Paper 1 - Biomolecules

Question 1

Structure and function of starch / glycogen

Answer 1

• Polymer of a-glucose → stores glucose to be used for preservation to produce ATP
• Coiled = compact
• Branched - hydrolyses to release glucose for respiration
• Large - cannot diffuse out of cells through membrane
• Insoluble - doesn’t affect the WP of the cell
• Chemically inert

Question 2

Structure and function of cellulose

Answer 2

• Long,straight,unbranded chains of B-glucose

       → joined by hydrogen bonds - many of them provides rigidity for the walls
       → forms microfibrils 

• Prevents osmotic lysis

Question 3

Structure of DNA

Answer 3

• Polymer of nucleotides → contains deoxyribose sugar, phosphate and nitrogenous base
• Nucleotides held together by phosphodiester bonds
• 2 strands held by hydrogen bonds - 2 in adenine and thymine, 3 for cytosine and guanine
• Double helix

Question 4

DNA replication

Answer 4

1. DNA helicase separate 2 strands by breaking the hydrogen bonds between the bases
2. Both strands acts as templates
3. DNA polymerase joins adjacent free nucleotides together through phosphodietser bonds
4. Hydrogen bonds reform
5. This is semi-conservative replication