3 3 plant disease

Symptoms that indicate disease in plants might include:

True. Monoclonal antibody kits can be designed to aid the identification of plant diseases. Plant disease can also be identified using reference manuals or websites, or by laboratory testing.

Tobacco mosaic virus is an example of a viral disease that affects plants.

Black spot disease is caused by a fungal pathogen.

False. The sugary substance is found in the phloem of plants, whereas the xylem contains water and mineral ions.

Aphids act as a plant disease vector when they transfer pathogens between plants as they feed.

Magnesium is required for chlorophyll production and chlorophyll is required for photosynthesis. If there is a lack of magnesium then there will be a lack of chlorophyll and this will mean photosynthesis will not happen as quickly resulting in stunted growth.

Chlorosis is the yellowing of leaves that occurs when chlorophyll is lacking as a result of low magnesium levels.

Nitrates are required by plants to build amino acids and therefore proteins.

Physical defences are physical features of a plant that prevent invasion of microorganisms e.g.

True. Bark is tough and so provides a barrier to pathogens and other threats.

False. A thick waxy cuticle is a physical defence designed to deter microorganisms rather than herbivores.

Chemical defence responses include:

True. Defence responses are features that increase survival chances; this is the definition of an adaptation.

Plants use mimicry to put off animals that may otherwise eat them, e.g. plants may droop to mimic diseased plants or resemble large insects to scare away threats.

A plant might protect itself with