Biology - Infection and response 2

Biology - Infection and response 2

1. DEFENCE IN PLANTS

   • superficial layer
     • physical barrier against pathogens
   • 1st line of defence
     • happens when detect presence of foreign invader
       • alert surrounding cells
         • build up cell wall for protection
         • release molecules harmful to invading pathogen
     • intact and impenetrable
       • composed of bark + waxy cuticle
       • compromised by weather
   • 2nd line of defence
     • hypersensitive response, defence mechanism
       • causes cells + tissue around infection to die to prevent spread of pathogen
         • seal off infected areas
   • roots release chemicals attract bacteria to fight infection
     • close stomata
   • produce antimicrobial chemicals + proteins + enzymes

2. DEFICIENCY IN PLANTS

   • nitrate deficiency
     • needed to build protein + growth
     • stunted growth, leaves yellow
   • magnesium deficiency
     • causes chlorosis
     • needed for photosynthesis
     • leaves turn yellow
     • Mg needed for green pigment
       • cannot trap light effectively

3. PLANT DISEASE

   • suffer from..
     • worms
     • bacteria
     • viruses
     • fungi
     • insects
   • FUNGAL DISEASE
     • rose black spot
       • affects leaves, reduces photosynthesis
         • destroys crops
           • barley,wheat
         • burn leaves/stems/ antifungal spray
   • VIRAL DISEASE
     • tobacco mosaic virus
       • discoloured leaves
         • reduces photosynthesis ability
         • stays in soil
         • remove decaying leaves from plant and surrounding soil, burn
   • INSECTS
     • aphids
       • live off plant sap
     • decrease growth + damage leaves
       • cannot photosynthesis
         • spray/use ladybugs to eat them
   • gardening manual/website
     • taking infected plants to a laboratory