B5 - Communicable Diseases

Question 1

Define health

Answer 1

Health is your state of physical and mental wellbeing

Question 2

What are communicable diseases caused by?

Answer 2

Communicable diseases are caused by pathogens

Question 3

What are pathogens?

Answer 3

Pathogens are micro-organisms that cause disease

Question 4

What is obesity a risk factor of?

Answer 4

Type 2 diabetes

Question 5

List the 4 main types of pathogens

Answer 5

Bacteria
Virus
Fungi
Protist

Question 6

What is a communicable disease and what is it caused by ?

Answer 6

It is a disease that can be passed from person to person and is caused by a spread of pathogens

Question 7

What is bacteria and what can it do to harm you?

Answer 7

• Bacteria are very small cells
• They reproduce rapidly in your body and make you feel ill by producing toxins that damage your cells and tissues

Question 8

What do viruses do?

Answer 8

-Like bacteria, they reproduce rapidly inside your body
-They live inside your cells and they replicate themselves using the cells machinery to produce many copies of themselves
-The cell will then burst releasing all new viruses
-This cell damage will make you feel ill

Question 9

What are viruses?

Answer 9

Viruses are not cells, they are much smaller

Question 10

What are protists?

Answer 10

• There are lots of different types of protists but they are all eurkaryotes and most of them are single celled
• Some protists are parasites and parasites live on or inside other organisms and can cause them damage. They are often transferred to the organism by a vector (e.g. an insect that carries the protist)

Question 11

What is Fungi?

Answer 11

Fungi is a pathogen that can be single-celled or have a body which is made up of hyphae

Question 12

What does hyphae do?

Answer 12

Hyphae can grow and penetrate human skin and the surface of plants causing disease and these hyphae can also produce spores which can be spread to other plants and animals.

Question 13

In what ways can pathogens be spread?

Answer 13

-Water - some pathogens are picked up by drinking or bathing in dirty water e.g. Cholera is a bacterial infection that is spread by drinking dirty water

-Air - Pathogens can be carried in the air and can be breathed in for e.g. some airborne pathogens are carried in the air in droplets produced when you cough or sneeze

-Direct Contact - Some pathogens can be picked up by touching contaminated surfaces, including the skin

Question 14

What are the 3 viral diseases and what do they do and how are they spread ?

Answer 14

Measles - it is a viral disease that is spread by droplets from an infected persons sneeze or cough and people that have measles develop a red skin rash and they will shows signs of a fever. Also measles can sometimes lead to lung infection and inflammation of the brain. Most people are vaccinated against measles when they’re young

-HIV - HIV is a virus that is spread by sexual contact or by exchanging bodily fluids such as blood and this can happen when people share needles. Initially HIV causes flu-like symptoms for a few weeks and then the person doesn’t experience any symptoms for a few years - during this time HIV can be controlled with antiretroviral drugs which stop the virus from replicating. The virus attacks immune cells. If the the bodys immune system is badly damaged, it cant cope with other infections or cancers. At this stage it is called AIDS.

-Tobacco mosaic virus - it is a virus that affects many species of plants and it causes a mosaic pattern on the leaves of the plants and parts of the leaves become discoloured and this discolouration means that the plant cant carry out photosynthesis as well so the virus affects the plants growth

Question 15

Name a fungal disease and what is does and how can you treat it? Also how does it spread?

Answer 15

• Rose black spot - it is a fungus that causes purple or black spots to develop on leaves of rose plants and later the leaves turn yellow and drop off and this means that less photosynthesis can happen therefore the plant dosn’t grow very well. It spreads through the environment in water or by the wind. You can treat it by using fungicides and by stripping the plant of its affected leaves

Question 16

Name a disease caused by a protist and say what is does and how it can be stopped

Answer 16

-Malaria is caused by a protist and is spread by mosquitos which are vectors that pick up the malarial protist when they feed on a infected animal and they spread it by feeding on other animals. Malaria causes repeating episodes of fever and it can be fatal. Malaria can be stopped by stopping the mosquitos from breeding or by using mosquito nets.

Question 17

Name two diseases that are caused by bacterial diseases and say what they do

Answer 17

-Salmonella - is caused by a type of bacteria that causes food poisoning and people that are infected suffer from fever, stomach cramps, vomiting and diarrhoea. These symptoms are caused by the toxins that the bacteria produce and you can get Salmonella by eating food that has been infected with the Salmonella bacteria

-Gonorrhoea - is a STD and is passed on by sexual contact and it is caused by a bacteria. People that have gonorrhoea will get pain when urinating and/or get a thick yellow or green discharge from the penis or vagina. To prevent Gonorrhoea you should use barrier methods like condoms

Question 18

What are the 4 ways to prevent the spread of disease?

Answer 18

1) Being hygienic like for e.g. washing your hands
2) Destroying vectors so getting rid of organisms that spread disease
3) Isolating infected individuals
4) Vaccinations - it means that people can’t develop the infection and then pass it on to someone else

Question 19

What physical defence do humans have against pathogens?

