1.3 Flashcards
What is the role of starch? (1)
Explain each of its properties. (6)
(1) energy store in plants
- (1) insoluble —> (4) osmotic balance in cells = unaffected + can’t diffuse out of the cell easily
- (2) compact —> (5) stored in a small space
- (3) hydrolysed easily to form a-glucose —> (6) transported easier for respiration
What are the 2 components of starch? (2)
Explain their properties (4+3)
(1) Amylose:
(1) a-glucose = UNbranched
(2) C1-C4 = glycosidic bonds
(3) tightly coiled
(4) compact = ideal for storage
(2) Amylopectin:
(1) a-glucose = branched
(2) C1-C4 & C1-C6 = glycosidic bonds
(3) globular
What is the role of glycogen? (1)
What is its structure? (3)
(1) energy storage in animals
— (1) a-glucose = highly branched
— (2) C1-C4 & C1-C6 = glycosidic bonds
— (3) smaller chains than amylopectin
What are the properties of glycogen? Explain each. (6)
(1) insoluble = (4) cell’s osmotic balance unaffected
(2) compact = (5) stored in small spaces
(3) smaller chains than amylopectin = (6) hydrolyses more easily for respiration
What is the role of cellulose? (1)
What is the structure of cellulose? (4)
— (1) structural strength in plant
(1) repeated B-glucose monomers
(2) to form glycosidic bonds, each B-glucose has to be rotated 180 degrees compared to the next monomer
(3) C1-C4 = glycosidic bonds
(4) straight & UNbranched
Describe the 4 properties of cellulose? (8)
(1) cellulose chains = (5) form microfibril chains = fibres
(2) Hydrogen cross-links = (6) form between each parallel layer to make it stronger
(3) Prevents cell wall from bursting = (7) its strength withstands pressure
(4) exerts pressure = (8) which allows the cell to stay turgid = MAX. S.A. for photosynthesis
“Explain 1 way in which starch molecules are adapted for their function in plant cells.” (2)
ANS MATCH IN ORDER
(1) insoluble // helical // large molecule
(2) doesn’t affect WP // compact // cannot leave the cell
“Explain how cellulose molecules are adapted for their function in plant cells.” (3)
(1) Long & straight chains…
(2)… become linked together by MANY HYDROGEN BONDS to form fibrils…
(3)…which provides strength
“Explain the difference in the structure of the starch molecule & the cellulose molecule.” (2)
(1) starch formed from = a-glucose
cellulose = B-glucose
(2) in cellulose only, the position of hydrogen & hydroxyl groups on C1 is inverted
“Glycogen is a very effective storage carb. Describe & explain 3 features of glycogen that makes it well suited for energy storage.” (6)
(1) Poorly soluble = (4) water potential in cells = unaffected
(2) compact/highly branched = (5) it can fit into small granules
(3) easily synthesised & broken down = (6) rapidly responds to insulin & glucagon
