Lesson 9: Plant disease/ defences

Question 1

What 7 ways can plant diseases be detected?

Answer 1

1.) Stunted growth
2.) Spots on leaves
3.) Areas of decy (rot)
4.) abnormal growths
5.) Malformed stems/ leaves
6.) Discolouration
7.) Presence of pests.

Question 2

Pests aren’t pathogens. So, how do they cause disease in plants?

Answer 2

• Pests carry pathogens!

Question 3

How can you identify the disease in plants after an unknown disease has been detected?

Answer 3

• Reference to gardening manual/ website
• Take infected plant to laboratory to identify the pathogen.
• Use test kits that contain monochlonal antibodies.

Question 4

Give an example of how a plant can be attacked by an insect and what the insect does.

Answer 4

• Alphids attack plants
• Extract nutrients, like sugars, from plant - stunting plant’s growth.

Question 5

Give two ion defficiency diseases that a plant may have and the effects the defficienies have on the plant.

Answer 5

• Nitrate deficiency: stunted growth
• Magnesium defficiency: Chlorosis

Question 6

What are magnesium ions needed for in plants?

Answer 6

• Magnesium ion is a component of chlorophyll.

Question 7

What are nitrate ions used for in plants?

Answer 7

• Needed for protein synthesis (make up amino acids) - proteins are then used for growth!!

Question 8

What 3 types of plant defence responses are there?

Answer 8

1.) Physical responses
2.) Chemical responses
3.) Mechanical responses.

Question 9

How are physical responses of plants useful?

Answer 9

• Physical responses of plants resist the invasion of microogranisms (creates a barrier between microorganisms/ inside plant.)

Question 10

Give 3 physical defence responses in plants.

Answer 10

1.) Cellulcose cell walls (difficult to penetrate.)
2.) Tough waxy cuticle on leaves (difficult to penetrate)
3.) Layers of dead cells around stems (bark on trees) which fall off and grow again (difficult to penetrate.)

Question 11

Give 2 chemical defence responses in plants.

Answer 11

1.) Antibacterial chemicals (kill bacteria. preventing them from attacking the plant.)
2.) Poisons to deter herbivores eating them.

Question 12

Give 3 mechanical defence responses in plants.

Answer 12

1.) Thorns/ hairs to deter animals from eating plants.
2.) Leaves which droop/ curl when touched to scare herbivores.
3.) Mimicry to trick animals

Question 13

Give an example of mimicry in plants; used to deter herbivores

Answer 13

• Plant may have leaves that look like stinging nettles but aren’t really.
• This appearance will scare herbivores away from the plant.