This page contains the detailed and easy notes for AQA GCSE Biology INFECTION AND RESPONSE for revision and understanding INFECTION AND RESPONSE.
AQA GCSE Biology Paper 2: Complete Revision Summary
INFECTION AND RESPONSE
- Communicable Disease
- Viral Diseases
- Bacterial Diseases
- Fungal Diseases
- Protist Diseases
- Human Defense System
- Vaccination
- Antibiotics and Painkiller
- Drug Discovery and Development
- Monoclonal Antibodies
- Plant Diseases
- Plant Defense responses
Disease is a disorder or abnormality in a body that produces sign and symptopms
Health is a state of physical and mental well-being.
TYPES OF DISEASES
COMMUNICABLE DISEASES
- It is an infectious disease.
- the disease can be transmitted from infected to healthy person.
- It is caused by pathogens.
- eg:- AIDS, Flu,cholera
- These diseases spread and develop quickly so are acute.
NON-COMMUNICABLE DISEASES
- It is non infectious disease.
- The disease cannot be transmitted from infected to healthy person .
- They have varied cause mainly deficiency of a nutrition or abnormal functioning of cells.
- eg Diabetes, Cancer
- They develop over a period of time,lasts longer so they are chronic.
FACTORS AFFECTING HEALTH
Obesity, Cancer, Diabetes Malnutrition, Defiency diseases like Scurvy are all linked to diet.
Mental stress is a diseases like cancer, heart problems diabetes,
cause of many
Living conditions like access to proper helath care, clean food and water, age, gender and wealth affects health .
All these factors are interconnected and can lead to diseases in interaction .
PATHOGENS
Pathogens are the microorganisms that cause a communicable disease. eq: Bacteria, Virus, Protists, Fungi etc .
Pathogens can be transferred from infected to healthy person, from one species to another or from contaminated air, water and food to a healthy person .
BACTERIA
Food poisoning Gonorrhoea
- Microscopic
- Unicellular
- Prokaryotes
- Found everywhere from air, water, sea, human intestine
- Good bacteria helps in digestion, making curd and decomposition.
- Bad bacterias multiply rapidly and release toxins which causes diseases.
VIRUS
AIDS Measles
Viruses are an exception as they are non living outside the living organisms.
Once they enter the living organism they become living, takes over the host machinery and use the cell resources to make copy of themselves and damage and destroy the cells.
GCSE Biology Paper 2: INFECTION AND RESPONSE Complete Revision Summary
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SPREAD OF PATHOGENS
VIRAL DISEASES
VIRUS
Animal Viral Diseases: Measles and AIDS
Plant Viral Diseases:Tobacco Mosaic Virus
- Virus are the pathogens and cause infectious diseases.
- They are at borderline of living and non living.
- They do not have a regular cellular structure.
- They have a genetic material enclosed in a protein coat.
- They take-over the whole cell machinery and make more copies of themselves and damage the host cells.
No anti-biotics work on them and the only management for viral diseases is isolation, vaccination and some anti-viral and anti-retroviral drugs.
VIRAL DISEASES IN ANIMALS
MEASLES
- Infectious diseases
- Causes skin rash and high fever
- It is an air borne disease and caused by inhalation of droplets with the pathogens.
- No cure available. Diseased person is isolated.
- Vaccination provides immunity against the diseases.
HIV/AIDS
- Acquired Immuno Deficiency Syndrome caused by Human Immuno Virus.
- This disease target the immune system and destroy immune cells so person die with a simple flu like disease.
- The disease spread by sexual contact, blood
transfusion or sharing needles.
The disease can be prevented by using condoms
or fresh needles - The disease is managed by taking antiretrovial drug.
VIRAL DISEASES IN PLANTS
- Is spread by the contact between a diseased crop with healthy crop or transmitted by insects or vectors.
- The virus damages the cells, causes discolouration of the leaves, reduces the yield and growth of the crop.
- No cure and treatment available.
- Good pest control and good agriculture practice and growing resistant crops helps mamanging this dieases.
BACTERIAL DISEASES
- Microscopic
- Unicellular
- Prokaryotes
- Found everywhere from air, water, sea,human intestine
- Good bacteria helps in digestion, making curd
and decomposition. - Bad bacterias multiply rapidly and release toxins which causes diseases.
Antibiotics and Vaccinations helps to treat bacterial diseases but antibiotic resistance is a bigger challenge for treating bacterial diseases.
BACTERIAL DISEASES IN ANIMALS
FOOD POISONING
- Salmonella or Campylobacter is the cause of food poisoning which is present
in the gut of other animals. - It is transferred from uncooked meat or eggs and disturbs the natural bacterial population in human’s intestine causing food poisoning.
- Symptoms include vomiting, stomach ache, abdominal cramps, diarrhoea and fever which are produced by toxins secreted by Salmonella.
