Infection and response - Plant diseases

Question 1

what are nitrates used for in a plant

Answer 1

to make proteins (protein synthesis) and grow

Question 2

how can you tell a plant has a nitrate defficiency

Answer 2

stunted growth

Question 3

what is magnesium ions used for in a plant

Answer 3

making chlorophyll which is needed for photosynthesis

Question 4

how can you tell a plant has a magnesium deficiency

Answer 4

the plant will have chlorosis, because magnesium is required to make chlorophyll

Question 5

common signs that a plant has a disease

Answer 5

• stunted growth
• abnormal growths e.g - lumps
• spots on the leaves
• malformed stems or leaves
• patches of decay ( rot )
• discolouration

Question 6

how can you find out what disease your plant has

Answer 6

• look up signs on a gardening manual or gardening website
• taking the infected plant to a laboratory where scientists can identify the pathogen
  using testing kits that identify the pathogen using monoclonal antibodies

Question 7

what are aphids

Answer 7

insects that can cause huge damage to plants, feed on the sap) in the phloem. This takes sugars away from plants

Question 8

physical defences plants have

Answer 8

• waxy cuticle to defend against pathogens and make it hard for them to penetrate
• call walls and cellulose provide a barrier to microorganisms and make it hard for them to penetrate
  -dead layers around stems e.g bark around trees to act as a barrier to stop pathogens from entering

Question 9

plants chemical defences

Answer 9

• some can produce antibacterial chemicals which kill bacteria- e.g mint plant, witch hazel
• other plants can produce poisons which can deter herbivores like tobacco plants, foxgloves, deadly nightshade

Question 10

plants mechanical defences

Answer 10

• thorns and hairs to stop animals from touching and eating them
• other plants have leaves which droop or curl when something touches them, so they can knock off insects that try to eat them
• ability to mimic other organisms - passion flower has bright yellow spots on leaves that look like butterfly eggs, this stops other butterflies from laying eggs here
• ice plant family plants look like stones and pebbles which tricks animals into not eating them

Question 11

what causes disease in a plant

Answer 11

a range of viral, bacterial and fungal pathogens as well as by insects such as aphids

Question 12

examples of mimicking responses in plants

Answer 12

• the white dead nettle looks similar to a stinging nettle but it has no sting
• herbivores are less likely to eat the white dead nettle as they can easily mistake it for a stinging nettle