B3 infection and response

What are pathogens?

Microorganisms that enter the body and cause disease. They cause communicable diseases and can infect both plants and animals

What are bacteria?

Very small cells which can reproduce rapidly inside your body. They produce toxins that damage your cells and tissues.

What are protists?

Single celled eukaryotes. Some protists are parasites which live on or inside other organisms and cause damage. Theybare often transferred by a vector.

What are three viral diseases?

1. Measles. It is spread by droplets from an infected persons sneeze or cough. People with measles develop a red skin rash, and they show signs of fever

2. HIV. It is spread by sexual contact or exchanging bodily fluids such as blood eg. sharing needles. It causes flu-like symptoms. It attacts immune cells

3. Tobacco mosaic virus (TMV). It affects plants like tomatoes. It causes a mosaic pattern on the leaves of the plants, parts ofthe plant become discolored. Plants cant carry out photosynthesis so it affects their growth

What is one fungal disease?

Rose black spot:

• It causes purple or black spots to develop on the leaves of rose plants.

• The leaves can turn yellow or drop off.

• This means less photosynthesis so tge plant cant grow

• It spreads through water or by the wind

• Gardeners can treat it using fungicides

What is one disease caused by a protist?

Malaria:

• the mosquito is the vector they pick it up when they feed on an infected animal

• it inserts the protists into the animals blood vessel

• malaria causes repeating episodes of fever and it can be fatal

What are two bacterial diseases?

1. Salmonella. It causes foood poisoning eg. fever, cramps, vomiting and diarrhoea. It is caused by the toxins that the bacteria produce. Most poultry is given a vaccination against Salmonella

2. Gonorrhoea. It is an STD. It is passed on by sexual contact. It causes pain while urinating and thick yellow or green discharge. It was originally treated by antibiotic called pencillin bet the bacteria became resistant to it.

1. How to reduce or prevent the spread of disease?

1. Being hygienic

2. Destroying vectors

3. Isolating infected individuals

4. Vaccination

How does our bodies defend us from diseases?

• Skin acts as a barrier to pathogens. It also secretes antimicrobial substances which kill pathogens

• Hair and mucus in your nose traps pathogens

• The trachea and bronchi secrete mucus to trap pathogens

• The stomach produces hydrochloic acid

What are three ways in which white blood cells attack invading pathogens?

1. Engulf them and digest. This is called phagocytosis

2. Produce antibodies

3. Produce toxins that counteract toxins produced by the invading bacteria

How white blood cells produce antibodies?

1. Every invading pathogen has unique molecules (called antigens) on its surface.

2. When some types of white blood cell come across a foreign antigen (i.e. one they don't recognise) they will start to produce proteins called antibodies to lock onto the invading cells so that they can be found and destroyed by other white blood cells. The antibodies produced are specific to that type of antigen — they won't lock on to any others.

3. Antibodies are then produced rapidly and carried around the body to find all similar bacteria or viruses.

4. If the person is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it — the person is naturally immune to that pathogen and won't get ill.