Tag: chemical organization in living beings

Proteins are the polymers of amino acids held together by peptide bonds and are also called as polypeptides. Carbohydrates (sugars) are polyhydroxy aldehyde or ketones or their derivatives. Nucleic acids are polymers of nucleotides held together by phosphodiester bonds. Fats are fatty acid derivatives and are one of the storage lipids. Thus, the correct answer is A.

Lipids are compounds of carbon, hydrogen and oxygen where ratio of hydrogen and oxygen is less than that of water. Lipids are esters of fatty acids and alcohol which form emulsion with water but are soluble in organic solvents. Some of the common examples of lipids are butter, ghee, cholesterol, carotene etc.

Lipids are hydrophobic means water hating. They are water insoluble. Lipids are non-polar molecules while water is polar molecule, so there is no way for water to attach to a lipid molecule. Instead, the non-polar lipids will bind to themselves, which is why oils and fats form droplets on the surface of water.

Membrane phospholipids are amphipathic having a polar head made of phosphate residue and a non-polar lipid tail. The polar phosphate head is exposed on the surface while non-polar lipids are embedded within the interior of membrane.

Lipids are hydrophobic (water repelling) and non-polar. Non-polar substances, for instance fats and oils cannot be dissolved in water because they have made up of only carbon-carbon and hydrogen-carbon bonds. Only polar solutes dissolve in polar solvents.

The polysaccharide is a carbohydrate that is formed by the bond formation between various monomers like glucose, fructose etc. Its examples are starch, cellulose, chitin, glycogen, etc.

Stachyose is a tetrasaccharide consisting of 2 galactose, one glucose and one fructose units. It occurs naturally in green beans, soya beans and other beans. It is less sweet than sucrose. Its molecular formula is $C _{24}H _{42}O _{21}$