1) The number of carbon-to-carbon double bonds (C=C) in a molecule can be identified by reacting the molecule with hydrogen gas, H2. The type of reaction involved is an addition reaction. 10.0 g of a fatty acid becomes fully saturated after reacting with 0.263 g of H2. The fatty acid is
A. oleic acid (M = 282 g mol-1).
B. linolenic acid (M = 278 g mol-1).
C. arachidic acid (M = 312 g mol-1)
D. arachidonic acid (M = 304 g mol-1).
Solution
2) Lactose is commonly found in milk and milk products. The enzyme used to hydrolyse lactose in the human small intestine is lactase. Lactose intolerance describes the limited ability of humans to hydrolyse lactose. Consider the following statements.
Which one of the following sets of statements is correct?
A. statement numbers 1, 2 and 3
B. statement numbers 1, 2 and 4
C. statement numbers 2 and 3
D. statement numbers 3 and 4
Solution
3) A commercial chocolate spread is commonly used in sandwiches and desserts. This food contains high amounts of proteins, triglycerides and sucrose. Proteins are an important part of food. Proteins are broken down into smaller molecules during digestion.
a. Proteins can be hydrolysed to produce alpha (α-) amino acids. Identify one structural feature common to all alpha (α-) amino acids.
b. i. What is the process by which amino acids are obtained from the chocolate spread?
ii. Identify the chemical process in which amino acids are predominantly used in the body.
iii. Two of the amino acids in the chocolate spread are aspartic acid and cysteine. Draw the chemical structure of the dipeptide Cys-Asp at high pH
Solution