How do antibodies help to fight infections?

Antibody tests can detect the presence of antibodies in the blood that

Antibodies, also known as immunoglobulins (Ig), are specialized proteins that bind to a uniquely shaped object—called an antigen—that is found on the surface of a pathogen. These pathogens can be things such as bacteria or viruses.

with a fitted molecular shape—and then either destroys the pathogen or tags it so other immune cells will recognize it.

liquid crystals are matters in a state which have properties between those of conventional liquids and those of solid crystals[1]. liquid crystal is partially ordered and anisotropic. in terms of molecular order, liquid crystal molecules have one-dimensional or two-dimensional long - range order.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?