Communicable diseases

Question 1

what is a pathogen?

Answer 1

a microorganism that causes disease

Question 2

why is a host body good for a pathogen

Answer 2

a host body creates a good environment for the pathogen to live in as it can live of the nutrients caused by the cells

Question 3

what does the pathogen do to the host body

Answer 3

causes damage to the cells and takes nurients from the host

Question 4

what kingdom does bacteria belong to

Answer 4

prokaryotae

Question 5

How does bacteria harm the body

Answer 5

they damage cells and release toxins and waste substances that are harmful to the host
- in plants they live in the vascular tissue

Question 6

where does fungi live

Answer 6

fungi lives in the skin of an animal where its hyphae, this forms a mycelium which grows under the skins surface
- in plants it lives in the vascular tissue where it gains nutrients

Question 7

how does fungus cause irritation and redness

Answer 7

it sends out special reproductive hyphae which grows on the surface of the skin to release spores this causes the redness and irritation

Question 8

in plants what does the hyphae do

Answer 8

it releases extracellular enzymes such as cellulases which digest the surrounding tissue and cause decay

Question 9

what are the symptoms of fungi in plants

Answer 9

• leaves - mottled in colour, curl up, shrivel and die

- fruit - turn black and decay

Question 10

what doe viruses do inside the cell

Answer 10

they invade the cell and take over the genetic machinery and other organelles of the cell
cell then manufactures more copies of the virus
host cell then bursts and new viruses invade other cells

Question 11

what do protoctista do?

Answer 11

they enter host cells and feed on the content as they grow

Question 12

what are the 4 types of pathogen

Answer 12

fungi, bacteria, protoctista, viruses

Question 13

tuberculosis

Answer 13

• bacteria

- affects many parts but kills cells and tissues, lungs are most affected

Question 14

bacterial meningitis

Answer 14

• bacteria
• infection of the meninges, membranes that surround the brain and spinal cord, the membrane swell and cause damage to the brain and nerves

Question 15

ring rot

Answer 15

• bacteria

- ring of decay in vascular tissue of a potato tuber or tomato accompanied by leaf wilting

Question 16

HIV/AIDs

Answer 16

• virus

- attacks cells in the immune system and compromises immune response

Question 17

influenza

Answer 17

• virus

- attacks respiratory system and causes muscle pains and headaches

Question 18

tobacco mosaic virus

Answer 18

• virus

- causes mottling and discolouration of leaves

Question 19

black sigatoka (banana)

Answer 19

• fungi

- causes leaf spots in banana a plants reducing yield

Question 20

blight (tomato and potatoes)

Answer 20

• protoctistan

- affect both the leaves and potato tubers

Question 21

ringworm (cattle)

Answer 21

• fungus

- growth of fungus in skin with spore cases erupting through skin to cause a rash

Question 22

athletes foot

Answer 22

• fungus

- growth under skin of feet particularly between the toes

Question 23

malaria

Answer 23

• protoctistan

- parasite in the blood that causes a headache and fever and may progress into coma and death

Question 24

what is the lifecycle of a pathogen

Answer 24

travel from one host to another
enter hosts tissues
reproduce
leave hosts tissues

Question 25

What are the factors effecting direct physical contact

Answer 25

``` hygiene keeping surfaces clean cleaning and disinfecting cuts sterilising surgical equipment using condoms ```

Question 26

What are the factors effecting faecal (oral) transmission

Answer 26

using sewage to treat crops treatment of waste and water washing all fresh food and careful preparation

Question 27

what are the factors affecting droplet infection

Answer 27

catch it - bin it - kill it cover mouth when coughing or sneezing use a tissue

Question 28

what are the factors affecting transmission by spores

Answer 28

use a mask | washing skin after contact with soil

Question 29

what are the means of direct transmission

Answer 29

direct physical contact - touching an infected person or contaminated surface that harbours the pathogens - HIV, ringworm, athletes foot faecal - usually by eating or drinking contaminated substances - cholera or food poisoning droplet infection - in which the pathogen is carried in tiny droplets in the air, TB, influenza spores - a resistant stage of the pathogen carried in air or residue on surface or in the soil - anthrax and tetanus

Question 30

what other things cause disease

Answer 30

``` overcrowding poor ventilation poor health poor diet homelessness living and working with people who have migrated from diseased areas ```

