Paper 1: Topic 3 Infection & response - Plant disease and defence (IV form) Flashcards Preview

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Flashcards in Paper 1: Topic 3 Infection & response - Plant disease and defence (IV form) Deck (30)
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1

List 3 mineral ions that plants need to maintain healthy growth

Potassium ions

Magnesium ions

Nitrate ions

2

Explain why plants need potassium ions

To produce some enzymes

To produce fruits and flowers

3

Explain why plants need nitrate ions

To produce amino acids to make new proteins

To produce nucleotides to make DNA

4

Explain why plants needs magnesium ions

To produce chlorophyll to allow the plant to photosynthesise

5

Describe and explain the signs of a lack of magnesium ions in plants

Description:

Yellowing of the leaves

Chlorosis occurs

Explanation:

Due to a lack of chlorophyll production the leaves do not have a green colour

6

Describe the signs of a lack of potassium ions in plants

Lack of fruits and flowers

Stunted growth

7

Describe and explain the signs of a lack of nitrate ions in plants

Description:

Stunted growth

 

Explanation:

Due to a lack of proteins for growth and repair of tissues and organs

8

State 3 types of pathogens that can cause diseases in plants

Fungi

Bacteria

Viruses

9

Define the term pathogen

A micro-organism that causes disease

10

State reasons how a plant may be infested

Insect infestation

Aphid infestation

11

State 7 general signs of disease in a plant

  1. Stunted growth
  2. Spots on leaves
  3. Patches of decay (called rot)
  4. Abnormal growths e.g. calluses
  5. Malformed stems and leaves
  6. Discolouration of stems and leaves
  7. Presence of pests

12

State 3 methods a gardener can use to identify a disease in his their plant(s)

  1. Consult a gardening manual or gardening website
  2. Take the infected plant to a specialised laboratory for testing
  3. Use a testing kit that uses monoclonal antibodies to detect the presence of a specific antigen

13

State the 3 types of defence a plant has

  1. Chemical defence
  2. Physical defence
  3. Mechanical defence

14

State 3 examples of physical defence mechanisms in plants

  1. Tough waxy cuticle 
  2. Cellulose cell walls 
  3. Layers of dead cells around their stems e.g. bark

 

HINT: do not say these defences prevents PREADTORS eating them herbivores do not hunt plants :)

15

State 2 examples of chemical defence mechanisms in plants

Production of antibacterial chemicals e.g. mint plant, witch hazel plant

Production of poisons e.g. tobacco plants, foxgloves and deadly nightshade plants

16

State 3 examples of mechanical defence mechanisms by plants

  1. Thorns and hairs 
  2. Drooping or curling their leaves when touched 
  3. Mimicry 

 

HINT: do not say these defences prevent PREADTORS eating them herbivores do not hunt plants :)

17

What type of defence mechanism does an ice plant use?

Mechanical defence – using mimicry the ice plants resemble stones and rocks and hence avoid being eaten by herbivores HINT: do not say these defences prevents PREADTORS eating them herbivores do not hunt plants 

18

Explain how thorns and hairs act as a form of plant defence

Prevent herbivores touching and eating them e.g. cacti, rose bush

 

Form of mechanical defence

19

Explain how drooping or curling their leaves when touched is a defence mechanism in plants

This is used to knock insects off their leaves to prevent the inset eating the leaves e.g. mimosa plant

 

Form of mechanical defence

20

Exalpain how plant mimicry is a form of plant defence

The plant mimics certain characteristics e.g. passion flower has yellow spots on its leaves which look like butterfly eggs. Butterflies then avoid laying eggs on those leaves as they think there will be competition between the caterpillars for food!

This is a form of mechanical defence 

HINT: do not say these defences prevent PREADTORS eating them herbivores do not hunt plants :)

21

Explain how chemical defence mechanisms used in plants

Production of antibacterial chemicals kill any bacteria that penetrate the waxy cuticle and cell walls

Production of poisons deter herbivores from eating them e.g. tobacco plants, foxgloves and deadly nightshade plants

22

Explain how plants use physical defnece mechanisms to protect themselves

Tough waxy cuticle – forms a barrier to prevent the entry of pathogens

Cellulose cell walls – surround every plant cell to form a physical barrier to any pathogen that may have passed through the waxy cuticle

Layers of dead cells around their stems e.g. bark – to form a physical barrier to prevent pathogens entering the plant

23

Name a plant disease caused by a virus

Tobaco Mosaic 

24

Describe 2 symptoms of Tobacco Mosaic disease

  • Discoloured leaves
  • Stunted growth

25

Explain why plants with tobacco mosaic virus often have stunted growth

  • The discolouration of the leaves cuases there to be less chloroplhyll in the leaves
  • This means the plant photosynthesise less
  • This means they produce less glucose
  • So there is less energy for the production of new cells and the production of new proteins
  • So there is less growth

26

Name a plant disease caused by a fungus

Rose black spot

27

Describe the symptoms of rose black spot disease

  • Black or purple spots on the leaves
  • Leaves turn yellow
  • Leaves fall of the plant early (called 'early drop')

28

Explain the lack of growth that is often seen in roses with black spot disease

The yellowing of the leaves causes there to be less chloroplhyll in the leaves

This means the plant photosynthesise less

This means they produce less glucose

So there is less energy for the production of new cells and the production of new proteins

So there is less growth

This gets worse as leaves fall off the plant

29

Describe how rose black spot disease is spread

  • The fungus can spread through water
  • The fungus can spread through the air

30

Describe 3 actions gardeners can take to treat rose black spot disease

  • Gardeners can apply fungicides to infected plants
  • They should also strip off any affected leaves from the plant 
  • The infected leaves must then be dedtoyed to prevent further spread of the fungus

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