Answer:
A. whether the glycoproteins or capsid proteins on its surface recognize those of the host cells.
Explanation:
Virus has different surface proteins that are recognized by the receptors present on its host cell. The range of a virus is determined by the recognition of these proteins by the host cell.
The interaction between the receptor on the host cell and surface proteins on the viral capsid is important for viral genome entry in the host cell and to determine the range of the host cells.
If the surface protein of the virus is not able to bind to the receptor on any cell then the virus can not infect the cell. For example, the HIV virus infects only those cell which have CD4 receptors. So the right answer is A.
Answer;
Phospholipid.
Phospholipid forms a double layer as the primary structure of cell membranes.
Explanation;
Cell membranes contains of lipids (phospholipids and cholesterol), proteins and carbohydrates groups that are attached to some of the lipids and proteins.
Phospholipids are composed of a polar head and non-polar (hydrophobic) tail. They line up such that the heads and the tail groups are side by side to form a single layer due to the interactions between the head groups and the tail groups. Two of these layers line up with the hydrophobic tail groups facing each other to prevent the hydrophobic groups away from the polar head groups of other phospholipids and from the water in the surrounding environment.
Scarlet fever or scarlatina is an infection for those people having sore throat. It's symptoms usually is a bright red rash with fever as well as sore throat. It affects children from 5-15 years old. It is cause by the streptococcus pyogenes. It's mode of transmission is droplet and direct contact and the virulence is cause by erythrogenic toxin.
