Topic 3 Infections And Responses

Question 1

Pathogens

Answer 1

Pathogens are microorganism that enter the body and cause communicable diseases that can be spread easily and can effect plants and animals

Question 2

Bacteria

Answer 2

Very small living cells around 1/100th of your body cells bacteria make you feel ill by producing toxins that can damage your cells and tissue

Question 3

Viruses

Answer 3

Around 1/100th of a bacterium. Can reproduce rapidly. Live inside your cells and replicate until the cell burst releasing the viruses. The cell damage is what makes you feel ill

Question 4

Protists

Answer 4

Single celled Eukaryotes. Some are parasites. Parasites live on or in organisms and causes damage normally passed on by a vector

Question 5

Fungi

Answer 5

Some fungi are single celled. Others have a body made of hyphae these can grow and penetrate human skin and the surface of plants causing diseases and the hyphae can produce spores which transfers it to other animals and plants

Question 6

3 ways pathogens can be spread

Answer 6

1. water- pathogens can be picked up by drinking dirty water e.g. Cholera and diarrhoea
2. Air - pathogens can be carried in the air and can be breathed in eg influenza virus
3. Direct contact - some pathogens can be passed on through touch contaminated surfaces such as skin e.g. athletes foot

Question 7

Measles disease

Answer 7

Spread by droplets from sneezes or coughs. The disease causes a red skin rash and fever. Measles can be serious or even fatal and it can sometimes lead to pneumonia (lung infection) or encephalitis (brain infection). However most people are vaccinated when they are young

Question 8

HIV Virus

Answer 8

Spread through sexual contact or by exchanging bodily fluids such as sharing needles. HIV causes flu-like symptoms for a few weeks usually the person doesn’t experience symptoms for years during this time the virus can be stopped from multiplying with antiretroviral drugs. The virus attacks the immune system. The damaged immune system means that t can’t cope with infections and cancers and in the late stages it can develop into AIDS

Question 9

Tobacco mosaic virus. (TMV)

Answer 9

A virus that affects plants e.g. Tomatoes. It creates a mosaic pattern on the leaves and parts of the leaves become discoloured. The discolouration means the plant can’t carry out photosynthesis so the virus affects growth

Question 10

Rose black spot (fungal disease)

Answer 10

Cause purple or black spots to develop on the leave of rose plants. The leaves can then turn yellow and fall off. So less photosynthesis can happen less so growth will slow down. Spreads through the environment in water or by wind. Can be treated by using fungicides and by stripping the play of it’s affected leaves. These should be destroyed so it can’t be spread

Question 11

Malaria (Disease caused by a protist)

Answer 11

Part of the malaria protist life cycle takes place in the mosquito they are vectors and the they pick up ten protists after feeding on infected animals. Every time it feeds it infects the animal by inserting the protist into the blood vessels. Malaria causes fever and can be fatal. The spread can be slowed by stopping them from breeding. People can be protected by using insecticides and mosquito nets.

Question 12

Salmonella (bacterial disease)

Answer 12

Salmonella is caused by food poisoning. They suffer from fever, stomach cramps, vomiting and diarrhoea. These are caused by toxins that bacteria produced. Salmonella can be got by eating food contaminated with salmonella. In the U.K. most poultry is given vaccination against Salmonella this controls the spread of the disease

Question 13

Gonorrhoea (STD)

Answer 13

Passed by sexual contact. It is caused by bacteria. Causes people to have pain when urinating another symptom is a yellow or green discharge from the vagina or penis. Initially antibiotics such as Penicillin but can’t be used now as it is resistant. The spread can be prevented by treating it with antibiotics or the barrier method e.g. Condoms

Question 14

The 4 ways the spread of diseases can be reduced or prevented

Answer 14

1. Being hygienic - simple hygienic measures can prevent the spread by washing your hands before preparing food or after sneezing
2. Destroying vectors - removing organisms that spread diseases are killed so that they can be killed and vectors that are insects can be killed by insecticides or destroying their habitat
3. Isolate infected individuals - isolate people so that if it is a communicable it can be prevented from being passed on
4. Vaccinations - vaccinating animals and humans means that can’t get the infection and pass it on

Question 15

Defence systems

Answer 15

1. Skin acts as a barrier to pathogens also secretes antimicrobial substances which kill pathogens
2. Hairs and mucus in your nose trap particles which could have pathogens
3. Trachea and bronchi secrete mucus to trap pathogens
4. Trachea and bronchi are lined with cilia these hairs waft up mucus up to the back of the mouth where it is swallowed
5. The stomach has hydrochloric acid tho kills pathogens which get past the mouth

Question 16

Immune system phagocytosis

Answer 16

White blood cells are mostly used for protecting the body. They consume foreign cells and digest them this is called phagocytosis.

Question 17

White blood cells producing antibodies and antitoxins

Answer 17

When they come across a foreign antigens they produce proteins Called antibodies to lock onto the invading cells so they can be found and destroyed. Antibodies are rapidly produced then sent around the body to find bacteria or viruses. If a person is infected with the pathogen again then the antibodies can be produced to kill it. Antitoxins are produced and these counteract toxins produced by invading bacteria

Question 18

Vaccinations

Answer 18

Vaccinations are when small amounts of dead or inactive pathogens are injected into the person so that the body produces antibodies so if they face the pathogen then antibodies can be produced to fight the pathogen

Question 19

Pros of vaccinating

Answer 19

1. Vaccines help control communicable diseases e.g. Polio, measles and rubella because of this smallpox no longer happens and polio has fallen by 99%
2. Big outbreaks (epidemics) can be prevented as most of the population are vaccinated so the disease can’t spread very quickly

Question 20

Cons of vaccinations

Answer 20

1. Vaccines don’t always work as they don’t always give immunity
2. You can sometimes have a bad reaction to a vaccine e.g. Swelling, or more serious things like fever or seizures but bad reactions are very rare

Question 21

Painkillers

Answer 21

E.g. Aspirin this relieve pain but don’t kill the pathogen just reduce the symptoms

Question 22

Antibiotics

Answer 22

E.g. Penicillin kills or prevents the growth of bacteria but doesn’t harm the body’s cells. Different antibiotics kill different types of bacteria. Antibiotics don’t kill viruses. The use antibiotics has reduced the number of deaths from communicable diseases caused by bacteria

Question 23

Why do antibiotics not kill viruses?

Answer 23

Viruses reproduce using the body cells so makes it hard to develop drugs to kill the virus but not the body’s cells

Question 24

Why are some bacteria resistant to antibiotics?

Answer 24

Bacteria can mutate so that they are resistant to antibiotics