B3 Flashcards
What is a pathogen?
a microorganism that causes disease
What are the four types of pathogens?
- protists
- viruses
- bacteria
- fungi
Give three ways that pathogens can be spread between people?
- through the air- breathed in or spread by airborne droplets e.g. influenza virus
- direct contact e.g. athlete’s foot
- water- drinking or bathing in dirty water e.g. cholera
Give three viral diseases
- Measles
- HIV
- Tobacco Mosaic Virus(TMV)
What is Tobacco Mosaic Virus?
a virus that can be transmitted by direct contact between plants (naturally or by the hands of farmers) which infects the chloroplasts of plant leaves and changes their colour from green to yellow or white in a mosaic pattern
- reduces the plant’s ability to photosynthesise and grow properly, which reduces the crop yield for farmers
What happens when a plant has a nitrate deficiency?
Stunted growth
What happens when a plant has a magnesium deficiency?
yellow leaves (discolouration) because magnesium helps with chlorophyll production
What is HIV and how can you treat it?
a viral disease that is spread by unprotected sex, sharing needles or infected blood. It attacks white blood cells and can develop into AIDS
antiretroviral drugs
Why might someone with AIDS take longer to recover from salmonella?
Their immune system would be weakened so their white blood cells would not be able to destroy the bacteria
Name a fungal disease
Rose black spots (causes purple/black spots to form on the leaves of roses)
How are protists usually transported?
By vectors (other organisms that do not get the disease)
What is a parasite?
An organism that depends on another organism to grow and reproduce
What is malaria caused by?
Malaria is caused by parasitic protists which means it needs a host to survive, transported between hosts by mosquitos.
Give symptoms of malaria
- high fever
- pain
- diarrhoea
- vomiting
- sweat and chills
Give two bacterial diseases and two symptoms of each
Salmonella
- fever
- stomach cramps
- vomiting
- diarrhoea
Gonorrhoea
- thick yellow/green discharge
- pain when urinating
Give four ways to reduce/prevent the spread of disease and explain
- being hygienic- using simple hygienic measures such as washing your hands thoroughly before preparing food or after sneezing
- destroying vectors- by getting rid of the organisms/ their breeding sites that spread disease you can prevent the disease being passed on
- isolating infected individuals- prevents the individual from passing it on
- vaccinations- stops people from being able to develop the disease, therefore reduces risks of it being spread
How does our first line of defence protect us from pathogens?
- skin acts as a physical barrier, it also secretes antimicrobial substances which kill pathogens
- nose is filled with little hairs and mucus which can trap the pathogens and any other particles
- trachea and bronchi are covered in a layer of mucus which would trap any particles and are lined with cilia, which waft the mucus up to the back of the throat(where it can be swallowed) to prevent the build up of this mucus
- stomach produces hydrochloric acid, which is very acidic and kills the pathogens
How does our immune system defend us against pathogens?
White blood cells continually patrol the blood circulating in our body
What are antigens?
antigens are unique substances on the surface of invading pathogens which our immune system detects as being foreign
What is a vaccine and how does it work?
an altered/weakened/inactivated form of a pathogen that are injected into the body.
- They carry antigens = our body produces antibodies to attack them even though they are harmless. This means if live pathogens of the same type enter the body again the white blood cells can rapidly mass-produce antibodies to kill off the pathogen
How does antibiotic resistance arise in a population of bacteria?
Antibiotic resistance happens when bacteria develop mutations in their DNA which can change their characteristics and this could result in the bacteria being less affected by the antibiotic.
The resistant bacteria quickly forms a new colony of its own which all have the gene for antibiotic resistance= an antibiotic resistant strain
What is the difference between painkillers and antibiotics?
painkillers relieve symptoms of disease whilst antibiotics kill or prevent the growth of bacteria therefore curing the problem
Which plant does aspirin originate from?
willow
Which plant does digitalis originate from?
foxgloves
What are the three main functions of white blood cells?
- phagocytosis- certain white blood cells directly engulf pathogens.
- by tracking the pathogen
- binding to them
- engulfing them at which point they kill the pathogen
- producing anti-toxins
anti-toxins are small molecules that can bind and counteract the toxins produced by bacteria - producing antibodies
- antibodies are small proteins made by our white blood cells that can lock onto these foreign antigens and act as signals to tell our white blood cells to destroy them
- each of our antibodies is specific for a particular antigen
- once our immune system knows which antibody binds to the antigen, they are produced rapidly the next time the person is infected with the same pathogen to destroy it before it get a chance to develop - immune to that disease
What is a placebo?
A substance that is similar to the drug being tested however it does not do anything
What is a double blind clinical trial?
This is when both the patient in the study and the doctor do not know whether they have received the drug or placebo until all the results have been gathered to prevent any subconscious influence
What are the three main stages in drug testing?
- Preclinical testing- drugs are tested on human cells and tissues
- Next step in preclinical testing is to test the drug on live animals (tests efficacy and finds out about its toxicity)
- If the drug passes then it is tested on human volunteers in a clinical trial (first it is tested on healthy volunteers to ensure there are no side effects)
What is a monoclonal antibody?
A monoclonal antibody is an antibody made from a single clone of cells
How can a monoclonal antibody be produced (using a mouse)?
- inject a mouse with an antigen
- then we extract the lymphocytes that make the specific antibody we want
- we combine this with the tumour cell to form a hybridoma cell
- we clone and harvest the antibodies
What are some uses of monoclonal antibodies?
- for diagnosis e.g. in pregnancy tests
- in laboratories to measure the levels of hormones and other chemicals in blood, or to detect pathogens
- in research to locate and identify specific molecules in a cell/tissue by binding to them with a fluorescent dye
- to treat some diseases e.g. cancer
How can monoclonal antibodies be used to treat cancer?
The monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops the cells from growing and dividing.
