7B: First Line of Defence

Question 1

Innate Immune System

Answer 1

a component of the immune system that is composed of generalised and non-specific defences/responses to pathogens

- Also known as non-specific immune system - Composed of the first and second line of defence

Question 2

First Line of Defence

Answer 2

a component of the innate immune system characterised by the presence of physical, chemical and microbiological barriers to keep pathogens out of the host organism

Question 3

Second Line of Defence

Answer 3

a component of the innate immune system characterised by the non-specific response to injury and or pathogens by a variety of cells and molecules

Question 4

Non-Specific

Answer 4

describes a component of the innate immune system which responds the same way to all pathogens

Question 5

Types of First line Defences in Plants: physical

Answer 5

barriers that prevent pathogens from physically entering the organism
E.g.
- Thick bark
- waxy cuticles of leaves
- closing up of stomata to prevent pathogen invasion
- Presence of thorns and trichomes to deter insects
- Formation of galls to prevent infection

Question 6

Types of First line Defences in Plants: Chemical

Answer 6

barriers involve the production of chemicals which are harmful to the pathogen that affect the functioning or development of the pathogen.
E.g:
- Chitiniases: enzymes that have antifungal properties
- Phenols: secreted by wounded plants, repelling or killing invading microorganism
- Defensins: small peptides that are toxic to microbes and fungi
- Saponins: disrupt the cell membranes of various fungi
- Oxalic acid: a substance that can be toxic if ingested
- Glucanases: defend plants against fungi

Question 7

Microbiological Barrier

Answer 7

a component of the first line of defence in which the presence of normal flora limits the growth of pathogenic bacteria

Question 8

First Line of Defence in Animals: Physical

Answer 8

Barriers that block or hinder pathogens from entering the organism
E.g.
- Intact skin and surfaces between internal and external environments
- Mucous secretion or hairs(nose) that trap organisms
- Cilia that sweep them away from the airways and into the throat where they are swallowed and destroyed

Question 9

First Line of Defence in Animals: Chemical

Answer 9

Barriers that work by producing chemical substances that make an environment unliveable for a pathogen
E.g.
- Presence of lysosome enzymes in tears and saliva destroy bacterial cell walls
- Stomach Acid that destroys pathogens that have been consumed
- Acidic sweat destroys pathogens growing on the body
- Antibacterial compounds in earwax
- Antibacterial proteins in semen
- Low pH in the vagina

Question 10

First Line of Defence in Animals: Microbiological

Answer 10

The presence of non-pathogenic bacteria in the body can prevent the growth of pathogenic bacteria as they compete for space and resources
E.g.
- Presence of bacteria on the skin in the lower gastrointestinal tract and the vagina