Biology/Physics ATP Preparation Thread

[Muhammad Talha]

http://www.xtremepapers.me/CIE/index.php?dir=Cambridge%20O%20Levels/5090%20-%20Biology/&file=5090_w09_qp_6.pdf
Q3b,can any one help me.
I did not understand even from markingscheme

Same number of shorter bean seeds and larger bean seeds are sown in a field with equal spacing. The soil is prepared by ploughing, adding water, and adding fertilizers in a uniform way before sowing. All other conditions such as light intensity, temperature and water supply at specific intervals are kept constant. When the plants develop seeds, the same number of seeds are collected as a sample and their length is measured. A table for the lengths of both shorter and longer bean seeds is made. The mean length of the seeds initially obtained from the shorter bean seeds will be less as compared to the ones obtained from larger bean seeds. For greater accuracy, the experiment should be repeated several times and the average lengths found out. This shows that "shorter bean seeds" is an inherited trait controlled by specific genes.
Hope this helped.

But how we will prove that the given statement is true or false??....plz help...

 

[Jinkglex]

it says of last few groups...what do they mean by that?..

 

[Muhammad Talha]

it says of last few groups...what do they mean by that?..

It means that on the x-axis we hv to take the group like "16-17" n on Y -axis we hv to show their total no of seeds in that group...bt m nt sure....!!!

 

[sksuriza]

http://www.xtremepapers.me/CIE/Cambridge%20O%20Levels/5090%20-%20Biology/5090_w09_qp_6.pdf

in question 3aiii) here i have a problem :s i dont understand how we are supposed to make that graph

u jxt have to concentrate
its a frequency graph so ofcoure no of seed will be at the y-axis
the length class(range) would be on the x-axis....
and draw a histogram its easy....
if u still have a prob u cn tell me

 

[sksuriza]

http://www.xtremepapers.me/CIE/index.php?dir=Cambridge%20O%20Levels/5090%20-%20Biology/&file=5090_w09_qp_6.pdf
Q3b,can any one help me.
I did not understand even from markingscheme

Same number of shorter bean seeds and larger bean seeds are sown in a field with equal spacing. The soil is prepared by ploughing, adding water, and adding fertilizers in a uniform way before sowing. All other conditions such as light intensity, temperature and water supply at specific intervals are kept constant. When the plants develop seeds, the same number of seeds are collected as a sample and their length is measured. A table for the lengths of both shorter and longer bean seeds is made. The mean length of the seeds initially obtained from the shorter bean seeds will be less as compared to the ones obtained from larger bean seeds. For greater accuracy, the experiment should be repeated several times and the average lengths found out. This shows that "shorter bean seeds" is an inherited trait controlled by specific genes.
Hope this helped.

But how we will prove that the given statement is true or false??....plz help...

the plants from which seeds were obtained were grown in different environments.... but they wre all small so its proven

 

[abcde]

^Exactly

 

[Jinkglex]

sorry i still dont get it :s

ok, so what i think the experiment has been is we have taken random seeds and planted them in same conditions (doesnt paper ask us to plant them in varying conditions) and then taken the seeds we got and measured them? how does that help? :s

 

[sksuriza]

sorry i still dont get it :s

ok, so what i think the experiment has been is we have taken random seeds and planted them in same conditions (doesnt paper ask us to plant them in varying conditions) and then taken the seeds we got and measured them? how does that help? :s

WT ABT THIS ONE
here u have to concentrate on ur knowledge abt heredity
n genetics....

here 1st u have to get a variety of seeds ie of different sizes....and ya
grown from the same plant.....keep in notice tht all other conditions (type of plant)should be kept constant to make a comparison....but plants whose seed r taken should be grown in different environment ie temp n soil concentaration.
but only one should be changed at a time ie u can change any 2 factors u like


once u have collected the seed u can compare them easily.,.....
u should record their sizes in tabular form n graph form.,.....
once u have achieved it u will notice that all the seed have lengths in the same range regardless of tall or small parents........





does it help or should i approach in a different way?

