plant and disease & defences Flashcards

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1
Q

what type of pathogens can cause disease

A
  • bacteria
  • virus
  • fungi
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2
Q

what organisms can cause disease

A
  • worms
  • insects
    (indirectly)
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3
Q

what are signs of plant disease

A
  • stunted growth
  • spots on leaves
  • areas of decay
  • abnormal growths
  • malformed leaves
  • malformed stems
  • discolouration of leaves
  • presence of pests
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4
Q

what is the fungi disease for plants

A

rose black spot

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5
Q

what pathogen causes rose black spot

A

fungi

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6
Q

give some symptoms of rose black spot

A
  • purple or black spots on leaves
  • leaves turn yellow and drop early
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7
Q

explain why the symptoms of rose black spot are bad

A
  • reduces area available for photosynthesis
  • less energy
  • less flowering
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8
Q

how is rose black spot transmitted

A

spores of the fungus spread by the wind or in rain

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9
Q

how is rose black spot treated and prevented

A
  • chemical fungicide
  • removing and burning affected leaves and stems
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10
Q

why is it a good idea to burn rose black spot infected leaves

A

the spores saty dormant over winter on dead leaves and on hte stems of rose plants so can infect again in summer

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11
Q

what is the viral disease for plants

A

tobacco mosaic virus

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12
Q

what pathogen causes the tobacco mosaic virus

A

virus

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13
Q

what plants does the tobacco mosaic virus affect

A

tomato and tobacco

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14
Q

what are the symtpoms of the tobacco mosaic virus (TMV)

A
  • small patched of light green, brown and yellow appear on the leaves
  • unusual growth ~ leaves are smaller than usual
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15
Q

why are the symptoms for TMV bad

A
  • less area for photosynthesis
  • reduced yield
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16
Q

how is TMV transmitted

A

the disease is spread by contact from plant to plant: direct and indirect (vectors)

17
Q

how can TMV be treated and prevented

A
  • there is no treatment but farmers grow TMV resistant strains of crop
  • good field hygiene and pest control stop the spred
  • brun any leaves suspected of being infected
18
Q

other than viruses, bacteria and fungi; give another way plants can be damaged

A

by pests = aphids

19
Q

what is the name given to the pests which bring damage to plants

A

aphids

20
Q

how can aphids damage plants

A
  • destroy plants directly by eating them
  • act as vectors of disease
21
Q

describe how aphids are specialised to damage and weaken plants

A
  • have sharp mouthparts that penetrate the phloem vessels to feed on the sap
  • attack in huge numbers, depriving the plant of products of photosynthesis
22
Q

how can aphids be removed from an evironment to prevent plant damage

A
  • using chemical pesticides
  • using biological pest control: releasing aphid-eating insects to control the aphid population
23
Q

give an insect which can control the aphid population by eating them

A

lady bugs

24
Q

give another plant pest other than aphids which damage plants

A

nematode worms

25
Q

how do nematode worms damage plants

A

feed in or on plant roots = damage and cannot absorb water and mineral ions effectively = fails to grow

26
Q

give all the ways plants can suffer from disease

A
  • viruses
  • bacteria
  • fungi
  • pests = aphids & worms
  • mineral deficiency (non-communicable diease)
27
Q

what is the plant version of a non-comunicable disease

A

mineral deficiencies

28
Q

why do plants need nitrate ions

A
  • they convert sugars made in photosynthesis into amino acids
  • amino acids are needed to make proteins
  • proteins are used for growth
  • = growth stunted & crop not produced efficiently
29
Q

why do plants need magnesium ions

A
  • magnesium ions make chlorophyll
  • chlorophyll needed to absorb light in photosynthesis
  • leaves = yellow
30
Q

what is the term used for when leaves yellow due to lack of magnesium ions

A

chlorosis

31
Q

what are the two most important ions to a plant

A
  • nitrate
  • magnesium