- Management of the disease include vaccinated the chicken for Salmonella, properly cooking chicken and meat and separate handling of the raw chicken.
GONORRHOEA
- It is a sexually transmitted diseases .
- It is caused by unprotected sex.
- Symptoms include discharge from vagina or penis, pelvic pain. Long term effect includes ectopic pregnancies and infertility.
- It is treated with antibiotics.
- Contraception and limiting the number of sexual partners prevent the spread of the disease.
BACTERIAL DISEASES IN PLANTS
- Crown Gall Disease Caused by Agrobacterium tumefaciens.
- The bacteria insert the plasmids into the plant cell and create genetically
modified mass of undifferentiated cells known as gall which develops
at the junction of root and shoot. - This bacteria is used in genetic engineering to create genetically
modified cells as scientist use them to insert the gene of their
interest into the host.
FUNGAL DISEASES
In Animals: It causes Athelet’s foot Disease
In Plants: Rose Black Spot
- Damaged heart Valves can develop Fungal Diseases.
- Some fungal diseases in humans can affect the
brain and the lungs. - The diseases are treated by anti-fungal drugs.
ROSE BLACK SPOT DISEASE
- The disease is spread by the wind carrying the spores of fungus.
- Once the spores land on the plant they are spread to other parts and
to other plants by wind and rain. - The disease causes purple black spots on the rose leaves, discoluration
of the leaves. The leaves are unable to photosynthesis and the plant
do not grow and flower. - The disease is treated by spraying fungicides. In winters the spores
stay dormant on the stems so farmers can remove them to prevent
the spread of the diseases.
Growing Fungus resistant crops can prevent the disease from developing.
PROTIST DISEASES
Symptomps include fever and shaking specially when gametocytes are released from the blood cells.
The disease is cured by anti-malarial drugs. Preventing the breeding and spread of mosquitos using insecticide and mosquito nets helps to control the disease.
- Protist are single-celled eukaryotic cells.
- They require a vector to spread like mosquito
for Malaria.
MALARIA
- It is caused by the plasmodium but the vector is Female Anopheles Mosquito.
- The protist reporduce sexually in mosquito and asexually in humans.
- The mosquito first injects the protist into the healthy person
which goes into the liver and produce many cells which then
goes into the red blood cells and makes gametocytes. - The mosquito then consumes the blood with gametocytes
and the gameotcytes then causes sexual reporduction in the
mosquito making more copies of protist sporozites and
the cycle repeats.
BACTERIAL CULTURE
BACTERIAL CULTURE CALCULATIONS
Calculating number of bacteria
a) Calculate (n) the number of time the bacteria will divide in a given time by dividing the time with doubling time.
b) Number of bacteria in that time will be calculated by 2 n
Q1 If bacteria divide every 20 minutes, calculate the number of bacteria after 5 hours ?
Given time= 5 hours = 5*60 = 300 minutes
Number of Divisions (n)= 300/20 = 15 div
Number of bacteria = 2^15
=32768 bacteria
PREVENTING BACTERIAL GROWTH
Antibiotic
Can be natural or synthetic drug It is used to kill, inhibit or prevent the growth of bacteria in a living host. eg Penicillin.
Antiseptic
It is a chemical which kills or inhibit the growth of microbes and is applied externally on living tissue like skin. eg; Savlon
Disinfectant
It is used to kill, inhibit or prevent the growth of bacteria on non living surfaces.eg Sanitizer
Antiseptics and Disinfectant can only be used externally.
To kill the infections internally antibiotic is used.
HOW ANTIBIOTICS WORK
- Antibiotics kills the bacteria without harming
the host cells. - Most of the antibodies target the bacterial
cell wall and kills the bacteria making the person
feel better.
Painkillers and analgesics like paracetamol and aspirin
cure the symptomps like pain and fever but does not
kills the disease. To kill the disease we need an antibiotic.
eg: Penicillin,
PROBLEMS WITH ANTIBIOTICS
a) Antibiotic Resistance
b) Antibiotics do not work against
Viruses.
EFFECT OF ANTIBIOTICS ON BACTERIA
HISTORY OF MICROBIOLOGY
IGNAZ SEMMELWEIS – mid 1850
He was a doctor and he found that diseases are caused by some kind of infectious agent.
He found that women died during that time with a fever after giving birth.
He found that medical students were not washing hands before assisting in delievery and when they started washing hand the death rate of women decreased.
Louis Pasteur- Mid 19th Century
He showed that infectious agents are microorganisms.
He developed vaccines for anthrax.
Joseph Lister
Started using antiseptics in the operation theatre to kill the micro-organisms
PREVENTING INFECTIONS
a) Quarantine or Isolation
b) Prevent the growth and spread
of vectors like Mosquitos
c) Vaccination
d) Sanitization and disinfection
e) Cooking the meat thoroughly and keeping raw and cooked meat separately
f) Propert Hygeine and Sanitation.
