Answer:
All cells are surrounded by a cell membrane. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.
Explanation:
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:
What is population?
A group of organisms of different species interacting with each other and the environment is called populatin.
The correct answer is Economic cycle.
The natural fluctuation in economy between the period expansion (economy growth) and contraction (recession) is known as the economic cycle.
The normal growth and downturn in the economy is the basic definition of Economic cycle.
During the time of expansion the investors seek to purchase companies and shares and during the time of contraction the investors look to invest and purchase the companies such as utilities and healthcare.
