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AS level - Biology > Chapter 12 - Communicable Diseases > Flashcards

Chapter 12 - Communicable Diseases Flashcards

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1
Q

What is a pathogen

A

An organism that can produce a disease

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2
Q

What is a vector

A

They carry the pathogens from one organism to another. Ex: wind or water

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3
Q

What are the 4 types of pathogens

A

Bacteria, viruses, protoctista and fungi

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4
Q

Bacteria as a form of pathogen

A

They can be classified using either the cell walls or the shape.

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5
Q

What is rod shaped bacteria called

A

Bacilli

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6
Q

What is spherical shaped bacteria called

A

Cocci

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7
Q

What is comma shaped bacteria called

A

Vibrios

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8
Q

What is spiralled shaped bacteria called

A

Spirilla

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9
Q

What is corkscrew shaped bacteria called

A

Spirochaetes

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10
Q

How can you use a bacteria’s cell walls to differentiate between bacteria

A

Gram staining.

Can see how bacteria will react to different antibiotics.

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11
Q

Viruses as a form of pathogen

A

They invade cells, then take over the genetic material and produce more viruses. They can attack bacteria as well, which are called bacteriophages. They destroy the cells.

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12
Q

Protoctista as a form of pathogen

A

They are a group of eukaryotic organisms with a wide variety of feeding mechanisms. A small % of them act as pathogens and enter through ex. malaria or infected water.

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13
Q

Fungi as a form of pathogen

A

They attack more plants rather than animals. Eukaryotic organisms can kill leaves, and prevent plants from photosynthesising. As fungi reproduces, they spread over distances.

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14
Q

What are the modes of action

A

Damaging the host tissue directly.

Or producing toxins which damage host tissues.

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15
Q

Ways to damage the host tissue directly

A

The viruses can take over the cell metabolism and insert its DNA and make new viruses, then burst to destroy the cell and continue.
Protoctista can break the cell open as new generation emerge. They dont take over the cell’s DNA.
Fungi digest living cells.

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16
Q

Ways to produce toxins which damage the host tissues

A

Most bacteria produce toxins to the hosts’ cells and damage the cell membrane, or DNA.
Toxins are by-products of normal functioning bacteria
Some fungi can also do this

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17
Q

Ring Rot - plant disease

A

A bacterial disease of potatoes, tomatoes, and aubergines.
Caused by Gram positive bacteria
Damages leaves, fruits and tubers.
Means the plants can’t be used in field for at least 2 years.

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18
Q

TMV - plant disease

A 
Infects tobacco plants
And tomatoes, peppers etc. 
No cure (but can be resistant)
Damages leaves, flower, fruits and stunts growth. 
Leads to total crop loss
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19
Q

Potato blight - plant disease

A

A fungus- like protoctista.
No cure (but can be resistant)
Destroys leaves, fruits and tuber

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20
Q

Black Sigatoka - Plant disease

A 
Banana disease 
Hyphae penetrates cell and digests them. 
Can cause 50% reduction in yield 
No cure (but can be controlled)
Attacks and destroys the leaves
The leaves then turn black.
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21
Q

TB- Animal Diseases

A

A bacterial disease
Destroys lung tissues and suppresses the immune system
People affected by AIDS/HIV are much more likely to develop TB.
It is curable and preventable.

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22
Q

Bacterial meningitis- Animal Disease

A

A bacterial infection of meninges of the Brain.
It can spread and cause blood poisoning and lead to rapid death.
Mainly affects teenagers.
If there is a purple rash that won’t leave when glass is pressed against it, that is a symptom.
Antibiotics can cure it.

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23
Q

HIV/AIDS - Animal diseases

A

They target “T Helpers” in the immune system, until the entire immune system is destroyed. HIV is a retrovirus with RNA as its genetic material. It contains the enzyme reverse transcriptase, which transcribes the RNA to a single strand of DNA.
It spread by sharing needles, and bodily fluids.
There is no vaccine and no cure, but antiretroviral drugs can reduce the impacts.

24
Q

Influenza - Animal diseases

A

A viral infection of the ciliated epithelial cells in the gas exchange system. By killing them, it leaves the airways open to another infection. Sometimes, there can be a major change in the surface antigens, starting a pandemic, as there are no antibodies available.

25
Q

Malaria - Animal diseases

A

Caused by a protoctista, spread by mosquitoes.
The female mosquito needs 2 blood meals to provide her with protein before she lays her eggs.
It invades the red blood cells, liver and the brain.
There is no vaccine, and the only option is to control the vector.

26
Q

Ring worm - Animal diseases

A

A fungal disease which affects dogs, cattle and humans.

It causes grey, crusty circular areas on the skin. Antifungal creams can help.

27
Q

Athlete’s Foot - Animal diseases

A

Human fungal disease

Causes cracking, scaling and antifungal creams can help.

