Ch 04 P2 LifeProcesses

7/14/2019 Ch 04 P2 LifeProcesses

1/12

1988

Direction: Question 42 refer to the following information:

An experiment was set up to investigate the action on egg-white of a digestive juice collected from a

man. Four test-tubes were prepared as shown in the table below and the results were observed after

one hour.

Test-

tube

Egg white suspension(cm3) Digestive juice (cm3) pH Appearance* after 1 hour

P 1 1 2 cloudy

Q 1 1 7 cloudy

R 1 1 9 clear

S 1 1(boiled juice) 9 cloudy

*A suspension of egg-white appears cloudy and a solution of digested egg-white appears clear.

42. Which of the following can be concluded from this experiment?

A. Egg-white can be broken down by an alkaline solution.

B. The digestive juice works best in an acidic condition.

C. The digestive juice contains a protein-digesting enzyme.D. The enzyme in the digestive juice is denatured in an alkaline condition.

44. Which of the following suggests that enzymes are proteins?

A. Enzyme activity is reduced at low temperatures.

B. Enzyme activity drops rapidly at high temperatures.

C. Enzyme can speed up chemical reaction.

D. Enzymes are not used up during a reaction.

1989

20. The diagram below shows the lengths of three fresh potato strips before and after immersing

them in sugar solutions (X, Y and Z) of different concentrations:

solution X solution Y

solution Z

Before immersion

After immersion for one hour


2/12

The water potential of the sugar solutions increases in the order of :

A. X, Y, Z.

B. X, Z, Y.

C. Y, Z, X.

D. Y, X, Z.

27. The graph below shows the optimum pH values for the digestive enzymes X, Y and Z :

These enzymes can be found respectively in the

X Y Z

A. mouth pancreas small intestine

B. stomach mouth small intestine

C. stomach mouth liver

D. mouth pancreas liver

28. Consider the set-up shown below :

Which of the following will happen after 30 minutes ?

Weight of the contents

inside the dialysis tubing

Concentration of sucrose solution

inside the dialysis tubing

decreases increases

increases decreases

increases increases

doesn't change doesnt change


3/12

50. Which of the following statements about enzymes are true ?

(1) Enzymes always work best at 37oC.

(2) Enzymes are only secreted by digestive glands.

(3) Enzymes can speed up the breaking down of large molecules into small molecules.

(4) Enzymes can speed up the synthesis of large molecules from small molecules.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (4) only

D. (3) and (4) only

1990

15. Enzymes CANNOT work properly at high temperatures because

A. they are catalysts.

B. they are proteins.

C. they work on specific substrates.

D. they work best at 37C.

1993

Directions :Questions 5 and 6 refer to the following experiment. Four filter paper discs (I to IV)

soaked with different solutions were put onto the surface of a starch agar plate as

shown below :

III

II

I

IVwater Saliva mixed withacid

saliva

Boiledsaliva

Starch agar plate as viewed from above


4/12

5. After incubation at 25C for one hour, the paper discs were removed and the starch agar plate

was flooded with iodine solution. Which of the following shows the probable result ?

I

II

III

I

II

I

Key : blue black region

brown region

*6. When the starch agar plate was re-examined a few minutes later, the brown region(s)

disappeared and the whole plate became blue black. The likely reason for this is that

A. sugar molecules in the brown region(s) combined to form starch.

B. starch diffused into the brown region(s) from the surroundings.

C. exposure to air changed the brown region(s) to blue black.

D. iodine combined with the starch lower down in the brown region(s).

Directions : Questions 10 and 11 refer to the experimental set-up shown below :

10. What will happen to the liquid levels in tubings (1) and (2) after one hour ?

Tubing (1) Tubing (2)

fall fall

fall rise


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rise rise

rise fall

11. Which of the following graphs shows the likely changes in liquid level in tubings (2) and (3) ?

Key : tubing (2)

-------- tubing (3)

A. B. C. D.

liquidlevel

water

1994

50. The graph below shows the effect of temperature on the activity of salivary amylase :

Which of the following statements concerning salivary amylase is correct ?

A. It is denatured at 0C.

B. Its activity increases steadily with a rise in temperature.

C. It is most active at 60C.

D. It is killed at 80C.


6/12

1995

5. The diagram below shows a set-up to study the effect of amylase on starch. After 3 hours, water

in the beaker was heated with Benedicts solution and a red precipitate appeared.

Which of the following can be deduced from the above experiment ?

A. Glucose was formed from the digestion of starch.

B. Starch could not pass through the dialysis tubing.

C. The dialysis tubing allowed reducing sugar to pass through.

D. The water potential of the solution in the dialysis tubing increased.

6. When the word box is viewed under the microscope, which of the following can be seen ?

A. box

B. pox

C. xop

D. xoq

Directions : Question 7 and 8 refer to the graph below which shows the changes in mass of

a potato strip in distilled water at 20C :


7/12

7. The rate of osmosis is the highest between

A. hour 0 and hour 0.5.

B. hour 0.5 and hour 1.0.

C. hour 1.0 and hour 1.5.

D. hour 1.5 and hour 2.0.

8. Which of the following is a correct description of the potato cells between hour 2 and hour 3 ?

A. The cell were turgid.

B. The cell vacuole burst.

C. The cell wall was impermeable to water.

D. The cell membrane was fully permeable.

1997

3. Which of the following processes is carried out by osmosis?

A. the upward transport of water in the xylem

B. the reabsorption of glucose in the kidney tubules

C. the return of tissue fluid into the blood capillaries

D. the uptake of mineral salts from the soil into the root

4. The graph below shows the effect of the change in the external concentration of an ion on the

concentration of the ion within some plant cells :

Ion concentration

within the cells

(10-3

mol kg-1

)

1 2 3

40

0

20

External ion concentration(10

-3mol kg

-1)

Which of the following conclusion(s) can be drawn from the graph ?

