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Biology Module 4 > Biology 4.1 > Flashcards

Biology 4.1 Flashcards

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1
Q

What is a pathogen and all the types?

A

Pathogens are organisms that cause disease, the organism they live in is called a host, and the 4 types of pathogens are bacteria, viruses, fungi and Protista

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2
Q

What is bacteria?

A

-They are prokaryotes (no membrane bound nucleus or organelles
-Can be lots of shapes (spherical, rod shaped)
-Have a cell wall (not made of cellulose)
-Bacteria damge host cells by releasing toxins

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3
Q

How do bacteria reproduce? and how is this different from mitosis?

A

-Binary Fission
-Binary fission is for growth and DNA replication happens at the same time as separation, no mitotic spindle.

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4
Q

How do viruses reproduce?

A
  1. Virus attaches to host cell
  2. Genetic material from virus is injected into the host cell
    3.Viral genes use replication machinery of host cell to make more viruses
  3. The host cell opens releasing more viruses
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4
Q

What are Viruses?

A

-50 times smaller than bacterium
-Reproduce rapidly and invade the genetic material of a host causing them to make more viruses until the cell bursts.
-Most viruses are pathogenic to organisms

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5
Q

What are Protista’s’?

A

-Eukaryotic
-Single celled but live in colonies
-A small amount act as pathogens, they are parasites so feed off the host organism for their benefit. e.g Plasmodium(Malaria) feed on the haemoglobin inside RBCs.
-Can be transferred by vectors or enter body via water.

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6
Q

What are fungi?

A

-Eukaryotic, can be single or multi-celled
-Live in surface of animals skin and hyphae forms mycelium which grows to the skin surface and releases spores, which cause redness and irritation.
-Live in vascular tissue of plants and release extracellular enzymes which damage tissue causing mottled and shrivelled leaves.
-Can’t photosynthesise so digest food extracellularly and feed on dead matter (Saprophytes)

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7
Q

What is Tuberculosis? and what pathogen causes it?

A

-Bacterial affects humans and cattle
-Damages many parts of body but lung tissue is most affected
-Suppresses immune system making you more susceptible to disease
-Cured with antibiotics or prevented with a vaccination.

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8
Q

What is Ring rot? and what pathogen causes it?

A

-Bacterial disease of potatoes and tomatoes.
-Causes a ring of decay in vascular tissue and leaf witling (droopy leaves)

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9
Q

What is HIV/AIDS? and what pathogen causes it?

A

-AIDS is caused by HIV, a virus
-The virus targets T helper cells, gradually destroying the immune system making people succeptible to disease.
-No cure yet

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10
Q

What is influenza? What type of pathogen causes it?

A

-Virus
-Affects cilated epithelial cells of the gas exchange system, leaving the airway open to secondary infection.
-Causes muscle pain and headaches

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11
Q

What is TMV? What type of pathogen causes it?

A

-Tobacco Mosaic Virus
-Infects tobbaco plants and other plants
-Spread via plasmodesmata and phloem of plants causing mottling and discolouration

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12
Q

What is Black Sigatoka? What type of pathogen causes it?

A

-Fungi
-Affects bananas destroying the leaves and reducing the yield
-Hyphae from the fungi penetrate and digest the cells turning the leaves black

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13
Q

What is athletes foot? What type of pathogen causes it?

A

-Fungal infection
-Grows in warm moist skin causing cracking and scaling
-Antifungal cream is very effective

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14
Q

What is Potato/Tomato late blight? What type of pathogen causes it?

A

-Protista
-Affects tuber(Starch store) or fruit causing necrotic brown lesions

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15
Q

What is Malaria? What type of pathogen causes it?

A

-Protista
-Spread by vectors (Mosquitos), invades liver and red blood cells and even the brain causing severe fevers and headaches.
-No vaccine or cure but preventative methods can control it (remove water they breed in, mosquito nets and insecticides).

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16
Q

Why is Malaria not in the UK?

A

-Too cold climate for mosquitos and pathogens
-Pathogens wouldn’t reproduce fast in cold climates.
-Going forward however global warming could cause malaria to be prevalent in the UK

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17
Q

What is the definition of direct transmission?

A

-The pathogen is directly transferred from one organism to another

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18
Q

What are different types of direct transmission?

A

-Physical contact (sexual intercourse or touching contaminated surfaces)
-Droplet infection (coughing or sneezing)
-Inoculation (sharing needles, break in skin)
-Ingestion (consuming contaminated food)

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19
Q

How can you reduce the risk of direct transmission?

A

-Wash hand regularly
-Cleaning cuts
-Use condoms
-Sterilize surgical equipment
-Use masks and social distance
-Treat waste products properly

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20
Q

What is the definition of indirect transmission?

