B5 - Communicable Diseases Flashcards
4 types of microorganisms (microbes)
- fungus
- protozoa
- bacteria
- virus
define pathogen
microbes that cause disease
how do pathogens cause a person to feel ill
- releasing toxins
- reproducing themselves and hijacking body cells
- immune system reaction making temperature higher
how are diseases transmitted
droplets - microbes in small droplets
direct contact
food contamination
water contamination
4 human physical defences against pathogens
eyes
skin
ciliated epithelial cells
stomach
how does the stomach defend against pathogens?
High acidity in stomach acid (pH 2) which kills pathogens
how do the eyes defend against pathogens?
antiseptics found in tears which kill pathogens
how do ciliated epithelial cells defend against pathogens?
Small hairs and mucus on these cells stop pathogens from entering the lungs. The hairs waft pathogens up to the mouth which is mixed with saliva and swallowed sending it to the stomach.
how does the skin defend against pathogens?
2
- dry and oily conditions so pathogens cannot easily live on the skin
- wounds clot and close because of platelets
define binary fission
asexual reproduction process where a cell replicates and splits forming two daughter cells, a simple form of mitosis
define antiseptic
chemical that kills microbes on the surface of the body
define antibiotic
chemical that kills microbes inside the body
define disinfectant
chemical that kills microbes on surfaces
formula to calculate the number of bacteria in a population
P = c · 2D
D = total division cycles
P = population
c = starting population
How to grow microorganisms on a petri dish.
- All equipment used must be sterilised to kill unwanted microbes
- Sterilise the inoculating loop with a Bunson burner, then let it cool
- Place the inoculating loop in the bacteria that you want to grow
- Spread the bacteria on the surface of the agar in the petri dish. Always keep the agar plate upside down when open and possible to make sure no particles contaminate the surface by landing on it
- fix the lid with tape to make sure that microbes in the air don’t contaminate the culture
- incubate (25°C) the petri dish for several days for the culture to grow
HIV facts
- viral disease
- spread by direct contact - usually sexual contact or sharing needles
- symptoms are flu-like
- controlled with antiretroviral drugs
- attacks the body’s immune cells
- HIV turns into AIDS when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers
- high mutation rate meaning that the immune system cannot fight off infection
list:
measles facts
pathogen type, spread by, symptoms, treatment
- viral disease
- spread by droplets
- symptoms: fever and red skin rash, fatality
- children are usually vaccinated at a young age (MMR)
TMV facts
pathogen type, spread by, symptoms
- Tobacco Mosaic Virus
- spread by direct contact and insects as vectors
- gives a black ‘mosaic’ like pattern on the plant’s leaves, yellow discoloration
- affects the growth of the plant as it has a lack of photosynthesis
list:
salmonella facts
pathogen type, spread by, symptoms
- bacterial disease
- spread by contaminated food
- symptoms: fever, abdominal cramps, vomiting and diarrhoea
- symptoms caused by toxins released
- UK poultry are vaccinated against Salmonella
list
gonorrhoea facts
pathogen type, spread by, symptoms, treatment
- bacterial disease
- spread by direct contact - sexual contact
- symptoms: thick yellow-green discharge from the vagina or penis, pain while urinating
- spread can be controlled by antibiotics or barrier methods such as a condom
list:
rose black spot facts
pathogen type, spread by, symptoms, treatment
- fungal disease
- spread by water or wind in spores
- purple-black spots develop on leaves, often turn yellow and drop early
- treated by using fungicides or removing and destroying the affected leaves
Malaria facts
- caused by protists
- fever-like symptoms
- can be fatal
- spread is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten
define antigens
protein markers on the surface of cells
role of T-lymphocytes
Collect antigens from pathogens to find the correct B-lymphocyte to help
role of B-lymphocytes
Recognise an antigen and then produce specific antibodies
How do white blood cells defend against pathogens?
- phagocytosis
- producing antibodies
- producing antitoxins
structure of an antibody
y-shaped protein
what do antibodies do
Binds to antigens on pathogens which labels them and causes them to clump and stick together. They also can kill the pathogens themselves
define:
phagocytosis
how phagocytes ingest and destroy pathogens
define:
active immunity
When an illness is beaten, almost all immune system cells are destroyed to save resources. A few memory cells remain which recognise the pathogen if it re-infects which makes the immune system response much faster and efficient.
describe:
immune response when a human cell is infected by a viral cell
Phagocytosis happens on the infected human cell - phagocytes recognise the virus as the infected cell has the virus’s antigens on the surface of itself.
Name 2 pests that damage plants
- aphids
- nematode worms
How do aphids damage plants?
- They attack in swarms and drain glucose from the plant’s phloem vessels.
- They can also act as vectors
Name 2 ways to kill aphids
- pesticides
- releasing ladybirds (predators)
How do nematode worms damage plants?
Feed on plant roots so they cannot effectively absorb water or mineral ions.
Name 2 observations for detecting disease in plants
- stunted growth
- spots on leaves
- discoloration on leaves
- decay/rotting
Name 2 plant ion deficiencies
- magnesium ion deficiency
- nitrate ion deficiency
list:
physical plant defence responses
3
- cellulose cell walls
- waxy cuticle
- bark (which falls off)
Chemical plant defence responses
- Antibacterial chemicals
- Poisons
Mechanical plant defence responses
- Thorns
- Curling when touched
- Mimicry
