Biomolecules

Glycogen is a complex carbohydrate found in the liver of mammals. Which of the statements is / are true?

Statement 1: glycogen contains 1,4-glycosidic bonds between alpha glucose molecules. Statement 2: glycogen contains 1,6-glycosidic bonds between alpha glucose molecules. Statement 3: branches occur within the glycogen molecule by the formation of 1-6 glycosidic bonds.

• 1, 2 and 3

• Only 1 and 2

• Only 2 and 3

• Only 1

The figure show the general structure of an amino acid.

Which of the following statements is correct?

• R groups can form hydrogen bonds in the secondary structure of a protein.

• R groups can form hydrogen bonds in the tertiary structure of a protein.

• Groups X and Y can form peptide bonds in the secondary structure of a protein.

• Groups X and Y can form peptide bonds in the tertiary structure of a protein.

A student wrote the following statement:

‘Water is polar because the oxygen side of the molecule is slightly positive in charge.’ Which of the following options, A to D,

explains why this statement is not correct?

• Water must be non-polar because it can dissolve non-polar molecules like carbon dioxide.

• Water must be non-polar because it can pass through the fatty acid tails of phospholipids.

• The oxygen side of the molecule is slightly negative in charge, not positive.

• Water is not polar, it is charged.

Which of the diagrams, A to D, represents a dipeptide molecule?

• A

• B

• C

• D

Which of the molecules, A to D, can be described as a pentose monosaccharide with a general formula of Cx (H2O)y ?

• A

• B

• C

• D

The table shows the type of bond present in the different levels of structure for a protein molecule.

Which of the rows, A to D, is correct?

• A

• B

• C

• D

Which of the rows, A to D, from the table below indicates the type of bond present (✓) or absent (×) in the secondary structure of a protein?

• A

• B

• C

• D

The table below shows the results of the investigation.

Linseed oil is a polyunsaturated triglyceride that can be extracted from the seeds of the flax plant, Linum usitatissimum. A diagram of a linseed oil molecule is shown below.

Which of the options, A to D, identifies the bond labelled W?

• glycosidic

• phosphodiester

• peptide

• ester

Haemoglobin is a protein molecule found in mammalian erythrocytes. Which of the statements, A to D, about the structure of haemoglobin is correct?

• Primary structure does not contain any oxygen-carrying haem groups.

• Secondary structure is stabilised by hydrogen bonds between different polypeptide chains.

• Tertiary structure has two α and two β polypeptide chains.

• Quaternary structure is stabilised by peptide bonds between the polypeptide chains.