4.3 Communicable Diseases

Question 1

What is disease ?

Answer 1

Is a condition that impairs normal function of an organism.

Question 2

What is a pathogen ?

Answer 2

Is a microorganism that can cause a disease. Eg bacteria, virus’s fungi, protoctists

Question 3

What are communicable diseases ?

Answer 3

A disease that can spread from person to person and is caused by a pathogen.

Question 4

What is TB caused by and who does it affect ?

Answer 4

Caused by bacterium and can affect animals.

Question 5

What is bacterial meningitis caused by and who does it affect ?

Answer 5

Caused by bacterium and can affect humans.

Question 6

What is ring rot caused by and who does it affect ?

Answer 6

Caused by bacteria and affects potatoes and tomatoes.

Question 7

What is HIV/AIDS caused by and who does it affect ?

Answer 7

Caused by a virus and affects humans.

Question 8

What is influenza caused by and who does it affect ?

Answer 8

Caused by virus and affects animals and humans.

Question 9

What is tobacco mosaic virus caused by and who does it affect ?

Answer 9

Caused by virus and affects plants.

Question 10

What is black Sigatoka caused by and who does it affect ?

Answer 10

Caused by fungus and affects banana plants.

Question 11

What is Ringworm caused by and who does it affect ?

Answer 11

Caused by fungus and affects cattle.

Question 12

What is athletes food caused by and who does it affect ?

Answer 12

Caused by fungus and affects humans.

Question 13

What is potato/tomato late blight caused by and who does it affect ?

Answer 13

Caused by protoctists and affects potatoes and tomatoes.

Question 14

What is malaria caused by and who does it affect ?

Answer 14

Caused by protoctists and it affects animals and humans.

Question 15

What is direct transmission ?

Answer 15

When disease is transmitted directly from one organism to another. Eg droplet infection, sexual intercourse, touching infected animals.

Question 16

What is indirect transmission ?

Answer 16

When disease is transmitted from one organism to another, via an intermediate. Eg air, water, food, vectors.

Question 17

How does living conditions affect transmission of disease ?

Answer 17

Overcrowded living conditions increase transmission of disease. Eg TB via droplet infection.

Question 18

How does social conditions affect transmission of disease ?

Answer 18

Income, occupations and where someone lives can affect transmission of disease.

Question 19

How does climate affect transmission of disease ?

Answer 19

Can affect the spread of communicable diseases.

Question 20

How does skin in animals defend against pathogens ?

Answer 20

Skin is a physical and chemical barrier that blocks pathogens from entering and produces chemicals that are antimicrobial and can lower the pH, which inhibits growth of pathogens.

Question 21

What does antimicrobial mean ?

Answer 21

Destroy/ slows growth of microorganisms.

Question 22

How do mucous membranes in animals defend against pathogens ?

Answer 22

They protect the body openings that are exposed to the environment. Some membranes secrete mucus, that traps pathogens and contains antimicrobial enzymes.

Question 23

How does blood clotting in animals defend against pathogens ?

Answer 23

They plug wounds to prevent pathogen entry and blood loss. They are formed by chemical reactions that take place when platelets are exposed to damaged blood vessels.

Question 24

What are blood clots and how are they formed ?

Answer 24

Mesh of protein fibres and are formed by chemical reactions that take place when platelets are exposed to damaged blood vessels.

Question 25

How does inflammation in animals defend against pathogens ?

Answer 25

Causes swelling and helps to isolate any pathogens that may have entered damaged tissues. Molecules cause vasodilation, increasing blood flow to area bringing new blood with white blood cells.

Question 26

What is inflammation in animals ?

Answer 26

Is triggered by tissue damages, where tissues releases molecules, which increase the permeability of blood vessels, so they leak fluid into surrounding areas.

Question 27

How does wound repair in animals defend against pathogens ?

Answer 27

Surface of skin is repaired by outer layer os skin cells dividing and migrating to edges of the wound. Tissue below the wound closes together the wound and is repaired using collagen fibres.

