Deduce the straight chain structure of ribose from its ring structure drawn in section 34 of the data booklet.

Using the partial structure given, complete the structural formula of the molecule formed from the condensation of two cyclic \(\alpha \)-glucose molecules.

Constructing models that allow visualizations of the stereochemistry of carbohydrates is essential to understand their structural roles in cells.

Describe how Haworth projections help focus on the position of attached groups.

State one advantage of starch based polymers besides being biodegradable.

Biodegradable boxes made from polylactic acid, PLA, disintegrate when exposed to water.

State the formula of the product formed when water reacts with PLA.

All OH groups must be on the same side.

Accept structures with chiral carbon atoms shown as C or C* instead of crosses.

[1 mark]

Accept –O– in a straight line provided both H’s are above the plane.

[1 mark]

«allow» 3-D perspective of structures «of cyclic monosaccharide molecules»
OR
«show» cis/same side arrangement of «attached» groups
OR
«show» trans/opposite side arrangement of «attached» groups
OR
«make» carbon and hydrogen implicit

[1 mark]

abundant/renewable/allows use of «local» vegetation
OR
less use of fossil fuel/oil based plastics
OR
air permeable/better breathing of products
OR
«can be» mixed/blended with synthetic polymers

Do not accept answers related to biodegradable examples.

Ignore any reference to cost.

Accept “carbon neutral/do not contribute to global warming”.

Accept “require less energy to produce”.

Accept “do not produce toxic products”.

[1 mark]

HO–CH(CH₃)–COOH/CH₃CH(OH)COOH

Do not accept C₃H₆O₃.

Do not accept OH–CH(CH₃)–COOH.

[1 mark]