Name the five cardiac cycle activities starting with excitation and ending with regulation of blood flow and volume.

Explanation:

1) Excitation brings about contraction.

2) Contraction leads to an increase in blood pressure.

3) Changes in blood pressure results in the opening and closing of the heart valves.

4) The opening and closing of heart valves then regulates the flow of blood and it's volume.

C) attachment, penetration, replication, assembly, release

Explanation:

The viral life cycle starts with its adsorption to the host cell and is mediated by the interaction between receptors present on the cell surface of the host and surface ligands of the virus.

This is followed by the entry of the viral genome or the whole nucleocapsid into the host cell and is known as penetration. Once inside the host cell, the viral genes are expressed and there is the synthesis of viral proteins and nucleic acids.

The newly formed capsid proteins and nucleic acids are assembled into virions which in turn are released from the host cell by one of the several mechanisms such as budding.