B3 - Infection and response Flashcards
What is Communicable Disease?
A disease that can be spread from person to person which are infectious and can are spread by pathogens.
What is a Non-communicable disease?
A disease that cannot be passed from person to person eg coronary heart disease.
What is health?
How can ill-Health be caused?
Health is defined as the state of physical and mental well-being.
Ill-Health can be caused by both communicable and non-communicable diseases. It can also be caused by poor diet, high stress or other situations(working with harmful chemicals).
What does it mean if someone has a defective immune system?
Give an example of a disease which takes advantage of defective immune systems.
People with defective immune systems are much more likely to suffer from infectious diseases.
HPV is extremely common. In most people it is harmless but for some people it can cause cervical cancer.
How can physical illness cause mental illness. Give an example.
In people who have arthritis, movement is very painful which means that they can sometimes feel lonely and depressed.
What is a pathogen? Give four examples
A pathogen is a microorganism that causes a infectious disease.
- Bacteria
- Viruses
- Protists
- Fungi
Give examples of non-communicable diseases
There are other types of disease which cannot be caught:
- Inherited genetic disorders like cystic fibrosis.
- Deficiency diseases which are caused by a lack of essential vitamins or minerals, such as scurvy which occurs when an individual has insufficient vitamin C.
- Diseases like cancer that develop as a result of exposure to carcinogens or develop naturally as cell division occurs incorrectly.
Give 5 Methods of Transmitting a disease and examples
- Direct Contact e.g. sex
- Dirty Water
- Through droplets in the air
- Unhygenic food preparation
- Vector e.g. Mosquitoes
Give three ways of preventing Pathogens from Spreading
Destroying Vectors
Practicing Hygenie
Isolation and vaccines
What are Viruses?
Are they alive?
How do they survive?
- Viruses do not fulfil the 7 life processes, therefore, they are not usually classified as living organisms
- Viruses do not have nuclei, organelles, or cytoplasm like cells do, and so they have no way to monitor or create change in their internal environment
- Viruses reproduce rapidly by inserting their genetic material into host cells and creating new protein capsules to build new viral particles. They do not divide and reproduce, but replicate their DNA and protein coats.
- Once many copies have been made, the host cell may burst open releasing the viral particles which can go on to infect other cells
What is the Tobacco Mosaic Virus?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
VIRUS
- It is a widespread plant pathogen that causes Discolouration of leaves in a mosaic pattern and stunted growth due to lack of photosynthesis which reduces yield.
- It is caused by direct contact and there is no cure. It can stay in the soil for a long time
- Sometimes Infected crops are killed to prevent transmission. and GM crops can be made which are resistant to TMV
What is the Measles?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
VIRUS
- Measles is a highly contagious and a potentially serious viral infectious disease that can be fatal.
- It causes a rash and fever and in serious situation brain damage
- You can protect yourself from it with a vaccine
- It is spread by inhalation of droplets
- Seen mostly in children
What is the HIV?
What is AIDS?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
Virus
- HIV (Human Immunodeficiency Virus) is a virus that can eventually lead to Acquired Immunodeficiency Syndrome (AIDS). AIDS stands for acquired immune deficiency syndrome.
- It is spread through direct sexual contact or exchange of bodily fluids(breast feeding)
- It starts off with flu-like symptoms then it can stay hidden for years
- Months or years after the infection of the HIV virus, it becomes active and starts to attack the patient’s immune system. HIV at this point has become AIDS.
- There is no cure but it can be slowed down in the early stages using anti-viral drugs
What is Bacteria?
How does Bacteria damage our cells?
What are optimum conditions for bacteria to grow?
- Bacterial pathogens are cells that can infect plants and animals, causing disease
- Not all bacteria are harmful (so not all bacteria are pathogens) – both the skin and large intestine, in particular, are home to hundreds of different bacterial species that play a vital role in maintaining our health
- Bacteria on the skin act as competitors to harmful pathogens
- Bacteria in the large intestine digest substances we can’t in food (such as cellulose) and provide essential nutrients (such as Vitamin K)
- Bacterial pathogens produce toxins that cause damage to cells and tissues directly
- In certain optimum conditions, some bacteria can reproduce rapidly
- Optimum conditions usually involve warmth, moisture and a supply of nutrients
What is the Salmonella?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
- Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions and it secretes toxins that cause fever, vomiting, diahorreha.
- It is found in the gut of many different animals
- BACTERIA
- It can be prevented by basic hygeine, cooking well and vaccination of chickens
What is the Gonorrhoea?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
- Gonorrhoea is a sexually transmitted disease (STD) – these diseases are also called sexually transmitted infections (STI). BACTERIA
- In 2018 it had the largest increase (26%) of infections in the UK (a total of 56,259 cases!). It was the cause of 13% of diagnosed STDs
- Gonorrhoea causes a burning pain when urinating and often forms a thick yellow or green discharge from an infected person’s penis or vagina. If untreated it can result in infertility. To prevent infection, people can abstain from having anal, oral or vaginal sex or use a barrier-type of contraception like a condom.
