4.1.1

Question 1

What are the 4 types of pathogens that cause communicable diseases?

Answer 1

Bacteria

Viruses

Protoctista

Fungi

Question 2

What are the three subsections of direct transmission in animals? Provide examples of each.

Answer 2

Direct contact or any contact with the body fluid of another person.

Inoculation - break in the skin, animal bite, needle sharing

Ingestion - contaminated food or drink, transfer of pathogens from hand to mouth

Question 3

What are the three subsections of indirect transmission in animals?

Answer 3

Fomites - inanimate objects e.g. bedding, socks, cosmetics

Droplet infection

Vectors - mosquitoes, rats, bats

Question 4

What increases the probability of catching a communicable disease in animals?

Answer 4

Overcrowded living and working conditions

Poor nutrition

Compromised immune system

Climate change

Socioeconomic factors - lack of trained health workers

Question 5

What are the two subsections of indirect transmission in plants?

Answer 5

Soil contamination. Bacteria, viruses, reproductive spores from Protoctista or fungi.

Vectors

Question 6

Name 4 vectors in indirect transmission of plant pathogens.

Answer 6

Wind
Bacteria, viruses, fungal spores

Water
Spores swim on the surface film of water on leaves

Animals
Insects and birds carry pathogens and spores. Aphids inoculate pathogens directly into plants.

Humans
Pathogens and spores are transmitted on hands, clothing, fomites, and by transporting plants around the world.

Question 7

What can affect the transmission of communicable diseases in plants?

Answer 7

Planting crops suspectable to diseases

Overcrowding means plants touch each other

Poor mineral nutrition reduces resistance

Damp, warm conditions increases survival and spread

Climate change - increased rain and wind promote spread

Question 8

What two categories of defence do plants have?

Answer 8

Physicial

Chemical

Question 9

What physical defence does a plant use?

Answer 9

Production of high levels of a polysaccharide called callose.

Deposited between cell walls.

Lignin is then added.

Callose blocks sieve plates, sealing off the infected area

Callose is deposited in the plasmodesmata between infected cells and neighbouring cells.

Question 10

What is the purpose of chemicals in plant defence?

Answer 10

Repel insect vectors - pine resin, citronella

Kill invading pathogens - insecticides, antibacterial compounds, antifungal compounds

Question 11

What are the primary non-specific defences against pathogens in animals?

Answer 11

Skin - lots of healthy organisms that outcompete pathogens for space. Sebum inhibits the growth of pathogens.

Mucous membranes protect the respiratory system by trapping pathogens

Blood clotting

Wound repair

Inflammation

Question 12

Explain how the inflammatory response works.

Answer 12

Mast cells are activated in damaged tissues.

Histamines and Cytokines are released.

Histamines make the blood vessels dilate.

Blood vessel walls become more leaky so blood plasma is forced out.

Tissue fluid causes swelling. Pain and heat.

Cytokines attract phagocytes.

Question 13

Draw and label an antibody.

Answer 13

Question 14

What are antibodies?

Answer 14

Y shaped glycoproteins called immunoglobulins which bind to a specific antigen on the pathogen or toxin.

Question 15

Explain the protein structure of an antibody.

Answer 15

Two identical long polypeptide chains called heavy chains and two much smaller identical chains.

The chains are held together by disulfide bridges.

Disulfide bridges also exist within the polypeptide chains, holding them in shape.

Question 16

What is an autoimmune disease?

Answer 16

A disease where the immune stop recognising ‘self’ cells and starts to attack healthy body tissue.

Question 17

Provide an example of one autoimmune disease and its effect.

Answer 17

Lupus. Affects the skin and joints. Causes fatigue. Can attack any organ in the body

No cure

Treated with anti-inflammatory drugs, steroids, immunosuppressants

Question 18

Immunity can occur naturally in the body. Provide two examples.

Answer 18

After exposure to a pathogen for the first time. T and B memory cells are produced.

Newborn babies are provided with some antibodies from the mother via the placenta.

Colostrum from the breast provides more antibodies.

Question 19

How does artificial passive immunity work?

Answer 19

Antibodies are extracted from another individual and injected into the bloodstream of another individual.

It does not last long.

Question 20

How does artificial active immunity work?

Answer 20

The immune system is stimulated to make its own antibodies by injecting a safe form of the antigen.

Question 21

How are antigens made safe to be used as vaccinations? (5)

Answer 21

Killed or inactivated bacteria or virus

An attenuated strain of bacteria or virus

Toxins molecules that have been altered and detoxified

Isolated antigens extracted from the pathogen

Genetically engineered antigens

Question 22

What do vaccines do?

Answer 22

They give long term immunity to many diseases.

Question 23

When vaccines are deployed to prevent epidemics, what sometimes has to happen?

Answer 23

They may have to be changed regularly to remain effective.

Question 24

Provide three examples of drugs and where they are derived from.

Answer 24

Penicillin - Antibiotic - originally extracted from mould on melons

Aspirin - Painkiller, Anti-coagulant, anti-inflammatory - compounds from willow bark

Digoxin - Heart drug - originally extracted from foxgloves

Question 25

What is the process of combining known drug actions with personal genetic material called?

Answer 25

Pharmacogenetics

Question 26

What are the two forms of synthetic biology?

Answer 26

Biological factories - using genetic engineering to grow bacteria that is used in drugs and that would otherwise be too expensive or not available.

Nanotechnology - tiny, non-natural particles are used for biological purposes. e.g. Drug delivery

Question 27

How do antibiotics work?

Answer 27

Selective toxicity - They interfere with the metabolism of the bacteria without affecting the metabolism of the human cells.

Question 28

How can antibiotic resistance be reduced?

Answer 28

Minimise the use of antibiotics

Ensure a course of antibiotics is completed, reducing the chance of resistance individuals surviving

Good hygiene in hospitals to reduce the spread of antibiotic-resistant strains

Question 29

Provide two examples of antibiotic-resistant bacteria.

Answer 29

MRSA

C. difficile