Communicable diseases

Question 1

What are pathogens?

Answer 1

Pathogens are microorganisms that enter the body and cause disease.

Question 2

Bacteria

Answer 2

ARE CELLS that reproduce rapidly inside your body and make you feel ill by producing toxins, that damage your cells and tissues.

Question 3

Viruses

Answer 3

ARE NOT CELLS that reproduce rapidly inside your body. They live inside cells and replicate themselves using binary fission and clone themselves. The cell will then burst releasing all the new viruses. This cell damage makes you feel ill.

Question 4

Protists

Answer 4

ARE SINGLE-CELLED EUKARYOTES. Some are parasites that live on or inside other organisms and cause them damage. They are normally transferred by a vector, which doesn’t get the disease itself. EG mosquitos, insects.

Question 5

Fungi

Answer 5

ARE normally SINGLE CELLED. Others have a body made up of hyphae, which grows and penetrates human skin and the surface of plants, causing diseases. They produce spores, which can be spread to other plants and animals.

Question 6

How are pathogens spread?

Answer 6

WATER-drinking, bathing in dirty water. EG cholera.
AIR-breathing in, some pathogens carried by droplets. EG influenza virus.
DIRECT CONTACT-Touching contaminated surfaces, including skin. EG athlete’s foot.

Question 7

Measles

Answer 7

VIRAL DISEASE. Spread by droplets from a sick person. Red skin rash, signs of a fever. Serious or fatal. Sometimes leads to pneumonia or encephalitis. Most people are vaccinated when they are young.

Question 8

HIV

Answer 8

Virus spread by sexual contact or exchanging bodily fluids. EG sharing needles when taking drugs. HIV can be controlled with antiretroviral drugs. They stop the virus replicating in the body. The virus attacks the immune cells and if the immune system is badly damaged it won’t cope with other infections or cancers. Then the virus is known as AIDs.

Question 9

TMV (Tobacco mosaic virus)

Answer 9

Virus effects plants e.g tomatoes. Causes a mosaic pattern on the leaves. The leaves become discoloured. Discolouration means the plant can’t carry out photosynthesis well so the virus affects growth.

Question 10

Rose Black Spot

Answer 10

Fungus, causes purple or black spots on leaves of rose plants. The leaves then turn yellow and drop off. Less photosynthesis can happen, so the plant doesn’t grow well.

Question 11

Malaria

Answer 11

Protist. Part of malarial protist’s life cycle takes place in the mosquito. Mosquitos are vectors, they pick up the malaria when they feed on the infected animal and then when it feeds on another animal it infects it by inserting the protist into the animal’s blood vessels. Malaria causes repeating episodes of fever. It can be fatal. It can be reduced by stopping mosquitos from breeding and can protect themselves from mosquitos by using insecticides and mosquito nets.

Question 12

Salmonella

Answer 12

Bacteria causes food poisoning. Suffer from fever, stomach cramps, vomiting and diarrhoea. Caused by toxins that the bacteria produce. Salmonella comes from food poisoning by food that’s been contaminated with the bacteria.

Question 13

Gonorrhoea

Answer 13

Bacterial. STD, passed on by sexual contact, unprotected sex. Pain when they urinate, thick yellow/green discharge from vagina or penis. Was originally treated with an antibiotic called penicillin but now some bacteria has become resistant to it. People can be treated with antibiotics and should use barrier methods of contraception.

Question 14

How do you prevent the disease?

Answer 14

BEING HYGIENIC, DESTROYING VECTORS-killing mosquitos. ISOLATING INFECTED INDIVIDUALS, VACCINATION.

Question 15

Defence Systems

Answer 15

SKIN, acts as a barrier, secretes antimicrobial substances that kill pathogens.
Hairs and MUCUS in nose trap particles that contain pathogens.
TRACHEA and BRONCHI secrete MUCUS to trap pathogens.
Trachea and bronchi are lined with CILIA, hair like structures, which waft the mucus up to the back of the throat where it can be swallowed.
The STOMACH produces HYDROCHLORIC ACID that kills pathogens that make it that far from the mouth.

Question 16

Immune system and attack of pathogens

Answer 16

WHITE BLOOD CELLS, travel in your blood, CONSUMING the pathogens and engulf and digest them. (PHAGOCYTOSIS).
PRODUCING ANTIBODIES. White blood cells come across foreign antigens and produce proteins called antibodies to lock onto the antigen. Then antibodies are produced rapidly and are carried round the body to find all similar bacteria or viruses. Then if the person gets the same pathogen again the white blood cells rapidly produce the antibodies to kill it. The person is naturally immune to it and won’t get ill.
PRODUCING ANTITOXINS- counteract with the toxins produced by the invading bacteria.

Question 17

What is a vaccination?

Answer 17

Injecting small amounts of dead or inactive pathogens. They carry antigens that cause your body to produce antibodies to attack them, even if the pathogen is harmless. The antibodies will memorise the pathogen with memory cells and the next time you get the disease you will be immune to it.

Question 18

What are the pros of vaccinations?

Answer 18

control lots of communicable diseases. For example small pox no longer occurs anymore.
Epidemics can be prevented if herd immunity is created and people who aren’t vaccinated are unlikely to get the disease.

