GCSE Revision 3/7 Flashcards
How do viruses and bacteria grow
They reproduce rapidly when inside the body
How do bacteria make you feel ill
They produce toxins which damage the body cells
How do viruses make you feel ill
The reproduce inside cells, damaging/destroying them
How are pathogens spread through air (2)
Wind currents
Droplets carrying pathogens (among humans during coughing/sneezing)
How are pathogens spread through direct contact (4)
Sexually
Skin contact (cuts, scratches, needle punctures etc)
Vectors such as mosquitos when sucking blood
If a portion of diseased plant is left in a field it could infect the whole crop
How are pathogens spread through water (2)
Drinking contaminated water
Fungal spores in splashes of water can spread plant disease
Binary fission
The way in which bacteria multiply rapidly
Steps for growing cultures (5)
Use agar gel as a culture medium
Pour hot, sterile agar gel into petri dish
Inoculate the sterile agar, using a sterilised wire loop, with the bacteria
Provide warmth and oxygen to grow
Keep the dish incubated at no higher than 25ºC
How to keep culture uncontaminated (3)
Kill all the bacteria on the equipment by boiling solutions and agar and passing loop through flame to sterilise
Prevent microorganisms from the air getting into the petri dish by closing up the petri dish once inoculated
Prevent microorganisms leaving the petri dish after the experiment by disposing of the culture correctly
How to prevent bacterial growth (4)
Raising/lowering the temperature
Disinfectants (kill bacteria in environment)
Antiseptics (kill bacteria on skin)
Antibiotics (kill bacteria inside body)
Measles symptoms (2)
Fever
Red skin rash
How is measles spread
Droplet infection
How can measles be prevented
Vaccination
HIV symptoms
Flu-like
How is HIV spread (3)
Direct sexual contact
Infected blood (shared needles)
Breast milk
How can HIV be prevented (3)
Condoms
Screening blood before transfusion
Bottle-feeding babies
TMV symptoms (2)
Discolouration of the leaves
Destroys cells so the plant cannot photosynthesise
How is TMV spread (2)
Contact between diseased and healthy plants
Animal vectors
How can TMV be prevented (2)
TMV-resistant crops
Good field hygiene and pest control
Salmonella symptoms (4)
Fever
Abdominal cramps
Vomiting
Diarrhoea
How is salmonella spread (2)
Undercooked food
Poor food hygiene
How can salmonella be prevented (2)
Vaccinating chickens
Good food hygiene
Gonorrhoea symptoms (2)
Discharge
Pain on urination
How is gonorrhoea spread (2)
Unprotected sexual contact with an infected person
How can gonorrhoea be prevented (3)
Antibiotics
Condoms
Limiting sexual partners
Rose black spot symptoms (2)
Purple/black spots on leaves
Leaves turn yellow and drop early so there is less photosynthesis
How is rose black spot spread (2)
Fungus spores carried by the wind
Splashes of water when it rains
How can rose black spot be prevented (3)
Gardeners remove and burn affected leaves
Fungicides prevent the spread
Breeding types of roses that are resistant to black spot
Malaria symptoms (2)
Fevers
Fatigue
How is malaria spread (2)
Spread by female mosquitoes, which act as vectors
The protists reproduce sexually in the mosquito and asexually in the human body
How does malaria pass from the mosquito and infect the human (5)
The mosquito bites the human
The protists are transferred through the mosquito’s saliva
They then move to the liver
Having matured in the liver, they move to the red blood cells.
They burst out of the red blood cells when matured
How can malaria be treated? (3)
Insect nets
Insecticides
Preventing them from breeding in standing water
How does the skin prevent infection? (3)
Covers the tissues underneath
Produces antimicrobial secretions to kill pathogens
Heals quickly when cut
How does the respiratory system prevent infection? (3)
Hair and mucus trap pathogens
The trachea and bronchioles secrete mucus to trap pathogens
Cilia beat to waft mucus back up to the throat
How does the stomach prevent infection
Produces acid which kills pathogens
How do white blood cells prevent infection (3)
Ingest pathogens
Produce antibodies to destroy pathogens (bind to antigens on pathogen)
Produce antitoxins to counteract the toxins produced by pathogens
How do aphids kill plants
They insert their mouthparts into the phloem, depriving the cell of nutrients and food
Why are nitrate ions needed in a plant
Converting sugars into protein
What are the symptoms of nitrate deficiency
Stunted growth
Why are magnesium ions needed in a plant
To make chlorophyll
What are the symptoms of magnesium deficiency
Leaves become yellow (chlorosis) so less photosynthesis.
