bio 1

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1. 1990/I/1a

The diagram below shows four types of cells :

(i) Which of the above are plant cells ? State TWO plant cell features that are common to the cells you

have listed. (3 marks)

(ii) For each of the cells A and B

(1) suggest ONE function, and

(2) state ONE structural feature, as shown in the diagram, which is essential for this function.

(4 marks)

(iii) Describe the changes in cells C and D after they have been placed in distilled water for thirty

minutes. Explain your answer. (6 marks)

2. 1990/I/2a

In an experiment to study the effect of pH on enzyme activity, five test-tubes containing equal volumes of an

enzyme solution each at a different pH were prepared. A 1 cm3 cube of coagulated (clotted) egg white was

then added to each tube. The tubes were allowed to stand at a room temperature of 25 oC. The time taken for

the disappearance of the cube in each tube was recorded as follows :

pH of the enzyme solution Time take for the disappearance of the egg white

cube (min)

1

2

3

4

5

13

9

11

45

The cube still remained after 60 minutes

(i) How is the time for the disappearance of the egg white cube related to the rate of enzyme activity ?

(1 mark)

(ii) At which pH was the enzyme most active ? (1 mark)

HKCEE BIOLOGY | 1 The cell and its activities | P.1

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(iii) Suggest TWO ways to enable this experiment to be completed in a shorter period of time.

(2 marks)

(iv) Besides noting the time for the disappearance of the egg white cubes, suggest ANOTHER way to

measure the rate of enzyme activity in this experiment. (2 marks)

(v) Name a region of the human alimentary canal which secrets such an enzyme. (1 mark)

(vi) What control experiment should be carried out to confirm that the disappearance of the egg white

cubes is due to enzyme action ? (2 marks)

3. 1991/I/1a

Photomicrograph 1 show some cells of a human blood smear.

Photomicrograph 2 shows some cells of an onion epidermis.

(i) With reference to the photomicrographs only, state TWO structural differences between cell A and

cell C. (2 marks)

(ii) (1) The central part of cell B looks lighter in colour. Explain this with reference to its shape.

(2 marks)

(2) How is the shape related to its function ? (2 marks)

(iii) Cell A is found in large numbers in wounds. What is the function of cell A there ? (1 mark)

(iv) Describe and explain what would happen if cell B were put into a concentrated sugar solution for 20

minutes. (2 marks)

(v) Make a labelled drawing of cell C if the onion epidermis were put into a hypertonic solution for 20

minutes. (3 marks)

4. 1993/I/1a

Catalase is an enzyme that catalyzes the breakdown of hydrogen peroxide into water and oxygen. In an

experiment to study the activity of catalase in potato tubers, a 2 cm long cylinder of potato tissue was

prepared using a cork borer. The cylinder was cut into 10 discs which were put into the barrel of a syringe.

Then 10 cm3 of dilute hydrogen peroxide solution was drawn into the barrel and the mouth of the barrel was


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sealed by a rubber cap. The gas released was collected as shown in the diagram below :

The volume of gas collected in the barrel was recorded throughout the experiment as shown in the table

below :

Time (min) 0 1 2 3 5 10 15 20 25 30

Volume of

gas collected

(cm3)

0

1.0

2.0

2.5

3.0

4.0

4.5

5.0

5.0

5.0

(i) Present the results of the experiment in the form of a graph. (3 marks)

(ii) At which time interval was the reaction rate

(1) the highest ?

(2) the lowest ? (2 marks)

(iii) Explain the changes in the reaction rate throughout the experiment. (4 marks)

(iv) On the same graph that you have plotted in (i), sketch a curve to show the volume of gas likely to be

collected throughout the experiment if 20 potato discs had been used instead of 10. (2 marks)

5. 1994/I/3b

A 10 cm long potato strip was placed in a sugar solution. Its length was measured at regular intervals over a

period of 3 hours. The results are shown in the table below :


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Time (hour) Length of the potato strip (cm)

0

0.5

1.0

1.5

2.0

2.5

3.0

10.0

9.7

9.4

9.1

8.9

8.8

8.8

(i) Present the results in the form of a graph, which should have a suitable title. (3 marks)

(ii) Explain the change in length of the potato strip in the first hour. (4 marks)

(iii) (1) From your graph, find the period of time during which the length of the potato strip remained

unchanged. (1 mark)

(2) Explain why there was no change in length during this period. (2 marks)

6. 1995/I/1a

Ordinary washing powder does not remove egg stains from clothes easily. These stains, however, can be

removed by biological washing powder.

Below is some information given on a packet of biological washing powder :

(i) Explain why the biological washing powder can remove egg stains from clothes more easily.

(3 marks)

(ii) Why is it necessary to soak the clothes in a solution of this washing powder for several hours before

washing ? (1 mark)

(iii) Suggest a way to shorten the soaking time. Explain your answer. (2 marks)

(iv) Why is it not advisable to use this washing powder with water at temperature above 60oC ?

