T3 plant disease

Question 1

how do aphids cause damage to plants

Answer 1

use their sharp mouthparts to extract sap from the plant phloem, weakening the plant

they are also vectors who can transfer pathogens from diseased plants to healthy plants

Question 2

how can we reduce the number of aphids

Answer 2

chemical pesticides

biological pest control - using ladybirds

Question 3

why do plants need a good supply of nitrate ions

Answer 3

required to convert sugars into proteins which are required for the plant to grow

as a result, the growth of the plant will be stunted if there is not an adequate supply of nitrates

Question 4

why do plants need a good supply of magnesium ions

Answer 4

required to synthesise chlorophyll, which absorbs light energy during photosynthesis

as a result, the leaves cannoT photosynthesise properly and they turn yellow (chlorosis)

Question 5

what are the symptoms of disease in plants

Answer 5

stunted growth (lack of nitrate ions)
spotted leaves 
decay/rotting
growths
malformation of stems/leaves
discolouration
presence of pests

Question 6

what are 3 ways in which plant disease can be identified

Answer 6

reference to gardening website or manual

laboratory testing

monoclonal antibody test kits

Question 7

give examples of physical defence responses used by plants

Answer 7

cellulose cell walls

tough waxy cuticle on leaves

outside later on stems/bark on trees

leaf fall

Question 8

give examples of chemical defence responses used by plants

Answer 8

antibacterial chemicals

poisons

Question 9

give examples of mechanical defence responses used by plants

Answer 9

thorns and hairs to deter animals

leaves that droop/curl on contact

mimicry to trick animals