Practical paper 1

Question 1

Devise a method to measure concentration of vitamin C changes during the course of a feed.

Answer 1

• Titration of breast milk using DCPIP.
• Standardisation technique.
• Use calibration of curve to determine vitamin C content in each breast milk sample.
• Repeat titration to achieve concordant results each time.

Question 2

Stat tests:

Answer 2

• Man whitney U test for comparing data.
• Spearman’s rank for general trend. The Spearman’s rank correlation coefficient (rs) is a method of testing the strength and direction (positive or negative) of the correlation (relationship or connection) between two variables.
• Chi squared test:The Chi-square test is intended to test how likely it is that an observed distribution is due to chance. It is also called a “goodness of fit” statistic, because it measures how well the observed distribution of data fits with the distribution that is expected if the variables are independent.

Question 3

Explain why pickling in vinegar would result in anthocyanin pigments leaving the onion cells.

Answer 3

Beetroot practical:

• Increased permeability of cell surface membrane.
• Low ph would change shape or denture proteins.
• Vinegar affects bonds in the protein.
• Vinegar acid can dissolve lipids.