- Gonorrhoea is treated by antibiotics, though some scientists believe that these antibiotics may one day stop working.
What is a Protist?
Protists are a group of microorganisms that have features that belong to animals, plants and fungi. Some are like animals, others more like plants and some, called moulds are closest to fungi. They are all eukaryotic, which means they have a nucleus.
- Only a small number of protists are pathogenic, but the diseases they cause are often serious
- Often need a vector to transfer from one host to the next
What is Malaria
Explain the Malaria life cycle
- The pathogens that cause malaria are protists from the Plasmodium family (four species); they have a complex life cycle but can infect red blood cells in humans
- The malarial protist has a life cycle that includes the mosquito as a vector
- Malaria causes recurrent episodes of fever and can be fatal in certain instances
- The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten
Malaria
What are its symptoms?
How does it spread?
How do you treat & prevent it?
IT causes fever, shaking and death.
IT can be prevented through Killing mosquitoes but if diagnosed early can be treated with a variety of drugs
What are Fungal Diseases?
Not all fungi cause disease. Yeast is a single-celled fungus that is economically important because we use it to make some bread and beer. Not all fungi are single-celled. Some such as mushrooms are multicellular and so much larger. These are still made of tiny cells like yeast, but have many more of them. Fungal cells have a nucleus and so are eukaryotic.
- Few fungal diseases that affect humans, one example is athletes’ foot. This is spread by contact with surfaces that have been touched by an infected person, such as shower room floors
- Often the fungus is unicellular, as in the case of yeast, but can have a body made up of thread-like structures called hyphae
- The hyphae can grow and penetrate the surface of plants and animals causing infections
- The hyphae can produce spores, which can spread the infection to other organisms
- Fungal infections are more common in plants and can destroy a crop or plant
What is the Rose Black Spot?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
- Rose black spot is a fungal disease of plants where purple or black spots develop on leaves, which often turn yellow and drop early
- It is carried to other plants by spores from the wind
- It affects the growth of the plant as photosynthesis is reduced
- It is spread in the environment by water or wind
- Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves
What is the Athletes foot?
What are its symptoms?
How does it spread?
How do you treat & prevent it?
Athlete’s foot is a rash caused by a fungus that is usually found between people’s toes.
It causes dry, red and flaky or white, wet and cracked skin. It is often found in communal areas like swimming pool changing rooms or gyms. It is transmitted by touching infected skin or surfaces.
It is treated by antifungal medication.
How do you prevent Cholera?
How do you prevent Salmonella?
How do you prevent Athlete’s Foot?
How do you prevent Measles?
How do you prevent HIV/AIDS?
What are the non Specific defence systems of the body?
The body is constantly defending against attacks from pathogens. The first line of defence against infection stops the pathogens from entering your body. These first lines are general defences, and are not specific to fight against certain types of pathogen. They are called non-specific, and they can be physical or chemical barriers.
- The non-specific defence systems of the human body against pathogens include:
- The skin
- The nose
- The trachea and bronchi
- The stomach
How does the Skin defend against pathogens?
The skin covers almost all parts of your body to prevent infection from pathogens. If it is cut or grazed it immediately begins to heal itself, often by forming a scab, which prevents infection as the skin acts as a physical barrier.
- eyes produce tears, which contain enzymes, and these are chemical barriers.
- The skin Produces an oily substance called sebum which can kill bacteria.
How does the Nose defend against pathogens?
The nose has internal hairs, which act as a physical barrier to infection.
Cells in the nose produce mucus. This traps pathogens before they can enter the lungs. When the nose is blown, mucus is removed and any pathogens are trapped within it.
Explain what Phagocytosis is
- Phagocytes engulf and digest pathogens, this can be non-specific or helped by antibodies which cause agglutination (clumping) of pathogens
- The phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it
Explain how Antibodies are produced
Production of antibodies
- Lymphocytes produce antibodies
- Antibodies are Y-shaped proteins – each individual has the potential to make millions of different types of antibodies, each with a slightly different shape
- The aim of antibody production is to produce the antibody that is specific (complementary) to the antigens on the surface of the pathogen
- This is a specific type of immune response as the antibodies produced are specific to each pathogen’s antibodies
- It can take a few days to make the antibodies that are specific to a pathogen and this may give the pathogen causing the infection enough time to make you feel unwell (as its numbers in the body, and consequently the damage caused by them, increases
How are antitoxins produces?
- Some pathogens (usually bacteria) can produce substances which act as toxins which make you feel unwell
- Lymphocytes can produce antibodies against these substances – in this case, they are called antitoxins
- The antitoxins neutralise the effects of the toxin
What is a risk factor and give examples?
Anything that increases a chance of developing a disease is called a risk factor. Risk factors can be part of a person’s lifestyle, or substances that a person consumes or their environment. Some diseases are caused by an interaction between risk factors.
- The effects of diet, smoking and exercise on cardiovascular disease.
- Obesity as a risk factor for Type 2 diabetes.
- The effect of alcohol on the liver and brain function.
- The effect of smoking on lung disease and lung cancer.
- The effects of smoking and alcohol on unborn babies.
