remembr for bio ppr 34

[UAEgurl]

these may be some helpful tips..

-we are likely to be asked to interpret unfamiliar data, e.g. result from an experiment you may
not have carried out or could not be carried out in a school. Dont be put off. Follow the same
rules as before. There will always be enough information in the question for you to answer it
-Follow the instructions for practical methods exactly. If you make a change in the method you
can alter the results
-Always label test tubes and other containers to help you remember which is which.
- If you are told to "Wash the apparatus thoroughly after each use" make sure you do. If there is
anything left in the apparatus the next stage may not work
-Make sure you put units!
-If you have to make calculations use the blank pages within the paper. Do not write in the
margin
.......................

lets all pray for the best tom!! ( well for those doing paper 34 bio) cant wait till the multiple choices r over and i'll be freee T_T

 

[fatema]

these may be some helpful tips..

-we are likely to be asked to interpret unfamiliar data, e.g. result from an experiment you may
not have carried out or could not be carried out in a school. Dont be put off. Follow the same
rules as before. There will always be enough information in the question for you to answer it
-Follow the instructions for practical methods exactly. If you make a change in the method you
can alter the results
-Always label test tubes and other containers to help you remember which is which.
- If you are told to "Wash the apparatus thoroughly after each use" make sure you do. If there is
anything left in the apparatus the next stage may not work
-Make sure you put units!
-If you have to make calculations use the blank pages within the paper. Do not write in the
margin
.......................

lets all pray for the best tom!! ( well for those doing paper 34 bio) cant wait till the multiple choices r over and i'll be freee T_T

Thanks... do u have any other tips and topics we need to know for practical

 

[UAEgurl]

well the i've heard tests are coming so here they r summarised up a bit: (benedicts test is long cuz i think we'll need it)

-The Iodine test is used to test for the presence of starch. Iodine solution is iodine dissolved in an aqueous solution of potassium iodide and it reacts with starch producing a purple black color from its original brown orange colour

-To test for the presence of monosaccharides and reducing disaccharide sugars in food we use the benedicts test. the solution to be tested is mixed with Benedict's test reagent (by volume, usually about 4 solution to 1 reagent) and heated almost to boiling which you can do by putting it in a water bath, for 4–10 minutes. NOTE that benedicts reagent is a mixture of (mainly) copper sulfate and sodium hydroxide.A color change from the blue of the reagent to almost any other color -- green, yellow, orange, red, brown -- is an indication of the presence of what are called "reducing" sugars. Reducing sugars are monosaccharides like glucose and fructose. Its imp. to note tht most disaccharides (like sucrose) will not give a positive Benedict's reaction. Sucrose produces a positive result with Benedict's reagent if boiled with dilute hydrochloric acid prior to the test and then neutralising it with sodium hydrogen carbonate. then carry out the test as you would for a reducing sugar

-biuret test is test for proteins and the Biuret Reagent is made of sodium hydroxide and copper sulfate. The blue reagent turns violet in the presence of proteins

- emulsion test for lipids - shake the substance with ethanol for a minute and pour this into water. if lipid present will turn milky.

 

[nisurju]

can u give some tips for microscope qsn?

 

[tpain365]

for the microscope thang, this link might be useful. jus remember that keep it cool in the preparation of the slide.
http://www.practicalbiology.org/observi ... 6,EXP.html

 

[tpain365]

@uaegurl are you sure we gotta neutralize the acid and sucrose sol with NaHCO3(it'd be complicated yo'). As far as i know NaOH is used in equal conc to that of the acid.

 

[UAEgurl]

oh yea u can use sodium hydroxide~ as long as it can neutralise the acidiness of the hcl and sample