B3: Infection And Response WIP [No Triple yet]

Question 1

What is a communicable disease and what is a pathogen?

Answer 1

A communicable disease is a disease that can spread between organisms.
A pathogen is a microbe that causes harm and disease to organisms.

Question 2

What are the four pathogens that cause disease?

Answer 2

+ Bacteria: Small prokaryotes
+ Viruses: Non-living microbes
+ Protists: Single-celled Eukaryotes
+ Fungi: Eukaryotic organisms consisting of hyphae

Question 3

What are the ways that pathogens spread, and how can their spread be reduced & prevented?

Answer 3

Pathogens can spread by...
\+ Molecules in the air (Airborne pathogens)
\+ Contaminated water (Like cholera)
\+ Direct physical contact
Their spread can be reduced by...
> Destroying Vectors
> Quarantining infected individuals
> Vaccinating Children
> Sneezing & coughing into sleeves

Question 4

What are the differences in the ways that bacteria & viruses make us feel ill?

Answer 4

+ Bacteria make us ill by releasing harmful toxins that damage our cells
+ Viruses make us ill by entering our cells and taking them hostage. They use the cell to reproduce copies of themselves until the cell lyses (bursts), which makes us ill

Question 5

What is Measles?

Answer 5

+ Measles is a Viral disease contracted through infected molecules in the air
+ Its symptoms include: Fever & a Red rash but can lead to pneumonia & brain infections
+ Its transmission and symptoms can be prevented by giving young children vaccines

Question 6

What is HIV?

Answer 6

+ HIV (Human immunodeficiency virus) is a viral disease transmitted through sharing bodily fluids (i.e. during intercourse, when sharing needles)
+ It attacks the immune system directly, and late stage HIV (AIDS) is when the body’s immune system is no longer capable of protecting against other diseases
+ Sterilising needles, using fresh needles and using barrier method contraception can all prevent its contraction
> Once contracted, antiretroviral drugs can be taken to prevent the virus from replicating

Question 7

What is Tobacco Mosaic Virus?

Answer 7

+ Tobacco mosaic virus is a viral disease that affects plants by entering through holes in their epidermal tissue
+ It causes a mosaic pattern of discoloration to appear on leaves, which restricts photosynthesis & stunts growth

Question 8

What is Salmonella?

Answer 8

+ Salmonella is a bacterial disease that is contracted when poorly prepared food is consumed
+ It causes: Fever, stomach cramps, vomiting & diarrhoea
+ Chickens are vaccinated against salmonella, and cooking food above 72 degrees will kill all molecules

Question 9

What is Gonorrhoea?

Answer 9

+ Gonorrhoea is a sexually transmitted bacterial disease
+ Its symptoms include: Yellow/green discharge from genitals, pain when urinating
+ Its spread can be prevented using barrier method contraceptives, such as condoms

Question 10

What is Rose Black Spot?

Answer 10

+ Rose black Spot is a fungal disease that affects plants and is spread by spores in the wind and water
+ It causes leaves to develop purple spots, turn yellow and fall off, reducing photosynthesis and stunting the growth & food production of the plant
+ To eradicate the disease, affected leaves must be removed and destroyed or the fungicides must be used

Question 11

What is Malaria?

Answer 11

+ Malaria is a protist disease, and is transferred via the vector of female mosquitoes when they drink blood
+ Its symptoms include recurring fever episodes, which can be fatal
+ The spread of malaria can be reduced using bug nets & by killing mosquitoes
> This can be done using bug spray or altering the genes of the mosquitoes to produce sterile offspring

Question 12

What are the non-specific human defence systems that work against pathogens?

Answer 12

+ Non-specific defence systems prevent pathogens from entering the body in the first place. These include…
> The Skin: Acts as a barrier & secretes antimicrobial oils to kill microbes
> The Nose: Hair & Mucus in the nose trap particles, pathogens included
> Trachea & Bronchi: Secretes mucus to trap pathogens & has cilia (small peudo-hairs) that waft mucus into the oesophagus to be swallowed
> Stomach: Hydrochloric acid in the stomach kills pathogens
+ Another Non-specific defence system is Phagocytosis

Question 13

What is the immune system, and how does it help defend against invading pathogens?

Answer 13

+ The immune system is a system consisting of several non-specific & specific ways of protecting your body from harmful pathogens
+ It detects foreign microbes using things called antigens, protein protrusions on the exterior of all cells. If a detected molecule has foreign antigens, the immune system acts to destroy or remove it

Question 14

What is Phagocytosis?

Answer 14

+ Phagocytosis is a non-specific defence system that involves phagocytes (White blood cells) destroying pathogens
> First, pathogens are identified by foreign antigens (protein protrusions) on their surface
> The phagocyte then changes shape and engulfs (surrounds) the pathogen
> Once engulfed, the phagocyte ingests (takes in) the pathogen
> It then proceeds to digest (break down) the pathogen

Question 15

What are antibodies and antigens, and how do they relate to the immune system’s way of fighting off diseases?

Answer 15

+ When a pathogen with foreign antigens (protein protrusions) enters the body, white blood cells called lymphocytes can produce antibodies (Immunoglobulin) to combat them
> The Antibodies take the shape of a Y, with their ends adapted to perfectly fit a single type of antigen
> The antibodies connect to the antigens of the pathogen and causes them to group in clusters
> Once grouped in clusters, they can be rendered harmless, digested by other cells or excreted in urine

Question 16

What is an Antitoxin?

