Tag: meaning of life

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.

For aquatic organisms the quality (chemical composition, PH) of water is very important. The salt concentration (measured as salinity in parts per thousand), is less than 5 parts per thousand in inland waters, 30-35 parts per thousand in the sea and more than 100 parts per thousand in some hyper saline lagoons. Many fresh water animals cannot live for long in sea water and vice versa because of the osmotic problems they would face. 

Raymond Lindeman gave the famous 10 % law. According to this law, at each trophic level, only 10% of the energy of the subsequent trophic levels is transmitted. So, the amount of energy goes on decreasing at each tropic level.

The flow of energy in the ecosystem is unidirectional. The energy enters the plants (from the sun) through photosynthesis during the making of food. This energy is then passed on to the successive trophic levels in a food chain is only 10% and rest energy get lost as heat during transfer and life process.