IGCSE Biology Paper-4: Specimen Questions with Answers 132 - 135 of 279

Passage

Plants produce glucose in leaves and convert some of it to sucrose.

Question 132 (7 of 7 Based on Passage)

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Short Answer▾

In plants the movement of sucrose is usually continuous. However, after 2 hours the movement of sucrose in tube X in Fig. 30.2 stopped.

Suggest why the movement of sucrose in tube X stopped.

Explanation

This movement of water and sugar molecules will continue until the concentration of entire system becomes uniform and will stop once a state of equilibrium is achieved. But if sugar molecules are either removed or converted into starch, the movement will continue endlessly.

Question 133

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One Liner▾

The same experiment was performed with trypsin, another protease enzyme.

Predict the optimum pH for trypsin.

Explanation

The optimum temperature and pH for the trypsin are .

Passage

A biologist performed an experiment to find the optimum pH for the activity of pepsin.

The enzyme activity was measured in four test-tubes. Each test-tube contained a cube of cooked egg white which contains protein.

Fig. shows the four test-tubes.

Solution of Enzyme

The biologist measured the time taken for the complete digestion of the cubes of cooked egg white.

Question 134 (1 of 2 Based on Passage)

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Temperature must be controlled in this experiment.

Describe how temperature could be controlled.

Explanation

Using water bath to regulate temperature.

  • Using incubator
  • Solutions must be equilibrated at a specific temperature
  • Using thermometer to check temperature

Question 135 (2 of 2 Based on Passage)

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The biologist ensured all the cubes of cooked egg white were the same size.

Suggest why.

Explanation

To provide equal surface area for enzymatic activity, it also allows comparison of product with proper experimental validation.

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