 

[Jinkglex]

ok, so we take seeds from same plant or species of plant, try growing them in different conditions, tabulate our results, and we find out that the range is the same, thus external factors/size of parents dont really matter??

 

[sksuriza]

ya it doesnt matter if the plants grown are tall or short.... they should be of same specie n we only have to change environment

 

[sksuriza]

we have to concentrate on seed not plants grown,.....
u r not gettin the point....
the plants whch are grown will give us the new seed for r results

R u Following?

 

[intelnehalem]

Just another quick question for you guys to prepare:

Describe an experiment to show that most water loss occurs from the lower surface of leaves . Conclude as to why this is so.

Please try and make your own questions and post here ! After the exams are over for M/J 2011, I will compile all the questions and answers and make it available for the next sessions

 

[intelnehalem]

Tips on testing for Reducing Sugar/lipids/Protein/Starch
Starch:
Crush and grind a given solid sample
either you can make a solution with this or you can directly proceed to adding Iodine solution
Place the sample on a WHITE TILE (important!!)
Add Iodine SOLUTION (iodine disqualifies, it should be iodine solution)
Colour change:
red brown to blue black if starch is present

Reducing sugars:
Always for solutions only
If solid sample, crush and grind add 2cm3 of water and make a solution
Add equal amounts of Benedicts solution(if you have a 2cm3 solution, you have to add 2cm3 of benedicts )
HEAT over a WATER BATH
Colour change if reducing sugar is present:
blue to green/yellow/orange if only a little concentration of reducing sugar present in test solution
otherwise it is blue to BRICK RED PRECIPITATE!!

Proteins:
Add 2cm of Sodium/Potassium Hydroxide solution into the sample
Add a few drops of Copper sulphate solution using a pipette into the test tube containing the sample
If proteins are present:
Colour change is blue(due to Copper sulphate) to purple/mauve/lilac!

Lipids:
If it is a DRY solid, crush and grind the sample
Place it in a DRY test tube (have to be dry otherwise the experiment will be inaccurate)
add about 2cm3 of ethanol to the test tube containing the dry sample
pour ONLY THE LIQUID PART OF THE SAMPLE SOLUTION containing ethanol into another test tube containing 2cm3 of water!
If Lipids/fats are present, a cloudy EMULSION is formed

Re-posting this as KarachiRocker requested!

 

[intelnehalem]

About genetics and Inheritance, we didn't get much notes about it since it is hard to do practicals on genetics in the school lab !
If you have any question, I''ll try and help

 

[KarachiRocker]

OK. You should use Cobalt Chloride paper for this. Remember paper is BLUE in normal conditions and PINK when water is poured onto it.
Stick the cobalt chloride papers on both the surfaces of leaf with the transparent tape by holding it using forceps. After that, place the plant in the sunlight for few minutes. After that you would measure the change of color. The more pinkish the color, the more water loss occurred from that place. The paper on lower surface would turn pink while the paper on upper surface will still be bluish.

Correct answer ?

 

[sksuriza]

correct.. but lower surface will be a lil pink

 

[KarachiRocker]

Pink to hai naaA Stop complaining Haha.

Thanks INTEL.

 

[KarachiRocker]

Sksuriza, when are you posting the guess paper ?

 

[intelnehalem]

OK. You should use Cobalt Chloride paper for this. Remember paper is BLUE in normal conditions and PINK when water is poured onto it.
Stick the cobalt chloride papers on both the surfaces of leaf with the transparent tape by holding it using forceps. After that, place the plant in the sunlight for few minutes. After that you would measure the change of color. The more pinkish the color, the more water loss occurred from that place. The paper on lower surface would turn pink while the paper on upper surface will still be bluish.

Correct answer ?

Absolutely !
And yeah, the upper surface may show a slight change to pink although this may not be the case always!

 

[sksuriza]

its ws sort of guess chapters.... as i mentioned earlier chapters like enzymes , plant diagram n labelling and use of microorganisms seems of utmost imp......
diffusion osmosis n inheritence are also imp...







my guess is tht it wud be a lil like as practical..... according to resources diabatic test of urine n plant structure r imp...... its a roush guess bt food tests r imp as well as plant diagrams