Topic 3 Plant diseases And defences + Flashcards
Where do plants get mineral ions from
The soil
What happens if a plant doesn’t get enough mineral ions
Will suffer deficiency symptoms
What are nitrates need for in plants
Nitrates are needed to make proteins and therefore growth.
Lack of nitrates causes sounded growth
What are magnesium ions needed for
Making chlorophyll which is needed for photosynthesis
What will plants suffer from if they don’t have enough magnesium ions
Suffer from chlorosis and have yellow leaves
What can plants be infected by
Viral, bacterial and fungal pathogens
What are aphids
Insect. That cause huge damage to planys
What’s are the signs of disease in plants
Stunted growth
Abnormal growths
Spots in the leaves
Malformed stems or leaves
Patches of decay
Discolaration
How would you know if a plant is infested by pests
Should be able to see them on the plant
How can plants diseases be identified
Looking at the signs in a gardening manual or on a gardening website
Taking the infected plant to elaborate on it we are scientists can identify the pathogen
Using testing kits that identify the pathogen using monoclonal antibodies
Physical defences in plants
Most leaves and stems have a waxy cuticle which provides a barrier to stop pathogens entering
Plant cells themselves are surrounded by cell walls made from cellulose which form a barrier against pathogens that make it past the waxy cuticle
Plants have layers of dead cells around their stems for example the outer part of the bark on trees act as a barrier to stop pathogens entering
Chemical defences in plants
Some can produce antibacterial chemicals which kill bacteria e.g. the mint plant and Witchhazel
All the plants produce poisons which kind of herbivores e.g. tobacco plants, foxgloves and deadly nightshade
Mechanical defences in plants
Some plants have adapted to have thorns and hairs to stop animals from touching and eating them
Other plants have leaves that droop or Curl when something touches them this means that they could prevent themselves from being eaten by knocking insects off and moving away
 some plants cleverly mimic other organisms e.g. the passion flower has bright yellow spots on its leaves which look like butterfly eggs this stops all the butterflies laying their eggs there
Several species of plant in the ice plant family in southern Africa look like stones and pebbles this tricks other organisms into not eating them
