Defence

Question 1

What are the four non specific defence systems?
Describe each one

Answer 1

Nose: hairs and mucus trap pathogens

Trachea: mucus traps pathogens, ciliated cells waft mucus to the throat where it is swallowed

Skin: acts as a barrier, forms scabs, anti microbial secretions

Stomach: contains hydrochloric acid which destroys any pathogens in food/drink/mucus

Question 2

What three ways do white blood cells fight pathogens? Describe each one

Answer 2

Phagocytosis: (phagocytes) ingest/digest pathogens

Producing antitoxins: neutralise toxins produced by bacteria

Producing antibodies: specific antibodies group together antigens, immobilising the pathogen

Question 3

What are the two forms of chemical defence in plants? Give a description and named example for each

Answer 3

Antibacterial chemicals ~ protect against invading pathogens, prevent many bacterial infections. Mint, witch hazel

Poisons ~ deter herbivores. Foxgloves, deadly nightshade, yew

Question 4

Describe and give an example for cell walls as a plant defence

Answer 4

Physical defence
Strengthen plant cell, resist invasion by microorganisms
All plants

Question 5

Describe and give an example for waxy cuticles as a plant defence

Answer 5

Physical
tough barrier to entry of pathogens
Cacti

Question 6

Describe and give an example for layers of dead cells surrounding the stem eg tree bark as a plant defence

Answer 6

Physical
Forms a protective layer which is hard for pathogens to penetrate
All trees

Question 7

Describe and give an example for leaf fall as a plant defence

Answer 7

Physical
Any pathogen infected leaves fall off the tree
Deciduous trees

Question 8

Describe and give an example for thorns as a plant defence

Answer 8

Physical
Unpleasant/painful for large herbivores to eat them
Brambles, cacti

Question 9

Describe and give an example for hairs as a plant defence

Answer 9

Physical
Deter insects/ larger animals from feeding or laying eggs on them.
Some are poisonous
Nettles

Question 10

Describe and give an example for drooping/curling leaves as a plant defence

Answer 10

Physical
Collapse suddenly, dislodging insects and frightening larger animals
Mimosa pudica

Question 11

Describe mimicry as a plant defence

Answer 11

Physical

mimic unhealthy plants + tricks animals into not eating them, some mimic butterfly eggs on the surface so that real butterflies don’t lay eggs on them to avoid competition with other caterpillars