HUMAN DEFENSE SYSTEM
FIRST LINE OF DEFENSE
SKIN
a) Skin is a physical barrier, water proof prevent the entry of microbes .
b) Skin produce sweat and other anti bacterial secretions .
c) Any cut or wound lead the platelets to clot the blood quickly to prevent the entry of microorganisms.
Hair and mucus in the nose
Hair and the mucus trap any infections coming with breathing preventing the entry of microbes in the body.
Cilia
Cilia lines the trachea and the bronchus which are tiny hair like structures which beat the mucus to the throat where it is swallowed and reaches the stomach and is digested by the stomach acids.
Stomach Acids
Any infection entering with the food is killed with the hydrochloric acid
produced by the stomach.
DRUGS FROM PLANTS
FOXGLOVE
- Digitalis and Digoxin is the drug extracted from Foxglove.
- It is used to cure heart problems.
BARK OF WILLOW TREE
Bark of Willow Tree is the source of aspirin which has anti-inflammatory and pain relieving properties.
PHAGOCYTOSIS
White blood cells are the soldiers of the body
- White blood cells are the second line of defense.
- If the infection still exist and is not killed by the first line
of defense then the white blood cells do the following
to kill it :-
a) Phagocytosis
b) Produce Antibodies
c) Product Antitoxins
Antigens are the specific proteins on the surface of micro-organisms against which the white blood cells create specific antibodies.
VACCINATION
Vaccine is a dead or a weakened form of a disease which stimulate the body to make the antibodies against them without making you seriously ill.
The memory cells of the white blood cells remember the antibodies produced and when the actual disease is encoutered the immune system respons rapidly killing the infection without even developing symptomps in some cases.
Vaccines are available for Bacterial Diseases: Tetanus and Diptheria Viral Diseases: Measles and Mumps Small pox is completely wipes with the use of vaccines
HERD IMMUNITY
Large Population need to be immunized to prevent the spread of the disease.
If only few people are immunized the disease can still spread.
DRUG DISCOVERY AND DEVELOPMENT
DRUG TESTING
EFFECTIVE→SAFE→STABLE→EFFECTIVE AGAINST TARGET
Test on Cell and Tissues
↓
Test on Animals (Pre-Clinical Test)
↓
Test on Humans (Clinical Testing)
PLACEBO
Giving an inactive version of the drug where the patient think that they are getting the drug.
DOUBLE-BLIND TRIALS
Where the doctor and patient does not know whether they are receiving a drug or the placebo. The scientist allocate the people into group and has the information on what each group is getting.
MONITORING AND PUBLISHING OF THE RESULT IS VERY IMPORTANT
OTHER PLANT DISEASES
APHIDS
- They suck the phloem sap and take all the food of the plant damaging the plants.
- They are also vectors of many infectious diseases as they can transfer bacteria, virus from infected to healthy plant.
- They are controlled by pesticides or biological pesticides like ladybird.
NEMATODE
They live in the soil, eat the plant roots and damage the roots of
the plant.
OTHER PLANT DISEASES
NITROGEN DEFICIENCY
Plants take nitrogen as nitrates. They need nitrogen for
protein synthesis so a deficiency of nitrogen will lead
to stunted growth and low crop yield.
MAGNESIUM DEFICIENCY
Magnesium is required for chlorophyll synthesis.
So deficiency of magnesium leads to chlorosis in
which leaves turn yellow and plants yield decreases
due to lack of photosynthesis.
The mineral deficiency is treated using the fertilizers.
PLANT DEFENCE RESPONSES
PLANT CELL WALL
The cell wall protects the plant and restrict the entry of pathogens.
WAXY CUTICLE
The waxy cuticle restricts the entry of pathogens.
LEAF BARK
The dead cells of the bark restricts the entry of the pathogens .
LEAF FALL
The decidous trees shed the leaves and that takes off any pathogens in the plant.
CHEMICAL SECRETIONS
Certain plants like Mint and Witch Hazel release the chemicals like antimicrobials that prevent the entre of pathogens.
PLANT DEFENCE RESPONSES AGAINST HERBIVORES
Foxglove plant, releases poison the prevent herbivore attack.
Plants like Cactus has thorns to prevent the herbivore attack.
Plants like
Lamb Ear’s have hairy stem and leaves that prevent herbivore attack. Some plants also release poison with the hairs that prevent them for other animals.
PLANT DEFENCE RESPONSES
MIMICRY
Plants mimic to be unhealthy or have spots on them that mimic butterfly egg to prevent other insect attack
DROOPING OR CURLING
Some plants like Touch Me Not, droop or curl with a touch frightening other animals.
