B6.3

Question 1

What can Human papilloma virus (HPV) lead to?

Answer 1

Certain types of cervical cancer

Question 2

What can Human immunodeficiency virus (HIV) lead to?

Answer 2

Tuberculosis

Question 3

How can pathogens spread between animals?

Answer 3

• through cuts in the skin
• through the digestive system (when food and drink is shared)
• through the respiratory system
• through the reproductive system (during intercourse)

Question 4

How can pathogens spread between plants?

Answer 4

• vectors, such as insects
• soil and water in which the plants grow
• direct contact of sap from infected to healthy
• the wind, fungal spores can be blown between plants

Question 5

What is the ‘incubation period’?

Answer 5

The time delay between harmful microorganisms entering your body, and you feeling unwell.

Question 6

How does a virus ‘take over’ an organisms cells?

Answer 6

The virus attacks a cell and inserts its genes. It ‘tells’ the nucleus to copy its genes and new viruses are made. The cell then bursts releasing the new viruses and destroying your cell.

Question 7

How do farmers prevent the spread of disease in plants and animals?

Answer 7

• diseased plant material is normally burnt to prevent the disease spreading
• livestock cannot be moved
• animals may be treated using drugs

Question 8

Example of fungi in animals

Answer 8

Athletes foot

Question 9

An example of a viral plant disease

Answer 9

Tobacco Mosaic Virus

Question 10

Symptoms of tobacco mosaic virus

Answer 10

• mottled or discoloured leaves, it does this by preventing chloroplasts from forming, which stunts the growth of the plant
• almost never kills the plant, but lowers quality and quantity of crop they produce

Question 11

Example of bacterial plant disease

Answer 11

Agrobacterium tumefaciens

Question 12

Example of a fungal plant disease

Answer 12

Powdery mildew

Question 13

Symptoms of powdery mildew

Answer 13

Displaying white powdery spots on the leaves and stems

Question 14

What are the two types of plant defences against communicable diseases?

Answer 14

Physical defences
Chemical defences

Question 15

Example of physical plant defences

Answer 15

Waxy cuticle
Cell wall

Question 16

Ways to identify plant diseases in the field

Answer 16

Microscopy
Observation

Question 17

How does skin act as a defence mechanism?

Answer 17

It’s a physical barrier. Sweat glands also help to kill microorganisms.

Question 18

How does acid in the stomach act as a defence mechanism?

Answer 18

Kills pathogens present in contaminated food or drink

Question 19

How do tears act as a defence mechanism?

Answer 19

They contain lysozymes which are enzymes that destroy bacteria

Question 20

What is the immune systems main form of defence?

Answer 20

White blood cells

Question 21

What are the two types of white blood cells?

Answer 21

Lymphocytes and phagocytes

Question 22

What do phagocytes do?

Answer 22

They engulf the microorganisms and then make enzymes that digest the microorganisms.

Question 23

What do lymphocytes do?

Answer 23

They make antitoxins or antibodies.

Question 24

Where are monoclonal antibodies produced and what are they produced with?

Answer 24

In the laboratory using special cells known as hybridomas.

Question 25

What are hybridomas?

Answer 25

A fusion of myelomas (cancer cells) and lymphocytes

Question 26

How are monoclonal antibodies produced?

Answer 26

Genetically modified mice are injected with the required antigen. Their bodies then produce antibodies to that specific antigen. The antibody-producing lymphocyte cells are then collected. These cannot survive outside the body so they are fused with myeloma cells (cancerous cells) from the bone marrow, which reproduce indefinitely.

As the hybridoma cells reproduce, they form clones. Each clone produces the required antibody, which is harvested. These proteins are called monoclonal antibodies.

Question 27

What are vaccines?

Answer 27

They usually contain small amounts of weakened or dead versions of a pathogen. They are injected into the body and cause your lymphocyte cells to produce antibodies to the pathogen.

Question 28

What do antiseptics do?

Answer 28

Kill or neutralise all types of pathogen, but do not damage the human tissue.
e.g. alcohol or iodine

Question 29

What do antivirals do?

Answer 29

They are drugs that destroy viruses, usually preventing them from replicating.

Question 30

What are antibiotics?

Answer 30

Drugs that kill bacteria without damaging your cells.

Question 31

What does aseptic technique do?

Answer 31

Prevents foreign microorganisms from being introduced into a test sample.

Question 32

What does aseptic mean

Answer 32

Without microorganisms

Question 33

Why should you wash working areas with alcohol before and after working?

Answer 33

To ensure that no microorganisms are present in the working area

Question 34

Why should you wear gloves if at risk of working with pathogens?

Answer 34

To prevent microorganisms passing from a sample to your skin

Question 35

Why should you work close to a Bunsen burner flame?

Answer 35

To prevent unwanted microorganisms from falling into an open sample.

Question 36

Describe how some plants use chemicals as a defence against pathogens.

Answer 36

Some plants produce antimicrobial chemicals to kill pathogen or inhibit their growth.

Question 37

How would you sterilise and inoculating loop?

Answer 37

By passing it through a hot flame

Question 38

Why are cultured incubated at a maximum of 25 degrees Celsius in schools?

Answer 38

Harmful bacteria are more likely to grow above this temperature.

Question 39

Why are tumour cells used to produce hybridomas?

Answer 39

Tumour cells can be grown easily, because they divide a lot

Question 40

What do antibodies bind to on the surface of cancer cells?

Answer 40

Tumour markers