- Carcinogens, including ionising radiation, as risk factors in cancer.
Why do we vaccinate?
- Vaccination will prevent illness in an individual by providing artificial immunity
- Vaccination involves exposing an individual to the antigens of a pathogen in some form, triggering an immune response which results in the formation of memory cells which can make antibodies against it. If a vaccinated individual is infected with the pathogen, they can destroy it before they become infectious
- Consequently, vaccines reduce the likelihood that an infected individual will spread the pathogen they have been vaccinated against to others
- If a large number of the population are vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen
- This is the principle behind the idea of herd immunity
How do Vaccines work?
- Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies
- If the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies, preventing infection
What is Herd Immunity?
Following a vaccination, a person can become immune to the specific disease. This immunity gives protection against illness in an individual. The majority of the population must be vaccinated against serious diseases, which can reduce the chance of people coming into contact with specific pathogens, leading to herd immunity.
There are three recognised scenarios in relation to herd immunity:
- The majority of the population are not vaccinated against a specific disease, however, a few people are ill and contagious. This can develop easily into a mass infection because the majority of the population are not vaccinated.
- Most of the population are not vaccinated against the specific disease but are well, some are vaccinated and healthy, and a few are not vaccinated, but ill and contagious. Mass infection can result again, but a small number of vaccinated individuals remain healthy and some that are not vaccinated will also be healthy.
- The majority of the population are vaccinated and healthy against a specific disease, a few are not vaccinated but well. A few are not vaccinated against the disease, and they are ill and contagious. The result is that the majority are protected due to the high level of vaccination. A few individuals will still become ill, but the large number of vaccinated individuals gives protection.
How do you grow Bacteria in cultures?
Bacterial growth
Bacteria can replicate approximately every 20 minutes by binary fission, which is a simple form of cell division. This level of replication will depend on the availability of nutrients and other suitable conditions such as temperature.
There are many ways to culture bacteria, and these include:
- nutrient broth solution
- colonies on an agar plate
Nutrient broth solution or culture medium, allows a liquid or gel to provide all the nutrients needed for bacteria to grow successfully. These must include: carbohydrates for energy, nitrogen for protein synthesis, plus other minerals.
Agar plates are created by pouring hot molten agar into sterile Petri dishes, which are then allowed to set. Bacteria can be spread onto the plates, and allowed to form individual colonies of the specific bacterium.
Uncontaminated cultures
If a specific bacterium is going to be cultured or grown, other contaminating bacteria would compete for nutrients in the broth or agar. Plus some bacteria could be harmful (such as pathogens) and would complicate the results of experiments when testing the efficiency of antibiotics or other anti-microbial compounds.
How do you calculate the effectiveness of antibiotics and antiseptics
The effectiveness of the chosen antibiotic or antiseptic can be measured numerically by using the formula πr2. Using the diagram below
- For π use 3.14. This value may vary slightly in a specific question.
- Measure the diameter of the zone of inhibition and divide it by 2 eg 10 ÷ 2 = 5 mm
- Use the equation: πr2
For example: 3.14 × 52 = 3.14 × 25 = 78.5 sq mm
How are monoclonal antibodies produced?
- The mouse is injected with the antigen
- They are produced by stimulating mouse lymphocytes to make a particular antibody.
- The lymphocytes are combined with a particular kind of tumour cell to make a cell called a hybridoma cell.
- The hybridoma cell is selected can both divide and make the antibody.
- Single hybridoma cells are cloned to produce many identical cells that all produce the same antibody.
- A large amount of the antibody can be collected and purified.
Monoclonal anti-bodies in pregnancy tests
(as) urine passes through reaction zone HCG hormone binds to the mobile HCG antibody (in the reaction zone) (passes up the stick)
HCG hormone binds to the immobilised HCG antibodies in the results zone (the other) antibodies which do not attach to HCG bind to antibodies in control zone
blue dye appears in both control and results zones (to show positive result)
Pros and Cons of monoclonal anti-bodies?
Pros:
- They are Highly specific
- They don’t damage healthy cells
- They could be cheap procedure in the future
Cons:
- They create side effects
- They are expensive to produce at the moment
Types of plant disease symptoms
- Infections in plants as with all organisms are better when detected and treated quickly
- Symptoms of diseases in plants include:
How do mineral deficiencies affect plants?
- Stunted growth caused by nitrate deficiency as nitrate is needed for protein synthesis
- Chlorosis(yellowing of leaves) and stunted growth caused by magnesium deficiency as it is needed to make chlorophyll for photosynthesis
- Plants like all organisms need the correct amount of nutrients to function properly. If plants are deficient in a mineral these can be replaced by fertilisers added to the soil. These fertilisers are often shown as NPK ratios depending on the need of the plant that is being grown
What are some Mechanical plant Adaptations Against Herbivores?
- Herbivores eating a plant can seriously damage the plant structures and they will not flower and reproduce
- Smaller insect infections can remove essential nutrients and energy from the plant and act as vectors for pathogens
Mechanical adaptations.
• Thorns and hairs deter animals.
• Leaves which droop or curl when touched dislodges animals
• Mimicry to trick animals
