1. Year 9 – The Knowledge – Science – Spring 2
Angle Properties
Year 9 – The Knowledge – Science – Spring 2
2. Types of Disease
1.Pathogens
Definition: microorganisms that cause communicable ( infectious) diseases.
Type of Disease
Name of Disease
Occurs in
Symptoms
Treatment/Vaccination
How it is spread
Additional Information
Viral
Measles
Humans
Fever, red skin rash
Children are vaccinated
Inhalation of droplets from sneezes and coughs
Can be fatal
Human immunodeficiency virus (HIV)
Flu-like illness
Antiretroviral drugs
Sexual contact, exchange of body fluids such as blood
Virus attacks immune cells e.g. white blood cells
Tobacco Mosaic Virus (TMV)
Plants (including tomatoes)
“mosaic” pattern of discolouration on leaves
Affects growth of plant due to lack of photosynthesis
Bacterial
Salmonella
Humans, poultry
Fever, abdominal cramps, vomiting, diarrhoea
Poultry are vaccinated
Bacteria in ingested food or on food prepared in unhygienic conditions
Symptoms arise from effect of bacteria but also the toxins they release
Gonorrhoea
Thick yellow/green discharge from vagina or penis, pain when urinating
Taking antibiotics (used to be treated by penicillin (type of antibiotic) but many resistant strains exist now)
Sexual contact
Can be prevented by using barrier contraceptive methods e.g. condom
Fungal
Rose black spot
Plants
Purple or black spots on leaves, often turn yellow and drop early
Fungicides and/or removing and destroying affected leaves
By water or wind
Affects growth of plant as photosynthesis is reduced
Protist
Malaria
Recurrent episodes of fever
Preventing vectors and mosquitos from breeding by using mosquito nets to avoid being bitten
By mosquitoes
Can be fatal,
Types:
Bacteria – may produce poisons (toxins) that damage tissues and make us feel ill
Virus – can only survive inside our cells. They use our cells to reproduce causing cell damage.
Protists – eukaryotic single celled organisms.
Fungi
Can reproduce rapidly inside body
3. Barriers to Diseases
1.Non-specific defence system: work against ALL pathogens by trying to prevent them entering body.
Skin – covers whole body, difficult for pathogens to penetrate skin’s dry, dead outer cells, has glands producing oils that help kill pathogens.
Nose – hairs trap particles that can contain pathogens;
Trachea and bronchi – mucus traps particles with can contain pathogens, cilia create wave motion which sweeps mucus along
Stomach – contains hydrochloric acid which kills bacteria in food/drink
2. Immune System: when pathogens enter body, immune system tries to destroy it. White blood cells help defend against pathogens by:
Phagocytosis – pathogen is surrounded, engulfed and destroyed
Antibody production –attach to antigens (chemicals on pathogen) which causes pathogens to clump together before being ingested and digested by phagocytes.
Antitoxin production – chemicals that neutralise poisonous effects of toxins.
4. Immunity
6. Primitive Drugs
7. Modern Day Medicine and Drug Development
If the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies. This prevents infection.
Vaccinations can prevent illness by:
Introducing small quantities of dead/inactive form of pathogen to body
This stimulates white blood cells to produce antibodies
If pathogen re-enters body, white blood cells will rapidly respond to produce correct antibodies, preventing an infection
Spreading of pathogens is reduced when the majority of the population are vaccinated/immunised.
Traditionally, drugs were extracted from natural sources (plants, microorganisms).
Drugs are synthesised by chemists in the pharmaceutical industry. The start point for a new drug can be a chemical extracted from a natural source.
Before bringing a drug to market, it must be tested for:
Toxicity (how much damage it can cause)
Efficacy (how good it is)
Dose (how much is needed)
Three stages of testing drugs:
Preclinical testing: (many drugs fail this test because they are toxic or ineffective)
using computer models
testing on human cells, tissues in laboratories
Animal testing: if drugs pass the pre-clinical, they are tested on live animals
Clinical Trials: if drugs pass the animal testing they are tested on humans. Volunteers are either given the drug being tested OR a fake drug known to have no effect body (placebo). Initially very small doses are given. Once deemed safe, the dose is increased in order to find optimum dosage. There are two phases:
Healthy volunteers: drugs are tested on healthy people to ensure the drug is safe (non-toxic)
People with illness: drugs then then tested for efficacy
Original natural source
Used for
Modern-day drug
Willow bark
Pains and fevers
Aspirin
Foxgloves
Heart problems (failure, rhythm)
Digitalis
Penicillium Mould
Antibiotic
Penicillin
5. Treating Disease
Medicines can either relieve the symptoms or treat the disease.
Treating disease: Antibiotics (e.g. penicillin)
Cure bacterial disease by killing infective bacteria
Cannot kill viral pathogens
Specific bacteria need to be treated by specific antibiotics
Reliving Symptoms: Painkillers Do not kill pathogens but treat symptoms by reducing pain
Problems:
It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
New antibiotics are needed as resistant strains of bacteria are emerging
Type of clinical trial
Who knows if volunteers are on placebo or drug?
Pros
Cons
Volunteers
/patients
Researchers
Blind No
Yes
Simple to set up
Results can be unreliable due to observer bias
False
Results more reliable as removes bias
Complex to set up

2. 8. Monoclonal Antibodies (mAB)
Angle Properties
Year 9– The Knowledge – Science– Spring 2
11. The Eye
8. Monoclonal Antibodies (mAB)
A sense organ containing receptors sensitive to light and colour, enabling us to see.
