The Immune System

Question 1

What is a pathogen?

Answer 1

An organism that causes disease

Question 2

Give 2 examples of bacterium

Answer 2

Ring rot, TB

Question 3

State 3 examples of viruses

Answer 3

HIV, Influenza, COVID-19

Question 4

Name 2 protists

Answer 4

Potato Blight, Malaria

Question 5

State three methods of disease transmission

Answer 5

• Droplet Infection
• Exchange of bodily fluids
• Direct Contact

Question 6

State the 3 intermediates involved in disease transmission

Answer 6

• Air
• Water
• Food

Question 7

Explain 2 functions of the skin as a non-specific defence

Answer 7

• Physical barrier; blocks pathogens
• Secretion of antimicrobial chemicals

Question 8

How do mucous membranes protect your body from pathogens?

Answer 8

• Sticky mucus traps pathogens
• Contains antimicrobial enzymes to kill pathogens

Question 9

Explain blood clotting is designed to protect your body from infection

Answer 9

• Platelets detect damaged blood vessels
• Release substances that form fibrin
• Fibrin meshes platelets together, forming blood clots

Question 10

How does inflammation protect your body against disease?

Answer 10

• Damaged tissue releases molecules
• Blood vessel permeability increases
• Swelling isolates pathogen

Question 11

How do expulsive reflexes defend your body from pathogens?

Answer 11

Coughing/Sneezing expels foreign objects from the body

Question 12

How does callose protect plant cells?

Answer 12

• Callose deposited in plasmodesma to prevent spread of viruses
• Strengthens cell walls

Question 13

State 2 ways the waxy cuticle protects a leaf from pathogens

Answer 13

• Acts as physical barrier
• Prevents build-up of intermediate of water

Question 14

How do saponins protect plant cells from pathogens?

Answer 14

They destroy cell membranes of fungi

Question 15

How do antimicrobial chemicals protect a plant?

Answer 15

• Kill pathogens
• Inhibit growth
• Prevent insects feeding

Question 16

What are antigens?

Answer 16

Receptors located on the surface of cells

Question 17

What is the 1st stage of an immune system response?

Answer 17

Phagocytes engulf pathogen

Question 18

How do opsonins aid phagocytes in the engulfing pathogens?

Answer 18

They hide negatively charged antigens so phagocyte can get closer

Question 19

What breaks down a pathogen in a phagosome?

Answer 19

A lysosome

Question 20

How do phagocytes activate other immune cells?

Answer 20

They present foreign antigens on cell surface (Antigen-Presenting)

Question 21

What type of immune cell do phagocytes activate?

Answer 21

T lymphocytes

Question 22

What do neutrophils respond to?

Answer 22

Cytokines

Question 23

What is special about receptors on T lymphocytes?

Answer 23

They are complementary to antigens on APC’s

Question 24

What do T lymphocytes undergo clonal expansion into?

Answer 24

T killer cells, T helper cells

Question 25

What is the role of T killer cells?

Answer 25

Destroy cells infected by viruses

Question 26

What is the function of T helper cells?

Answer 26

To release substances to activate B lymphocytes and T killer cells

Question 27

What are B lymphocytes covered in?

Answer 27

Antibodies

Question 28

Are antibodies on B lymphocytes complementary?

Answer 28

YES

Question 29

What 2 things do B lymphocytes divide into?

Answer 29

Plasma and memory cells

Question 30

Describe the quaternary structure of antibodies

Answer 30

4 polypeptides; 2 heavy and 2 light chains

Question 31

What are plasma cells?

Answer 31

Clones of B lymphocytes

Question 32

What is the role of plasma cells?

Answer 32

To secrete antibody into the blood

Question 33

What holds the structure of an antibody together?

Answer 33

Disulfide bridges

Question 34

What occurs at the variable regions of antibodies?

Answer 34

Antigens bind to sittes

Question 35

What binds to the constant region of antibodies?

Answer 35

Receptors from immune system cells

Question 36

What does the hinge region provide antibodies?

Answer 36

Flexibility

Question 37

Give the 3 main functions of antibodies

Answer 37

- Agglutination - Neutralising toxins - Preventing binding to cells

Question 38

What is agglutination?

Answer 38

The clumping of pathogens to concentrate them (2 binding sites)

Question 39

What neutralises toxins produce from bacteria?

Answer 39

Antitoxins

Question 40

How does the binding of antibodies to pathogens prevent spread?

Answer 40

Pathogen receptors blocked so can't attach to host cells

Question 41

Why is the primary immune response so slow?

Answer 41

Few B lymphocytes that can make the specific antibody

Question 42

Which cells produce memory cells?

Answer 42

T and B lymphocytes

Question 43

What do memory T lymphocytes do?

Answer 43

Remember specific antigens

Question 44

What is the function of memory B lymphocytes?

Answer 44

To record specific antibodies

Question 45

Why is the secondary response so much faster?

Answer 45

Clonal selection of memory cells destroys pathogen much quicker

Question 46

What is clonal expansion?

Answer 46

When T lymphocytes form killer cells or helper cells

Question 47

What is clonal selection?

Answer 47

When T helper cells release substances that activate B lymphocytes