Question 28

How does expulsive reflexes in animals defend against pathogens ?

Answer 28

A sneeze happens when mucous membranes are irritated and a cough is an irritation in the respiratory tract. Both coughing and sneezing expel foreign objects, such as pathogens, which happens automatically.

Question 29

How do physical plant defences protect against pathogens ?

Answer 29

-Waxy cuticle prevents entry.
-Cell wall forms barrier.
-Produces glucose so calls gets deposited between plant cell walls and plasma membranes.

Question 30

How does physical barriers in plants defend against pathogens ?

Answer 30

Callose deposition may make it harder for pathogens to enter cells. Calls deposition at plasmodesmata may limit spread of viruses between cells.

Question 31

How does chemical defences in plants defend against pathogens ?

Answer 31

Plants produce antimicrobial which kill pathogens or inhibit their growth. Other chemicals secreted by plants are toxic to insects. This reduces amount of insects feeding on plants and reduces risk of infection.

Question 32

What is an immune response ?

Answer 32

Body’s reaction to a foreign antigen.

Question 33

What are antigens ?

Answer 33

Molecules that are found on the surface of cells.

Question 34

What activates an immune response ?

Answer 34

When a pathogen enters, antigens are detected on the pathogen, which activates the immune response.

Question 35

What is non-specific and specific response ?

Answer 35

Non-specifc happens in the same way for all microorganisms but specific response is antigen specific using white blood cells.

Question 36

What is phagocytosis ?

Answer 36

Engulfment of pathogens using phagocytes and are found in blood and tissues and are non-specific.

Question 37

What are the steps in phagocytosis ?

Answer 37

-Phagocytes recognises antigen.
-Phagocytes surround the pathogen and can be helped by opsonins.
-Lysosomes break down pathogen in phagocyte.
-Sticks antigens to surface of phagocyte to act as an antigen-presenting cell to activate other immune system cells.

Question 38

What moves toward wound in response to cytokines ?

Answer 38

Neutrophils are a type of white blood cell that move toward the wound.

Question 39

What are cytokines ?

Answer 39

Proteins that act as messenger molecules.

Question 40

What is T lymphocyte activation ?

Answer 40

T lymphocytes are another type of white blood cell. It surface is covered with receptors. Receptor bind to antigens presented by antigen-presenting-cell.

Question 41

What occurs in T lymphocyte activation ?

Answer 41

Each T cell has different receptors. When receptor on surface of T lymphocyte meets a complementary antigen, it binds to it. This process activates T lymphocytes and is called clonal selection.

Question 42

What is clonal expansion ?

Answer 42

Activated T lymphocytes undergoes clonal expansion, where it divides and produces clones of itself.

Question 43

What do T helper cells do ?

Answer 43

It releases substances to activate B lymphocytes and T killer cells.

Question 44

What does T killer cells do ?

Answer 44

They attach and kill cells with the virus.

Question 45

What do T regulatory cells do ?

Answer 45

They suppress immune system from attacking host body cells.

Question 46

What are B lymphocytes ?

Answer 46

Type of WBC that are covered with antibodies, that are proteins that bind to antigens to form antigen-antibody complex. Each B lymphocyte has a different shaped antibody on its membrane.

Question 47

What is B lymphocyte activation ?

Answer 47

When antibodies on surface of B lymphocytes meet complementary antigen, it binds to it. This along with substances released from helper T cells, activates B lymphocytes. (Another example of clonal selection).

Question 48

What is plasma cell production ?

Answer 48

When activated B lymphocytes divide by mitosis into plasma cells and memory cells. This is another form of clonal selection.

Question 49

What is antibody production ?

Answer 49

Plasma cells are clones of B lymphocyte cells and they secrete loads of antibody specific antigens in blood. These antibodies bind to antigens on surface of pathogen to form lots of antigen-antibody complexes. This is the signal for immune system to attach and destroy the pathogen.

Question 50

What is cell signalling ?

