Fats are excellent energy storage molecules because
a) they have a relatively high ratio of energy storing C—H bonds.
b)they have a relatively high ratio of energy storing C=O bonds.
c)they are hydrophobic and do not easily mix with water.
d)they have a relatively high concentration of oxygen atoms, which are very electronegative.
e) they are more difficult to hydrolyze than most other molecules.
The correct answer is a) they have a relatively high ratio of energy storing C—H bonds.
To understand why fats are excellent energy storage molecules, we need to consider their chemical composition. Fats, also known as triglycerides, consist of a glycerol molecule attached to three fatty acid molecules.
The fatty acids are made up of long carbon chains with hydrogen atoms attached to most of the carbon atoms. These carbon-hydrogen (C—H) bonds contain a significant amount of energy and are considered high-energy bonds.
When fats are metabolized, the carbon-hydrogen bonds are broken, releasing energy that can be used by the body to perform various functions. The high ratio of C—H bonds in fats ensures that they provide a large amount of energy per unit weight compared to other molecules.
The other options (b, c, d, and e) are not accurate explanations of why fats are excellent energy storage molecules. Fats do not have a high ratio of energy storing C=O bonds (option b), and the presence of C=O bonds actually makes carbohydrates better energy sources due to their higher oxygen content.
The fact that fats are hydrophobic and do not mix with water (option c) is related to their structure but doesn't directly explain their energy-storage properties. Similarly, the concentration of oxygen atoms (option d) is not a significant factor in the energy storage capacity of fats.
Regarding option e, while it is true that fats are more difficult to hydrolyze compared to other molecules, this property doesn't directly correlate to their energy storage capacity.
In summary, the main reason why fats are excellent energy storage molecules is their relatively high ratio of energy-storing C—H bonds.