Grass Anatomy: Roots & Stems. A grass plant is composed of a root, a stem, leaves and a seed head. The root is fibrous, or composed of many small roots that move out in all directions.The stem, or culm, starts out a single section but develops nodes and internodes that segment it along its length.eaves & Seed-heads. Grass leaves emerge from nodes on the stem, with the newest growing on the opposite side from an older leaf below it. A single leaf is composed of a blade, sheath, ligule, auricle and collar.
HIV is the cause of the spectrum of disease known as HIV/AIDS. HIV is a retrovirus that primarily infects components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. It directly and indirectly destroys CD4+ T cells.
Shares & Saves. Save. HIV is the virus that causes AIDS. AIDS is a series of opportunistic infections that occur when the immune system is weakened by the HIV virus. HIV is a blood-borne pathogen and is transmitted through the exchange of bodily fluids, specifically, blood and semen.he most common routes of transmission are unprotected sex with an infected person and exposure to infected blood and blood products, where the blood comes in contact with broken skin. There is no cure for HIV or AIDS, so prevention is the best course of action.