plant defence and deficiencies

• what type of defences do plants have?

  physical, chemical and mechnical
• cellulose cell wall protects the plant by...


  providing strength and rigidity to the plant and enables plant to maintain shape
• thick waxy cuticle protects the plant by...

  reducing water loss from the leaf by being waterproof, also a protective layer than allows light in
• leaf fall protects the plant by...


  getting rid of leaves unable to do their job and allowing new leaves to grow
• layers of dead cells around the stem (bark) protects the plant by...

  preventing infection by not allowing pathogens to pass through
• thorns and hairs protects the plant by...

  acting as protection from damage from pests and diseases from pathogens as well as to defend itself from predators
• the curling of leaves protects the plant by...

  discouraging predators to eat it or dislodge insects on the leaves
• mimicry protects the plant by...

  disguising the plant in order to camouflage or imitate other organisms
• antibacterial chemicals protects the plant by...

  acting as a defence mechanism against predators that can attack/kill threatening bacteria or warn insects
• poisons protects the plant by...

  disrupting the nervous system of predators and harming them
• typical symptoms of plant disease include...

  - areas of decay (rot)

  - unusual growths

  - malformed stems or leaves

  - discolouration

  - the presence of pests
• aphid insects


  insects that have sharp, needle like mouthparts called a stylet, which they use to suck out liquid from the vascular system of the plant. They are most likely to target the phloem, which ingest sugars, nitrogen compounds and other nutrients
• pathogen


  a microorganism which spreads disease(s) to its host
• symptoms of Tobacco Mosaic Virus (TMV) are...

  - light green/white on leaves

  - stinging leaves

  - stunt in growth

  - decay
• symptoms of Rose Black Spot are...

  feathery, edged black spots on lower leaves that become larger blotches that turn yellow and fall off the plant
• symptoms of Crown Galls are...

  - swelling of plant stem and/or roots

  - hardening and enlargement of galls

  - affected growth
• plants need...

  mineral ions from the soil
• calcium deficiency in plants is spotted when...

  new leaves are misshapen or stunted while existing ones remain green
• plants need calcium because...

  it helps with structural roles in the cell wall and membranes and the upholding of physical barriers against pathogens
• iron deficiency in plants is spotted when...

  young leaves are yellow/white with green veins
• plants need iron because...

  it is involved in the synthesis of chlorophyll and in other enzymatic and metabolic processes without which plants cannot carry out their lifecycle
• nitrogen deficiency in plants is spotted when...

  upper leaves are light green while lower leaves are yellow and bottom or older leaves are yellow and shrivelled
• plants need nitrogen for...

  photosynthesis as it is a major component of chlorophyll
• potassium deficiency in plants is spotted when...

  dead or yellow patches develop on leaves
• plants need potassium because...

  it helps regulate the opening and closing of the stomata, which regulates the exchange of water vapor, oxygen and carbon dioxide
• carbon dioxide deficiency in plants is spotted when...

  there are white deposits visible on leaves and growth is stunted
• plants need carbon dioxide because...

  some of the carbon is used for plant growth, and some of it is used in respiration, where the plant breaks down sugars to get energy
• manganese deficiency in plants is spotted when...

  yellow spots and/or elongated holes between the veins appear
• plants need manganese because...

  it is an important micronutrient for plant growth and development and sustains metabolic roles within different plant cell compartments
• phosphate deficiency in plants is spotted when...

  leaves appear darker than normal and there's a loss of leaves
• plants need phosphate because...

  it is essential for growth, energy production and the making of important molecules such as DNA
• Magnesium deficiency in plants is spotted when...

  lower leaves turn yellow from the outside going in while veins remain green
• plants need magnesium because...

  magnesium is the central core of the chlorophyll, which is needed for photosynthesis