bengkel menjawab sains 2010

7/30/2019 BENGKEL MENJAWAB SAINS 2010

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TO WRITE OBSERVATION AND INFERENCE (KERTAS 2 SECTION A)

Diagram 1 shows an experiment to study the reactivity of metal P, Q and R when reacts

with water within 5 minutes.

Rajah I menunjukkan satu eksperimenu ntuk mengkaji kereaktifan logam P, Q dan R apabila

bertindakbalas dengan air selama 5 minit.

Write down one observation for this experiment. [1 mark] Tuliskan satu pemerhatianbagi eksperimen ini.

Answer?? (Just choose any observation you can see at the diagram - the easiest is

to pick the most obvious reading.. ie: from metal Q)

--> The reaction between metal Q and water produces 30cm3 of hydrogen /gas

or(you can also answer like this - compare between metal Q & metal P)

--> The reaction between metal Q and water produced higer volume of

hydrogen / gas compared to the reaction of metal P and water.

But the second answer is longer...-----------------------------------------------------------------------------------

Write down one inference based on the result of this experiment. [1 mark]
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Tuliskan satu inferens berdasarkan keputusan eksperimen ini.

Answer?? (Clue - the gas production shows the reactivity of metal)

--> Metal Q is the most reactive metal when reacts with water

But can you answer like this??

--> Metal R is the least reactive metal when reacts with water


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THE VARIABLES ((KERTAS 2 SECTION A)

As from theprevious post, the next question is to write the variables involved.

In this question, you are requested to give the responding variable of the experiment..

Clue: Observe the diagram given.. what had changed??

From the diagram you'll see that it was the gas volume that's different for each measuring

cylinder.So, it must be the volume of the gas (hydrogen) is the responding variable, don't you

think?

Correct!!

The answer is: "The volume of the gas produced"

OR

You can also refer to the statement, "...to study the reactivity of metal..." at the beginning

of the question above... This statement shows the AIM of the experiment.

What are we going to study? The reactivity of metals... So, the reactivity of metals shouldbe the responding variable.

To answer, just COPY that statement back! ---> "The reactivity of metals" in the

answer area. You'll get correct answer!

Extensions:

Which, do you think are the

manipulated variable? (Clue: look back at the beginning of this question)

Can you see the statement, "...to study the reactivity ofmetal P, Q and R..."?In this experiment, we used three types of metal, right? Which means, we manipulate thetype of metals used for the experiment.. so, that IS the manipulated variable.

To answer this question, just write "The types of metal" in the answer area.

ORjust copy "Metal P, Q and R" from the statement...

Constant variable? (clue: Look at the statement AGAIN!)
http://medansains.blogspot.com/2009/12/to-write-observations-inference.htmlhttp://1.bp.blogspot.com/_csljYrAE4ek/SzdsVpt9QgI/AAAAAAAAALE/X1VECEwi-zQ/s1600-h/metal+reactivity1a.JPGhttp://4.bp.blogspot.com/_csljYrAE4ek/SzdpulHglJI/AAAAAAAAAK8/BNjlg5XGNLM/s1600-h/metal+reactivity2.JPGhttp://medansains.blogspot.com/2009/12/to-write-observations-inference.html


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Can you see the "...when reacts with water within 5 minutes."?

In this experiment, we fix the time of reaction to 5 minutes only, not 10, not 20. All three

measuring cylinders undergo the SAME time duration. It means, we made the timeremain CONSTANT along the experiment, this is the constant variable.

To answer, just write "Time of experiment" in the answer line. That's all!Share |

RELATIONS FROM GRAPH

What do you think is the answer?

(Clue: Look at the graph, you can see that the line is increasing in height from minute 0

to 5 and from volume 0cm3 to 18cm3)

The answer should be;

--> As time increases, the volume of gas (hydrogen) increases
http://www.addthis.com/bookmark.php?v=250&username=cikgunorzahttp://3.bp.blogspot.com/_csljYrAE4ek/Sz4PIAqaPqI/AAAAAAAAALM/vVfbcdrKAts/s1600-h/metal+reactivity5.JPGhttp://www.addthis.com/bookmark.php?v=250&username=cikgunorza


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TEKNIK MENJAWAB SAINS (KERTAS 2 SECTION C)

Question 10(Compulsory)

Study the following statement:

Kaji pernyataan berikut:

You are given a sterile nutrient broth andBacillus subtilis culture (bacteria culture).

''Anda diberikan bubur nutrient steril dan kultur Bacillus subtilis (kultur bakteria).

(a) Suggest one hypothesisto investigate the above statement. [ 1 mark]

Cadangkan satu hipotesis untuk menyiasat pernyataan di atas [1 markah]

Notes: You can use...

1.

the "The higher..............(MV) ..................., the lower............ (RV)

..................//viseversa" statement OR

2.

You can just COPY the statement in the box

as your answer. Both are accepted!

Answer:

"The higher the light intensity, the lower the growth ofBacillus subtilis"

Remember; use the named organism given in the question.

(b) Describe one experiment to test your hypothesis in l0(a) based on the following

criteria:

Huraikan satu eksperimen untuk mengkaji hipotesis di 10(a) berdasarkan kriteria

berikut:

(i) Aim of the experiment [1 mark] Tujuan eksperimen [1 markah]

(ii) Identification of variables [2 marks]Mengenalpasti pembolehubah [2 markah]
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(iii) List of apparatus and materials [1 mark]

Senarai radas dan bahan [1 mark]

(iv) Procedure or method [4 marks]

Prosedur atau kaedah [4 markah]

(v) Tabulation of data [1 mark]

Penjadualan data [1 mark]

Answer:

(i) Aim: "To study the effect oflight intensity on the growth ofBacillus subtilis

(bacteria)"

Note: The answer must begin with "To study....." then followed by MV and "on the"

RV.

In short, the answer should look like this "To study........MV...... on the..........RV.........."

-----------------------------------------------------

(ii) Variables:- (the CORRECT way to write the answer)

Manipulated - Light intensity Responding - The growth of Bacillus subtilis

Constant - (Temperature, humidity, nutrient, pH of nutrient broth) ie. other factors

that can affect the growth of microorganisms, or volume of nutrient broth/bacterialculture or number of days

Notes: PLEASE write down every variable separately! Don't just list all variables in oneblow.

For example... (WRONG way to answer).. Variables: Light intensity, growth of microorganism and volume of nutrient

broth.

-----------------------------------------------------------------------------

(iii) Apparatus and materials: (this time, PLEASE write all apparatus & materials

together - to avoid mistakes)

Bacterial culture, sterile nutrient broth, test tubes, sterile cotton wool, syringe

Note: list all materials & apparatus that are used in the experiment.

--------------------------------------------------------

(iv) Procedures: (you can answer in point form)


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Set up apparatus as shown in the diagram above (this type of answer must

accompanied with a labelled diagram as above)

Transfer1 ml (CV) of bacterial culture in each test tube and plug them withsterile cotton wool

Place the test tube in the following places:

A - under bright light }

B - on the cabinet } MV

C - in a dark cupboard }

Keep for2 days (CV)

Observe the cloudiness of the nutrient broth (RV) in each test tube and record

in the table

------------------------------------------------------------------

(v) Data: (in table form - should clearly stated the MV and RV on the title)

(MV) (RV)

That's all! - easily 10 marks for you....

Wassalam,
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bengkel menjawab sains 2010

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