Cholesterol is a crystallisable lipid of high molecular weight which possesses 17 carbon nucleus of four fused hydrocarbon rings (cyclopentane perhydrophenanthrene) and a long side chain. Cholesterol is insoluble in water and therefore, when cholesterol level rises in blood, it tends to get deposited in the wall of arteries. This causes arteriosclerosis. 

Difference between primary and secondary metabolites are as follows

Terpenes, steroids and carotenoids are examples of derived lipids.

Difference between ligases and ligases and lyases is given below

Arthropods have sclerotein protein and polysaccharide called chitin in their exoskeleton.

Homopolysaccharide : Starch
Heteropolysaccharide : Chitin

Temperature and pressure are the two physical factors that affects activity of an enzyme

Tyrosine and tryptophan are the two aromatic amino acids.

Higher nucleotides.

Fat is being manufactured by many companies in pharmaceuticals business as well as in food business. Vitamins come in many combination and are being used as supplementary medicines. Lactose is made by companies manufacturing baby food.
All of us are buyers of fat, protein and lactose.

A glycosidic bond is a certain type of functional group that joins a carbohydrate (sugar) molecule to another group, which mayor may not be another carbohydrate.
          
A peptide bond (amide bond) is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amine group of the other molecule, thereby releasing a molecule of water (H₂O). This is a dehydration 'synthesis reaction (also known as a condensation reaction) and usually occurs between amino acids. The resulting CO-NH bond is called a peptide bond, and the resulting molecule is an amide. The four-atom functional group -C(=O) NH-is called an amide group or (in the context of proteins) a peptide group. Polypeptides and proteins are chains of amino acids held together by peptide bonds, as is the backbone of PNA. Polyamides, such as nylons and aramids, are synthetic molecules (polymers) that possess peptide bonds.
              
A phosphodiester bond is a group of strong covalent bonds between a phosphate group and two other molecules over two ester bonds. Phosphodiester bonds are central to all life on Earth, as they make up the backbone of the strands of DNA. In DNA and RNA, the phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon of another, deoxyribose in DNAand ribose in RNA.

(i) Double helix model of DNA (Waston-Crick model of DNA).
(ii) (A) 2 nm
(B) 3.4 nm
(C) 0.34 nm.
(iii) The bonds between C and G are three.
(iv) This is B-form of DNA.
(v) B-DNA is right - handed spiral structure.

Cofactors are non-protein molecules that are relatively stable at high temperature consisting of thhree main types i.e inorganic ions, coenzymes and prosthetic groups.
(i) Examples of inorganic ions are calcium ions(activates the enzyme thrombokinase to convert prothrombin into thrombin during thye blood clotting process) and chloride ions(activates salivary amylas to convert starch into maltose)
(ii) Examples of coenzymes are NAD, acetyl coenzyme A ATP and NADP
(iii) Prosthetic groups are molecules that are permanently attached to the enzyme.Examples of prosthetic groups are heam and FAD 

Properties of enzymes are as follows:
i) Lowering the activation energy
ii) Lowering the energy of the transition state
iii) Providing an alternative pathway
iv) Reducing the reaction entropy change
v) Increases in temperatures speed up reactions
vi) Unique enzyme for unique substance
vii) Small quantity is enough to facilitate faster reaction.

Enzymes generally function at a narrow range of temperature. The temperature at which the enzyme shows its maximum activity, is called its optimum temperature. The enzyme activity decreases at temperatures below and above the optimum temperature.
At low temperatures, the enzyme is inactive, while at high temperature, the enzyme is denatured and so it loses its activity.

The most important fact of biology systems is that all living organisms exist in a steady-state characterised by the concentration of each of the biomolecule. These biomolecules are in a metabolic flux. Any chemical or physical process moves spontaneously to equilibrium. Thus, the steady state is a non-equilibrium state.
As living organisms work continuously, they cannot afford to reach equilibrium. Hence, the living state is a non-equilibrium steady-state to be able to perform work. This is achieved by energy input. Metabolism provides a mechanism for the production of energy.
Hence, the living state and metabolism are synonymous. Without metabolism, there cannot be a living state.

Difference between anabolism and catabolism are

Some proteins and their functions