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Biology Paper 1 > B5 Communicable diseases > Flashcards

B5 Communicable diseases Flashcards

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1
Q

what are communicable diseases?

A

Diseases caused by pathogens that can be passed on from an infected person to other people

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2
Q

what are pathogens?

A

disease-causing micro-organisms

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3
Q

what is health?

A

A state of physical and mental well-being

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4
Q

How do bacteria cause disease?

A

Once inside the body, they divide rapidly by binary fission. They kill cells and produce harmful toxins that make us feel ill.

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5
Q

How do viruses cause disease?

A

They invade and reproduce inside living body cells, causing cell damage

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6
Q

What are the four main groups of pathogens?

A
  • Viruses
  • Bacteria
  • Fungi
  • Protists
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7
Q

Why is it advised to avoid washing raw chicken?

A

It sprays bacteria around the kitchen

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8
Q

Fungal diseases in humans

A
  • There are relatively few fungal diseases that affects humans
  • Athlete’s foot is a well known, relatively minor fungal skin condition
  • A small number of fungal diseases can be fatal when they attack the lungs or brains of people who are already ill
  • Damaged heart valves can also develop some serious fungal infections
  • However these conditions are rare
  • Antifungal drugs are usually effective against skin fungi like athlete’s foot, but it can be hard to treat Depp-seated tissue infections
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9
Q

What are disinfectants?

A

Chemicals used to kill bacteria in the environment around us

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10
Q

What are antiseptics?

A

Disinfectants that are safe to use on human skin

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11
Q

What are antibiotics?

A

Chemicals used to kill bacteria inside human body

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12
Q

What is the zone of inhibition?

A

An area on the nutrient agar plate where there is no bacterial growth due to presence of antibiotics/disinfectants

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13
Q

Why must we not incubate cultures above 25 degrees?

A

Prevent harmful bacteria growth

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14
Q

State the three ways in which white blood cells defend the body

A

Engulf pathogens: some white blood cells ingest pathogens, digesting and destroying them so they cannot make us ill

Produce antibodies: antibodies target particular bacteria or viruses and destroy them, a unique antibody is needed for each type of pathogen

Produce antitoxins: some white blood cells produce antitoxins, these counteract the toxins released by pathogens

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15
Q

What are antibodies?

A

Proteins that bind to specific antigens on pathogens

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16
Q

What are antigens?

A

Proteins on cell surface for cell recognition

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17
Q

How do aphids damage plants?

A
  • Aphids have sharp mouthparts that penetrate into the phloem vessels of the plant, so the plant loses its nutrients
  • Aphids also act as vectors, transferring viruses, bacteria, and fungi from diseased plants into the tissues of healthy plants on their mouthparts
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18
Q

How to detect plant diseases by symptoms

A
  • Stunted growth, nitrate deficiency
  • Spots on leaves, black spot on roses
  • Areas of decay or rotting, black spots on roses, blights on potatoes
  • Growths, crown galls caused by bacterial infections
  • Malformed stems and leaves, due to aphid or nematode infestation
  • Discolouration, yellowing or chlorosis in magnesium deficiency, mosaic patterns resulting from tobacco mosaic virus
  • Presence of visible pests, aphids, caterpillars
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19
Q

Why do plants need nitrates?

A

To convert sugars made in photosynthesis into proteins needed for growth in protein synthesis

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20
Q

Why do plants need magnesium ions?

A

To make the chlorophyll needed for photosynthesis

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21
Q

Mineral deficiency - nitrate and magnesium ions

A

Nitrate deficiency:
- protein growth will be limited
- growth of plants will be stunted
- they will not produce a crop properly

Magnesium deficiency:
- if the level of magnesium ions in the soil is low, the plant cannot make enough chlorophyll
- the leaves become yellow and growth slows down because the plant cannot photosynthesis fully
- the yellowing of the leaves due to lack of magnesium ions is known as chlorosis

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22
Q

What is a symptom of magnesium deficiency in plants?

A

Discolouration of leaves

23
Q

what are some physical plant defences against pathogens?

A
  • Cell walls help to resist invasion by micro-organisms
  • Tough waxy cuticle on the surface of leaves acts as a barrier to the entry of pathogens
  • Bark on trees, and a layer of dead cells on the outside of stems, form a protective layer that is hard for pathogens to penetrate. When the dead cells are lost or shed, the pathogens fall off with them
  • Leaf fall, deciduous trees lose their leaves in autumn, any pathogens that infect the leaves, such as rose black spot, fall off the tree when the leaves are lost
24
Q

what are some of the chemical defences in plants?

A
  • Many plants produce antibacterial chemicals that protect them against invading pathogens, and these are very effective at preventing bacterial disease in many plants
  • Poisons to deter herbivores
25
Q

what are some plant defences against herbivores?

A
  • Thorns, make it unpleasant or painful for large herbivores to eat them
  • Hairy stems and/or leaves deter insects and larger animals from feeding on them and laying their eggs on the leaves or stems
  • Dropping or curling when touched, leaves to collapse suddenly, dislodging insects and frightening larger animals
  • Mimicry, some plants drop to mimic unhealthy plants and this tricks animals into not eating them, some mimic butterfly eggs on their surfaces so real butterflies do not lay eggs on them to avoid competition with other caterpillars
26
Q

How do monoclonal antibodies work to stop HIV from developing AIDS?

