The modern taxonomists classified organisms on the general basis of evolutionary, morphological, and genetic traits
Explanation:
- Evolutionary relationships provides the phylogeny of evolutionary ancestors and descendants
- Homologous structures are structures which look the same but perform different functions
, like bones of a human leg compared to bones on a bird's wing
- Analogous structures have different structure but same function like an insect’s and a bird’s wing
- Embryo developmental pattern and similar relationships
- Similarities in DNA and protein sequencing in related organisms
The above basis provided modern taxonomists to classify organisms according to the various disciplines like Genetics, Cytology, Embryology, Physiology, Anatomy and many more.
The immune system is spread throughout the body and involves many types of cells, organs, proteins, and tissues. Crucially, it can distinguish our tissue from foreign tissue — self from non-self. Dead and faulty cells are also recognized and cleared away by the immune system.
If the immune system encounters a pathogen, for instance, a bacterium, virus, or parasite, it mounts a so-called immune response. Later, we will explain how this works, but first, we will introduce some of the main characters in the immune system.
