ ANYONE....

You are comparing the effects of light intensity on the two types of leaves so you would vary light intensity, wouldn't you?

 

[honeycoveredcookie]

In Oct / 2007, question 3 a ii.
Why do they divide the value of X^2 by 58.42 ?
The mark scheme says 39.9/58.42; I can't understand why though.

No it's not that you have to divide the two values... the chi-squared value will be either 39.9 or 58.42 ... 39.9 when "E" is taken as 80 and 58.42 when "E" is taken as 58.42...

Oh, HAHA.
I feel like an idiot.

 

[angel eyez]

YOU R RITE...
BUT DO V HAVE TO COMPLETELY IGNORE THE TWO TYPES OF LEAVES USED....
IT WILL MAKE A DIFFERENCE...

 

[beacon_of_light]

RESPIROMETER

- When using it to compare the rate of respiration of two different species, make sure the same mass of each species is used in the test.
- When testing the rate of respiration of seedlings, make sure they have not sprouted green shoots yet (as they will photosynthesize and give back the oxygen it takes and cheat us of our readings). Nevertheless, if you HAVE to use green sprouts, conduct the experiment in a dark room or in a container deprived of light)
- Soda lime and Potassium Hydroxide are two of the best carbon dioxide absorbents but always make sure to separate them from the individuals of the species using a wire mesh (keeping in mind the carbon dioxide has to make through from the organisms to the absorbent but the absorbents should not be able to come in contact with the organisms as they can be corrosive, poisonous, etc.
- Closing the clip on the respirometer to disallow the escape of air and opening it to reset the apparatus, blah blah, the basic workings will give you marks to write home about
- The use of a manometer or a gas syringe to measure the decrease in the volume of air inside the container is a staple to the answer
- Make sure the gas syringe is completely pulled so that a rather large decrease in volume can be measured for more accurate results
- You're supposed to time how long it takes for a particular decrease in volume to be indicated by the gas syringe or you can also measure how much of the volume decreases in a particular interval of time (for example: 2 to 3 minutes, more if you're measuring the rate for something really small or sluggish)
- Also, EQUILIBRATION TIME. You should allow time for the species to adapt to the environment of the respirometer.
- Temperature should be controlled.
- CLICHE: repeat procedure multiple times and take mean
- Rate of respiration = decrease in volume/time taken
- If you are planning to calculate the respiratory coefficient, remove the carbon dioxide absorbent (if the total volume INCREASES then the RQ is greater than one but if it DECREASES it is probably less than one)
- add more here

a little more...
To measure RQ , when the manometer fluid moves away from the tube containing living organisms ... more carbon dioxide is given out than oxygen consumed... and if the manometer fluid moves towards the tube containing living organisms, more oxygen is consumed than CO2 given out... then by using two formulas calculate RQ ...

 

[beacon_of_light]

In Oct / 2007, question 3 a ii.
Why do they divide the value of X^2 by 58.42 ?
The mark scheme says 39.9/58.42; I can't understand why though.

No it's not that you have to divide the two values... the chi-squared value will be either 39.9 or 58.42 ... 39.9 when "E" is taken as 80 and 58.42 when "E" is taken as 58.42...

Oh, HAHA.
I feel like an idiot.

Haha lol that's okey