A

Monoclonal antibodies bind directly to the viral antigens and stimulates the immune system response. They can also block the virus’ ability to enter cells and slow down the infection.

27
Q

what is measles?

A
  • a serious viral disease that can cause blindness and brain damage
  • the main symptoms are a fever and rash
28
Q

how is measles spread?

A

by air - through inhalation of droplets from coughs or sneezes

29
Q

what is HIV/AIDS?

A
  • a virus which attacks and damages the immune system until it can no longer function properly
  • AIDS is the condition resulting from a long-term HIV infection
  • there is no cure or vaccine for HIV/AIDS
30
Q

how is HIV spread?

A

direct sexual contact and exchange of bodily fluids e.g. blood, breastmilk

31
Q

how can the spread of HIV/AIDS be prevented?

A
  • using condoms
  • not sharing needles
  • screening of blood used for transfusions
  • bottle feeding by HIV-positive mothers
32
Q

what is tobacco mosaic virus?

A
  • a plant pathogen which causes leaf discolouration when cells are damaged
  • affected areas cannot photosynthesise, reducing the crop yield
  • as there is no treatment, farmers grow TMV-resistant crop strains to avoid infection
33
Q

how is TMV spread?

A

contact between infected and healthy plants, insects may act as vectors which transfer the virus between different plants

34
Q

what are the examples of viral diseases?

A
  • tobacco mosaic virus
  • HIV/AIDS
  • measles
35
Q

what is salmonella?

A
  • a type of bacteria found in raw meat, poultry and eggs
  • if they enter the body via food poisoning, they can affect natural gut bacteria
36
Q

what are the symptoms of salmonella?

A
  • fever
  • abdominal pain
  • vomiting
  • diarrhoea
37
Q

how can the spread of salmonella be limited?

A
  • vaccinated animals intended for consumption
  • keep raw meat away from cooked meat when cooking
  • disinfect hands and surfaces after contact with raw meat
  • thoroughly cook meat
38
Q

why is it advised to avoid washing raw chicken?

A

it sprays the bacteria around the kitchen, therefore increasing the spread of salmonella

39
Q

what is gonorrhoea?

A

a sexually transmitted bacterial infection caused by unprotected sex with an infected individual

40
Q

what are the early symptoms of gonorrhoea?

A
  • discharge from penis or vagina
  • pain on urination
41
Q

how can the spread of gonorrhoea be controlled?

A
  • using antibiotics
  • using condoms
  • limiting sexual partners
42
Q

what are the example of bacterial diseases?

A
  • salmonella
  • gonorrhoea
43
Q

what is rose black spot?

A
  • a fungal disease which caused purple or black spots to develop on rose leaves
  • reduces the area of leaf which is available for photosynthesis and causes leaves to turn yellow and drop prematurely
44
Q

how is the rose black spot fungus spread?

A

fungal spores are spread by the wind and in the water

45
Q

how can the spread of rose black spot be controlled?

A
  • using fungicides
  • destroying infected leaves
46
Q

what is malaria?

A
  • a disease caused by protist pathogens
  • carried from host to host by mosquitoes, and the protists enter the human bloodstream when they feed
47
Q

what are the symptoms of malaria?

A
  • fever
  • shaking
48
Q

how can the spread of malaria be reduced?

A
  • using mosquito nets to prevent mosquito bites
  • using insecticides to kill mosquitoes
  • taking antimalarial drugs
  • prevent mosquito breeding by removing standing water
49
Q

how does the skin prevent pathogens from entering the body?

A
  • the skin covers the body and acts as a barrier, it prevents bacteria and viruses reaching the tissues beneath
  • antimicrobial secretions which can kill pathogens
  • scab formation by platelets when cut forms a seal over the cut stopping pathogens from entering the body
  • healthy skin is covered with microorganisms that compete with pathogens and acts as an additional barrier
50
Q

how does the respiratory system prevent pathogens from entering the body?

A
  • Nose is full of hairs and produces a sticky liquid, called mucus. The hairs and mucus trap particles in the air that may contain pathogens or irritate the lungs
  • The trachea and bronchi also secrete mucus that traps pathogens from the air. The lining of the tubes is covered in cilia, tiny hair-like projections from the cells. The cilia beat to waft the mucus up to the back of the throat where it is swallowed
51
Q

how does the stomach prevent pathogens from infecting the body?

A

secretes hydrochloric acid which kills any pathogens present in the mucus that is swallowed and food and drinks

52
Q

how does phagocytosis protect us against diseases?

A

white blood cells (phagocytes) ingest pathogens, digesting and destroying them so they cannot infect more cells and make you ill

53
Q

how does antibody production protect us against disease?

A
  • white blood cells produce antibodies which are complementary in shape to a specific antigen on a pathogen
  • the binding of the antigens to antibodies destroys the pathogens
  • in the case of second infection, the correct antibodies can be produced rapidly, preventing the person getting the same disease twice
54
Q

how does antitoxin production protect us against disease?

A

antitoxins bind to toxins released by pathogens and neutralise them

Biology Paper 1 (12 decks)

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