How do plants prevent infection (4)
Cellulose cell wall strengthen plant cells
Tough waxy cuticle
Bark on trees, layer of dead cells on the outside of stems (work like the skin)
Deciduous trees will lose their leaves, and any pathogens with it
What are some plant defence mechanisms (5)
Poisons
Thorns
Hairy stems/leaves
Drooping or curling when touched
Mimicry
What is a vaccine made up of
Dead/inactive forms of a pathogen
How does your body react to vaccines? (2)
White blood cells produce antibodies
This makes the person immune
What is herd immunity
Most people in a population being vaccinated to protect society from serious diseases
What is an example of herd immunity
The MMR vaccine, which prevents measles, mumps and rubella, which is one of the vaccines given to children at birth
What do antibiotics do
Kill bacteria
What do drugs/painkillers do
Treat the symptoms of a (usually viral) disease
What is the problem with new strains of bacteria (3)
They can evolve to become resistant to available antibiotics
This means the antibiotics cannot kill the bacteria and the disease cannot be cured
Scientists need to find new drugs to kill the bacteria
Which drug came from Penicillium mould
Penicillin
Which drug came from the foxglove plant
Digitalis/digoxin
Which drug came from willow tree bark
Aspirin
Stages of testing a drug (4)
Preclinical testing- on cells/tissues/organs; sees of the drug seems to work; then used with animals
Clinical trials- tested first in small doses on healthy human volunteers and finally on patients
Bigger clinical trials- used to find the optimum dose of the drug
Peer review- see whether the results are actually accurate
What are blind trials? (2)
In a normal blind trial, a placebo is used. This does not contain the drug. This is to check that the drug being tested really has an effect on the patient
In double-blind trials, neither the doctor nor the patient know who has received the real drug.
Monoclonal
Coming from one type of cell
Stages of making monoclonal antibodies
A mouse is injected with a vaccine to start the formation of antibodies
Spleen cells (T and B cells/lymphocytes) which form these antibodies are collected in operation
Scientists fuse the lymphocyte with a tumour cell- myeloma to form hybridoma cells
The cells are cloned
The antibodies are collected and purified
How can monoclonal antibodies be used (5)
Pregnancy tests rely on monoclonal antibodies that bind to the hormone human chorionic gonadotrophin, and change colour if it is present
Monoclonal antibodies can be used to diagnose disease, by binding to specific antigens on a pathogen/types of cancer cells
They can be used to measure and monitor the levels of hormones in the blood
Scientists can locate specific molecules by adding fluorescent markers
Treating disease
Why are monoclonal antibodies good for treating disease? (3)
Some can carry cures (eg a toxic drug) to the pathogen without damaging other body cells
Some can trigger the immune system to recognise and destroy cancer cells
Some can block receptors on the surface of cancer cells to stop them dividing (stop growth stimulating hormone from binding to cancer cell)
Disadvantages of monoclonal antibodies (2)
Side effects (when human cells are used in hybridomas, this may be reduced)
Expensive
What risk factors are linked to an increased rate of disease? (6)
Age
Genetic make-up
Diet
Exercise
Inhaling carcinogens (eg smoking)
Ionising radiation (UV light from the sun)
Correlation
A link between two factors (eg a rise in one might lead to a change in another)
Causal
How one factor influences another through a biological process
Tumour
A mass of abnormally growing cells
Benign tumour
Grows in one place. Does not invade other tissues. However, it can still be dangerous
Malignant tumour
Cells can spread to healthy tissue. This is cancer. Some cells may enter the bloodstream and circulate to other parts of the body
Causes of cancer (4)
Genetic factors
Mutations in genes caused by carcinogens (eg tobacco smoke to lung cancer)
Ionising radiation
Viral infections
Tobacco smoke contains:
Nicotine, an addictive substance
Carbon monoxide, a toxic gas, which replaces oxygen in red blood cells
tar, a sticky black substance, which accumulates in the lungs and is carcinogenic
Chemicals that anaesthetise the cilia in the airways, preventing them from wafting up the mucus
Problems caused by smoking (5)
Blood carries less oxygen around the body; pregnant women’s babies will also receive less oxygen
Mucus containing dirt and pathogens builds up in the airways, leading to infection
Tar and other chemicals lead to bronchitis because they inflame the bronchi.
Tar and other chemicals also damage the alveoli.
Tar and other chemicals also cause respiratory cancers.
How does regular exercise reduce your risk of developing cardiovascular disease (3)
Lowers blood cholesterol levels and reduces fatty deposits in the blood vessels
Builds muscle tissue, increasing metabolic rate
Improves blood supply to the heart
How does alcohol impact the body (5)
Enters the bloodstream and reaches all parts of the body including brain and liver
Large amounts of alcohol affect the nervous system, slowing reaction times and thought processes
The liver breaks down alcohol. However, the liver can become damaged over time, which leads the cirrhosis
Damage to the brain
In pregnant women, alcohol can pass to the fetus and can cause physical problems
How does ionising radiation impact the body
Radiation damages the chromosomes, leading to DNA mutation