(1 mark)

(v) Suggest why this washing powder should not be used with silk and wool. (1 mark)

Ingredients:

� Protease 0.2%

� Detergent 15%

Directions:

� Soak clothes in a solution of the washing powder for several hours before washing.

� Use warm water for best results.

� Do not use water at temperature above 60oC

Cautions:

� Do not use with silk and wool.

� Rinse your hands well after contact with this product.


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7. 1996/I/4a

In order to study the conditions for osmosis, a student prepared two set-ups as shown in the diagrams below.

The skin of each potato was removed and a cavity was made for holding the sucrose solution.

(i) Explain why the level of sucrose solution of set-up A rose after 12 hours. (3 marks)

(ii) What can you conclude from the results of the two set-ups ? (2 marks)

(iii) Referring to set-up A, draw a labelled diagram to show the possible appearance of a complete potato

cell which is in contact with

(1) the sucrose solution,

(2) the distilled water. (4 marks)

(iv) At the end of the experiment, sucrose was found in the distilled water in set-up B. Explain why this

occured. (2 marks)

8. 1998/I/1b

Two similar pieces of dialysis tubing were set up as shown in the following diagrams. The concentrations of

the sucrose solution and the glucose solution were the same.

The height of the solution column in each capillary tube was measured and recorded in the table below :


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Height of solution column in the capillary tube Time (min)

Set-up A(mm) Set-up B(mm)

0 0 0

10 103 25

20 170 40

30 200 45

40 205 46

50 205 44

60 205 41

(i) Present the results in the form of a graph. (4 marks)

(ii) Explain the change in the solution level in the capillary tube of set-up A during 0 - 20 minutes.

(3 marks)

(iii) Explain the difference in the rate of change of solution levels between set-ups A and B during 0 - 20

minutes. (3 marks)

9. 1999/I/1c

Jelly contains a kind of protein called gelatin, which causes the jelly solution to solidify after cooling. In

order to prepare some jelly for a party, Mary dissolved the jelly powder in different ways as shown in the

table below :

Jelly solution Method of preparation

A Jelly powder dissolved in water at 40oC

B Jelly powder dissolved in water at 40oC + fresh pineapple juice

C Jelly powder dissolved in water at 80oC + fresh pineapple juice

(i) Solution A solidified after cooling while solution B did not. Suggest why

solution B failed to solidify. (2 marks)

(ii) Solution C was found to solidify after cooling. How would you explain the

difference in the results between solutions B and C ? (3 marks)

(iii) It is found that if beef is mixed with small pieces of fresh pineapple and left

to stand for about half an hour before cooking, the meat will become tender (less tough).

Based on the answer to (ii), explain why this treatment can tenderize the beef. (3 marks)

10. 2000/I/4a

In the production of beer, the raw material used is barley grains, which contain a large amount of starch.

When barley grains germinate, amylase is produced. The grains are then crushed and mixed with warm

water. After several hours, yeast is added to the mixture for fermentation.

(i) What is the action of amylase on the starch in the barley grains ? (1 mark)


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(ii) After the crushed grains are mixed with warm water, why is it necessary to wait for several hours

before adding the yeast ? (1 mark)

An investigation was carried out to study the effect of temperature on the activity of barley amylase. For

each temperature, the same amount of crushed grains and water were used. The amylase activity was

estimated by the rate of disappearance of starch using the iodine test. The results obtained are shown in the

graph below :

(iii) What conclusions can be drawn from the graph about the effect of temperature on amylase activity ?

(3 marks)

(iv) If you want to store the mixture of crushed grains and water with minimal reaction so that it can be

used several days later, what temperature would you choose ? Why ? (3 marks)

(v) Suggest another method to estimate the amylase activity for this investigation. (2 marks)

11. 2002/I/4c

A kind of Chinese dessert is made by mixing milk with ginger juice so that the milk becomes coagulated.

The coagulation of milk is due to the conversion of a soluble milk protein into an insoluble form. To find out

the conditions for milk coagulation, a person mixed milk at different temperatures with some fresh ginger

juice. The mixtures were observed for 15 minutes to see if coagulation would occur. The results are shown

in the table below :

Temperature of milk (oC) Result

20 No sign of coagulation after 15 minutes

40 Fully coagulated in 14 minutes

60 Fully coagulated in 1 minute

80 Fully coagulated in 1 minute

100 No sign of coagulation after 15 minutes

Note : The same study was repeated using boiled ginger juice and the milk did not coagulate at any

temperature.

(i) Referring to the above results, describe the effect of milk temperature on the rate of milk coagulation

by ginger juice. (3 marks)

(ii) How would you explain the action of fresh ginger juice in bringing about the coagulation of milk ?

