Based on my analysis of the image, I need to identify which molecules are structural isomers - compounds with the same molecular formula but different structural arrangements.
Looking at the molecules in Figure 5.8:
1. Molecule 1 appears to be glucose (C₆H₁₂O₆), a linear carbohydrate with an aldehyde group.
2. Molecule 4 appears to be fructose (C₆H₁₂O₆), a ketose sugar with a different arrangement of functional groups.
3. Molecule 5 is a phospholipid with a different molecular formula.
4. Molecule 14 is another form of glucose, likely in its ring structure.
5. Molecule 15 is also glucose in a different ring conformation.
Structural isomers must have the same molecular formula but different connectivity or arrangement. Glucose and fructose are classic examples of structural isomers - both have the formula C₆H₁₂O₆ but glucose is an aldose (aldehyde group) while fructose is a ketose (ketone group).
Looking at the answer choices:
A. 1 and 4 - This would be glucose and fructose, which are structural isomers.
B. 5 and 14 - These have different molecular formulas.
C. 4 and 15 - Fructose and glucose (ring form) - these are structural isomers.
D. 13 and 15 - These appear to be different forms of the same molecule.
E. 14 and 15 - These are likely different conformations of the same molecule (glucose).
The correct answer should be A. 1 and 4, as these represent glucose and fructose, which are well-known structural isomers with the same molecular formula (C₆H₁₂O₆) but different functional group arrangements (aldehyde vs. ketone).
Parent Tip: Review the logic above to help your child master the concept of biology macromolecules worksheet.