(1) The ion is taken up by the cells against a concentration gradient.

(2) The uptake of the ion occurs only in living cells.

(3) The cell membrane becomes impermeable to the ion when the external ion

concentration reaches 2x10-3 mol kg-1

A. (1) only

B. (3) only

C. (1) and (2) only

D. (2) and (3) only


8/12

1999

Directions : Questions 8 and 9 refer to the diagram below, which shows the initial condition of

two set-ups :

8. After 1 hour, the liquid level in the capillary tube of set-up 2 is much higher than that of set-up 1.

Which of the following is a probable reason for this result ?

A. Solution 1 has a lower water potential than solution 2.

B. The dialysis tubing of set-up 1 is less permeable to water than that of set-up 2.

C. Sugar is produced in solution 2.

D. Less starch is present in solution 2.

9. Which of the following treatments might increase the rate of rise of the liquid level in set-up 2 ?

(1) using a narrower dialysis tubing

(2) using a capillary tube with a smaller internal diameter

(3) raising the temperature of the distilled water from 20 to 30

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) onlyD. (1), (2) and (3)

2001

4. Which of the following statements about enzymes is correct?

A. Enzymes are made up of proteins or fats.

B. Enzymes are denatured at 0.

C. The optimum temperature of most enzymatic activities is 37.

D. The activity of most enzymes is low at 80.


9/12

2007Directions : Questions 7 and 8 refer to the following experiment :

Two boiling tubes containing 5 cm3 of hydrogen peroxide solution and

1 cm

3

of catalase solution respectively were kept at 25C for 10 minutes.The contents of the two tubes were then mixed and maintained at the sametemperature, and the amount of oxygen released was recorded for 5 minutes.The results are shown in the graph below :

7. The line levels off at the 3rd minute. Which of the following is a correct explanation forthis ?

A.The reaction stops at the 3rd minute because catalase has been used up.*B. The reaction stops at the 3rd minute because hydrogen peroxide has

been used up.C.The reaction rate reaches the maximum at the 3rd minute because theamount of oxygen released is highest.

D.The reaction rate reaches the maximum at the 3rd minute because there is nomore increase in the amount of oxygen released.

8. The same experiment was repeated but the contents were kept at 35C. Which of thefollowing would best indicate the results of this experiment ?


10/12

2008

Directions: Question 13 and 14 refer to an experiment about osmosis. Three strips

of the same size were cut from a fresh potato and immersed into

sucrose solutions of different concentrations for four hours. The

experiment was repeated using a potato that has already been stored for

a certain period of time. The results obtained are shown in the table

below:

Concentration of

sucrose solution (%)

Percentage change in mass of the strips

Fresh potato Stored potato

0 +20.0 +25.05 +6.0 +10.0

10 -7.0 -2.0

13. The dependent variable in the experiment is measured as the percentage change in

mass of potato strips because

A. the final masses of the potato strips are different.

B. the initial masses of the potato strips are different.

C. there is a significant change in the mass of the potato strips.

D. the mass can be measured accurately by using an electronic balance.

14. Which of the following about the interpretation of the results is correct?

Water potential of

potato after storage

Explanation

A. decreases some starch is converted to sugars during

storage

B. decreases some starch is used for growing during storage

C. increases water is lost through evaporation during storage

D. increases the permeability of cell membrane increases

during storage

Directions: Question 35 and 36 refer to the graph below, which shows the results

of an investigation of an enzyme reaction performed by a group of

students:


11/12

35. Which of the following is the correct explanation for the above results?

A. More enzymes can be reused as the temperature increase.

B. Enzyme is made up of proteins, it is denatured as the temperature increases.

C. Enzyme collides with substrate more frequently as the temperature

increases.

D. Enzyme is inactive at low temperature and therefore there is no reaction at

0.

36. After the investigation, one of the students concluded that the optimum

temperature of this enzyme is 40. However, another student disagreed with this

conclusion. We can verify whether the conclusion is correct by repeating the

experiment

A. several times.

B. with a wider range of temperature.

C. with a smaller interval of temperature.

D. with a greater amount of enzyme and substrate.


12/12

1988

42 44

C B

1989

20 27 28 50

B B A D

1990

15

B

1993

5 6 10 11

A D A B

1994

C

1995

6 7

C D A

1997

3 4

C A1999

8 9

C C

2001

4

D

..

..

2007

7 8

B C

2008

13 14 35 36

B A C B

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Ch 04 P2 LifeProcesses