Pathogens and vaccines (p)

Question 1

Pathogens affect humans. They also affect farm animals. Once pathogens haveentered the body of an animal they can cause disease. Vets sometimes have difficulty identifying the disease from which a particular animal is suffering. Until recently, theyhave had to take blood samples and send them to a laboratory. The laboratory carriesout tests on the sample. New tests have been developed. Some of these new tests use monoclonal antibodies. Tests using monoclonal antibodies are fast, specific and allow vets to identify a disease while they are still on the farm.Brucellosis is a disease of cattle. It is caused by bacteria. These bacteria can infectpeople who drink milk or eat dairy products from infected cattle. A test using monoclonal antibodies allows vets to identify cattle that are carriers. The carriers arecattle that carry the brucellosis bacteria but do not show any symptoms of the disease.Use the information from the passage and your own knowledge to answer the following questions.(a) Other than bacteria, name one type of pathogen (b) Give two ways in which a pathogen may cause disease when it has entered the body

Answer 1

(a) Virus / fungus / protozoan(b) 1.Damages cells / tissues / example given e.g. cell lysis 2.Producs toxins

Question 2

Some new tests use monoclonal antibodies .Explain why these antibodies are referred to as monoclonal.

Answer 2

produced from the same B cell / plasma cell

Question 3

Tests using monoclonal antibodies are specific . Use your knowledge of protein structure to explain why (3)

Answer 3

(Specific) primary structure / order of amino acids; (Specific) tertiary / 3D structure;(So) Only binds to / fits / complementary to one antigen

Question 4

The tests using monoclonal antibodies allow vets to identify brucellosis while they are still on a farm. Explain the advantages of this. (3)

Answer 4

(Rapid) treatment of carriers / infected cattle / disease;Can isolate / cull carriers / infected cattle;Infected (dairy) products not sold / consumed / tracked; Reduces spread of disease;No need to kill / prevents the death of non-infected animals;

Question 5

Scientists use an antibody to detect an antigen on the bacterium that causes stomach ulcers. Explain why the antibody will only detect this antigen.

Answer 5

1. Antibody/variable region has specific amino acid sequence/primary structure2. The shape/tertiary structure of the binding site3. Complementary to/fits/binds with these antigens4. Forms complex between antigen and antibody