Neco 2019 Biology Question 4

Practice practical question 4 from the 2019 Neco Biology examination. This question covers Respiration rate, Respirometer .

Neco 2019 Biology Practical

Topics: Respiration rate Respirometer

Question 4 NECO • 2019 • BIOLOGY • practical

A student investigated the rate of respiration in germinating beans using a closed respirometer (BOD bottle). The set‑up was as follows: - Five freshly germinated beans (total fresh mass = 1.20 g) were placed in the bottle. - The bottle was filled with water and a water column of 0 cm was marked on the graduated tube attached to the bottle. - The cross‑sectional area of the tube is 3.14 cm² (radius = 1 cm). - The bottle was kept at a constant temperature of 25 °C for 30 minutes. - After 30 minutes the water level had risen to 2.5 cm. A control experiment (no beans) under identical conditions gave a rise of 0.2 cm. The student repeated the experiment at 35 °C and observed a water‑column rise of 3.4 cm (control at 35 °C gave 0.2 cm). Answer the following questions:

( a )

Calculate the volume of CO₂ produced by the beans at 25 °C (in millilitres), correcting for the control.

( b )

Determine the respiration rate expressed as millilitres of CO₂ per gram of bean per minute at 25 °C.

( c )

Repeat the calculation of the respiration rate for the experiment conducted at 35 °C.

( d )

Explain why the respiration rate increased with temperature, citing the underlying biochemical principle.

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This is Neco 2019 Biology Question 4. It is one of the practical questions from the 2019 Neco Biology examination.

The question covers Respiration rate, Respirometer .

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