Physiology of nutrition UE Past Papers Questions.

1. Define malnutrition and discuss the forms in which it can e manifested and symptoms aassociated with it.
2. Explain the process of digestion and absorption of nutrients in the body.

Answer / Solution

UNSOLVED

Determination of sugar content of soft drink.

A research wanted to determine the sugar content of a soft drink introduced recently in the market using the colorimetric dinitrosalicyclic acid method (DNS-method).

The principle behind this method is that, reducing sugars tend to reduce dinitrosalicyclic acid in an alkali media to form a coloured compound. The absorbance of the formed compound is determined by using a spectrophotometer at 520nm. The obtained absorbance is interpolated in a glucose solution standard graph to get the concentration of the sugar in the soft drink.

Procedure:

In soft drinks sugar is mostly present as sucrose, which in non-reducing disaccharide, so needs to be inverted to glucose (acid inversion). Because the reduction of dinitrosalicyclic acid is only performed in an alkali media, the acid solution is neutralized after completing the inversion.

1. The soft drink (1 ml) was added in 100 ml volumetric flask.
2. Then 2 ml of concentrated HCL(12N) was added to the same volumetric flask followed by 49 ml of distilled water.
3. The sample mixture was incubated at 60-70°C for 5 minutes to allow the inversion to take place and then cooled down.
4. The sample was later neutralized by adding 24 ml of NaOH(1N).
5. Distilled water was added to the volumetric flask to adjust the volume to 100ml.
6. From the sample, 0.5 ml of the solution was added in a test tube, followed by 1.5 ml of DNS reagent.(This applies also to Glucose standard solutions).
7. The sample was incubated at 100 °C for 5 minutes and then cooled fast by adding 10ml of distilled water.
8. The absorbencies of the sample (in duplicate) was measured using a spectrophotometer at 520 nm.

Preparation of glucose standard graph.

Standard glucose solution provided had 1.5g/L concentration. The standard glucose graph was obtained through serial dilutions making concentrations between 0.15 g/L to 1.5 g/L.

Question 1: For drawing a glucose standard graph, using dilutions of glucose concentrations of 0.15 g/L, 0.3g/L, 0.6 g/L, 0.9g/L, 1.2g/L and 1.5g/L, Calculate the volumes of the provided standard glucose solution (1.5 g/L) required to get solutions of these concentrations by diluting the standard solution wih water to make a total volume of 10 ml in each case.

Question 2: Given that the absorbencies for the glucose dilutions were:

Draw a glucose standard graph o Absorbance against Concentration taking into consideration that the concentration of the blank was 0.00g/L.

Question 3: Given that the asorbencies for the soft drink sample was 0.262 nm and 0.278 nm, using the standard glucose graph, calculate the concenration of he soft drink in g/L, taking into account of all dilutions made.

Answer / Solution

UNSOLVED

1. Illustrate the alimentary canal sysem, labeling all parts clearly.
2. Mention the factors which control food hydrolysis including enzymes which perform hydrolytic digestion.
3. Give an account of saliva and gastric juice contents.

Answer / Solution

UNSOLVED

1. Explain the processes of Carbohydrate metabolism.
2. Explain regulation of blood glucose.

Answer / Solution

UNSOLVED

1. Define transaminaion .
2. Explain how amino acids can be synthesized through transamination.

Answer / Solution

UNSOLVED