A

-When a disease is transmitted from one organism to another via either a vector (organism that spreads disease by carrying pathogen) or a fomite (inanimate objects that harbor pathogens)

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21
Q

What are living condition factors that can affect transmission?

A

-Overcrowding
-Poor nutrition
-Poor disposal of waste

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22
Q

What are social and climate factors that affect transmission?

A

-Culture (traditional factors can increase transmission)
-Socioeconomic factors (poorly trained health workers)
-Climate (new vectors and diseases can emerge as temperatures rise)

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23
Q

What are stages of inflammation?

A

1.Tissue gets injured and bacteria enters site
2.The site become filled with tissue fluid due to inflammatory factors
3.Tissue cells release cytokines which attract phagocytotic white blood cells
4.phagocyte engulfs pathogen to form a phagosome
5.Phagocyte fuses with lysosome and releases hydrolytic enzymes which digest bacterium

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24
Q

What is the difference between cell mediated response and humoral?

A

-Cell mediated response target pathogens that have invaded cells or cells that have been changed (cancer) whereas humoral targets pathogens in bodily fluids using antibodies

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25
Q

How does blood clot?

A

1.Blood vessel is damaged and blood is exposed to collagen fibres
2.Platelets stick to exposed to collagen fibres forming a plug, they also release clotting factors.
3.Prothrombin is converted into thrombin, this process requires calcium and vitamin k.
4.Thrombin catalyses the conversion of inactive soluble fibrinogen into insoluble active fibrinogen, this forms a fibrin mesh which traps RBCs creating a clot.
5.Blood clot is reabsorbed

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26
Q

Why doesn’t blood normally clot?

A

Anticoagulants such as hepanin prevent blood clotting.

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27
Q

How does the cell mediated response happen?

A

1.Macrophage destroys pathogen and displays its antigen on its surface (antigen-presenting cell)
2.APC interacts with specific t-helper cell and releases interleukin 1
3.This stimulates T-helper cell to release a cytokine, interleukin 2 which stimulates growth of t-killer cells (the process of activating a t helper cell is called clonal selection).
4.T-killer cell detects antigen and produces peforin which forms pores in its membrane allowing water and ions in and causing lysis.
5.T memory cells are formed and are ready to respond if they ever come in contact with that antigen

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28
Q

What is humoral response?

A

1.Macrophage destroys pathogen becoming an APC.
2.APC interacts with t helper cell, binds with it, releasing interleukin 1
3.This stimulates the T-helper cell to release interleukin 2 which stimulates the differentiation of a b-effector cell into a plasma cell
4.Plasma cell divides by mitosis which produces loads of clones which can produce antibodies that destroy the pathogen by agglutination and neutralization.
5.B memory cells are produced and ready to respond if they come in contact with that antigen

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29
Q

How can humans prevent the spread of disease

A

-Regular hand washing
-Improving living conditions e.g good nutrition and reducing overcrowding
-Effective disposal of waste

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30
Q

What is a disease that can spread between humans and animals? How can you prevent the transmission of these diseases?

A

-A zoonotic disease e.g. bird flu strain H1N1
-You can prevent transmission by reducing contact with these animals

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31
Q

How can Pathogens be transmitted between plants?

A

-Direct transmission ( when a healthy plant infects an uninfected plant through contact e.g between leaves)
-Indirect transmission(1. Soil pathogens can remain in soil and infect plants when planted they get into the soil for e.g. via dead plant leaves dropping into soil 2. Vectors like wind, water, infected insects (when an infected insect attacks a plant pathogen enters).

32
Q

Where does fungus live in a plant and why?

A

-The vascular tissue(the same for other pathogens)
-It grows here to acquire nutrients and its hyphae release enzymes which digest surrounding tissue causing the leave to mottle and die as it can’t photosynthesize.

33
Q

How does fungus reduce crop yield and reproduce when the conditions are harsh?

A

-It causes mottling and discolouration which reduces photosynthesis, less carbohydrate is produced, so plants are smaller in size and yield is reduced
-In harsh conditions they produce spores which can spread large distances rapidly.

34
Q

How do pathogens as a whole reduce plant growth and yield?

A

1.Reduce the rate of photosynthesis by blocking light/destroying chloroplasts
2.Increase the rate of respiration as the plant fights the infection
3.Feed on the plants’ sugars
4.Make plant lose water through wounds
5.Can block xylem and phloem

35
Q

What are factors that affect the transmission of plant communicable diseases? and how can farmers prevent the spread of these diseases?

