Communicable Diseases

Question 1

Pathogens

Answer 1

Organisms that cause disease
-they live in organisms called hosts
-bacteria, viruses, fungi, protocists

Question 2

Bacteria

Answer 2

Produce toxins and cause cell damage
-cocci (spherical)
-bacilli (rod shaped)
-vibrio (curved)
-spirilli (spiral)
Divide by binary fission

Question 3

Problems with quick spreading bacteria

Answer 3

-food spoilage
-spread of disease

Question 4

Virus

Answer 4

Virus attaches to host cell
-genetic material injected into host cell
-causing host cell makes new virus
-host cell splits open releasing new virus

Question 5

Fungi

Answer 5

fungus send out specialised reproductive hyphae which grow. To the surface of the skin to release spores
-causes redness and irritation

Question 6

Protoctista

Answer 6

These organisms cause harm by entering host cells feeding on the contents as they grow
-unicellular & have nucleus
eg amoeba and plasmodium

Question 7

Types of viruses

Answer 7

HIV (animals)
tobacco mosaic virus (plants)

Question 8

Types of bacterial infections

Answer 8

Tuberculosis (animals)
Ring rot (plants) - ring of decay

Question 9

Types of fungal infections

Answer 9

Athletes foot (humans) - growth under skin of feet
Black sigatoka (bananas)
-leaf spots

Question 10

Types of protoctists

Answer 10

Malaria (humans)
-headache, fever
Blight (tomatoes)

Question 11

Direct transmission

Answer 11

-physical contact
-faecal oral transmission
-droplets in air or water
-transmission by spores in soil

Question 12

Indirect transmission

Answer 12

Pathogens transmitted by a vector
eg mosquito bite passes malaria pathogen on

Question 13

Factors affecting transmission

Answer 13

-over crowding
-poor ventilation
-poor health

Question 14

Physical Plant defences

Answer 14

Cellulose cell wall-barrier
Lignin-waterproof
Bark-contains chemical defences
Stomata closure- prevents entry for pathogens

Question 15

Chemical plant defences

Answer 15

Plant tissues contain chemicals that have anti pathogenic properties
-terpenoids
-phenols
-alkaloids

Question 16

Necrosis

Answer 16

Deliberate cell suicide
-saves the rest of the plant
-stops further spread of infection

Question 17

Blood clot

Answer 17

Damaged tissue exposes collagen and releases clotting factors ➡️
platelets activated by damaged tissue ➡️temporary plug formed
➡️thromboplastin (enzyme) catalyses prothrombin catalysed to thrombin (enzyme)
➡️fibrinogen (soluble) —> fibrin (insoluble) mesh of fibres

Question 18

human primary defences

Answer 18

Skin- barrier
-reflexes (coughing, sneezing)
-nose (hairs)
-eye contains lysozymes kill pathogens
-clilia- mucus traps microbes
ciliates cells waft to throat to swallow(hcl)

Question 19

human secondary responses

Answer 19

opsonins- protein molecule that attaches to antigens on pathogen surface -helps phagocyte bind
-phagocytosis
-Lymphocytes
-Fever and inflammatory response

Question 20

Vaccines

Answer 20

Intentional exposure to a pathogen to be IMMUNE
-harmless or attenuated (weakened) version

Question 21

HIV

Answer 21

Retrovirus
HIV replication-single stranded RNA instead of DNA
-reverse transcriptase enzyme uses RNA as template to make single strand DNA
-DNA polymerase makes double stranded DNA
-Attached to host DNA
-Host cell makes new virus

Question 22

Types of vaccination

Answer 22

Herd - all/most of population are provide with immunity preventing spreads
Ring- all the immediate vicinity of the outbreak get vaccinated

Question 23

Active immunity

Answer 23

active - your immune system makes its own antibodies after being exposed to antigens

Question 24

Passive immunity

Answer 24

Antibodies are made by another organism can be achieved naturally or artificially

Question 25

Why do we need new drugs

Answer 25

Antibiotic resistance -MRSA
-if you don’t finish course still traces of virus/pathogen that can mutate

Question 26

How does HIV affect immune system

Answer 26

HIV turns into aids
-affects T helper cells
-won’t produce plasma cells & antibody
-weaker immune system

Question 27

Cellular response

Answer 27

-the T cells & other immune system cells they react with eg phagocytes

Question 28

Humoral response

Answer 28

B cells, clonal section and production of monoclonal antibodies
antigen exposure
⬇️
engulfed by Macrophage
⬇️
becomes antigen presenting cell
⬇️
B cell⬅️helper T Cell➡️cytoxic T cell
⬇️ ⬇️ ⬇️
Plasma Memory helper Active
cells. T cell. Cytoxic T
⬇️. 2nd ⬇️.
Memory B cells. Memory T cells

Question 29

Roles of the cells produced in immune response

Answer 29

T helper cells- release cytokines that stimulate the B cells to stimulate phagocytosis
T killer cells- attack and kill host body cells that have antigen
T memory cells - provide long term immunity
T regulator cells - shut down immune response after pathogen removed

Question 30

phagocytosis

Answer 30

phagocyte recognises the antigens
-cytoplasm of phagocyte moves round the pathogen to engulf it
-lysosome containing digestive enzymes fuses with phagosome
-enzymes break down pathogen

Question 31

neutrophils

Answer 31

type of phagocyte
-first responders to cytokines(proteins)released by cells at site of a wound
-multilobed nucleus
-made in bone marrow

Question 32

antibodies

Answer 32

composed of 4 polypeptide chains, which are linked together by disulphide bridges
-constant region- phagoctye interaction
heavy chain-middle
light chain at sides

Question 33

antibiotics

Answer 33

kill bacteria and stop growth
-bacterial antibiotics- kill bacteria by destroying their cell wall (burst)
-bacteriostatic antibiotics- inhibit the growth of bacteria, stopping protein synthesis

Question 34

T- cell clones

Answer 34

killer T cell- destroys antigens
Helper T cell- stimulates T & B cells
suppressor T cells- inhibits T & B cells
Memory T cells- remembers antigens for future encounters