Answer 16

+ An antitoxin is a substance released by lymphocytes in the body in response to a bacteria
> The antitoxin neutralises the harmful toxins released by the bacteria

Question 17

What is vaccination, and how can it protect populations from disease?

Answer 17

+ Vaccination is a form of artificial immunity, where dead or inactive pathogens are introduced into the body to strengthen the immune system by tricking it into producing the relevant antibodies
> Natural immunities come from antibodies passed down during pregnancy or breastfeeding or from diseases you have contracted before
+ Vaccines keep the spread of diseases under control (and in some cases eradicate them)
> When most of a population is vaccinated & immunized, they are said to have herd immunity
+ They also prevent local epidemics and pandemics
+ However, they don’t always work and select individuals may have bad reactions to them

Question 18

How does Vaccination help the body’s immune system better combat disease?

Answer 18

+ The dead or Inactive pathogen is injected into the bloodstream
+ White blood cells detect the foreign microbe’s antigens and begin to analyse them
+ Not soon after, antibodies are produced that are specific to the pathogen’s antigens. The pathogens are then destroyed
+ Memory cells that retain the ability to produce those antibodies remain in the bloodstream
+ Upon reinfection, particularly by live pathogens, the opposing antibodies are produced rapidly & in much greater quantities
+ The live pathogens are quickly eradicated and symptoms are minimal

Question 19

What are Antibiotics & other medicines used to treat disease?

Answer 19

+ Antibiotics, such as penicillin, are medicines that kill infectious bacterium in the body
> The discovery of antibiotics has greatly reduced deaths
+ Antivirals & antifungals also kill their respective pathogens
+ Painkillers such as Aspirin, paracetamol, Ibuprofen & Nurofen simply alleviate symptoms of disease, but don’t cure it

Question 20

What are issues concerning certain medicines?

Answer 20

+ Different bacterial infections require different antibiotics
+ Medicines that cure viral diseases are hard to manufacture, since viruses live in body cells, and attacking them harms the body’s tissue as well
+ Antibiotics can cause resistant strains of bacteria to come about

Question 21

How have resistant strains of bacteria evolved, and how can their creation be prevented?

Answer 21

+ Random mutations in bacteria can cause them to be resistant to antibiotics
+ When antibiotics are taken, the resistant strains survive
+ Those resistant bacteria are left to produce more, just as resistant copies of themselves & go on to spread to other, being untreatable by antibiotics
> This is an example of natural selection, and occured in MRSA (Methicillin resistant staphylococcus Aureus), which causes wound infections
+ To prevent resistant bacteria strains from developing, doctors should…
> Only prescribe antibiotics when necessary
> Afflicted patients should finish their course of antibiotics to ensure all bacteria are eradicated

Question 22

How have medicines been discovered & produced in the past (with some examples), and how has that changed in the modern era?

Answer 22

+ Previously, medicines have been synthesised from plants & micro-organisms
> Some heart medicines are from fox gloves (Usually poisonous)
> Aspirin is from Willow bark
> Morphine is from poppies
> Alexander Fleming discovered Penicillium & its antibiotic properties
+ Nowadays, most drugs are synthesised chemically in laboratories by chemists
> They may still use an initial chemical from plants

Question 23

When developing new drugs, what are the three characteristics biologists must test for?

Answer 23

+ Efficacy: How effective the drug is at treatment
+ Toxicity: Whether the drug is harmful or has side effects
+ Dosage: What is the optimum dosage for the drug

Question 24

What are the three stages of testing new drugs?

Answer 24

+ The preclinical trials
+ The clinical trials
+ The (Double-blind) Placebo tests

Question 25

What occurs during the preclinical trials?

Answer 25

+ During pre-clinical trials, the drug is tested on cells, tissue samples & live animals
> The trials test for toxicity

Question 26

What occurs during the clinical trials?

Answer 26

+ During the first stage of clinical trials, the drug is tested on healthy volunteers in low doses to look for side effects & toxicity
+ During the second stage of clinical trials, low doses are used to test for the drugs efficacy on patients
+ During the third stage of clinical trials, the drug is administered to a large quantity of patients to test efficacy & find the optimum dosage

Question 27

What is a double blind trial?

Answer 27

+ A double-blind trial is the final test performed to test a drug
+ It involves a group of patients being divided in two
> One group takes the drug
> The other takes a placebo (A false drug)
+ In this test, neither the doctor nor patient is aware whether they are receiving a placebo or the actual drug
> This prevents doctor or patient bias affecting the results
+ This test identifies whether it is actually the drug that is causing the results

Question 28

-O- What is a Monoclonal Antibody, and how are they produced?

Question 29

-O- How are monoclonal antibodies used in pregnancy tests?

Question 30

-O- How are monoclonal antibodies used in treatments for some diseases, like cancer?

Question 31

-O- How are monoclonal antibodies used in laboratories & used in research?

Question 32

-O- What are the issues that have been found with using monoclonal antibodies?

Question 33

-O- What are the ways plant diseases can be detected?

Question 34

-O- What are the ways plant diseases can be identified?

Question 35

-O- What are the ways ion deficiencies can damage plants?

Question 36

-O- What are the physical, Chemical & Mechanical ways plants protect themselves from pathogens, pests & herbivores?