2019 mokasa biology paper 3
- You are provided with the following: suspension labeled L, dilute HCl, NaOH, unboiled solution M1 and boiled solution M2.
- Perform procedures (i) to (iii) and in each procedure maintain the mixture at a temperature of between 340C to 38oC for 30 minutes and fill in the table that follows.
- Mix suspension L with 1ml of solution M1 and add 1ml of dilute HCl to the mixture.
- Mix suspension L with 1ml of solution M1 and add 1ml of NaOH solution to the mixture.
- Mix suspension L with 1ml of solution M2 and 1ml of HCl to the mixture.
Fill in the table below: (3marks)
| Procedure | Observation |
| i) |
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| ii) |
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| iii) |
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- Account for the difference in observation between procedure (i) and (ii) and (i) and (iii).
(2mks)
b) Identify solution M and give two reasons for your answer.
- Identity …………………………………………………………………… (1mark)
- Reason (1 mark)
c) You are provided with specimen K, hydrogen peroxide (H2O2) solution, stop watch, motor and pestle. Make two cylinders each measuring 2cm long. Crush one of the potato cylinders to make a paste and add 1ml of H2O2 solution to each of the potato paste and cylinder.
Between the two which one takes a longer time to stop producing foam?
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ii) Record the time taken by the crushed potato to stop producing foam. (1mark)
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Account for the above difference in time taken for foam to stop forming. (3marks)
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Calculate the rate of foam formation in the crushed potato cylinder. (3marks)
2. Study the diagrams below and answer the questions that follow.
a) i) Name part A,B,C,D (4mks)
(ii) State the adaptation of the part labeled A to its function. (2marks)
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(iii) State one function of the part labeled C. (1mark)
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State three adaptations of the parted labeled D. (3marks)
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Identify the structures that perform similar function as D, above, in:
- Amoeba……………………………………………………………………….. (1mark)
- Fish ……………………………………………………………………….. (1mark)
- The diagram below illustrates the life cycle of a certain organism.
- (i) Giving reasons, name the division to which the organism belongs.
Division……………………………………………………………………………… (1mark)
Reasons (2marks)
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(ii) Which portion of the plant’s life is independent? (1mark)
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iii) Name parts A & B (2mks)
(ii) State one function of the part labeled B. (1mark)
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(i) Define the term alternation of generation. (1mark)
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(ii) Identify the generations labeled K and L. (2marks)
K …………………………………………………………………………….
L ……………………………………………………………………………
(iii) In what way is generation L advantageous to generation K? (2marks
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