a. the virus must be able to cross-link red blood cells directly.
Explanation:
Viral hemagglutination assay is a method which is used for the quantification of the relative concentration of the viruses.
The principle on which the hemagglutination assay works is as follows:
There are sialic acid receptors present on the surface of the red blood cells which will bind to the haemagglutinin glycoprotein present on the surface of the viral particle.
Due to the binding of the sialic acid receptors with haemagglutinin particle there will be cross-linking of the red blood cells by the viral particles and a lattice formation will take place.
The lattice will remain suspended in the solution however if the concentration of the virus particles will be less, the lattice will settle down in the well.
Thus, this method allows knowing the relative concentration of the virus.
<em>Due to its basic principle of cross-linking this method works well for only a few viruses such as influenza virus. </em>
Wegener used fossil evidence to support his continental drift hypothesis. The fossils of these organisms are found on lands that are now far apart. ... Wegener suggested that these creatures were alive in warm climate zones and that the fossils and coal later had drifted to new locations on the continents.
plankton are eaten by pretty much everything as they are so small. they also get food through photosynthesis therefore they do not eat any other animals. i am pretty certain krill eat them but i dont know
