Bio 7B

Question 1

what is the first line of defence and what does it entail?

Answer 1

a component of the innate immune system
- composed of generalised and non-specific defences and/or responses to pathogens
- provides physical, chemical, and microbiological barriers to prevent pathogen invasion
- respond to injury and antigens extremely quickly
- NO memory of prior infection

Question 2

what are physical barriers?

Answer 2

Component that features solid or fluid obstacles that block pathogen entry (e.g. skin, mucus)

Question 3

what are chemical barriers?

Answer 3

Component that features the use of enzymes, toxins, and acids to protect against pathogen invasion by destroying them

Question 4

what are microbiological barriers?

Answer 4

A component in which the presence of normal flora (non-pathogenic bacteria) limits the growth of pathogenic bacteria

Question 5

what are examples of physical barriers in plants?

Answer 5

plants:
- Waxy cuticles of leaves
- Thick bark
- Thorns and trichomes
- Formation of galls (prevent the spread of infection)
- Closing of stoma (prevent pathogen invasion during carbon dioxide intake)

Question 6

what are examples of chemical barriers in plants?

Answer 6

• Chitinases (enzyme that has antifungal properties)
• Phenols (secreted by wounded plants - repels or kills microorganisms)
• Defensins (small peptides that are toxic to microbes and fungi)
• Saponins (disrupts the cell membrane of various fungi)
• Glucanases (defends plants against fungi)

Question 7

what are examples of physical barriers in animals?

Answer 7

• Intact skin and surfaces between external and internal environments (e.g. respiratory, gastrointestinal, integumentary, genitourinary tracts)
• Mucous secretions and/or hairs in the respiratory tract (trap organisms)
• Cilia that sweep organisms away from the airways and into the throat (then swallowed and destroyed by gastrointestinal tract)

Question 8

what are examples of chemical barriers in animals?

Answer 8

• Presence of lysosome enzymes and saliva (destroy bacterial cell walls)
• Acidic sweat (destroys pathogens growing on the surface of the body)
• Stomach acid (destroys pathogens that have been eaten/swallowed
• Antibacterial compounds in earwax
• Antibacterial proteins in semen
  Low pH in vagina

Question 9

what are examples of microbiological barriers in animals?

Answer 9

• presence of bacteria on the skin, lower gastrointestinal tract, and vagina