Biomolecules and Enzymes

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals, and is the main nitrogen-containing substance in the urine of mammals.

This option is correct because cystein is an amino acid.which contains the thiol group along the side chain. This group participates in the enzymatic reaction and behaves as a nucleophile.

Acute intermittent porphyria (AIP) is caused by a deficiency of porphobilinogen deaminase (also known as hydroxymethylbilane synthase), which is the third enzyme in the heme biosynthesis pathway. This deficiency causes accumulation of porphobilinogen and ALA, leading to acute neurovisceral attacks. The other enzymes listed are deficient in different types of porphyria: uroporphyrinogen III cosynthase in congenital erythropoietic porphyria, protoporphyrinogen oxidase in variegate porphyria, and coproporphyrinogen oxidase in hereditary coproporphyria.

Enzymes are cellular machinery.

These are the intermediates in the urea cycle.

The plasma membrane allows only lipid-soluble substances to pass through it. Water-soluble substances such as glucose, amino acids, ions and water can pass through the plasma membrane with the help of the various proteins. Amino acid permeases are integral membrane proteins involved in the transport of amino acids into the cell.

Many legumes contain symbiotic bacteria within root nodules of their root. These bacteria have the special ability of fixing nitrogen from atmospheric, molecular nitrogen (N₂) into ammonia (NH₃) by using an enzyme called nitrogenase present in root nodules.

Lactase enzyme catalyzes the hydrolysis of lactose into glucose and galactose.

This is the correct answer.

Carnosine is a dipeptide of the amino acids beta-alanine and histidine.

This is the correct answer.

Ruminants like cows, sheep, and deer have a specialized four-chambered stomach that allows them to digest plant material in two steps: initial swallowing and fermentation, followed by regurgitation and re-chewing of cud. This breaks down cellulose more thoroughly.

This option is correct because starch is catalysed by amalyase to form maltose.

This is the correct option as actin is a protein that is not included in the matrix of bone.

VADAR (Volume, Area, Dihedral Angle Reporter) is a comprehensive protein structure validation tool that analyzes stereochemical quality, geometry, and other structural parameters. Alignment tools (option A) are for sequence comparison, and structure prediction tools (option B) generate models rather than validate them.