Biological Molecules
655 questions· page 1 of 66
What could take place during a hydrolysis reaction?
1 A glycosidic bond is broken.
2 A molecule of water is produced.
3 A sucrose molecule is split into fructose and glucose.
Options
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
Sugars with a ring structure can also have a linear structure.
Which sugar molecules could be represented by the linear structure shown in the diagram?
Options
A glucose, deoxyribose and ribose
B glucose only
C deoxyribose and ribose only
D deoxyribose only
Which statement about triglycerides is correct?
Options
A Each triglyceride molecule is formed by combining three fatty acid molecules with a glycogen molecule.
B A triglyceride molecule contains four ester bonds, each formed in a condensation reaction.
C Triglyceride molecules form a bilayer in the cell surface membranes of cells due to hydrophobic and hydrophilic interactions.
D The ratio of oxygen atoms to carbon atoms is lower for triglyceride molecules than for carbohydrate molecules.
Hydroxyproline is synthesised by addition of an –OH group to the R-group of the amino acid proline.
Hydroxyproline is a major component of collagen and has an important role in increasing the stability of its structure.
Which statement explains why the addition of an –OH group to proline could increase the stability of collagen?
Options
A It strengthens hydrogen bonding between the R-groups of adjacent polypeptide chains, resulting in a tertiary structure that is more resistant to heat denaturation.
B It increases the number of sites available for the formation of hydrogen bonds within the secondary structure of collagen, resulting in more stable alpha helices.
C It increases the formation of hydrogen bonds between R-groups and water molecules, which help to hold the chains of the collagen triple helix together by strengthening hydrophilic interactions.
D It strengthens the quaternary structure of collagen by providing more sites for hydrogen bonding between the R-groups of distantly separated amino acids within the same polypeptide chain.
Plant cell walls are strengthened by cellulose molecules that are arranged in several layers. Within each layer, the cellulose molecules are arranged in the same direction (parallel).
Which row shows the bonds that hold adjacent cellulose molecules together within each layer and the arrangement of cellulose molecules in different layers?
Options
| bonds that hold adjacent cellulose molecules together | arrangement of cellulose molecules in different layers | |
|---|---|---|
| A | glycosidic | in different directions |
| B | glycosidic | parallel |
| C | hydrogen | in different directions |
| D | hydrogen | parallel |
Galactogen is a storage polysaccharide in some animal species. It is a branched polymer that is formed from -galactose monomers.
Which comparison of galactogen with another polysaccharide correctly summarises one similarity and one difference?
Options
A Glycogen and galactogen are both branched, but glycogen is not a storage polysaccharide in animals.
B Glycogen and galactogen are both storage polysaccharides in animals, but glycogen is unbranched.
C Cellulose and galactogen are both branched, but cellulose is a structural polysaccharide found in plants.
D Amylopectin and galactogen are both storage polysaccharides, but amylopectin is formed from -glucose monomers.
Which levels of protein structure are always involved in forming the active site of an enzyme?
Options
| primary | tertiary | quaternary | |
|---|---|---|---|
| A | ✓ | ✓ | ✓ |
| B | ✓ | ✓ | ✗ |
| C | ✗ | ✓ | ✓ |
| D | ✗ | ✗ | ✓ |
key
✓ = always involved
✗ = not always involved
The diagrams show three different bonds.
Which bonds are found in an antibody molecule?
Options
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
The iodine test and the Benedict’s test were carried out on samples of a starch solution. Amylase was added to another sample of the starch solution and incubated for 10 minutes. The Benedict’s test was then carried out on this sample.
What were the results of the tests?
Options
| iodine test before adding amylase | Benedict’s test before adding amylase | Benedict’s test after adding amylase | |
|---|---|---|---|
| A | ✗ | ✓ | ✓ |
| B | ✓ | ✓ | ✗ |
| C | ✓ | ✗ | ✓ |
| D | ✗ | ✗ | ✗ |
key
✓ = positive result
✗ = negative result
Which row about -glucose and -glucose molecules is correct?
Options
| carbon atom on which the OH position is different | cellulose contains both molecules | |
|---|---|---|
| A | 1 | no |
| B | 1 | yes |
| C | 4 | no |
| D | 4 | yes |