UNIT 3 - KA6

Question 1

What are the two types of lymphocytes

Answer 1

There are two types of lymphocyte, B lymphocyte and T lymphocyte

Question 2

What are lymphocytes

Answer 2

Lymphocytes are white blood cells involved in the body’s specific immune response

Question 3

What do lymphocytes respond to

Answer 3

Lymphocytes respond to specific antigens on the pathogens surface.

Question 4

Explain the term specific in relation to immunity

Answer 4

Acts on a particular pathogen only

Question 5

What is an antigen

Answer 5

Antigens are molecules often proteins located on the surface of cells that trigger a specific immune response

Question 6

Which type of receptors do each lymphocyte have

Answer 6

Lymphocytes have a single type of membrane receptor which is specific for one antigen

Question 7

What does antigen binding lead to

Answer 7

Antigen binding leads to repeated lymphocyte division resulting in the formation of a clonal population of identical lymphocytes

Question 8

What do B lymphocytes produce against antigens

Answer 8

B lymphocytes produce antibodies against antigens this leads to the destruction of the pathogen

Question 9

What are antibodies

Answer 9

Antibodies are Y shaped proteins that have receptor binding sites specific to a particular antigen on a pathogen

Question 10

Explain how antibodies prevent the pathogen causing further infection

Answer 10

Antibodies become bound to antigens, inactivating the pathogen. The resulting antigen-antibody complex can then be destroyed by phagocytosis

Question 11

Which substances can B lymphocytes respond to

Answer 11

B lymphocytes can respond to antigens on substances that are harmless to the body e.g pollen

Question 12

What is the hypersensitive response in which b lymphocytes can respond to antigens on substances that are harmless to the body

Answer 12

This hypersensitive response is called an allergic reaction

Question 13

How do T lymphocytes destroy infected body cells

Answer 13

T lymphocytes destroy infected body cells by recognising antigens of the pathogen on the infected cells membrane and inducing apoptosis.

Question 14

What is apoptosis

Answer 14

Apoptosis is programmed cell death

Question 15

Describe the main events in apoptosis of an infected cell

Answer 15

T lymphocytes attach onto infected cells and release proteins. These proteins diffuse into the infected cells causing production of self destructive enzymes which cause cell death.

Question 16

How are the remains of dead cells removed from the tissue

Answer 16

• virus particles are broken down along with cell components and are not released into the body so cannot cause further infection. They are removed by phagocytosis

Question 17

What can T lymphocytes normally distinguish

Answer 17

T lymphocytes can normally distinguish between self antigens on the body’s own cells and non self antigens on the infected cells

Question 18

What happens as a result of failure of regulation of the immune system

Answer 18

Failure of the regulation of the immune system leads to T lymphocytes responding to self-antigens.

Question 19

What is a self antigen

Answer 19

A self antigen is on a persons own body cells so that the immune system does not launch an attack

Question 20

What causes auto immune disease

Answer 20

Failure of the regulation of the immune system leads to T lymphocytes responding to self antigens. This causes autoimmune diseases

Question 21

What happens in autoimmunity

Answer 21

In autoimmunity, the T lymphocytes attack the bodys own cells

Question 22

What autoimmune diseases are a result of T lymphocytes attacking the body’s own cells

Answer 22

This causes autoimmune disease such as type 1 diabetes and rheumatoid arthritis

Question 23

What happens to some of the cloned B and T lymphocytes

Answer 23

Some of the cloned B and T lymphocytes survive long term as memory cells

Question 24

Describe how memory cells rescind to a secondary exposure to the same antigen

Answer 24

When a secondary exposure to the same antigen occurs, these memory cells rapidly give rise to a new clone of specific lymphocytes these destroy the invading pathogens before the individual shows symptoms

Question 25

Compare antibody production during the primary and secondary immune response

Answer 25

During the secondary response, antibody production is greater and more rapid than during the primary response

Question 26

What does the human immunodeficiency virus do to T lymphocytes

Answer 26

The human immunodeficiency virus attacks and destroys T lymphocytes

Question 27

How does HIV cause aids

Answer 27

HIV causes depletion of T lymphocytes which leads to the development of aids

Question 28

AIDS

Answer 28

Acquired immune deficiency syndrome

Question 29

How are individuals with aids affected by the condition

Answer 29

Individuals with aids have a weakened immune system and so are more vulnerable to opportunistic infections