Communicable Diseases

Question 1

Define health

Answer 1

A complete mental state of physical, mental and social well-being and being free of disease

Question 2

What does being healthy mean

Answer 2

-being active
-good diet
-free of diseases

Question 3

What is a pathogen

Answer 3

A microorganism that causes disease

Question 4

What are the 4 types of pathogen

Answer 4

Bacteria
Virus
Fungi
Protist

Question 5

What is bacteria

Answer 5

Reproduces rapidly (every 20 mins)
Releases toxins making us feel ill

Question 6

Give 3 examples of bacteria

Answer 6

Tuberculosis- (mycobacterium and m. Bovis)
~ affects many parts of the body
~kills cells and tissues - affects mostly the lungs

Meningitis -( streptococcus pneumonia)
~ infection of the meninges (membranes that surround brain and spinal cord)
~ membranes become swollen and causes nerve damage

Ring rot- in plants- (clavibacter michiganensis)
~ ring of decay in vascular tissue in tomato and potato
~ leaf wilting

Question 7

What is a virus

Answer 7

Invades cell and burst out of them infecting healthy ones

Question 8

Give 3 examples of a virus

Answer 8

HIV- human immunodeficiency virus
~attacks cells in immune system

Influenza- family orthomyxoviridae
~attacks respiratory system and causes headaches and muscle pain

Tobacco mosaic virus - tobacco mosaic virus
~ caused discolouration of leaves (in mosaic pattern)

Question 9

What is fungi

Answer 9

Lives in skin of animals
Hyphae grows to surface and releases spores = red and itchy
In plants = vascular tissue

Question 10

3 examples of fungi

Answer 10

Black Sigatoka- in bananas (mycosphaerella fiji ensis)
~ causes leaf spots on banana
-reducing yield

Ringworm (cattle) - tricophyton verrucosum
~growth of fungus in skin with spores erupting through skin to cause a rash

Athletes foot (tricophyton rub rum)
~ growth under skin of feet especially between toes

Question 11

What is a protist

Answer 11

It enters host cell and feeds on their contents while it grows

Question 12

Give 2 examples of protist

Answer 12

Blight (potato or tomato) - phytophthara infestans
~ affects potato tubers and leaves

Malaria - plasmodium
~ parasite in blood that causes headache and fevers
~ can progress to comas and death

Question 13

What is the life cycle of a pathogen

Answer 13

-Transmission- travels from host to host
-enters host tissues
-reproduces
-leaves host tissues

Question 14

What is DIRECT transmission between animals - physical contact and factors affecting it

Answer 14

-touching infected person
-contaminated surface
E.g HIV, meningitis, ringworm

Factors affecting it
-wash hands regularly
-keep surfaces clean
-use condoms

Question 15

DIRECT transmission between animals - faecal-oral transmission and factors affecting this

Answer 15

-Usually by drinking contaminated water or eating contaminated food
E.g cholera, food poisoning

Factors affecting it;
-treatment of drinking water
-thorough washing of fresh food

Question 16

DIRECT transmission- droplet infection and factors affecting it

Answer 16

-pathogen carried in tiny water droplets in air
E.g influenza, tuberculosis

Factors affecting this transmission
- catch it- bin it- kill it
-cover mouth when coughing or sneezing

Question 17

DIRECT transmission- Transmission by spores

Answer 17

• carried in air
• or carried by soil or on surfaces

Factors affecting this is
- wear masks
- wash skin after contact with soil

Question 18

Other factors affecting transmission - social

Answer 18

-Overcrowding
-poor health
-poor ventilation

Question 19

Indirect transmission in animals

Answer 19

Vector
- pathogen uses another organism to enter primary host

Question 20

give 2 Transmission ways of PLANT pathogens

Answer 20

-Fungi spores - carried in wind - airborne transmission
-Pathogens present in soil infects plant by roots

Question 21

Indirect transmission of PLANT pathogens

Answer 21

Insect attack - insects attack infected plant then attacks another plant

Question 22

What do Passive defences include

Answer 22

Physical barriers and chemicals

Question 23

Give examples of physical defences

Answer 23

• cellulose cell wall- physical barrier and has lots of chemicals
  -callose- in sieve tubes- blocks flow so can stop pathogen spreading
  -stomatal closure- when pathogen is detected guard cell closes stomata

Question 24

Chemical defences

Answer 24

-Menthols - produced by mint- which is an e.g of terpenoids (oils with antibacterial properties)
-Alkaloids such as caffeine and morphine which is bitter prevents herbivores eating them
-phenols such as tannin interfere with digestion thus inhibiting insects from attacking the plant

Question 25

Primary defences are non specific, what is non specific defences

Answer 25

Prevent entry of any pathogen

Question 26

What are the primary defences (skin)

Answer 26

Skin
-acts as physical barrier blocking pathogens from entry
-also acts as a chemical barrier

Question 27

Another defence (mucous membranes)

Answer 27

-Secrete mucous to trap pathogens
-contains anti microbial enzymes

Question 28

Blood clotting

Answer 28

-plug wounds to stop entry of pathogens
-platelets are exposed to damaged blood vessels
-clot prevents bleeding
-also forms a scab

Question 29

Inflammation

Answer 29

-swelling, pain and heat
-by tissue damage- releases molecules and starts to leak fluid (swelling)
-molecules cause vasodilation increasing blood flow to area and brings white blood cells

Question 30

Expulsive reflexes

Answer 30

-Sneezing and coughing
-mucous membranes are irritated in nostrils
-sneezing/coughing is an attempt to get rid of foreign objects

Question 31

Wound repair

Answer 31

Skin repairs itself in injuries
-uses collagen to repair
-surface is repaired by layer of skin dividing

Question 32

What are antigens

Answer 32

-Molecules on the surface of cells
-when a pathogen enters the body the antigen on it is foreign so it initiates a body response

Question 33

Fill in the gaps
1.Immune system involves - - - and - - - stages
2.The specific response is - - - aimed at specific pathogens
3.it involves white blood cells called - - - and - - - lymphocytes

Answer 33

1.Specific and non specific
2.Antigen specific
3. T and B

Question 34

Stage 1: Steps of phagocytosis

Answer 34

-phagocyte recognises the antigens on a pathogen
-phagocyte engulfs the pathogens (made easier by opsonins)
-it is now contained in a phagosome
-lysosome fuses either the phagosome and enzymes breakdown the pathogen
-the phagocyte then presents the pathogens antigens
~it sticks the antigens on its surface to activate other immune system cells

Question 35

What is opsonins

Answer 35

Chemicals that bind to foreign cells making it easier for phagocytes to recognise

Question 36

What is stage 2: phagocytes activating T lymphocytes

Answer 36

-