Question

Pectin occurs in-
A) Blood proteins
B) Plant cell wall
C) Milk proteins
D) Liver cells

Answer 1

Pectin is a component of cell wall and cell wall is absent in animal cells.It is exclusively produced in terrestrial plants.Human body cannot digest the natural pectin.

Complete answer:
Structurally, pectin is an acidic hetero-polysaccharide, it is found in the lamella and cell walls of terrestrial plants. Its main component is galactose derived galacturonic acid. It is abundantly found in the non-woody parts of terrestrial plants. Pectin is deposited by the process of exocytosis into the cell wall, it is carried via vesicles produced by the golgi. Cell wall is a structural layer which surrounds the cell just outside the cell membrane. It could be tough, flexible, or rigid. Its function is to provide structural support as well as protection to the cell by acting as a filter.
The amount and composition of pectin differs among plants, it is an important cell wall polysaccharide which allows extension of the primary cell wall and plant growth. When the fruit ripens, pectin is broken down by the enzymes pectinase and pectinesterase, this process softens the fruit by breaking middle lamellae and separating the cells from each other. Apart from pectin, cellulose, hemicellulose, lignin, suberin, cutin are also found in cell walls of different organisms.
Pectin is used commercially as a gelling agent for production of jams, it is also used in medicines against constipation as it increases the volume and viscosity of stool. It is also used as a stabilizer in cosmetics.

Thus the correct answer is option ‘B’ i.e, plant cell wall

Note: Pectin is a major component in the cell wall of terrestrial plants, and cannot be digested in its natural form by humans, thus, cannot become a component of proteins or any other part of the body.