MONOCLONAL ANTIBODIES
USES OF MONOCLONAL ANTIBODIES
Pregnancy Testing
- The urine of pregnant woman contains the hormone HCG-Human chorionic gonadotropin.
- The pregnancy kits contain monoclonal antibodies that bind to the HCG hormone.
- If the urine has HCG hormone, it will bind to the monoclonal antibody present in the kit and will show a colour change.
Diagnosis
- The monoclonal antibodies binds to the antigens of the pathogens.
- If the patient blood is added to the antibodies of the diseasesand it results in binding and can detect the disease before producing the symptomps.They can also be used to monitor the concentration of a drug or a hormone.They can also use to locate a chemical in a cell.Monoclonal antibodies are specific and only target the diseased or cancerours cells without affecting the healthy cells.
They are specific so can treat many diseases
But they are expensive, need expertise and they hve side effects as they are produced in mouse so have side-effects in humans.
MONOCLONAL ANTIBODIES IN TREATING CANCER
EXPOSING THE CELLS
Monoclonal antibodies can bind to the antigens on the cancer cells and make them more exposed and trigger the immune response where white blood cells kills them.
BLOCKING THE RECEPTORS
They can bindto the cancer cells and block the receptors of growth hormone. So the growth hormone can no longer bind and stops the division of cancer cells .
DELIEVER THE DRUG
They can bind to the cancer cells and release the drugs to kill the cells.
Since monoclonal antibodies are specific to an antigen they will only bind to a cancer cell without harming the healthy cell.
KEY TERMS
- Disease :- Disease is a disorder or abnormality in a body that produces sign and symptopms Health is a state of physical and mental well-being.
- COMMUNICABLE DISEASES :- It is an infectious disease.
→ the disease can be transmitted from infected to healthy person.→It is caused by pathogens. eg:- AIDS, Flu,cholera
→These diseases spread and develop quickly so are acute.
- NON-COMMUNICABLE DISEASES :- It is non infectious disease.
The disease cannot be transmitted from infected to healthy person .
They have varied cause mainly nutrition or abnormal functioning of cells.
deficiency of a eg Diabetes, Cancer.
They develop over a period of time,lasts longer so they are chronic.
- Antiseptic :- It is a chemical which kills or inhibit the growth of microbes and is applied externally on living tissue like skin. eg; Savlon.
- Disinfectant :-It is used to kill, inhibit or prevent the growth of bacteria on non living surfaces.eg Sanitizer.
- Antibiotic :- Can be natural or synthetic drug It is used to kill, inhibit or prevent the growth of bacteria in a living host. eg Penicillin .
- PATHOGENS :- Pathogens are the microorganisms that cause a communicable disease. eq: Bacteria, Virus, Protists, Fungi etc .
- Culture Medium
:- Culture medium is the growth medium which can be solid, liquid or semi-solid and it is used to support the growth of microorganisms. - Agar Gel:- Agar Gel is the jelly like carbohydrate which is used as a growth medium for growing microorganisms in the laboratory.
- Mutation:- Mutation is the change in the genes or the DNA.
- Vaccine :- Vaccine is a dead or a weakened form of a disease which stimulate the body to make the antibodies against them without making you seriously ill.
- Chlorosis :- Chlorosis is the loss of green colour in the leaves which is caused by lack of chlorophyll due to mineral deficiency.
- Clinical trial :- Clinical trial is the testing of drug on the group of people to validate its effectiveness.
- Placebo:- Placebo are the substances which mimic the actual drug but they are not the drug.
- Double blind trials :-Double blind trials are the clinical trial in which neither the patient nor the doctor knows who is getting the placebo and who is getting the drug.
- Monoclonal antibodies :- Monoclonal antibodies are the antibodies made from the clone of a single B cell.
- Disclaimer: I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.References:BBC Bitesize
Wikipedia
Wikimedia Commons
Image Source:
Wikipedia
Wikimedia
Commons
Flickr
Pixabay
Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.
B5 Communicable Disease
B6 Preventing The Disease
- Antibiotics and Painkiller QP
- Antibiotic and Painkiller MS
- Bacterial Diseases QP
- Bacterial Diseases MS
- Detecting Plant Diseases QP
- Detecting Plant Diseases MS
- Drug Development QP
- Drug Development MS
- Drug Discovery QP
- Drug Discovery MS
- Fungal and Protist QP
- Fungal and Protist MS
- Human Defence Response QP
- Human Defence Response MS
- Microorganism QP
- Microorganism MS
- Producing Monoclonal Antibodies QP
- Producing Monoclonal Antibodies MS
- Uses of Monoclonal Antibodies QP
- Uses of Monoclonal Antibodies MS
- Vaccinations QP
- Vaccinations MS
- Viral Diseases QP
- Viral Diseases MS
