inquiry question 2 module 7

Question 1

what system do plants use to respond to infection

Answer 1

innate immune system

passive (physical and chemical barriers) and active defence (systemic acquired resistance, hypersensitive response, basal resistance)

Question 2

physical barriers of plants

Answer 2

• Thorns and spikes
• Thick bark
• stomata opens in rainy weather, cooler weather
• Tough waxy cuticle
• Trichomes: Fine hairs, spines, outgrowths found on plants
• Thick cell wall
  Resin: Thick sticky substance produced in response to an insect attack, fungal infection eg. eucalyptus

Leaf dropping: Infected leaves may drop off the plant, Prevents disease from spreading to other parts of the plant

Question 3

chemical barriers/ defence in plants

Answer 3

• enzymes that break down pathogen-derived toxins chitanase that breaks down cell wall of fungi
  lemon myrtle: distinct smell due to oil it produced that has microbial and insect repelling properties
• saponins: Produced in the cell membrane of plants Degrade the cell membranes of fungal cells
• caffeine: Toxic to fungi and insects

Question 4

Systemic acquired resistance

Question 5

Pattern recognition receptors

Answer 5

triggers the thickening of the cellulose wall of the cell which prevents pathogen from spreading to the next cell

Question 6

hypersensitive response

Answer 6

triggers cell suicide (apoptosis) at the infected site if a pathogen infects a cell
- the plant detects the presence of specific pathogen proteins and kills the infected cell

Question 7

basal resistance

Answer 7

natural inherent defences of the plant

Question 8

animal disease control in agriculture

Answer 8

australia = strict quarantine procedures in place → prevent introduction of contaminated animals/plants
- intensive farming
disadvantages: More animals being kept in smaller places
advantages: more efficient production

Question 9

animal diseases in australia

Answer 9

foot and mouth disease
- virus that affects sheep, cattle
- spread through saliva etc
- symptoms: ruptured blisters on feet and mouth

impact on australia:
- Effect on australia if outbreak → livestock industry makes up a large part of the economy → reduce the value of potential livestock exports
- prevention of spread: vaccinations

mad cow disease:
- caused by prion in nervous system
- spread through contaminated soil etc.

impact on australia:
- meat exports cancelled
- prevention of spread: Infected animals are destroyed → prevent the spread of disease

anthrax
- bacterium causing sudden death and bleeding
- prevention: affected farm is quarantined

avian influenza:
- virus - flu like symptoms
- effect on agriculture: infected birds destroyed
- affected farm is quarantined

Question 10

animal immune response

Answer 10

first - innate, physical and chemical barriers to entry

second - innate, inflammatory response and phagocytosis

third - adaptive, specialised B-cells, T-cells and antibodies, response specific to pathogen

Question 11

antigen vs pathogen

Answer 11

antigen : molecule that signals immune response , usually on surface of pathogen which the body recognies as harmful

pathogen: disease causing organism or agent

Question 12

first line of defence

Answer 12

protects against the entry of pathogens into the body and is non-specific such as areas with opening like the mouth, eyes, ears

physical barriers: skin, sticky mucous membrane, cilia
chemical barriers: lysosomes, enzymes, acidity

Question 13

skin

Answer 13

physical barrier
- top layer of dead keratinised cells that prevent pathogens from penetrating
- basal layer = undergoes mitosis to continuously grow new skin cells and maintain the barrier
- microflora present on skin: competes with pathogens for space and nutrients which prevents them from growing

cut or wound: controlled bleeding, blood clotting and scab formation to it can heal underneath

Question 14

mucous membrane

Answer 14

physical barrier
Sticky layers of tissue that line the body where it needs to remain moist like digestive and respirtory tracts that trap pathogens and stop them from progressing any further into the body
- pathogens are trapped in the mucous which is swept away with cilia
- coughing and sneezing expels the mucous

Question 15

what produces mucous

Answer 15

goblet cells

Question 16

cilia

Answer 16

physical barrier
- Tiny hair-like projections on the surface of a cell found on respiratory surfaces eg. bronchial tubes, nose
- Beat and sweep mucous away so it can be removed from the body and moved from lungs to be expelled through coughing

Question 17

sebum

Answer 17

chemical barrier
- water resistant
- oily barrier that is broken down to become acidic

Question 18

sweat

Answer 18

chemical barrier
- secreted by skin and contains enzymes with lysozymes that destroy pathogens

Question 19

lysozymes

Answer 19

enzymes that break down the cell walls of some bacteria

Question 20

cerumen

Answer 20

chemical barrier
- ear wax
- secreted by cells in the ear canal
- Trap and eventually remove pathogens or particles that have entered the ear

Question 21

acids and enzymes

Answer 21

chemical barrier
- exist in secretions from gastric juice, tears, saliva, vaginal excretions

acids:
- Speeds up the chemical breakdown of proteins and carbohydrates
- Vagina: microflora break down cells shed from walls of the vagina and create acidic conditions → inhibits growth of pathogenic bacteria and fungi to prevent thrush
- Creates hostile environment for entering pathogens

enzymes:
- Lysozymes in tears, saliva, sweat, nasal secretions that help kill pathogens
- Dissolve the cell membranes of pathogens

