Lipids, Fats, and Biochemistry

Waxes are complex lipids that provide waterproof coatings. They are found on plant leaves, animal fur, and in products like beeswax and earwax.

Cell membranes are primarily composed of a phospholipid bilayer. Phospholipids are a major class of lipids.

A biomolecule is any organic molecule produced by a living organism. These include carbohydrates, lipids, proteins, and nucleic acids, all of which contain carbon.

Fat is the most energy-dense macronutrient, providing approximately 9 kcal per gram, whereas carbohydrates and proteins provide about 4 kcal per gram.

Carbohydrates and fats are primarily composed of carbon, hydrogen, and oxygen. Proteins and DNA also contain nitrogen, but C, H, and O are the fundamental building blocks present in all four categories.

Salt, sugar, and oil are all commonly used as food preservatives to inhibit the growth of microorganisms. Thus, 'All of these' is the correct answer.

Glycolipids yeild fatty acids, glycerol and carbohydrates on hydrolysis. Monogalactosyldiglycerides are glycolipids which are commonly found in plant leaves and algae. They contain a high proportion of poly unsaturated fatty acids and appear to play a role in photosynthesis.

• Polyhydroxy aldehydes or ketones are molecules with more than one hydroxyl group $(−OH)$, and a carbonyl group $(C=O)$ either at the terminal carbon atom (aldose) or at the second carbon atom (ketose) are called carbohydrates.
• Monosaccharides are polyhydroxy aldehydes and are called Simple Sugar, any of the basic compounds that serve as the building blocks of carbohydrates. 
  

Bile emulsifies fats, which increases their surface area for lipase enzymes to work, but it does not chemically digest fats itself. Chemical digestion is performed by enzymes like pancreatic lipase.

Chylomicrons are large lipoprotein particles formed in enterocytes that are too large to enter blood capillaries, so they are absorbed into lacteals (lymphatic vessels).

Micelles are small aggregates of bile salts, fatty acids, and monoglycerides that transport these lipids to the intestinal surface for absorption.

After fats are broken down and processed by enterocytes, they are reassembled into triglycerides and packaged with proteins and phospholipids to form chylomicrons. These chylomicrons are too large to enter blood capillaries and are instead absorbed into the lacteals.

Due to their large size, chylomicrons cannot pass through the basement membrane of blood capillaries. They enter the lymphatic capillaries, known as lacteals, which have larger pores.

Glyoxysomes are microbodies which occur only in fat rich plant cell, where they take part in $\beta$-oxidation of fats and perform glyoxylate cycle. Glyoxysomes also possess catalase enzyme. In fat storing plant cells, first fats are converted to carbohydrates which are then metabolised.