A

-Planting plants susceptible to diseases, overcrowding plants, poor minerals means plants will be less resistant, damp warm conditions promotes spread of spores and pathogens, climate change (more rainfall and changing conditions means new vectors will enter new areas)
-Leaving space between plants, cleaning fields after harvesting, crop rotation, strict hygiene procedures and controlling insect vectors.

36
Q

What are passive plant defences?

A

-Cellulose cell wall- not only a physical barrier but contains chemicals that can be activated
-Lignin thickening of cell walls- waterproof and completely indigestible
-Waxy cuticle- prevents water from collecting on surface of plant and therefore any pathogens living in water from infecting the plant
-Bark-contains chemical defences]
-Stomata- when pathogenic organisms are detected the gurd cells close the stomata at that part of the plant.

37
Q

What is callose

A

-Callose is a large polysaccharide that is deposited in the end of growing end in the sieve tubes which can prevent a pathogen in the phloem spreading to the rest of the plant

38
Q

What is tylose

A

Tylose is a balloon like swelling that fills the xylem vessel this prevents the spread of pathogens, they also contain a high number of chemicals e.g terpenes

39
Q

What are chemical defences of a plant

A

-Terpenoids
-Phenols
-Alkaloids
-Defensive proteins
-Hydrolytic enzymes

40
Q

How does a plant recognise an attack?

A

1.Receptors respond to molecules on the pathogen or chemicals released by pathogen
2.They release signalling molecules which switch on genes
3.These trigger cellular responses

41
Q

How does a plant actively defend against a pathogen once recognised?

A

-Cell walls thicken and become strengthened with lignin and cellulose
-Callose is deposited between plant cell wall and cell membrane near pathogen
-Oxidative burrs produce highly reactive oxygen molecules which can damage cells of invading organisms
-increase in production of chemicals

42
Q

What is necrosis?

A

-Deliberate cell suicide, a few cells are sacrificed to save the plant (intercellular enzymes are released)

43
Q

What is canker

A

A sunken necrotic lesion in the woody tissue of the plant caused by pathogens. Cambium bark tissue dies as a result.

44
Q

When are necrosis and canker used?

A

As a last result the plant will use they just to survive from infection.

45
Q

What is the difference between primary non-specific and specific immune response

A

-Primary non specific defences are allways present and defend against pathogens in the same way whereas specific immune responses are slower and defend differently against different types of pathogens.

46
Q

How does the skin defend against pathogens

A

-Surface of the skin contains a layer of dry dead cells which prevent pathogens from entering the body
-When sweat evaporates it leaves salt making skin slightly acidic
-The skin harbours healthy microorganisms which outcompete pathogens for resources.
-This is a primary non specific defense

47
Q

What is sebum?

A

-Primary non-specific defenses
-Oily waxy substance produced by sebaceous glands, coats and protects skin with antimicrobial properties

48
Q

How does the gut protect against pathogens?

A

-Hydrochloric acid is secreted by parietal cells in stomach, this kills pathogens which are ingested with food, mucus is also along the length of the gut to protect against the acid
-This is a non-specific primary response

49
Q

How do mucous membranes help protect against pathogens?

A

-Line the gut, respiratory system and reproductive system
-Secreted by goblet cells
-mucous is made up of glycoproteins and traps dust and pathogens cilia then wafts it to be removed
-Also contains lysozymes which destroy cell walls of bacteria and fungi and it also contains phagocytes

50
Q

How do expulsive reflexes help protect against pathogens?

A

-Primary non specific defense
-Sneezing and coughing remove pathogens from the airways and diarrhoea and vommiting expel contents of the gut

51
Q

How do lysosomes help protect humans from pathogens?

A

-Lysozomes are in boby fluids and act as antimicrobial angents breaking down bacterial and fungal cell walls

52
Q

How are wounds repaired once clotted?

A

-Platelets secrete growth factors that stimulate stem cells and the production of collagen fibres which are deposited under the scab. Granulation tissue fills the wound as stem cells which divided by mitosis to become skin cells go to the edge of the wound and differentiate. New blood vessels form to suppy oxygen to the tissue The skin contracts to draw edges together and once epidermis is a normal thickness the scab falls off.

53
Q

What is the role of opsonins?

A

Chemicals that bind to pathogens making them more recognisable to pathogens they also act as binding sites so its easier to bind for phagocytosis.

54
Q

Why do fevers happen?

A

-When a pathogen invades cytokines stimulate the hypothalamus to set the body temperature to a higher temp, this helps the immune system work at a faster rate and slows down the reproduction of pathogens as they reproduce best at 37 degrees Celsius.

55
Q

What is the role of mast cells?