Answer 19

• The skin acts as a barrier to pathogens and secretes oils and antimicrobial substances that kill pathogens
• Hairs and mucus in your nose trap particles that could contain pathogens
• The trachea and bronchi have mucus to trap pathogens and they also are lined with cilia which are hair like structures that waft the mucus up to the back of the throat where it can be swallowed
• The stomach produces HCL which kills pathogens that made it far from the mouth

Question 20

How does your immune system attack pathogens?

Answer 20

-If pathogens do make it to your body your immune system kicks in to destroy them
-The most important part of our immune system is your white blood cells as they patrol your whole body looking for microbes

Question 21

How do your white blood cells destroy microbes?

Answer 21

1) White blood cells can consume foreign cells and digest them
2) When a white blood cell comes across a foreign antigen it starts to produce protiens called antibodies to lock on to the invading cells so they can be found and destroyed by other white blood cells
3) Some white blood cells also produce anti-toxins

Question 22

What is binary fission?

Answer 22

It is when Prokaryotic cells replicate by binary fission

Question 23

Explain the process of binary fission ( prokaryotic cells replicate by binary fission )

Answer 23

1) The circular DNA and plasmids replicate
2) The cell gets bigger and the circular DNA strands move to opposite ends of the cell
3) The cytoplasm begins to divide and new cell walls begin to form
4) The cytoplasm divides and the 2 daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmids

Question 24

Explain how to plate the bacteria in the microbiology practical

Answer 24

Sterelise the agar jelly and the petri dish to stop any unwanted microorganisms from going inside
1) Wash your hands and disinfect the work area
2) Place a bunsen burner on a heatproof mat in the middle of the work space
3) Use a marker to label the underside of a nutrient agar plate ( A,B,C,control )
4) Turn the bunsen burner to the blue flame and flame the neck of the bottle containing the bacteria ( after taking the lid of )
5) Use a clean pipette to collect 0.2ml of bacteria culture from the bottle and then flame the neck of the bottle again and replace the lid
6) Lift the lid but dont open it completly and pipette the bacteria in to the middle of the agar plate
7) Then heat the inoculating loop in the blue flame and then try to spread the bacteria culture evenly

Question 25

How do you add the antiseptic discs in the microbiology practical?

Answer 25

1) Soak three paper discs in different antiseptics and soak the 4th disk in sterile water for the control variable
2) Then use forceps to place the discs in the middle of each zone sterelising the forceps in the blue flame after each use
3) Use 2 pieces of tape to secure the petri dish lid - to stop unwanted microorganisms getting in
4) Turn the petri dish upside down - to stop drops of condensation falling onto the agar surface
5) Incubate them at 25C to allow the bacteria to grow

Question 26

What do plants need from the soil?

Answer 26

They need mineral ions from the soil and if there is not enough of it, plants will suffer from defiency problems

Question 27

What are nitrates needed for in plants?

Answer 27

Nitrates are needed to make proteins and therefore growth. A lack of nitrates causes stunted growth

Question 28

What are magnesium ions needed for?

Answer 28

They are needed for making Chlorophyll which is needed for photosynthesis and whithout it plants suffer from chlorosis and have yellow leaves

Question 29

What are the common signs that a plant has a disease?

Answer 29

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

Question 30

How can diseases be identified in plants?

Answer 30

Gardening manual or website
Taking the infected plant to a lab
Using testing kits to identify the pathogen using monoclonal antibodies

Question 31

What are the physical defences of plants against pathogens?

Answer 31

Waxy cuticle provides a barrier to stop pathogens entering
Cell walls made from celluose form a physical barrier
Plants have a layer of dead cells around their stems that act as a barrier

Question 32

What are some chemical defences that plants have?

Answer 32

• Some plants can produce antibacterial chemicals which kill bacteria
• Other plants produce poisons which deter herbivores

Question 33

What are some mechanical defences that plants have?

Answer 33

Some plants have adapted to have thorns and hairs
Some plants have leaves that droop or curl when something touches them ( to knock insects of themselves and to move away from things )
Some plants cleverly mimic other organisms to trick them into not eating them

Question 34

What are spores

Answer 34

They are a thing that lets fungi reproduce. Can be spread in the wind etc

Question 35

What are the stages of phagocytosis ?

Answer 35

1 Phagocytosis is carried out by a special type of white blood cell called a phagocyte.

2 The first step is for the phagocyte to track down a pathogen, and then bind to it.

3 The phagocyte’s membrane will then surround the pathogen and engulf it.

4 Finally, enzymes inside the phagocyte break down the pathogen in order to destroy it.

Question 36

What is an antigen ?

Answer 36

An antigen is any substance that your body sees as foreign, which then causes your immune system to produce antibodies against it. For example, the toxins and cell walls of pathogens would be considered antigens.

Question 37

What is an antibody ?

Answer 37

An Antibody is a protein produced by our white blood cells that binds to specific antigens. This acts as a signal to our immune system to destroy the antigen (or the pathogen it is part of).