The covalent bonds formed by C are strong. Life on Earth is a carbon based system. All biochemistry involves carbon compounds carrying specific functional groups. These are atomic groupings that have characteristic physical properties and chemical reactivities regardless of their molecular location. Carbon can form chains with carbon atoms bonded together in linear forms .
Carbon can also form branched chains and cyclical molecules .
So hydrocarbons do not readily dissolve in aqueous solvents. Simple hydrocarbons are not very important in familiar biological chemistry. But many biological molecules are modifications of hydrocarbons, which include other atoms or functional groups. Sugars are poly-alcohols and so are very soluble in water. The electronegativity of the oxygen polarizes this bond and increases water solubility.