A

-They respond to damage by releasing histamines(cause vasodilation and capillaries to become leaky so white blood cells can enter tissue) and cytokines (attract phagocytes)

56
Q

What causes swelling of lymph nodes?

A

-Excess tissue fluid drains into lymph vessels, so pathogens in tissue fluid enters lymph vessels and are transported along the lymph system to lymph nodes.

57
Q

What is the structure of an antibody?

A

-Y shaped glycoproteins
-Made up of two identical polypeptide chains called heavy chains joined to two pairs of shorter chains called light chain held together by disulfide bonds
-Disulfide bonds are also found in the polypeptide chain
-They are specific to only one type of antigen

58
Q

What parts of the antigen bind to what?

A

-Antigen binding site binds to pathogen
-The constant region binds to the pathogen

59
Q

What are the two mechanisms by which antibodies destroy pathogens?

A

-NEUTRALISATION antibodies surround the pathogen by binding onto them, this prevents the pathogen from binding onto a host cell and therefore hindering its damage
-AGGLUTINATION antibodies bind to many pathogens in one place creating a clump for a phagocyte to engulf

60
Q

How do antitoxins protect cells?

A

combine with toxins preventing them from entering the host cell.

61
Q

Describe a primary and secondary immune response?

A

-Primary immune response- antibodies break down and b and t cells form memory cells, plasma cells also dont live for long
-Secondary immune response- longer and faster response, with a higher concentration of antibodies, clonal selection is faster, t lyphocytes form t killer cells and memory b lymphocytes differentiate into plasma cells, no symptoms are therefore shown

62
Q

Why do vaccinations not cause illness and what are the two types of immunity?

A

-Attenuated of versions of the pathogen are injected or some versions only contain antigens so can’t cause disease.
-active immunity(immune system responds to foreign antigens creating antibodies) and passive immunity (immune system doesn’t respond and antibodies come from another source.

63
Q

What is the difference between immunisation and vaccination?

A

-Vaccination is when you are given a vaccine whereas immunisation is what happens to you after you have a vaccine

64
Q

How does a vaccine work?

A

1.Vaccines contain antigens
2.immune system recognizes as non self, attacks it and produces memory cells
3. if infected again person produces plasma cells which release antibodies to neutralize pathogens

65
Q

What can be in a vaccine?

A

-Live microorganisms with similar antigens to the real pathogen
-attenuated version of a pathogen
-dead pathogen
-A toxoid (harmless version of a toxin)

66
Q

What is herd immunity?

A

-When almost all people in a community are vaccinated so the disease becomes extremely rare
-This can prevent an epidemic

67
Q

What are routine vaccinations?

A

-MMR (Measles,Mumps and Rubella)
-Meningitis C vaccine
-Polio Vaccine

68
Q

What are the problems with antigenic variations?

A

-Memory cells from first infection won’t recognise pathogens so a primary immune response will have to be carried out again.
-Makes it difficult to develop vaccines for some diseases.

69
Q

What is an antigenic variation

A

-When a pathogen mutates to have different antigens on their surface and turn into a new strain

70
Q

What is the difference between an epidemic and a pandemic?

A

-epidemic is an infectious disease that spreads rapidly locally whereas pandemic is global

71
Q

What is an autoimmune and an example?

A

-immune response where antibodies attack self antigens
-Rheumatoid arthritis (caused by immune system attacking cells in joints and causes pain and inflammation)

72
Q

What are different ways medicine can be discovered?

A

1.Accidental discovery
2.Traditional remedies
3.Observation of wildlife
4.Plant research

73
Q

Why is maintaining biodiversity important for future drug discoveries?

A

-New plant discoveries could lead to discoveries of new medicines.

74
Q

When and who discovered Penicillin?

A

-Alexander Flemming
-1928

75
Q

How do antibiotics kill bacteria?

A

-They interfere with the metabolism of bacteria without affecting the metabolism of human cells therefore inhibiting/killing bacteria
-This is called selective toxicity

76
Q

How does personalised medicine work?

A

-Doctors can look at your genetic information to predict how you would respond to certain drugs and prescribe one which is the most effective
-They can also use computers to build up 3d models of drugs which are targeted to specific antigens on a pathogen

77
Q

How does antibiotic resistance develop?

A
  1. Genetic mutation occurs making bacteria more resistant to antibiotics
  2. Bacteria without gene for resistance die
  3. Those with the advantageous allele survive and reproduce so the allele becomes common
78
Q

How do we avoid antibiotic resistance?

A

-High standards of hygeine for e.g in hospitals and care homes.
-Minimising the use of antibiotics and making sure every course is completed fully.

Biology Module 4 (3 decks)

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