BM - Monomers + Polymers

Question 1

Describe the processes of condensation and hydrolysis reactions and explain their importance in the formation and breakdown of biological molecules.
[6 marks]

Answer 1

• Condensation: Joins monomers by forming covalent bonds and releases a molecule of water (e.g., peptide bond in proteins, glycosidic bond in carbohydrates).
• Hydrolysis: Breaks polymers into monomers by adding water (e.g., digestion of starch into glucose).
• Importance: Allows synthesis of macromolecules essential for structure and function (e.g., enzymes, DNA).
• Enables digestion and energy release during metabolism.

Question 2

Compare and contrast alpha-glucose and beta-glucose, and explain how their structures relate to their functions in polysaccharides.

Answer 2

Differences:
* Alpha-glucose: -OH group below carbon 1.
* Beta-glucose: -OH group above carbon 1.

Functions:
* Alpha-glucose forms starch and glycogen (energy storage, easily hydrolyzed).
* Beta-glucose forms cellulose (straight chains, hydrogen bonding, structural support in plant cell walls).

Question 3

Explain how the structure of starch and glycogen relates to their roles in energy storage.

Answer 3

Starch:
* Composed of amylose (unbranched, compact) and amylopectin (branched, fast energy release).
* Insoluble, preventing osmotic effects in cells.

Glycogen:
* Highly branched, allowing rapid hydrolysis for energy release in animals.
* Compact for efficient storage.

Question 4

Describe the structure of cellulose and explain how it is adapted for its function.

Answer 4

Structure:
* Made of beta-glucose molecules linked by 1,4-glycosidic bonds.
* Straight, unbranched chains.
* Chains linked by hydrogen bonds to form strong microfibrils.

Function:
* Provides strength for structural support in plant cell walls.

Question 5

Explain the role of monomers such as glucose, amino acids, and nucleotides in the synthesis of polymers.

Answer 5

Glucose: Forms polysaccharides like starch, glycogen, and cellulose.

Amino acids: Link via peptide bonds to form polypeptides (proteins).

Nucleotides: Join via phosphodiester bonds to form nucleic acids (DNA and RNA).

Significance: Essential for cellular structure, metabolism, and genetic information.

Question 6

Explain the similarities and differences between starch, glycogen, and cellulose.

Answer 6

Similarities:
* All polysaccharides formed from glucose monomers.

Differences:
* Starch: Alpha-glucose, energy storage in plants, amylose and amylopectin.
* Glycogen: Alpha-glucose, highly branched, energy storage in animals.
* Cellulose: Beta-glucose, straight chains, structural support in plants.

Question 7

Explain how the structure of polysaccharides affects their rate of hydrolysis and their role in living organisms.

Answer 7

Structure:
* Starch and glycogen: Branched structure allows rapid hydrolysis.
* Cellulose: Straight, unbranched chains resist hydrolysis, providing strength.

Role:
* Starch and glycogen for energy storage and release.
* Cellulose for structural integrity in plants.