Unit 3: The Immune System

The role of antibodies in the human body is to

• stimulate pathogen reproduction to produce additional white blood cells

• increase the production of guard cells to defend against pathogens

• promote the production of antigens to stimulate an immune response

• recognize foreign antigens and mark them for destruction

White blood cells are most closely associated with which two body systems?

• circulatory and digestive

• immune and circulatory

• digestive and excretory

• excretory and immune

The diagnostic test for HIV, the virus that causes AIDS, involves testing the blood for antibodies associated with this pathogen. Antibodies are produced when the body

• stimulates enzyme production

• secretes specific hormones

• detects foreign antigens

• synthesizes microbes

An immune response is primarily due to the body's white blood cells recognizing

• a hormone imbalance

• abiotic organisms

• foreign antigens

• known antibiotics

Harmless Skin Virus Fights Acne

...Acne is caused when hair follicles become blocked with an oily substance called sebum, which the body makes to stop the hair and skin from drying out.

Normally harmless bacteria, such as Propionibacterium acnes, that live on the skin can then contaminate and infect the plugged follicles.

Phages [a type of virus] appear to help counteract this.

When the scientists sequenced the DNA coding of the phages, they discovered that, as well as sharing most of their genetic material, the viruses all had some key features in common.

All carry a gene that makes a protein called endolysin – an enzyme thought to destroy bacteria by breaking down their cell walls.

And unlike antibiotics, which kill many types of bacteria, including "good" ones that live in our gut, phages are programmed to target only specific bacteria...

Source: BBC News September 25, 2012

The typical response of the human body to an infection by bacteria is to

• stimulate the production of antigens

• decrease the number of enzymes in the blood

• ignore the organisms, unless they are pathogens

• produce white blood cells and antibodies

When people receive organ transplants, they often need to take medications that decrease immune responses because

• transplanted organs contain antigens that can trigger white blood cell activity

• hormones present in replacement organs prevent the synthesis of antibiotics

• transplanted organs produce their own antibiotics

• antigens present in these organs attack antibodies already present in the blood

A direct indication that the white blood cells of the body are functioning would be

• an increase in the number of oxygen molecules in the lungs

• a decrease in the number of pathogens in the body

• a decreased secretion of hormones by certain glands

• an increase of carbon dioxide in the cells of the body

The two reactions illustrated in the diagrams below often occur when a foreign substance enters the body.

The cells labeled A and B are examples of cells known as

• guard cells

• reproductive cells

• white blood cells

• specialized skin cells

Cells of the immune system are able to respond to the presence of invading organisms because they recognize the

• antigens present on the invaders

• antibodies present in invading pathogens

• DNA pattern in the nuclei of viruses

• antibiotics released from microbes

A new vaccine was developed and then tested on a large sample of individuals. This new vaccine will be considered effective if it helps prepare the body to fight future invasion by

• inhibiting the response of red blood cells

• stimulating the reproduction of microbes

• inhibiting the action of immune cells

• stimulating the production of antibodies