Give three symptoms that may indicate disease in plants. (Higher Tier Only)
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Give three symptoms that may indicate disease in plants. (Higher Tier Only)
Symptoms that indicate disease in plants might include:
stunted growth
spots on leaves
areas of decay (rot)
growths
malformed stems or leaves
discolouration
the presence of pests
True or False?
Monoclonal antibodies can be used in the identification of plant diseases. (Higher Tier Only)
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.
Give one example of a viral disease in plants.
Tobacco mosaic virus is an example of a viral disease that affects plants.
What type of pathogen causes black spot disease in plants?
Black spot disease is caused by a fungal pathogen.
True or False?
Aphids feed off the sugary substance found in the xylem of plant stems.
False.
The sugary substance is found in the phloem of plants, whereas the xylem contains water and mineral ions.
How can aphids can act as a vector for plant disease?
Aphids act as a plant disease vector when they transfer pathogens between plants as they feed.
Why does a magnesium deficiency result in stunted growth of plants?
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.
Define the term chlorosis.
Chlorosis is the yellowing of leaves that occurs when chlorophyll is lacking as a result of low magnesium levels.
Which mineral ion is required in the production of amino acids and proteins?
Nitrates are required by plants to build amino acids and therefore proteins.
Give examples of physical defences against disease in plants.
Physical defences are physical features of a plant that prevent invasion of microorganisms e.g.
cellulose cell walls
a tough waxy cuticle on leaves
dead cells that form a layer around the outside of stems
True or False?
Bark provides a physical defence to protect trees from pathogens.
True.
Bark is tough and so provides a barrier to pathogens and other threats.
True or False?
A tough waxy cuticle acts as a chemical defence to deter herbivores.
False.
A thick waxy cuticle is a physical defence designed to deter microorganisms rather than herbivores.
What is an example of a chemical defence response in plants?
Chemical defence responses include:
Antibacterial chemicals
Poisons to deter herbivores
True or False?
Defence responses are examples of plant adaptations.
True.
Defence responses are features that increase survival chances; this is the definition of an adaptation.
How does mimicry function as a mechanical defence in plants?
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.
How might a plant protect itself from herbivores?
A plant might protect itself with
physical defences, e.g. cellulose cell walls, tough waxy cuticle or a layer of dead cells around stem
chemical defences, e.g. antibacterial chemicals or poisons
mechanical defences, e.g. thorns and hairs, leaves which droop or curl when touched or mimicry