immune system

In lymph nodes

• white blood cells mature into T cells.

• lymph drains back into the circulatory system.

• old and damaged red blood cells are destroyed.

• B and T cells gather and attach to foreign antigens.

An inflammation reaction involves the

• release of histamines.

• agglutination of bacteria.

• production of immunoglobulin.

• vaseconstriction of blood vessels.

First-line defences that mammals have against invasion by disease-causing bacteria include

• lysozymes.

• interferons.

• antibodies.

• cytotoxic T cell.

First-line defence mechanisms in humans include

• development of fever.

• the action of phagocytes.

• the use of antibiotics.

• the presence of cilia on some cells.

A young woman stood on a dirty, rusty nail. The diagrams show bacteria isolated from the wound and a range of antibodies that were already present in her body. The microorganism most likely to cause a severe infection is

• M.

• N.

• O.

• P.

The part of the virus labelled R is its

• antigenic marker.

• lipid envelope.

• protein coat.

• viral genome.

A typical characteristic of such a virus is that it

• is destroyed by antibiotics.

• releases toxins into the body of the host.

• evades detection by the host's immune system.

• manipulates the host cell's DNA to produce copies of itself.

The diagram shows a bacterial infection within a human. Cells moving from the blood vessel towards the bacteria

• are natural killer cells.

• would act as phagocytes.

• cause vasodilation in the blood vessel.

• release histamine in response to tissue damage.

Cytotoxic T cells are

• antibodies.

• able to kill virus-infected cells.

• part of the humoral immune response.

• part of the second line of the immune defence.

HIV is spread by

• intravenous drug use

• sexual contact

• contact with infected blood.

• all of the above