Definition: identical copies of antibodies that have been made in the laboratory.
Producing Monoclonal antibodies from single clone of cells
The mABs produced are specific to one binding site on one antigen (chemicals on pathogens, made of protein)  can target a specific chemical or cells in the body.
Problem: Once a lymphocyte starts producing antibodies, it can no longer divide.
Solution:
Vaccinate a mouse to stimulate antibody production of lymphocytes
The lymphocytes are fused with a tumour cell, the combined cell is called a hybridoma cell
Hybridoma cells can divide AND they now make the antibody
Single hybridoma cells are cloned resulting in many cells all producing the same antibody
Antibody is removed from the cell, collected and purified
Uses of Monoclonal Antibodies
Diagnosis: pregnancy tests (mAB detect small levels of hormone HCG present in urine of pregnant women)
Laboratories: to measure levels or hormones and other chemicals in blood or to detect pathogens.
Research: to locate/identify specific molecules in cells or tissues by binding to them with a fluorescent dye
Treating cancer: mAB can bind to radioactive substance, toxic drug or a chemical which stops cancerous cells from growing and dividing. Since mABs target specific cells, other body cells are not harmed.
Part of Eye
Description
Function
Cornea
Tough, transparent covering over the front part of the eye. Convex in shape.
Refracts light as it enters the eye
Iris
Coloured part of the eye, contains muscles that relax or contract to adjust the size of the pupil.
Controls how much light enters the pupil.
Pupil
Hole in the middle of the iris.
Allows light to pass through as it enters the eye.
Ciliary muscles
Muscles connected to the lens by suspensory ligaments.
Adjust the shape of the lens to increase or decrease the refraction of light.
Suspensory ligaments
Connect the ciliary muscles to the lens and hold the lens in place.
Slacken or stretch as the ciliary muscles contract or relax, to adjust the thickness and curvature of the lens.
Retina
The lining of the back of eye containing two types of light receptor cells: Rod – sensitive to dim light and black and white. Cones – sensitive to colour.
Contains the light receptors, which trigger electrical impulses to be sent to the brain when light is detected.
Problems with Monoclonal Antibodies
Common side effects: chills, fevers, rashes, nausea, wheeziness, headaches, changes in blood pressure.
Main reason for side effects is that the antibodies are produced from mice cells and so can be treated as foreign by our bodies.
9. Plant Diseases
Accommodation
The process of changing the shape of the lens to focus on near or distant objects.
As well as viral, bacterial and fungal diseases (see 2. Types of Disease) plants can be infected by insects (aphids suck sap from young plants restricting and distorting their growth).
Detecting Plant Disease
If a plant has a disease is will display one of more of the following:
Stunted growth
Spots on leaves
Areas of decay/rot
Growths/tumours
Malformed stems or leaves
Discolouration
Presence of pests (e.g. aphids)
Plant Deficiency Conditions
If a plant is deficient in certain ions, it can develop deficiency conditions:
Object
Ciliary muscles
Suspensory ligaments
Lens
Refraction of light rays
Near
contract
Loose
Thick
strong
Distant
relax
Pulled tight
thin
weak
Ion
Required for
Deficiency condition
Nitrate
Protein synthesis
Stunted growth
Magnesium
Making chlorophyll
Chlorosis (leaves turn yellow)
Defects of the Eye
There are two types of defect resulting from the rays of light not focusing on the retina
Identifying Type of Disease
To identify the type of disease one can:
Use gardening manuals or websites
Identify the pathogen by taking infected plant to laboratory
Use testing kits containing monoclonal antibodies
Plant Defence Responses
Physical response: cellulose cell walls, tough waxy cuticle on leaves, layers of dead cells around stems (bark on trees) which fall off
Chemical response: antibacterial chemicals, poisons to deter herbivores
Mechanical adaptation: thorns and hairs deter animals, leaves which droop or curl
Scientific name
Known as
Focal point of light
Symptom
Treatment
Myopia
Short sightedness
In front of retina
Blurred vision for distant objects
Concave lens
(diverging lens)
-Use spectacle lenses
-Hard and soft contact lenses
-laser surgery to change shape of cornea
-laser surgery to replace lens in eye
Hyperopia
Long sightedness
After retina
Blurred vision for near objects
Convex lens
(converging lens)
10. The Brain
Part of brain
Function
Cerebral cortex
Controls memory, personality and conscious thought
Cerebellum
Controls balance and coordination of movement
Medulla
Controls heart rate and breathing
Cerebral cortex
Myopia: light from distant objects refracted too much
Cerebellum
Treat Myopia:
Use concave lens to first diverge the light rays before reaching eye
11. The Eye
Medulla
It is difficult to investigate the brain and treat brain disorders because:
Hard to access the brain inside the skull
Internal structure is very complex
It is very delicate
Neuroscientists have been able to map regions of the brain to particular functions by:
Studying patients with brain damage to learn which parts of brain are responsible for different jobs
Electrically stimulating different part of the brain and seeing response of patient
Magnetic Resonance Imaging (MRI) shows details of brain structure and function. Patients are asked to perform tasks and by looking at scan, scientists can see which parts of brain are active during task completion.
Hyperopia: light from near objects refracted too little
Treat Hyperopia:
Use convex lens to start converging the light rays before reaching eye