Polymers and biomolecules — Question 4

4a)

Enzymes convert starch into glucose via hydrolysis that breaks the glycosidic bond.

• identifies that enzymes break glycosidic bonds in starch to form glucose [1 mark]

• explains that enzymes convert starch to glucose via hydrolysis [1 mark]

4b)

• describes that the monomer for amylose and amylopectin is α-glucose [1 mark]

• describes that amylose contains 1,4-glycosidic bonds and amylopectin contains 1,4 and 1,6- glycosidic bonds [1 mark]

• describes that amylose has a straight chain structure and that amylopectin has a branched chain structure [1 mark]

• describes that amylose is helical in shape and that amylopectin forms spheres [1 mark]

4c)

0 1 2 2 1 2 +1 4 2

+ − − + − + −

C H O 2(C H O H)

2 C O

$\rightarrow$

+ 2

6 12 6 2 5

Carbon in glucose is oxidised to CO₂. Oxidation number increases from 0 to +4. Carbon in glucose is reduced to C₂H₅OH. Oxidation number decreases from 0 to –2.

• determines fermentation is a redox reaction [1 mark]

• explains carbon in glucose is oxidised to CO₂; oxidation number increases from 0 to +4 [1 mark]

• explains carbon in glucose is reduced to C₂H₅OH; oxidation number decreases from 0 to –2 [1 mark]

4d)

$\mathrm{M}\mathrm{o}\mathrm{l}\mathrm{a}\mathrm{r}\,\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}\,\mathrm{g}\mathrm{l}\mathrm{u}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{e}\,=\,180\,\,$

$\mathrm{M}\mathrm{o}\mathrm{l}\mathrm{a}\mathrm{r}\,\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}\,\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{o}\mathrm{l}\,=\,2(46)\,\,$

$(\mathrm{C}\,=\,12,\,\mathrm{H}\,=\,1,\,\mathrm{O}\,=\,16)\,=92\,$

$\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}\,\mathrm{e}\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{o}\mathrm{m}\mathrm{y}\,=\,\frac{92}{180}\,\times \,\frac{100}{1\,}=51\%$

• determines the molar mass of glucose is 180 and molar mass of ethanol is 92 [1 mark]

• calculates atom economy [1 mark]