Answer 50

Is how cells communicate. A cell may release a substance that binds to receptors on another cell causing a response in other cells.

Question 51

Why is cell signalling important ?

Answer 51

Is important in immune response as it activates all different types of blood cells needed.

Question 52

What are blood smear ?

Answer 52

Smear of blood on a slide. Stains are added to increase contrast.

Question 53

What are antibodies ?

Answer 53

They are a blood protein produced in response to and counteracting a specific antigen. They combine chemically with substances.

Question 54

What is the structure of antibodies ?

Answer 54

Antibodies are glycoproteins and are made of 4 polypeptide chains and each chain has a variable region and a constant region.
-Variable regions = complementary shape
-Hinge regions = allows flexibility
-Constant region = binding to receptors.
-Disulphide bridges = holds polypeptide chains together.

Question 55

What are agglutinating pathogens ?

Answer 55

Each antibody has 2 binding sites so can bind to 2 pathogens at same time. Pathogens then bind to antibodies and phagocytes lots at once.

Question 56

What are neutralising toxins ?

Answer 56

Toxins have different shapes so anti-toxins can bind to toxin produced by pathogen. This prevents toxin from affecting human cells so toxins are neutralised . Toxin-antibody complexes are phagocytose.

Question 57

What occurs in preventing the pathogen from binding to human cells ?

Answer 57

When antibodies bind to antigens on pathogen, they may block cell surface receptors that pathogen binds to host cells. This means pathogen cannot attach or infect host cells.

Question 58

What is the primary immune response ?

Answer 58

When a pathogen enters the body for the first time the antigens on its surface activate the immune system.

Question 59

Why is the primary response slow ?

Answer 59

Slow because there aren’t many B lymphocytes that can make antibodies that bind to pathogens. Eventually the body will produce enough of the right antibody to overcome the infection. Meanwhile the infected person shows symptoms of disease.

Question 60

What are memory T lymphocytes ?

Answer 60

They remember specific antigens and will recognise it the second time round.

Question 61

What are memory B lymphocytes ?

Answer 61

They record specific antibodies needed to bind to antigen.

Question 62

What is the secondary immune response ?

Answer 62

If the same pathogen enters body again and immune system produces quicker and stronger immune response.

Question 63

How do you maintain immunity ?

Answer 63

Memory B and T lymphocytes have a limited lifespan so immunity won’t last forever. Immunity can be maintained by being continually exposed to pathogen so you make more lymphocytes.

Question 64

What is active immunity ?

Answer 64

When immune system makes 2 of its own antibodies after being stimulated by an antigen.

Question 65

What is natural active immunity ?

Answer 65

When you become immune after catching a disease.

Question 66

What is artificial active immunity ?

Answer 66

When you become immune after given a vaccination containing a harmless dose of an antigen.

Question 67

What is passive immunity ?

Answer 67

Type of immunity from being given antibodies made by different organisms (your immune system doesn’t make any antibodies on its own).

Question 68

What is natural passive immunity ?

Answer 68

When baby becomes immune due to antibodies received from its mother, through placenta and breast milk.

Question 69

What is artificial passive immunity ?

Answer 69

When you become immune after being injected with antibodies from somewhere else.

Question 70

What are autoimmune diseases ?

Answer 70

When an immune system treats self-antigens as foreign and launches response against the organisms own tissues.

Question 71

What is vaccination ?

Answer 71

Contains substances that cause you body to produce memory cells against a particular pathogen, without the pathogen causing a disease.

Question 72

What is the difference between epidemic and pandemic ?

Answer 72

When communicable diseases spread rapidly locally vs internationally.

Question 73

What is pharmacogenetics ?

Answer 73

Personalised medicine that works with individual combination of genetics and disease.

Question 74

What is synthetic biology ?

Answer 74

Uses techniques of genetics engineering to develop populations of bacteria for expensive drugs.

Question 75

What is antibiotics having selective toxicity good ?

Answer 75

This means antibiotics will interfere with bacterias metabolism not the metabolism of human cells.