Question 19

What are the cons of vaccinations?

Answer 19

Vaccinations don’t always work and give you immunity. Sometimes you may get a bad reaction to a vaccine like swelling or fevers and seizures.

Question 20

Painkillers

Answer 20

e.g. aspirin relieve pain but don’t tackle the cause of the disease or kill pathogens they just reduce the symptoms.

Question 21

Antibiotics

Answer 21

e.g. penicillin kill or prevent the growth of the bacteria causing the problem without killing your own body cells.

Question 22

Problems with antibiotics

Answer 22

They don’t destroy viruses as viruses reproduce using your body cells. It’s hard to produce a drug that kills something inside your cell without killing your actual cell.

Question 23

Bacteria and it’s resistance to antibiotics

Answer 23

Bacteria mutates, some mutation makes it resistant to an antibiotic, so when you treat the infection only the non resistant strains of bacteria are killed. Individual resistant bacteria reproduces and the resistant strain will increase. This could cause a serious infection that cannot be treated by antibiotics. Therefore doctors have to avoid over-prescribing antibiotics. You should also finish the whole course of antibiotics and don’t stop taking them just because you feel better.

Question 24

Plants and drugs

Answer 24

ASPIRIN, used as a painkiller, from a chemical found in willow.
DIGITALIS, used to treat heart conditions, from a chemical found in foxgloves.

Question 25

Microorganisms and drugs

Answer 25

Alexander Fleming, cleared out some petri dishes containing bacteria, noticed one of the dishes had mould on it and the area around the mould was free of the bacteria. The mould called PENICILLIUM NOTATUM was producing a substance that killed bacteria, the substance was PENICILLIN.

Question 26

Preclinical testing

Answer 26

drugs tested on human cells and tissues, test the drug on live animals this tests the efficacy, does it work and produce the effect you’re looking for. Find out about its toxicity and find the best dosage. Tested on human volunteers in a clinical trial. first tested on healthy volunteers to see side effects. Then tested on people with the illness. Then they test how well the drug works with the real drug and the placebo. one group is given the real drug, the other the fake. Then if it works are published after they’ve gone through a peer review and this helps prevent false claims.

Question 27

Monoclonal antibodies

Answer 27

Antibodies produced by B-lymphocytes. Monoclonal antibodies are produced from lots of clones of single white blood cell. They are identical and target one specific protein antigen. lymphocytes don’t divide easily. Tumour cells don’t produce antibodies but divide rapidly. You can fuse a mouse b-lymphocyte with a tumour cell to create a hybridoma. They can be cloned to get identical cells that produce monoclonal antibodies rapidly.

Question 28

How are monoclonal antibodies used in pregnancy tests?

Answer 28

HCG hormone is only found in the urine of a woman when they are pregnant. The stick detects the hormone. Antibodies are on the end of the stick that you wee on with blue beads attached. The test strip has more antibodies to the hormone stuck onto it. If you’re pregnant and you wee on the stick the hormone binds to the antibodies on the blue beads, urine moves up the stick carrying the hormone and the beads, they bind to the antibodies on the strip and the blue beads turn the strip blue. If you’re not pregnant the blue beads don’t stick so it doesn’t turn blue.

Question 29

How do monoclonal antibodies treat diseases?

Answer 29

monoclonal antibodies bind to specific cells in the body. Cancer cells have antigens on their cell membranes that normal body cells don’t have (tumour markers). Monoclonal antibodies will bind to them. an anti cancer drug is attached to the monoclonal antibodies e.g. a radioactive substance, a toxic drug or a chemical that stops cancer cells from growing or dividing. The antibodies are given through a drip and target the specific cells and kills it but not the normal body cells near the tumour.

Question 30

Cons of monoclonal antibodies?

Answer 30

They have some side effects that can cause fever, vomiting, low blood pressure.

Question 31

What do nitrates in plants do?

Answer 31

Used for growth, lack of nitrated=stunted growth.

Question 32

What do magnesium in plants do?

Answer 32

Used for making chlorophyll, which is needed for photosynthesis. without enough magnesium plants suffer from chlorosis and have yellow leaves.

Question 33

Plant disease traits

Answer 33

Stunted growth, spots on leaves, patches of decay, abnormal growths, malformed stems or leaves, discolouration.

Question 34

How do you identify plant diseases?

Answer 34

search signs on a website or in a gardening manual. Taking the infected plant to a laboratory where scientists identify the pathogen. Using testing kits that identify the pathogen using monoclonal antibodies.

Question 35

Plant Physical Defences

Answer 35

WAXY CUTICLE, provides a barrier. CELL WALL made from cellulose. layers of dead cells around stems e.g. bark to act as a barrier.

Question 36

Plant Chemical Defences

Answer 36

ANTIBACTERIAL CHEMICALS that kill bacteria e.g. mint plant and witch hazel. produce POISONS that deter herbivores e.g. tobacco plants, foxgloves and deadly nightshade.

Question 37

Plant Mechanical Defences

Answer 37

THORNS and HAIRS to stop animals from touching and eating them. leaves that DROOP or CURL when something touches them, this knocks the insects off. Some plants MIMIC the organisms. e.g. Passion flower looks like butterfly eggs so butterflies won’t lay their eggs there.