Give evidence to support your answer. (2 marks)


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(iii) Milk protein also coagulates at low pH. In which part of the alimentary canal does this coagulation

occur ? Based on your biological knowledge, suggest why the coagulation of milk protein can

facilitate its digestion in that part of the alimentary canal. (3 marks)

12. 2003/I/3b

The following shows the procedure of an experiment to study the effect of pH on the activity of catalase

extracted from bean seedlings :

The results of the experiment are shown below :

pH of hydrogen peroxide solution T (s)

3 > 100

5 50

7 20

9 20

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(i) Explain why the paper discs rose to the surface of the solution in some of the tubes. (2 marks)

(ii) (1) Work out the rate of reaction from the value of T for each tube. Tabulate your answer.

(2 marks)

(2) Using the data obtained in (1), plot a graph on graph paper to show the effect of pH on catalase

activity. (3 marks)


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(iii) (1) Based on your graph, estimate the optimum pH, what further work would you carry out in this

experiment ? (1 mark)

(2) In order to get a more accurate estimate of the optimum pH, what further work would you carry

out in this experiment ? (1 mark)

(iv) A sample of bean extract was refrigerated at 4oC and then allowed to warm to room temperature. If

the experiment was repeated using this sample, would the catalase activity be different from that of

the previous experiment ? Explain your answer. (2 marks)

13. 2007/I/2

One day, when Keith and Jane walked past a fresh fruit juice shop, Keith noticed that some pears were cut

into pieces and stored in a tank of water before use.

(a) Keith thought that the shopkeeper stored the cut pears in water in order to extract more juice. Explain

the biological principle behind Keith's idea. (3 marks)

(b) Jane disagreed with Keith because she found that the shopkeeper also stored whole pears in water

tanks. Explain why this observation provides Jane with evidence to oppose Keith's idea. (2 marks)

(c) Suggest one possible hygienic problem of storing the cut pears in water tanks. (1 mark)

14. 2007/I/4

A student carried out an investigation to compare the activity of three brands of yeast. He added a mixture of

fixed amounts of dough and yeast into a measuring cylinder and recorded the volume of the mixture. After

putting the measuring cylinder in a water bath at 30oC for one hour, the volume of the mixture was recorded

again. The diagram below shows his set-up:

(a) The results of the investigation are shown in the table below. Complete the table by finding out the

percentage change in the volume of mixture for brand C. (1 mark)

Brand of

yeast

Initial volume of

mixture (cm3)

Volume of mixture

after 1 hour (cm3)

Percentage change in the

volume of mixture (%)

A 20 28 40

B 20 49 145

C 20 46

(b) Draw a bar chart to show the activity of the three brands of yeast in terms of the percentage change in

the volume of mixture. (3 marks)


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(c) Explain why the yeast can make the mixture rise. (3 marks)

(d) The student wants to make a cake that is the most spongy. Based on the above results, which brand of

yeast should be used? (1 mark)

(e) Why should the set-up be kept in a water bath? (1 mark)

(f) If the student wanted to study the effect of temperature on the activity of yeast, suggest two changes

that should be made in his experiment design. (2 marks)

15. 2008/I/4b,c

Read the passage below and answer the questions that follow.

(b) Later, scientists found that living cells are made up of many cellular structures. State two cellular

structures present in all living cells. (2 marks)

(c) The following table shows some steps of preparing a temporary slide of onion epidermis and the

purpose behind each step. Complete the table. (2 marks)

Step Purpose

Peeling of epidermis Separate a thin tissue for observation

Staining with iodine solution (i)

Adding a drop of water Reduce the refraction of light

(ii) Flatten the tissue

The Discovery of Cells

Most cells are too small to be observed with the naked eye. Thus the existence of cells

remained unnoticed until 17th

century. In 1665, Robert Hooke studied a thin section of cork

under his self-made compound microscope. He found that the cork was made up of many

units which he named ‘cells’. According to his observation, a cell is an empty space

bounded by a thick wall. At that time, Antonie van Leeuwenhoek, using the single-lens he

made, discovered single-celled organisms.


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16. 2008/I/6

Ginger milk curd (薑汁撞奶) is a Chinese dessert. Below is a recipe of this dessert.

Having studied the recipe, a science student, Kelvin, conducted an investigation on the making of ginger

milk curd. He followed the steps in the recipe with the use of raw ginger juice for one setup and boile ginger

juice for another setup. The results are shown below:

Result

Boiled ginger juice No coagulation

Raw ginger juice Coagulation occurred

(a) With reference to the treatment used by Kelvin, what do you think is his hypothesis about the

coagulation of milk in making ginger milk curd? (1 mark)

(b) What is the principle behind the design of this investigation? (1 mark)

(c) Kelvin then carried out another investigation on the effect of temperature on milk coagulation by

cooling the boiled milk to different temperatures before mixing it with ginger juice. He found that milk

coagulation only occurs at around 65oC. After that, he would like to test if boiling of milk is necessary.

Suggest the procedure he would have to carry out in his test. (2 marks)

Recipe:

1. Grind the ginger to obtain some ginger juice.

2. Boil the milk.

3. Wait until the temperature of the milk drops to around 65°C.

4. Pour 220 mL of milk into 15 mL of ginger juice.

5. Ginger milk curd is made as the milk coagulates.


bio 1

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