Question 22

microflora

Answer 22

• first line of defence
• diverse mixture of microorganisms that are regularly present on our bodies and necessary for the proper functioning and good health
• mutualistic relationship with humans
  Microflora = gain from host → supply of nutrients, stable environment, constant temperature, protection and transportation

Humans = presence of microflora → difficult for pathogenic microorganisms that could cause disease to establish themselves and multiply in the host

Question 23

second line of defence

Answer 23

If first line of defence was breached body resorts to second line of defence that is non-specific and apart of the innate immune system

Question 24

inflammatory response

Answer 24

A chemical response that helps wound repair and leads to pathogen destruction
1. chemical signal such as histamines is released
2. increasing permeability of blood vessels, leakiness and increasing dilation to increase circulation in the area, phagocytes migrate to the area, Endogenous pyrogens are released
3. phagocytes consume bacteria and cell debris

Question 25

five signs of inflammation

Answer 25

• redness
• pain
• swelling
• heat
• loss of function

Question 26

histamines

Answer 26

released by mast cells trigger vasodilation and increase vascular permeability

Question 27

what are released by mast cells

Answer 27

histamines

Question 28

vasodilation

Answer 28

increase in diameter of blood vessels → increasing the blood flow to the site of infection to increase the amount of fluid and number of white blood cells that can move to the area and destroy pathogens;

Question 29

how does increasing permeability help the immune response

Answer 29

allows certain white blood cells to move from the blood into the tissues to attack the invading pathogens

Question 30

function of inflammation

Answer 30

1. destroy any pathogens present
2. limit pathogen from spreading
3. repair/replace and damaged tissues

Question 31

phagocytes

Answer 31

specialised white blood cells that engulfs and destroys foreign particles, bacteria ad dying cells
- attracted to the site of inflammation due to presence of chemotactic factors
- exit blood vessels and move into tissues to destroy invading pathogens

• neutrophils
• macrophages
• dendritic cells
• natural killer cells

Question 32

mast cell

Answer 32

• releases histamines
• recruits neutrophils and macrophages

Question 33

macrophage

Answer 33

• phagocyte involved in phagocytosis of pathogens
• antigen presenting cells: After the macrophage has destroyed the foreign particle, parts of the antigen are displayed on the surface of the macrophage
• lives up to several months
• migrates from blood vessels into tissues (chemotaxis)
• differentiated from monocytes

Question 34

neutrophils

Answer 34

-phagocyte involved in phagocytosis of pathogens
- short lived
- releases toxins that kill or inhibit bacteria and fungi
- migrates from blood vessels into tissues (chemotaxis)

Question 35

dendritic cells

Answer 35

antigen -presenting cells
- triggers adaptive immune system
- in epithelial cells
- differentiated from monocytes

Question 36

natural killer cells

Answer 36

kills tumour cells and virus-infected cells
-circulates in blood and migrates to tissues (chemotaxis)

Question 37

phagocytosis

Answer 37

is the process by which phagocytes change their shape so they can surround a foreign particle, such as a bacterium, and completely enclose it
- Once the foreign particle is inside the cell, enzymes are released to destroy it

Question 38

process of phagocytosis

Answer 38

1.Phagocyte moves to the bacterium.
2.Phagocyte changes shape so it completely encloses bacterium.
3. Lysosomes contain destructive enzymes.
4.Enzymes are released and destroy bacterium.
5. Harmless particles are released from phagocyte

Question 39

Endogenous pyrogens

Answer 39

released during inflammatory response → chemicals that increase the body temperature → inhibit the growth of pathogens and inactivate some enzymes and toxins made by pathogen, Increases rate of biochemical reactions

Question 40

monocytes

Answer 40

differentiate into phagocytic cells –> dendritic and macrophages
- stored in the spleen and move to infected tissue though blood vessels

Question 41

fever response

Answer 41

slows rate of infection and increases activity of immune cells by increasing temperature
- The body may react to pathogens by altering the hypothalamic set point of body temperature and allowing the tissue to heat up

Question 42

lymphatic system

Answer 42

System of vessels and nodes that return body fluid and proteins back into the blood system and filters cell debris

• plasma seeps out of blood stream into tissues –> interstitial fluid –> taken to lymphatic vessels –> lymph –> lymph is emptied into the bloodstream

Question 43

spleen

Answer 43

Reservoir for blood
Filters and purifies the lymph and blood that passes through it
If damaged → more susceptible to infections

Question 44

major lymph organs

Answer 44

spleen, bone marrow, lymph nodes, thymus, tonsils, adenoid

Question 45

lymph nodes

Answer 45

act as filters as lymph fluid passes through –> Produced additional lymph fluid, lymphocytes, antibodies and memory cells indicate site of infection

Question 46

bone marrow

Answer 46

Produces lymphocytes (white blood cell which are important for the immune response and are capable of producing antibodies)