T11

Question 1

Cells of immune system

Answer 1

1. Phagocytes (neutrophils & macrophages)

2. Lymphocytes

Question 2

Phagocytes

Answer 2

1. Produced in bone marrow (myeloid stem cells), stored there before being distributed through blood
2. Neutrophils (lobed nuclei)
3. Macrophages

Question 3

Neutrophils (lobed nuclei)

Answer 3

1. Travel throughout body
2. Can leave blood by squeezing through capillary walls to patrol tissues
3. Short-lived

Question 4

Macrophages

Answer 4

1. Larger than neutrophils
2. Found in organs such as lungs, liver, spleen, kidney, lymph nodes
3. Made in bone marrow, travel in blood as monocytes
4. Long-lived
5. Cut up pathogens to display antigens to be recognized by lymphocytes

Question 5

Phagocytosis

Answer 5

1. Cells under attack release chemical called histamine, attracting passing neutrophils
2. Neutrophils moves towards pathogen, which may be clustered together and covered with antibodies
3. Antibodies further stimulate the neutrophil to attack pathogens
4. This is because neutrophils have receptor proteins on surfaces that recognise antibody molecules and attach to them
5. When neutrophils attaches to pathogen, neutrophils membrane engulfs pathogen, and traps it in a phagocytic vacuole (endocytosis)
6. Digestive enzymes secreted into phagocytic vacuole to destroy pathogen
7. After killing and digesting pathogens, neutrophil dies
8. Dead neutrophils often collect at infection site to form pus

Question 6

Lymphocytes

Answer 6

1. Smaller than phagocytes, large nucleus

2. Produced in bone marrow (lymphoid stem cells)

Question 7

B- lymphocytes

Answer 7

1. Spread throughout body, concentrating in lymph nodes & spleen
2. Become plasma & memory cells

Question 8

Maturation of B-lymphocytes

Answer 8

1. In bone marrow, immature cells divides by mitosis
2. Still in bone marrow, each B cells matures
3. Mature B cells produce antibody receptors in surface membrane
4. Mature B cells circulate & concentrate in liver & spleen

Question 9

Mode of action of B-lymphocytes

Answer 9

1. a B cell has specific antibodies to antigen
2. B cell divides by mitosis, daughter cells become plasma/memory cells
3. plasma cells secrete antibodies bind to antigens
4. when antigen re-enters body, memory cells produced earlier respond by dividing into plasma cells and more memory cells;  Second response is faster than first due to memory cells.

Question 10

Antibodies

Answer 10

1. globular glycoproteins with quaternary structure 
2. form groups of plasma proteins called immunoglobulins
3. Consists of four polypeptide chains (two long/ heavy-chains; too short/light chains)
4. disulphide bonds hold chains together
5. variable region of one light in one heavy-chain make antigen binding sites
6. hinge region between 2 heavy chains give flexibility in binding to antigen
7. heavy chains have chain of sugar molecules attached to them

Question 11

Function of antibodies

Answer 11

1. Combine with virus/toxins
2. Attach to bacteria flagella
3. Cause agglutination of bacteria
4. Coat bacteria, makes it easier for phagocytes to ingest them

Question 12

T-lymphocytes

Answer 12

1. Created in bone marrow, and collect in thymus when mature

1. Helper & killer T cells

Question 13

Maturation of T-lymphocytes

Answer 13

1. in bone marrow, immature T cells divide by mitosis
2. in thymus, each T cells matures
3. T cell produce receptors in cell-surface membrane
4. mature T cells circulate as helpers/killers

Question 14

Mode of action of T-lymphocytes

Answer 14

1. helper/killer T cells bind to antigens of infected body cells
2. helper/killer cells divide by mitosis
3. helper T cells wither :
   
   • divide into memory cells
   • Secrete cytokines that stimulate B cells to divide and form plasma/memory cells
4. killer T cells either :
   
   • divide into memory cells
   • find holes in cell surface membrane of infected body cells and secrete toxic substances to kill body cell and pathogen inside

Question 15

Helper T Cells

Answer 15

Either

1. Divide into memory cells
2. Secretes cytokines that stimulate B cells to divide & form plasma/memory cells

Question 16

Killer T cells

Answer 16

Either

1. Divide into memory cells
2. Punch holes in cell surface membrane of infected body cell and secrete toxic substances to kill body cells & pathogen inside

Question 17

Active and Passive Immunity

Answer 17

1. Active
2. Passive
3. Natural
4. Artificial

Question 18

Active immunity

Answer 18

Immunity gained when antigen enters body; immune response occurs

Question 19

Passive immunity

Answer 19

Immunity gained without immunity response

Question 20

Natural immunity

Answer 20

Immunity gained by being infected or by receiving antibodies from breast milk

Question 21

Artificial immunity

Answer 21

Immunity gained by vaccination or injecting antibodies

Question 22

Vaccines

Answer 22

1. Preparation containing antigens
2. Used to stimulate immune response
3. Artificial active
4. Given by injection or taken orally

Question 23

Eradication of small pox

Answer 23

Success caused by:

1. Variola virus stable
2. vaccine made of harmless strain of similar virus
3. vaccine was freeze dried and could be kept at high temperatures
4. infected people were easy to identify
5. vaccine easy to administer
6. virus did not linger in body
7. virus did not infect animals
8. teens were enthusiastic vaccinators /suppliers of information

Question 24

Autoimmune diseases

Answer 24

1. Myasthenia Gravis (MG)
2. Multiple sclerosis
3. Rheumatoid arthritis
4. Type 1 diabetes
5. Systemic lupus erythromatosus

Question 25

Production of Monoclonal Antibodies (MABS)

Answer 25

1. Antigen injected to mouse; mouse B cells recognise antigen and form plasma cells 2. plasma cells harvested from mouse spleen 3. plasma cells fused with cancer cells 4. hybridoma cells 5. tiny samples are taken so that there is only one cell present in a well; every well tested so hybridoma cells that produce required antibody can be found

Question 26

Uses in diagnosis (MABS)

Answer 26

1. Locate cancer cells 2. identify exact strain of virus/bacterium causing infection 3. blood-typing before transfusion 4. Tissue typing before transplants

Question 27

Antibodies produced by non-humans, trigger immune response; solution:

Answer 27

1. Altering gene code for heavy/light polypeptide chain in antibodies 2. Change type/position of sugar groups attached to heavy chain