1. Relative solubilities of alkanes, alcohols and sugars

2. Solubility of alkanes in water.
Alkanes are immiscible in water as they can only form van der Waals forces.
So they cannot interact with polar water molecules.
Water

3. They readily form van der Waals forces with these solvents.
Instead alkanes dissolve in non-polar solvents.
They readily form van der Waals forces with these solvents.
Some alkanes, eg hexane and cyclohexane, are themselves used as non-polar solvents.

4. Solubility of alcohols
Alcohols are miscible in water.
The hydroxyl groups can hydrogen bond with water molecules.
The solubility, however, decreases with chain length as hydrocarbon chains can only make van der Waals interactions.

5. Solubility of sugars OH OH OH OH OH
Sugars are rich in OH groups which can H bond with water.

6. So sugars are soluble in water, making them easy to transport around our bodies and metabolise by our cells.