Question 31

what is a vector used for

Answer 31

its used by the pathogen to gain entry to the primary host

Question 32

describe the malaria cycle

Answer 32

``` 1. gametes of plasmodium in blood 2, female anopheles mosquito sucks blood 3. plasmodium develops and migrates to mosquitos salivary gland 4. uninfected person is bitten 5. plasmodium migrates to liver 6. plasmodium migrates to blood 7. person with malaria ```

Question 33

how do plants have diseases transmitted to them

Answer 33

enter the roots many fungi produce spores due to sexual and asexual reproduction - these are carried by the wind enter fruit and seeds and will distribute with the seeds so offspring are infected pathogens in the leaves when the leaves are shed carry the pathogen back to the soil where it can grow and infect another plant

Question 34

what does a pathogen do in a plant

Answer 34

effects all vascular tissue,

Question 35

what effect does climate have on disease

Answer 35

warm and moist conditions increase growth of bacteria, fungi, protoctista this provides a greater variety of diseases in warmer countries

Question 36

What is a primary defence?

Answer 36

a primary defence are the mechanisms which evolve to prevent entry of pathogenic organisms from entering the body, for example the skin

Question 37

Why are primary defences non-specific?

Answer 37

they are non-specific as they have to prevent entry into the body from the various types of pathogens

Question 38

What is the main primary defence?

Answer 38

skin

Question 39

Describe the outer layer of skin

Answer 39

the outer layer is called the epidermis and consists of layers of cells called keratinocytes

Question 40

describe the process of keratinisation

Answer 40

the cells are produced by mitosis at the base of the epidermis they then migrate to the skin surface and dry out, the cytoplasm is replaced by keratein and takes 80 days when they reach the skin surface they are dead, this acts as a barrier

Question 41

What does blood clotting do?

Answer 41

temporary skill to precvent infection and repair the skin

Question 42

describe how a clot forms

Answer 42

1. Damaged blood vessels expose collagen and releases clotting factors as connective tissue is now exposed platelets bind to collagen releasing clotting factors this causes a temporary platelet plug clot 2. The platelets binding to the collagen causes the inactive thrombokinase in the blood to change shape and form an active site so the thrombokinase becomes active 3. The active throbokinase plus calcium ions causes the prothrombin in the blood to turn into active thrombin, this active thrombin turns soluble fibrogen into an insoluble fibrin 4. the fibres attach to platelets in plug and a blood clot forms this traps the red blood cells and platelets

Question 43

What happens after a clot has formed

Answer 43

the clot begins to dry and form a scab the scab then shrinks as it drys and draws the sides of the cut together sealing the skin 1. the first stage is the deposition of fibrous collagen under the scab 2. the stem cells then divide by mitosis to form new cells these migrate to the edges of the cut and differentiate to form new skin 3. new blood vessels then grow to supply oxygen and nurtients to the tissues 4. the scab is then released

Question 44

Why is where the food enters more at risk

Answer 44

where food enters the blood the exchange surfaces are quite thin and less well protected so are more at risk

Question 45

What produced mucus

Answer 45

goblet cells in the epithelial layer

Question 46

Where is the mucus/ciliated epithelium

Answer 46

``` gut genital areas anus ears nose ```

Question 47

How does mucus trap the pathogens

Answer 47

traps pathogens that are in the air, the mucus is then wafted along the trachea by cilia cells where it enters the oesophagus this is swallowed and digested by the pathogen and then killed by the acidity of the stomach

Question 48

what is an expulsive reflex

Answer 48

coughing or sneezing as a response to irritation, it is caused by the presence of pathogens

Question 49

what are the other primary defences

Answer 49

eyes produce antibodies and enzymes and tissue fluid ear wax traps pathogens female reproductive system has mucus plug in cervix and acidic conditions

Question 50

How does inflammation work

Answer 50

1. presence of pathogens detected by specialised cells called mast cells 2. mast cells release signalling substance called histamine this causes vascodilation around the infected area and increases the blood flow bringing more phagocytes to the area 3. vascodilation causes the redness, it also increases the size of the pores within the capillary wall this allows the phagocytes to change shape and squeeze out into the tissue fluid 4. the excess tissue fluid is then drained into the lymphatic system where the lymphocytes are stored 5. the pathogen come into contact with the lymphocytes and a specific immune response is started 6. the swelling is caused by an increase in tissue fluid