28
Q

What are the 2 ways that a communicable disease can spread between animals

A

Direct and indirect

29
Q

Examples of direct contact between animals

A

Kissing
Sexually transmitted disease
Direct skin contact

30
Q

Examples of inoculation between animals

A

Break in the skin
Animal bites
Sharing needles

31
Q

What does direct contact between animals include

A

Inoculation
Ingestion
Direct contact

32
Q

What does indirect contact between animals include

A

Fomites
Droplet inhalation
Vectors

33
Q

Examples of fomites

A

Inanimate objects (sharing socks)

34
Q

Examples of vectors between animals

A

Water

Other animals

35
Q

Factors that affect the transmission of communicable disease

A 
Overcrowded living 
Poor nutrition 
Having immunosuppresants 
A poor immune system. 
Poor disposal of waste
Climate change (new vectors)
Culture and infrastructure (traditional medical practices)
Socioeconomic factors (Lack of trained workers)
36
Q

Indirect transmission of communicable disease in plants

A

Soil contamination

Infected pants can leave bacteria or viruses in the soil

37
Q

Vectors in transmission of communicable disease in plants

A

Wind
Water
Animals
Humans

38
Q

Factors affecting transmission of communicable disease in plants

A 
Planting crops that are vulnerable to disease
overcrowding
Poor mineral nutrients 
Damp, warm conditions
Climate change (more rainfall and wind)
39
Q

What are some easy ways to prevent pathogens from getting into plants?

A

thick waxy cuticle
bark
cellulose cell walls
This is all because plants don’t heal diseased tissues. They just seal it and then sacrifice it.

40
Q

How can plants recognise the attack

A

The molecules in the pathogens (or any chemical enzymes secreted by the pathogens) are detected by the receptors in the cell. Then, this triggers the release of molecules that switch on genes in the nucleus. This means that any of the defences are set up.

41
Q

What is the main plant physical defence

A

Producing high levels of callose. This is a carbohydrate molecules, which has 1-3 and 1-6 bonds.

42
Q

What are all the physical plant defences

A

In minutes of an attack, plants gather callose at the area of infection by the pathogen to create a barrier.
Lignin also gather to add extra strength.
Callose gathers and blocks sieve plates too, to prevent spreading.
Callose is deposited in the plasmodesmata between infected cells and their neighbours.

43
Q

What are the plant’s chemical defences

A 
Insect repellent 
Insecticides
Antibacterial compounds 
Antifungal compounds 
Anti-oomyceles (eg.  glucanase)
General toxins (cyanide)
44
Q

How can the body keep out pathogens

A 
Skin 
Healthy microorganisms 
Sebum 
Lined by mucous membranes
Phagocytes 
Lysosomes in tears and urine
Acid in stomach 
Sneezes and coughs 
Vomiting and diarrhoea.
45
Q

How does blood clotting help keep pathogens out of the body

A

If you cut yourself, blood clots to seal the wound. As blood platelets come into contact with the collagen in your skin, they begin to secrete 2 chemicals.
They are: thromoplastin and serotonin

46
Q

Thromoplastin

A

Results in the formation of blood clotting

47
Q

Serotonin

A

They narrow and reduce the supply of blood to the area.

48
Q

Wound repair

A
  1. A hard scab is formed.
  2. Epidermis cells below the scab starts to grow.
  3. Sealing the wound permanently
  4. Damaged blood vessels begin to regrow.
  5. Collagen fibres are deposited to give strength
  6. When the epidermis reaches a normal thickness, the scab is healed and it peels off.
49
Q

Inflammatory response includes what

A

Mast cells are activated in the damaged tissues so that they can inflame.
It includes:
Histamines and cytokines

50
Q

Histamines (Inflammatory response )

A

Makes the blood vessels dilate, which causes redness and heat.
Heat prevents the pathogens being produced.
It makes the blood vessels’ walls more leaky.
So blood plasma is forced out as is called tissue fluid.
This causes pain and swelling.

51
Q

Cytokines (Inflammatory response )

A

Attracts phagocytes to the site to engulf pathogens

52
Q

How does the body respond to get rid of pathogens (main list)

A

Fevers
Phagocytosis
Macrophages
Chemicals

53
Q

Explain fevers (How does the body respond to get rid of pathogens)

A

Most pathogens reproduce best at temperature below 37 degrees.
So, the specific immune system works faster at higher temperatures.

54
Q

Explain phagocytosis (How does the body respond to get rid of pathogens)

A
  1. Pathogens produce chemicals that attract phagocytes.
  2. Phagocytes recognise non-human proteins and it engulfs the pathogen and enclosed it in a vacuole called phagosome.
  3. The phasosome combines it with a lysosome to form a phagolysosome.
  4. The pathogen is digested and destroyed.
55
Q

Explain Macrophages (How does the body respond to get rid of pathogens)

A

It digests the pathogens by combining its antigens from the pathogen surface membrane with special glycoproteins called Major Histocompatibility complex.
The complex moves these pathogens’ antigens to the macrophages’ own surface membrane, called an antigen-presenting cell.
The antigens now stimulate other cells involved in the specific immune system.

56
Q

Explain Chemicals (How does the body respond to get rid of pathogens)

A

Phagocytes produce cytokines when they have engulfed pathogens.
They inform other phagocytes that the body is under attack, they also increase the body temperature.
Opsonins bind to pathogens and ‘tag them’ so they can be easily recognisable to phagocytes.
Phagocytes have receptors on their cell membranes that bind to common opsonins.

AS level - Biology (12 decks)

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