Infection - essential knowledge quiz

What is a pathogen

A microorganism that causes disease

What is a communicable disease

A disease caused by a pathogen that can be spread between organisms

Name the 4 different pathogens

Bacteria, virus, fungi, protist

How do bacteria make people ill

They reproduce rapidly in the body and produce toxins that damage tissues

How do viruses make people ill

Viruses live and reproduce inside host cells, causing cell damage

Name the three ways pathogens can be spread

Direct contact, air or water

How does the skin protect us from pathogens

Acts as a physical barrier

How does the cilia in the trachea protect us from pathogens

The cilia move the mucus from the trachea to the throat, the mucus traps pathogens

How does the stomach protect us from pathogens

Contains hydrochloric acid which kills pathogens

Name two diseases caused by bacteria

Gonorrhoea or salmonella

What are the symptoms of gonorrhoea

Thick yellow or green discharge from the vagina or penis and pain while urinating

How is gonorrhoea spread

Sexually transmitted disease

How can the spread of gonorrhoea be controlled

By using a barrier method of contraception such as a condom

How can gonorrhoea be treated

Antibiotics

What are the symptoms of salmonella

Fever, abdominal cramps, vomiting, diarrhoea

How is salmonella spread

By eating food containing bacteria, or on food prepared in unhygienic places

How can the spread of salmonella be controlled

In the uk, chickens are vaccinated against salmonella to control the spread

Name the three diseases caused by viruses

Measles, TMV, HIV

What are the symptoms of measles

Fever and rash

How is measles spread

By inhalation of droplets from sneezes and coughs

How can measles be prevented

By vaccinating young children

How is HIV spread

Sexual contact of exchange of bodily fluids such as blood which occurs when drug users share needles

What is the late stage HIV called and why is this dangerous

AIDS, occurs when the body’s immune system becomes so badly damaged that it can no longer deal with other infections or cancers

How can HIV be treated

With antiretroviral drugs

TMV is a plant disease, what are the symptoms

Gives a mosaic pattern of discolouration on the leaves

How can TMV affect plant growth

Discolouration→less chlorophyll present→less light absorbed→less photosynthesis→less glucose made→less energy released from respiration for growth

Name the disease caused by fungi

Rose black spot

How is rose black spot spread between plants

By wind or water

How is rose black spot treated

Using fungicides or by destroying the affected leaves

What pathogen causes malaria

Protist

What are the symptoms of malaria

Recurring fever which can be fatal

How is malaria spread

By a vector, mosquitos. When they bite humans they can spread the malarial protist

How can the spread of malaria be controlled

By preventing the vectors from breeding by draining water from swamps where they breed, and by using mosquito nets to avoid being bitten

What happens in phagocytosis

White blood cells called phagocytes engulf the pathogen, digesting and killing the pathogen

Describe the importance of antibodies

White blood cells produce antibodies which bind to antigens on invading cells and kill them. Each antibody is specific to each pathogen

Describe the role of antitoxins

White blood cells produce antitoxins. They bind to toxins neutralising them so they can no longer damage tissues

What is a vaccine

A dead/inactive/weakened version of the pathogen

What happens when someone is injected with a vaccine

A patient is injected with the vaccine. This triggers an immune response and white blood cells produce antibodies specific to the pathogen. Memory cells are also made

If the patient is exposed to the pathogen again, after receiving the vaccine, what happens

The memory cells recognise the pathogen. This causes the white blood cells to produce the correct antibodies quicker and at a higher concentration. This means the pathogen is killed more quickly, the pathogen population does not become large enough to cause the disease

What is the pre clinical testing and what is the purpose

Preclinical testing is done in a laboratory. The drug is tested on live cells, live tissues and live animals (mice). The purpose is to find out if the drug is toxic.

What is stage 1 of clinical trials and what is the purpose

Phase 1 clinical trials: the drug is tested on healthy volunteers using low doses. The main purpose of phase 1 testing is to see if the drug is safe to use

Why are healthy volunteers used in stage 1

Because the risk is too great for an I’ll patient. The side effects of the drug are easier to identify in a healthy patient

What is stage 2 of clinical trials and what is the purpose

The drug is tested on patients. The purpose of this stage is to test the effectiveness/efficacy of the drug and to test for side effects/toxicity

What is stage 3 of clinical trials and what is the purpose

The drug is tested on a larger number of patients. The purpose of this stage is to verify the effectiveness and to determine the correct dose

What is the review and approve stage for

The results of the trial must be reviewed by other scientist (peer review) to prevent false claims, to avoid bias and to make sure the conclusions are valid

What is a double blind trial

The patients nor the doctors know who is given the placebo

Why can’t antibiotics be used to treat viral infections

Antibiotics cannot be used to kill viruses because viruses live inside cells, so the virus is inaccessible to the antibiotics

Who discovered the first antibiotic

Alexander Fleming

What is the name of the first antibiotic

Penicillin

Which drug originated from foxglove plants

Digitalis (used to treat heart beat irregularities)

Which drug originated from willow trees

Aspirin

Describe how bacteria become resistant to antibiotics

Bacteria mutate randomly, this can cause them to be resistant to antibiotics (meaning they can no longer be killed by the antibiotic). The resistant bacteria survive, passing on their resistant gene during reproduction, leading to a large population of antibiotic resistant bacteria

How can antibiotic resistance be controlled

Antibiotics should not be prescribed for mild infections. Patients taking antibiotics should finish the course because any bacteria left may develop resistance, survive and reproduce rapidly due to lack of competition

What are lymphocytes

White blood cells that produce antibodies

When making monoclonal antibodies, mice are injected with an antigen, why

This stimulates the mouse lymphocytes to produce an antibody specific to that antigen

What are the mouse lymphocytes combined with

The mouse lymphocytes are combined with a tumour cell to make a hybridoma cell, which can divide rapidly and make the antibody

What is done with the single hybridoma cell

The hybridoma cell is cloned to produce many identical cells that all produce the same antibody. The antibody can then be collected and purified

Name 4 uses of monoclonal antibodies

• diagnosis (e.g. pregnancy)

• Laboratory testing (e.g. hormone levels)

• In research (e.g. to locate molecules by binding the monoclonal antibody with fluorescent dye)

• To treat diseases like cancer

Why are monoclonal antibodies not used as widely as first anticipated

They produce more side effects than thought

How can plant disease be detected

Stunted growth, spots on leaves, areas of decay, growths, malformed stems or leaves, discolouration, the presence of pests

How can insects like aphids cause plant disease

Aphids cause disease in plants because they are sap sucking, they can spread viral diseases and can leave sticky honeydew on the surface which encourages mould to grow

What can a deficiency in nitrate ions cause in plants

Can cause stunted growth in plants. This is because nitrate ions are needed for protein synthesis

What can a deficiency in magnesium ions cause in plants

Can cause chlorosis in plants. This is because magnesium ions are needed to make chlorophyll

Describe 3 physical defences plants have to stop the entry of pathogens

Cellulose cell walls, tough waxy cuticle on leaves, layers of dead cells around stems (bark) which fall off

Describe 2 chemical defences plants have

Antibacterial chemicals and poisons to deter herbivores

Describe 3 mechanical adaptations plants have to deter predators

Thorns and hairs deter animals, leaves which droop or curl when touched, mimicry to trick animals.