B1 - Pathogens

Question 0

What are the 2 main types of pathogen?

Answer 0

Bacteria

Viruses

Question 1

What are pathogens?

Answer 1

Viruses, bacteria or fungi that enter the body and cause infectious diseases

Question 2

What are bacteria?

Answer 2

Very small cells (100th of body cell size) which can reproduce rapidly inside your body

Question 3

What are the 2 ways that bacteria make us feel ill?

Answer 3

Damaging your cells

Producing toxins (poisons)

Question 4

What are viruses and how do they replicate inside the body?

Answer 4

They are infections that are not cells and are 100th the size of bacteria

They replicate themselves by invading your cells and using your cells’ machinery to produce many copies of themselves, the cell then bursts releasing all of the new viruses

Question 5

How do viruses make us feel ill?

Answer 5

When the cell bursts to release the new viruses, this causes us to feel ill

Question 6

What are the 3 ways that our bodies fight pathogens?

Answer 6

Skin, hairs and mucus in the breathing system stop a lot of pathogens from getting in your body

Platelets (cell fragments) in the blood help blood clot so that pathogens don’t get in your body via cuts

If pathogens make it through, the immune system kicks in. The white blood cells patrol the blood and attack invading pathogens

Question 7

What are the 3 ways that white blood cells destroy pathogens?

Answer 7

Consuming them (and break them down)

Producing antibodies

Producing antitoxins that counter toxins made by bacteria

Question 8

Describe fully how antibodies work

Answer 8

All cells have antigens (unique molecules) on their surface

When white blood cells come across a foreign antigen, they produce called antibodies that lock on and kill the invaders (the antibodies are specific to that antigen)

Those specific antibodies are produced rapidly and are carried around the blood to destroy the rest of that type of pathogen

If someone is infected with the same pathogen again, the white blood cells will very quickly produce the same antibodies again so the person is immune

Question 9

How do vaccinations work?

Answer 9

When you are infected with a new pathogen, you become seriously ill before the antibodies are produced and you become immune

If a small amount of dead or inactive pathogen is injected, the antibodies for that pathogen are produced and destroy it

You are now immune to that pathogen so without becoming seriously ill. If the real pathogen infects you, the antibodies that destroy it are produced before it can cause damage

Question 10

What are the 2 advantages of vaccinations?

Answer 10

Vaccines have helped control many infectious diseases that are very serious and even completely stopped some

Big outbreaks of diseases (called epidemics) can be prevented if everyone is vaccinated so that the disease can’t spread

Question 11

What are the 2 disadvantages of vaccinations?

Answer 11

Sometimes vaccines don’t work

Some people can have serious reactions to vaccines but they are quite rare

Question 12

What is the problem with painkillers?

Answer 12

They don’t actually tackle the cause if the disease, just relieve the pain

Question 13

What are antibiotics?

Answer 13

Medicines that actually kill bacteria causing the problem without killing body cells (they are specific to types of bacteria)

They don’t do anything to viruses

Question 14

Why is it difficult to develop drugs that destroy viruses?

Answer 14

They reproduce using your own body cells so it is hard to make a drug that destroys the virus and doesn’t harm your body cells

Question 15

What is the problem with antibiotics?

Answer 15

Bacteria can quickly evolve inside the body to become resistant to the antibiotics

Question 16

Describe how bacteria can become resistant to antibiotics

Answer 16

Bacteria can mutate and sometimes these mutations make the bacteria resistant to the antibiotics

When you are treated, only the non-resistant bacteria are killed

The resistant bacteria survive and reproduce

This means that all of the bacteria are now resistant to antibiotics

Question 17

Describe fully how microorganisms are cultured (grown)

Answer 17

They are cultured in a culture medium which is agar jelly with carbohydrates, minerals, proteins and vitamins they need to grow

All equipment is sterilised before use to prevent contamination including agar and dish

Inoculating loops are sterilised with a flame

Hot agar jelly is poured into shallow round plastic dishes called Petri dishes

When the jelly is cooled and set, inoculating loops (wire loops) are used to transfer microorganisms to the culture medium

A lid has to be taped on the Petri dish to prevent contamination

The microorganisms then multiply

Question 18

What must be done in a school lab when culturing microorganisms?

Answer 18

Must be done below 25 degrees C to prevent harmful pathogens growing

Question 19

Describe what Semmelweis did

Answer 19

He was working in a hospital and saw that many women were dying after childbirth from puerperal fever

He believed that the doctors were spreading the disease from their unwashed hands so he told them all to always wash their hands with antiseptic solution which cut the death rate massively

The antiseptic solution was killing the microorganisms on the doctors’ hands

Question 20

Why is antibiotic resistance becoming more common?

Answer 20

Antibiotics are used much more and more than they need to be

The resistant bacteria are spread easily by people

Question 21

What are the 2 main dangers of bacteria?

Answer 21

Diseases made from resistant bacteria are much more common now

A new bacterial disease could come along and no one would be immune so it could spread rapidly

Question 22

What are the 3 main dangers of viruses?

Answer 22

They tend to mutate often so it is hard to develop vaccines against them because their antigens keep changing

It is a possibility that a virus could evolve to be very deadly and infectious

In the case of viral epidemics, it can take a long time to develop vaccines against them