CHAP 3 BIOLOGICAL MOLECULES

Question 1

Describe the ROLES of CARBOHYDRATES [2]

Answer 1

1) immediate source of energy - produces energy for cellular activities
2) Structural support for plant cells - cellulose is essential component of call wall

Question 2

Describe ROLES of FATS [3]

Answer 2

1) long term storage of energy
2) Insulation for the body
2) Solvents for fat-soluble vitamins A , D , E , K

Question 3

describe ROLES of PROTEINS [2]

Answer 3

1) synthesis of hormones & proteins
2) Forms antibodies to combat diseases

Question 4

Describe the synthesis of STARCH from glucose [2]

Answer 4

• glucose molecules are linked together in long straight chains / branched chains
• It is a storage molecule in plants

Question 5

Describe the synthesis of GLYCOGEN from glucose [2]

Answer 5

• glucose molecules are linked together in highly branched chains
• storage molecule in animals & fungi

Question 6

describe the synthesis of CELLULOSE from glucose [2]

Answer 6

• glucose molecules are linked in long straight chains
• similar to starch but differs in the glucose unit linkages

Question 7

State reasons why GLYCOGEN & STARCH are the storage forms of glucose in animal & plant cells respectively.

Answer 7

1) insoluble in water -> do not affect water potential in cells
2) too large to diffuse out of the cells -> remains in the cells
3) compact -> more glucose units are packed in a small space
4) easily hydrolyses into glucose for cellular respiration