B5 - Communicable Diseases

What is the definition of health?

Health is a state of mental and physical well-being

What is the major cause of ill health?

diseases, both communicable and non-communicable

Name factors that can affect mental and physical health

diet, stress, life situations

Different types of diseases...

may and often do interact

What are communicable diseases?

Communicable diseases are disease that are caused by microorganisms called pathogens. They are infectious

What are all the types of pathogens?

Bacteria
virus
protist
fungi

What are the differences between viruses and bacteria?

Viruses are much smaller in comparison to bacteria.

Some bacteria are helpful to our health and well being whereas all viruses cause disease in organisms

How do pathogens cause disease?

Bacteria split rapidly by splitting in two (binary fission). They may produce toxins that affect your body. Sometimes they directly damage your cells

Viruses take over the cells of your body. They live and reproduce inside cells which eventually kills them.

What are some common diseases symptoms?

high temperature , headaches and rashes

What are three ways that pathogens can spread?

By air (including droplet infection)
Direct contact
By water

What is a culture medium?

A liquid or gel containing nutrients

Explain a method which grows an uncontaminated culture of microorganisms

Carry out experiment in front of a lit Bunsen burner with yellow flame, preventing contamination.

Hot agar jelly is poured into a sterilised petri dish and left to cool. They are heated to a high temperature to prevent unwanted microorganisms

An inoculating loop is passed through a hot flame before transferring bacteria to the culture medium

Petri dishes opened as little as possible facing the Bunsen burner

The lid of the petri dish is secured with tape at intervals around the dish and stored upside down

the cultures should not be incubated above 25 degrees in a school laboratory.

What is the maximum temperature bacteria can be incubated at in schools and colleges?

25 degrees

How often does bacteria multiply?

Bacteria multiplies by simple cell division every 20 minutes if they have enough nutrients and a suitable temperature

How can the spread of the disease be prevented?

By destroying vectors, isolating affected individuals and by vaccination.

What is measles and how is it spread?

Virus. Caused by droplet infection. It causes fever and a rash and can be fatal. Isolation and vaccination prevents spread

What is HIV and how is it spread?

HIV causes flu-like illness unless it is controlled with antiretroviral drugs. Late stage HIV, or aids, occurs when the body's immune system is so badly damaged that it can no longer deal with other infections. HIV is spread by sexual contact.

What is tobacco mosaic virus and how is it spread?

Tobacco mosaic virus is spread by contact and vectors . It damages leaves and reduces photosynthesis. There is no treatment and spread is reduced by field hygiene and pest control.

What is salmonella and how is it spread?

Salmonella is spread through undercooked food and poor hygiene. Symptoms include fever, abdominal cramps, diarrhoea and vomiting. Caused by toxins produced by the bacteria.

What is Gonorrhoea?

A sexually transmitted disease. Symptoms include discharge from penis or vagina and pain on urination. Treatment involves using antibiotics although many strains are now resistant. Using condoms and limiting sexual partners.

What is rose black spot?

A fungal disease spread by the environment by wind and water. It damages leaves which affects photsynthesis. Spread is controlled by removing affected leaves and chemical sprays.

What is malaria and what is it caused by?

Malaria is caused by parasitic protists and is spread by the bite of mosquitos. It damages the blood and liver cells. Causes fever and shaking. could also be fatal. Some drugs are effective but protists are becoming resistant. Spread is reduced by preventing vectors from breeding and by using mosquito nets.

What is all the lines of defence your body has against pathogens?

Skin, nose, trachea, bronchi and stomach

Name three ways white blood cells defend against pathogens

Ingesting microorganisms (phagocytosis)
producing antibodies
producing antitoxins

What can plants be infected by?

Viral, fungal, and bacterial pathogens aswell as insect pests

What can plants be damaged by

A range of ion deficiency conditions

What are some signs of plant disease

A range of symtoms identified by a number of ways, including gardening manuals and laboratory tests, some involving monoclonal antibodies

* Stunted growth –
* Spots on leaves –
* Areas of decay –
* Growths –

Name some examples of physical plant defences

cellulose cell walls, waxy cuticles and layers of bark or dead cells

Name some examples of chemical plant defences

antibacterial chemicals and poisons to deter herbivores

name some plant mechanical adaptations against herbivores

Thorns or hairs , leaves that droop or curl when touched and mimicry to trick animals