10 Communicable diseases

Question 1

What is a pathogen

Answer 1

a microorganism that causes disease

Question 2

the 4 types of pathogens + examples

Answer 2

• Bacteria = tuberculosis (TB)

-virus = HIV/ AIDS , influenza

-Protoctista = malaria

-Fungi = ring worm, athletes foot

Question 3

what is a vector

Answer 3

carries the pathogen from one host to another

Question 4

what do bacteria do (4)

Answer 4

-infect host
-multiply rapidly
-causes damage to cells
-releasing waste products and toxins

Question 5

what do viruses do (4)

Answer 5

-invade cells
-take over genetic machinery
-manufacture more viruses
-host cells burst

Question 6

subcutaneous infection

-how the infection takes place
-how its transmitted
-an example

Answer 6

occurs by direct implantation of spores into the skin via a puncture wound

by contact with soil or plant material

porotrichosis

Question 7

systematic infection

-how the infection takes place
-how its transmitted
-an example

Answer 7

occurs deep inside the body, often starting in the lungs and spreading to other parts of the body

usually through inhalation of spores

histoplasmosis

Question 8

Cutaneous infection

-how the infection takes place
-how its transmitted
-an example

Answer 8

occurs when fungi break down the protein keratin in hair, skin , nails

by contact with an infected person or spores

tinea pedis (athletes foot)

Question 9

what are the direct ways that a pathogen can be passed on (4)

Answer 9

-direct physical contact
-faecal oral
-droplet infection
-spores

Question 10

what are the indirect ways/way that a pathogen can be passed on.

Answer 10

via a vector

Question 11

what is ring rot in plants and its effect (3)

Answer 11

-Bacteria disease of potatoes, tomatoes and aubergines caused by the gram positive bacterium, clartbacter mithiganeusis. Can destroy up to 80% of the crop and there is no cure.

infects a field

field cannot be used for at least 2 years

Question 12

What is tobacco mosaic virus (TMV) and its effect (5)

Answer 12

-infects tobacco plants + 150 other species such as tomatoes, peppers, cucumbers

-damages, leaves, flowers + fruit

-stunts growth

-reduces yield

-spreads via vectors

Question 13

What is black sigatoka and its effect (5)

Answer 13

-banana disease

-caused by fungus

-attacks + destroys leaves

-penetrates + digests the cells, turning leaves black

-can cause a 50% reduction in yield

Question 14

what is blight and its effect (3)

Answer 14

-potatoes + tomatoes

-spreads by wind as spores

-only grows (notice it) in warm + humid conditions

Question 15

Physical defences against plant pathogens (5)

Answer 15

-cellulose cell walls
-lignin
-waxy cuticle
-bark
-stomatal closure

Question 16

Human primary defences (7)

Answer 16

-lysome in tears (salty)
-bronchi, mucus, cilia
-gut acid
-rapid pH changes
-Low pH and commensals of vagina
-skin
-commensals

Question 17

3 rapid expulsive reflexes

Answer 17

coughing
sneezing
vomiting

Question 18

info card how does blood clot ( 8 steps)

Answer 18

-Damage to blood vessel exposes collagen
-platelets bind to exposed collagen; release clotting factor
-platelet plug is formed
-inactive thrombokinase is activated due to clotting factors
-active thrombokinase and Ca2+ turns prothrombin into active thrombin (an enzyme)
-Active thrombin catalyses the reaction of soluble fibrogen into fibrin (insoluble)
-insoluble fibrin fibres attach to platelets in platelet plug
-a clot is formed (red blood cells + platelets are trapped )

Question 19

what cells recognise the pathogen

Answer 19

lymphocytes

Question 20

what do the lymphocytes recognise

Answer 20

antigens

Question 21

what’s an antigen

Answer 21

unique shaped molecules

Question 22

what 4 types of cells can be detected by lymphocytes

Answer 22

-pathogens (bacteria, fungi virus)

-cells from other organisms of same species

-abnormal body cells

-toxins

Question 23

how do many different types of lymphocytes do you have in your body and why

Answer 23

10 million

each one can recognise different shaped antigens

Question 24

why do you not have lymphocytes complementary to your own cells?

Answer 24

When you are a foetus, since you are unlikely to be exposed to any cells that are not your own, any lymphocytes complementary to the antigens on your body their production will be stopped.

Question 25

when you have some lymphocytes complementary to your own cells what’s it called

Answer 25

autoimmune disease

Question 26

why is a new flu vaccine have to be created each year and what’s it called (7 steps)

Answer 26

-pathogen DNA mutates frequently
-if a mutation occurs in the gene coding for the antigen, then the shape of the antigen will change
-previous immunity is no longer effective
-memory cells in blood will have a memory of the old antigen shape
-lymphocytes no longer work for flu
-known as ANTIGEN VARIABILITY
-only will a new effective lymphocyte be created once a natural or artificial infection has occurred

Question 27

in exam questions what would describe mean for a graph VS explain

Answer 27

Describe
-what the pattern is
-e.g. negative correlation

Explain (expand or elaborate)
-say WHY
-explain the biology of why there is a negative correlation

Question 28

what do Tcells and Bcells do

+full names (what type of cell)

Answer 28

T cells = T lymphocytes
-respond to antigen

B cells = B lymphocytes
-produce antibodies

Question 29

how are pathogens detected and the response given until antibodies are released (6 steps)

Answer 29

• pathogen detected by its unique antigens
  -phagocyte engulfs the pathogen
  -phagocyte displays the antigens on its surface to a T helper cell (T lymphocyte)
  -T helper cell produce interleukins that activate the B cells (B lymphocytes)
  -B cells divide by mitosis
  -B cells differentiate into plasma cells which synthesize and release antibodies

Question 30

what are interleukins

Answer 30

its a communication hormone that acts as a cell signalling molecule to activate B cells

Question 31

what an antibody works

Answer 31

The antibodies has a Y shaped glycoproteins called immunoglobulins which bind to a specific antigen on the pathogen/ toxin

specific antibody for each antigen

Question 32

how antigens actually work

Answer 32

Antigen- antibody complexes cause pathogens/ toxins to clump together, so a phagocyte can engulf a number of pathogens/ toxins at the same time

antibodies act as anti-toxins by binding to the toxins produced making them harmless.