Non-Specific Immune System

Question 1

State how the genetic material in HIV differs from the genetic material in the bacterium Mycobacterium tuberculosis that causes TB

Answer 1

1. RNA in HIV and DNA in bacterium.
2. Circular in bacterium and linear in HIV
3. Plasmids in bacterium and no plasmids
   in HIV

Question 2

Explain why unbroken skin is an effective barrier against HIV infection.

Answer 2

1. Keratin / protein in skin surface.

2. Forms a {hard / impenetrable / physical /barrier

Question 3

Explain the change in numbers of CD4 T-lymphocytes during the first 6 weeks after infection with HIV.

Answer 3

1. Glycoprotein is present.
2. Binds with receptors.
3. On surface membrane.
4. Viral DNA enters.
5. By action of reverse transcriptase.
6. New viruses form.
7. Cell is destroyed when virus leaves.
8. T killer cells destroy T helper cells.

Question 4

Suggest one effect that this change would have on one other component of
the infected person’s blood.

Answer 4

B {cells / lymphocytes} { not activated / not stimulated /
are inhibited / eq} / fewer antibodies / T killer cells
{increase / multiply

Question 5

Enzyme released in secretions that break down the cell walls of bacteria.

Answer 5

Lyzosome

Question 6

Inflammation caused by a chemical released by white cells in connective tissue

Answer 6

Histamine

Question 7

Explain why the processes shown in the flow diagram will only happen in response to some types of bacteria.

Answer 7

1. reference to protein nature of {antigens /
   antibodies} ;
2. antigens are specific (to each bacteria) / eq ;
3. antibodies need to be {complementary /
   specific} (to the antigen) ;
4. idea that {binding / eq} can take place ;
5. (some bacteria) have {different / changed}
   antigens / eq ;
6. idea that this is a primary infection ;
7. reference to {mucus / slime} {coat /capsule}
   (of bacterial cells) ;
8. idea that some bacteria are inside body cells

Question 8

Describe how the production and action of interferon differs from the and action of lysozyme.

Answer 8

1. Interferon is involved in viral infections. Lysome effects bacteria.
2. Interferon is produced by infected cells. Lysosome is present in macrophages.
3. Interferon stops replication of viruses. Lysome kills bacteria.

Question 9

Suggest why the protein structure of lysozyme is important to the way in which it acts against pathogens.

Answer 9

1. Lysozyme is an enzyme.
2. Enzymes have a specific shape.
3. Lysozyme acts on the cell wall of bacteria.

Question 10

Explain why an insect bite, which breaks the surface of the skin, may lead to inflammation around the injury.

Answer 10

1. Histamine is produced as a result of damaged tissue.
2. Histamine is released from platelets.
3. Histamine makes arterioles dialate.
4. Inflammation causes swelling.

Question 11

Suggest why applying this cream might be better than taking tablets containing antihistamines.

Answer 11

1. Cream applied to the specific area where the production of histamine is.
2. Relives pain more quickly.
3. Tablets have side effects.
4. Higher concentration of antihistamine at site.