plant diseases and defences

• plants need mineral ions from the soil
• nitrates are used to make proteins and for growth
• magnesium ions are needed for making chlorophyll, which is needed for photosynthesis
• plants without enough magnesium suffer from chlorosis and have yellow leaves
• plants have physical, chemical and mechanical defences
• most plant leaves and stems have a waxy cuticles, which provide a barrier to pathogen
• plants have layers of dead cells on their stems to protect from pathogens
• some plants can produce antibacterial chemicals which kill bacteria
• some plants produce poisons which can prevent herbivores from eating them
• some plants have thorns and hairs which stop animals from touching and eating them
• some plants can mimic other organisms to prevent from being eaten
• some plants have leaves that droop or curl when something touches them to prevent them from being eaten