Waec Model Questions Vol1 2019 Biology Question 3

Practice practical question 3 from the 2019 Waec Model Questions Vol1 Biology examination. This question covers Nutrition .

Waec Model Questions Vol1 2019 Biology Practical
Topic: Nutrition
Question 3 WAEC_MODEL_QUESTIONS_VOL1 • 2019 • BIOLOGY • practical

A group of students carried out a qualitative and quantitative analysis of starch in three food samples (Sample X, Sample Y and Sample Z) using the iodine test. The procedure involved extracting the soluble starch from 2.00 g of each sample, reacting the extract with iodine solution, and comparing the colour intensity with a standard colour chart. The colour chart relates intensity rating (0‑5) to starch concentration in the extract as follows: 0 = 0 mg, 1 = 40 mg, 2 = 80 mg, 3 = 120 mg, 4 = 160 mg, 5 = 200 mg. The intensity ratings obtained were: Sample X – 3, Sample Y – 5, Sample Z – 2.

Question Parts

( a )
Calculate the percentage (w/w) of starch in each sample.
( b )
Rank the samples from highest to lowest starch content.
( c )
Identify two possible sources of error that could affect the accuracy of the percentage values obtained.
( d )
Suggest one modification to the procedure that could reduce each of the errors identified in part (c).

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About This Question

This is Waec Model Questions Vol1 2019 Biology Question 3. It is one of the practical questions from the 2019 Waec Model Questions Vol1 Biology examination.

The question covers Nutrition .

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