Biology Test 25

A typical prokaryotic cell contains the plasma membrane, cytoplasm, ribosomes and genetic material etc. It does not have well-defined nucleus, membrane-bound organelles, and centrioles etc.

Cutin is an insoluble mixture containing waxes, fatty acids, soaps and resinous material that forms a continuous layer on the outer epidermal wall of a plant.

Ribozymes are RNA molecules that are capable of catalyzing a chemical reaction. They occur naturally inside cells where they play an essential role in the ribosome, joining amino acids together to form protein chains. Ribozymes also play a role in other vital reactions such as RNA splicing, removal of introns, transfer RNA biosynthesis and viral replication.

During glycolysis enzyme hexokinase changes glucose to glucose‑6‑ phosphate. Glucose‑6‑phosphate is inhibited by Feedback inhibition, a mechanism by which the concentration of certain cell constituents is limited.

The isoelectric point or isoionic point is the pH at which the amino acid does not migrate in an electric field. This means it is the pH at which the amino acid is neutral i.e. the zwitterion form is dominant.

In coconut, repeated free-nuclear divisions take place. If a cell wall is formed it will form after free-nuclear divisions. This process is known as Nuclear endosperm formation.

First statement, Mitosis takes place in the somatic cells and meiosis takes place in the germ cells, is true.

Due to crossing over, independent assortment and segregation, the daughter cells differ from parent cell in having half the number of chromosomes in meiosis. They also differ among themselves qualitatively.