Explain how viruses are grouped?

Viruses are classified into four groups based on shape: filamentous, isometric (or icosahedral), enveloped, and head and tail. Many viruses attach to their host cells to facilitate penetration of the cell membrane, allowing their replication inside the cell.

chromosomes carry the genetic information for organisms. also, chromatin is the thread like dna which is located in the nucleus of an organism.

the tricuspid valve is present between right atrium and right ventricle