Neco Model Questions Vol1 2018 Biology Question 3

Practice practical question 3 from the 2018 Neco Model Questions Vol1 Biology examination. This question covers Nutrition .

Neco Model Questions Vol1 2018 Biology Practical
Topic: Nutrition
Question 3 NECO_MODEL_QUESTIONS_VOL1 • 2018 • BIOLOGY • practical

A group of students carried out a qualitative test for reducing sugars in three food samples (A, B and C) using Benedict’s reagent. The sample that gave a positive result was then quantified by spectrophotometric analysis. The spectrophotometer was calibrated with standard glucose solutions as shown in the table below. **Standard glucose solutions** | % (w/v) glucose | Absorbance (A) | |----------------|----------------| | 0.2 | 0.12 | | 0.4 | 0.24 | | 0.6 | 0.36 | | 0.8 | 0.48 | The unknown sample gave an absorbance of 0.33. The unknown was prepared by dissolving 2.0 g of the food in 100 mL of distilled water. Answer the following:

Question Parts

( a )
State the observation for each of the three food samples when Benedict’s reagent was added and identify which sample contains reducing sugars.
( b )
Using the standard curve (assume a linear relationship passing through the origin), calculate the concentration of reducing sugar in the unknown sample in % (w/v). Show all steps.
( c )
If the original sample was prepared by dissolving 2.0 g of the food in 100 mL of water, estimate the percentage (w/w) of reducing sugar in the food sample.

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About This Question

This is Neco Model Questions Vol1 2018 Biology Question 3. It is one of the practical questions from the 2018 Neco Model Questions Vol1 Biology examination.

The question covers Nutrition .

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