Lipids, Fats, and Biochemistry

Suberin is a type of lipid found in the cell wall of plants especially cork cells. It is a mixture of fatty acid material along with glycerol and phellonic acid. It gives rigidity and strength to cell wall in addition to imparting impermeability to cork cells.  Waxes are esters of long chain fatty acids with cetyl or mericyl alcohol. They are found in leaf surfaces of plants, bees wax, wool fat of animal furs and ear wax.  Cutin is a complex lipid formed by polymerisation of  hydroxy fatty acids with or without esterification by alcohols other than glycerol. It is found in the epidermal cell walls of plants and also as a separate layer outer to epidermis. It prevents the water loss due to transpiration. 

Lipids are storage compounds, triglycerides serve as reserve energy of the body. These are an important component of cell membranes structure in eukaryotic cells that helps in regulating membrane permeability. They serve as the source for fat-soluble vitamins like A, D, E, K. Example of lipids are fats, oils and steroids.

Many animals, plants and yeast synthesize sterols and their derivatives. Sterols are widely distributed in living organisms as lipid constituents. Cholesterol is a major sterol found as component of plasma membrane lipid bilayer in higher animals such as humans and other mammals. Cholesterol is metabolised to bile acids and steroid hormones. Intestinal microorganisms reduce a certain amount of cholesterol to coprosterol which is then excreted out as faeces. A form of coprosterol termed as 5-coprosterol has a low water solubility and therefore remains stable for many hundreds of years in the environment. Coprosterol is therefore, also used as an indicator of faecal pollution in water from different sources. Ergosterol is a sterol found in fungi and protozoa necessary for their survival and has functions similar to that of cholesterol. Lanolin is a lipid derivative secreted by the sebaceous glands of wool bearing animals. Lanolin is a wax, but it is not a true fat since it lacks glycerides.
So, the correct answer is option D.

Wax is a long chain of sterol ester. These are hydrophobic. They are insoluble in water but soluble in organic and nonpolar solvents. It consists of long alkyl chains. Hexacosyl palmitate is an ester derived from the palmitic acid and cetyl alcohol. It is white in color and forms an important constituent of tissues of stony corals. It is the main constituent of bee wax.

So, the correct option is 'A-(iii),B(ii),C(i),D(iv)'.

In animals, body stores excess carbohydrates as fats. Fats are stored around visceral organs and underneath the skin as adipose tissue. Excess deposition of fats underneath the skin in adipose tissue gives rise to obesity. Obesity leads to a number of life style diseases and disorders like hypertension, diabetes, joint pain etc.

Groundnut seeds are rich in fats, protein, vitamin, B1, B2, B6, E and nicotinic acid (vitamin B3) and lecithin.

$\text{Adenine has the least tendency to attract with water molecules.}$

Primary metabolites are the substances that are involved in the basic metabolic processes, this includes the proteins and carbohydrates and lipids. Plant cells have different molecules other than the primary metabolite and these are considered as secondary metabolite which is not directly involved in the metabolism.

Immunoglobulin also known as antibodies are glycoprotein molecules produced by plasma cells (white blood cells). They act as a critical part of the immune response by specifically recognizing and binding to particular antigens, such as bacteria or viruses and help in their destruction.The antibody immune response is highly complex and exceedingly specific. Hence, antibodies are complex glycoproteins.

Chylomicrons are essentially fat droplets (triglycerides) coated with proteins and phospholipids to make them water-soluble for transport in the lymph and blood.