Diseases & Immune System

Question 1

Define disease

Answer 1

illness or disorder of the body or mind that leads to poor health

Question 2

Name 4 types of pathogen

Answer 2

bacteria
viruses
fungi
protoctists

Question 3

infection method of viruses?

Answer 3

hijack host cell machinery to replicate

Question 4

what pathogen is TB

Answer 4

bacteria

Question 5

method of transmission - TB

Answer 5

airborne via droplets

Question 6

pathogen type - HIV

Answer 6

virus

Question 7

method of transmission - HIV

Answer 7

direct exchange of bodily fluids

Question 8

pathogen type - influenza

Answer 8

virus

Question 9

method of transmission - influenza

Answer 9

close proximity transmission via droplets

Question 10

pathogen type - malaria

Answer 10

protoctists

Question 11

method of transmission - malaria

Answer 11

vectors (mosquitoes)

Question 12

pathogen type - athletes foot

Answer 12

fungi

Question 13

pathogen type - ring rot

Answer 13

bacteria

Question 14

plant host - ring rot

Answer 14

potato, tomato

Question 15

method of transmission - ring rot

Answer 15

infected tuber can lead to the growth of infected new plants
contaminated soil, water + equipment

Question 16

pathogen type - TMV

Answer 16

virus

Question 17

Method of transmission - TMV

Answer 17

Direct contact between infected individuals

Question 18

Pathogen type - late blight

Answer 18

Protoctists

Question 19

Plant host - late blight

Answer 19

Potato, tomato

Question 20

Method of transmission - late blight

Answer 20

Spore dispersal through wind/water

Question 21

Pathogen type - black sigkota

Answer 21

Fungi

Question 22

Plant host - black sigakota

Answer 22

Banana

Question 23

Method of transmission - black sigakota

Answer 23

Leaf to leaf contact
Spread of spores by humans or within infected plant matter

Question 24

Define is a passive defense mechanism of plant

Answer 24

Defence that is always present in plants, regardless of infection status

Question 25

Give examples of passive physical barriers in plants

Answer 25

Waxy cuticle Cellulose cell wall Closed stomata

Question 26

Give examples of passive chemical defences in plants

Answer 26

Sticky resin in bark Toxic compounds eg catechol

Question 27

Define active defence mechanisms in plants

Answer 27

Triggered upon pathogen invasion

Question 28

Give examples of active physical barrier formation in plants

Answer 28

Reinforced cell walls (invasion stimulates release of callose and lignin which deposit between cell membrane and cell wall) - callose forms matrix Plasmodesmata narrowing Xylem and phloem blocking

Question 29

What are phytoalexin

Answer 29

antimicrobial compounds produced by plants as a defensive response to pathogens

Question 30

What process is essential for active plant defence

Answer 30

Cell to cell signalling (receptors on cell membrane recognises pathogen and signalling molecule alerts nucleus - nucleus produces defence molecules to alert other cells)

Question 31

What is humans first line of defence against pathogens

Answer 31

Skin - physical barrier, inhospitable environment Mucous membranes - line gut, airways and reproductive system Expulsive reflexes Chemical secretions - lysozymes, hydrochloric acid Comensal microorganisms ‘friendly bacteria’

Question 32

What is the second line of defence in humans

Answer 32

Blood clotting Inflammation Wound repair Phagocytosis

Question 33

Describe the process of blood clotting

Answer 33

Platelets release substances that undergo a series of chemical reactions (cascade) The end product is that fibrin is formed, which forms a network, trapping platelets and forming a clot

Question 34

Describe the process of wound repair

Answer 34

New blood vessels form Collagen produces Granulation tissue forms to fill the wound Stem cells move over the new tissue and divide to produce epithelial cells Contractile cells cause wound contraction Unwanted cells die

Question 35

What is inflammation

Answer 35

A localised response to infection and tissue damage

Question 36

What are the effects of histamine

Answer 36

Stimulates vasodilation Makes capillaries more permeable (leaky) allowing fluid to enter tissues and cause swelling Facilitates plasma proteins leaving the bloodstream Enables phagocytes to exit blood vessels and enter damage tissues

Question 37

Name the 3 types of phagocytes

Answer 37

Neutrophlils Macrophages Dendritic cells

Question 38

Describe the process of phagocytosis

Answer 38

Chemotaxis - neutrophils attracted to infection site by chems released by pathogens and dead body cells Recognition - neutrophils move towards pathogens and recognise antibodies that may be attached to pathogen surface antigens using receptor proteins on their surface Endocytosis - neutrophils cell membrane extends around the pathogen, engulfing it and creating a phagocytic vacuole Digestion - lysosomes release lysozymes (digestive enzymes) Destruction - these enzymes destroy the pathogen (hydrolyse) Death - neutrophils die, forming pus at infection sites

Question 39

Describe the role of antigen presenting cells

Answer 39

T cells will only bind to an antigen if it is present on the surface of an antigen presenting cells They help to recruit other cell of the immune system to produce a response Could be a macrophage or an invaded body cell Once the surface receptor of the T cell binds to complementary antigen it starts dividing to produce a clone of cells