2009-8-24 17:14 florence1314
bio f.2~4

唔識做
幫下我la
thx


Objective:
To let students get familiar with the medium of instruction in English in the Biology curriculum.

1.        Complete the following table concerning cell organelles.               (8 marks)
          Write your answers on the single lined paper.

Descriptions                                                                                           Name        Functions
May be present or absent in cells
When present, there is only one in each cell                                                               a.             b.
Present in all living cells,  exist in large numbers in active cells                               c.             d.
Contain a pigment, only found in plant cells but not present in all plant cells               e.              f.
Large and single in plant cells, small and multiple in animal cells                               g.              h.


2.        A kind of Chinese dessert is made by mixing milk with ginger juice so that the milk becomes coagulated. The coagulation (change from liquid to solid state) 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

a.        i.        Referring to the above results, describe the effect of milk temperature on the rate of milk coagulation by ginger juice.         
        ii.        How would you confirm that the results obtained are due to the action of an enzyme in ginger juice?

b.        A sample of ginger juice was refrigerated at 4°C and then allowed to warm to room temperature. If the experiment was repeated using this sample, would the enzyme activity be different from that of the previous experiment? Explain your answer.       

3.        Daniel carried out an experiment to study the diets of two bats. He suspected that one bat fed on blood and the other fed on fruit juice. He took some food samples from their stomachs and performed several food tests.

                              Food samples from bat A        Food samples from bat B
Appearance                              red liquid        colourless liquid
Albustix paper test                                         +        -
Benedict's test                                         +        +
DCPIP test                                                          -                        +
                (+: positive result; -: negative result)

a.        Describe the procedure of Benedict's test on the food samples from bat A and the positive result (if any).        (4 marks)
b.        Describe the procedure of DCPIP test on the food samples from bat B and the positive result (if any).                (3 marks)
c.        According to the results of the food tests, which bat fed on fruit juice? Explain your answer.                                                (3 marks)



4.        Read the news below and answer the questions that follow.

23 October 2004
Five men and seven women developed symptoms of ciguatoxin poisoning, including limbs numbness, diarrhoea and abdominal pain, after eating hump head wrasse in a sea food restaurant yesterday. The Department of Health reminded the public to be extra cautious when eating large coral reef fish. To prevent ciguatera fish poisoning, a spokesman of the department advised the following:
•        eating fewer large coral reef fish
•        avoid eating the liver, guts, head and skin of coral reef fish
•        buying coral reef fish from reputable and licensed shops

a.        Explain why ciguatera fish poisoning is more likely caused by eating large coral reef fish.                                                (5 marks)
b.        Why did the spokesman suggest the public not to eat the liver, guts, head and skin of coral reef fish?                (1 mark)
c.        A student said that it would be safe if we cook the coral reef fish thoroughly before eating. Do you agree with this student? Give one reason to support your answer.        (2 marks)

2009-8-31 22:21 magiyafeimo
Objective:
To let students get familiar with the medium of instruction in English in the Biology curriculum.

1.        Complete the following table concerning cell organelles.               (8 marks)
          Write your answers on the single lined paper.

Descriptions                                                                                           Name        Functions
May be present or absent in cells
When present, there is only one in each cell
a. nucleus   b. contain the DNA of cell

Present in all living cells, exist in large numbers in active cells
c.  enzyme?           d. to activate the activity of cell

Contain a pigment, only found in plant cells but not present in all plant cells               
e. chloroplast             f.  absorb light

Large and single in plant cells, small and multiple in animal cells         
g. vacuole             h. isolating harmful material and waste

2.        A kind of Chinese dessert is made by mixing milk with ginger juice so that the milk becomes coagulated. The coagulation (change from liquid to solid state) 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

a.        i.        Referring to the above results, describe the effect of milk temperature on the rate of milk coagulation by ginger juice.         
There is no coagulation in 20 degree c. and the rate of coagulation increase when the temperature increase from 20 degree C. however at temperature from 60 to 80 the rate keep even and does not increase. And at 100 degree c no coagulation.

        ii.        How would you confirm that the results obtained are due to the action of an enzyme in ginger juice?
I could make a control by put only milk in the same temperature and see if coagulation occur.

b.        A sample of ginger juice was refrigerated at 4°C and then allowed to warm to room temperature. If the experiment was repeated using this sample, would the enzyme activity be different from that of the previous experiment? Explain your answer.        

no because the enzyme was in normal state and does not put in 100 degree c which will make it denature so it will function as usual.

2009-9-2 22:06 florence1314
thx for help<3*

2009-12-4 21:51 siupo_kathrine
個答案吾係咁咩?
Present in all living cells, exist in large numbers in active cells
c.  mitochondria        d. to undergo respiration to release energy

Contain a pigment, only found in plant cells but not present in all plant cells               
e. chloroplast             f.  absorb light energy to undergo photosynthesis

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