Detection of plant diseases

Question 1

What is are the minerals magnesium and nitrates used for and their effects of deficiency?

Answer 1

Magnesium - Color of leaves (chlorophyll) - yellow leaves known as chlorosis

Nitrates - needed for protein synthesis - poor growth

Question 2

What are the signs for plant diseases?

Answer 2

Stunted growth
Spots on leaves
Areas of decay (rot)
Growth
Discoloration
Malformed stems or leaves
Sign of pests

Question 3

What are plant defences?

Answer 3

Chemical defence, physical defence and mechanical defence.

Question 4

Give examples for mechanical, chemical and physical defences.

Answer 4

Physical defence responses to resist invasion of microorganisms.
• Cellulose cell walls.
• Tough waxy cuticle on leaves.
• Layers of dead cells around stems (bark on trees) which fall off.
Chemical plant defence responses.
• Antibacterial chemicals.
• Poisons to deter herbivores.
Mechanical adaptations.
• Thorns and hairs deter animals.
• Leaves which droop or curl when touched.
• Mimicry to trick animals.