Chapter 4.1 - Communicable Diseases

Question 1

What is a Pathogen?

Answer 1

an organism that causes disease

Question 2

What is a bacteria?

Answer 2

A prokaryote that damages cells directly via toxins - e.g. salmonella, tuberculosis

Question 3

What is a virus?

Answer 3

A non-living parasite that takes over host cells and uses their metabolic function to replicate until the host cell bursts and dies - e.g. HIV, influenza, TMZ

Question 4

What is a Fungi?

Answer 4

a eukaryotic organism that uses hypae to form mycellum - uses spores to transmit - e.g. ringworm.

Question 5

What is a protocista?

Answer 5

Unicellular parasites that feed off host cells to grow - e.g. malaria or blight.

Question 6

What are some examples of primary human defence?

Answer 6

• skin
• blood clotting
• skin repair
• coughing / sneezing
• earwax
• lysosomes in tears
• cilia in trachea

Question 7

What are some examples of secondary human defence?

Answer 7

• opsonins - cells that ‘mark’ antigens

- Phagocytes in immune system

Question 8

What are some examples of passive plant defence?

Answer 8

• Cellulose cell wall
• lignin
• bark
• waxy cuticle
• stomatal closure

Question 9

What are some examples of active plant defence?

Answer 9

• cell necrosis - controlled cell death to stop viruses spreading
• canker (death of cambium)
• oxidative bursts
• chemicals - Terpenoids + Phenols - antibac. + antifungal
  - Bitter alkaloids - stop plants being eaten
• callose deposited in plasmodesmata

Question 10

What are opsonins?

Answer 10

Cells that bind to antigens and ‘mark’ them

also allows for easy binding site for phagocytes

Question 11

What are agglutinins?

Answer 11

cells that bind to multiples antigens at once and bind all the pathogens together

Question 12

What are anti-toxins?

Answer 12

cells that bind to toxins released by pathogens and neutralize them

Question 13

What is the difference between the primary immune response and the secondary immune response?

Answer 13

The primary immune response is much slower than the secondary immune response, as the t memory cells are present during the secondary immune response and not the primary.

Question 14

What is phagocytosis?

Answer 14

The process by which pathogens are engulfed and neutralised by phagocytes - lysosome enzymes within phagocytes destroy pathogen.

Question 15

What are T helper cells?

Answer 15

Cells that bind to antigens + activate to mark them. They can also reproduce rapidly and differentiate into any T cell.

Question 16

What are T killer cells?

Answer 16

Cells that recognize foreign cells that are marked and release perforin to destroy the foreign cells.

Question 17

What are T memory cells?

Answer 17

Cells that live for a long time that remember and can recognise foreign hostile pathogens, for a more rapid immune response.

Question 18

What are T regulator cells?

Answer 18

Cells that regulate the immune system, occasionally neutralising it if necessary to stop it from destroying cells that are native and necessary for the human body.