Plant Diseases

Question 1

What are communicable diseases

Answer 1

Diseases that can be spread either of the same species or sometimes between different species.

Question 2

What are communicable diseases spread by

Answer 2

Pathogens

Question 3

What are pathogens

Answer 3

Microorganisms that can cause disease

Question 4

What is the host

Answer 4

The organism that the pathogen infects

Question 5

What are the 4 main categories of pathogens

Answer 5

Bacteria, viruses, fungi and protoctista

Question 6

What are bacteria and what are features of them

Answer 6

They are prokaryotes and in bacteria, the genetic material is not found in a membrane-bound nucleus and instead the bacterial chromosome and plasmids are found in the cytoplasm.

Question 7

What are toxins

Answer 7

chemicals which damage host cells and tissues, leading to the symptoms of the disease. They can break down cell membranes or inactivate enzymes or interfere with the hosts genetic material

Question 8

What can some bacteria do when they enter the host cells

Answer 8

Prevent the host cells from functioning normally

Question 9

What are viruses

Answer 9

They are non-living, that have no cellular structure at all and consist of genetic material (either DNA or RNA), which is wrapped in a protein structure called a capsid.

Question 10

What happens when bacteria enter the body

Answer 10

Pathogenic bacteria release toxins

Question 11

What allows viruses to attach to host cells

Answer 11

Attachment proteins

Question 12

What is a feature of viruses

Answer 12

They can’t reproduce outside of a host cell.

Question 13

how do viruses reproduce

Answer 13

They attach to the host cell, and then pass through the cell membrane, it then inserts its genetic material into the host cell. The Virus particles then leave the host cell and can go on to infect new host cells and continue reproducing.

Question 14

What do viruses do

Answer 14

They prevent a host cell from functioning normally. And in many cases can lead to the death of the host cell.

Question 15

What are fungi

Answer 15

They are eukaryotic organisms that are unicellular or multicellular

Question 16

How do fungi obtain nutrients

Answer 16

By releasing enzymes and digesting the material around them. The products of digestion are then absorbed back into the fungal cells. This can cause damage to host cells and tissues.

Question 17

What happens when fungi reproduce

Answer 17

They can spread a large number of spores so fungal diseases can spread very widely.

Question 18

Where are pathogenic fungi found

Answer 18

On living organisms where they cause disease

Question 19

What can protoctista act as

Answer 19

pathogenic parasites in humans

Question 20

What are protoctista

Answer 20

Eukaryotic organisms

Question 21

how do protoctista affect cells

Answer 21

They are parasitic and they use host organisms. And in order to transfer them to their cells they made need a vector. They then digest and use the cell contents to reproduce.

Question 22

How can fungi affect plants

Answer 22

They can stop the leaves from photosynthesising quickly killing the plants.

Question 23

what are bacteriophages

Answer 23

Viruses that take over the bacterial cells and use them to replicate destroying the bacteria at the same time.

Question 24

What are the two different types of bacteria

Answer 24

Gram positive and negative bacteria, where after staining gram positive appears blue-purple under the microscope and negative appears red.

Question 25

What can fungi also produce

Answer 25

toxins

Question 26

What is the plant disease that is caused by bacteria

Answer 26

Ring rot disease

Question 27

What are the symptoms of ring rot disease

Answer 27

the bacteria infect the vascular tissue preventing the transport of water, causing the plant to wilt and die. It then spreads to the potato tubers, where the vascular tissue is arranged in a ring producing a black ring of rot.

Question 28

What is the viral disease in plants

Answer 28

Tobacco mosaic disease

Question 29

What are the symptoms of tobacco mosaic disease

Answer 29

it causes a distinct yellowing of the leaves producing a mosaic pattern

Question 30

What is the protoctista disease in plants

Answer 30

Potato blight

Question 31

What are the symptoms of potato blight

Answer 31

Small, dark brown marks on the leaves which quickly increase in size and number They destroy potato and tomato crops leaving them completely inedible.

Question 32

What is the fungal disease in plants

Answer 32

Black Sigatoka

Question 33

What are the symptoms of the fungal disease in plants

Answer 33

it spread through the leaves in the plant reducing its ability to photosynthesises. The lack of photosynthesis causes parts of the leaf to die to producing black streaks Eventually the whole lead dies.

Question 34

How are potato tubers transmitted

Answer 34

An infected tuber can lead to the growth of infected new plants Contaminated soil and equipment

Question 35

How is the tobacco mosaic disease transmitted

Answer 35

leaf-to-leaf contact between plants Humans touching different

Question 36

How is late blight transmitted

Answer 36

Spores are carried by wind from plant to plant

Question 37

how is black Sigatoka transmitted

Answer 37

Leaf to leaf contact Spread of spores by humans or within infected plant matter

Question 38

What are passive defence

Answer 38

That are always present in the plant

Question 39

What are examples of passive defence mechanisms

Answer 39

Physical barriers that prevent pathogens from entering Some are chemicals that reduce or prevent the growth of pathogens

Question 40

What are active defense mechanics

Answer 40

They are mechanisms in plants are activated when pathogens invade

Question 41

What are examples of passive defense mechanisms (1)

Answer 41

Waxy cuticle Cellulose cell wall Closed stomata Bark Casparian strip

Question 42

What does the waxy cuticle do

Answer 42

The only way that viruses and bacteria can penetrate the waxy cuticle of a leaf is if there is a wound on the leaf surface or stem. Wounds are commonly caused by grazing herbivores.

Question 43

What does the casparian strip do

Answer 43

Some fungi species can invade a plant all the way to the endodermis but they are unable to push past the Casparian strip.

Question 44

Examples of passive chemical defences

Answer 44

Toxic Compounds Sticky resin found in the bark Compounds that encourage the growth of competing microorganisms Enzyme inhibitors

Question 45

What do microorganisms

Answer 45

Such as yeast found on the leaf surface are completely harmless to plants. They are strong competitors against harmful pathogens.

Question 46

What is hypersensitivity

Answer 46

The rapid death of tissue surrounding the infection site, depriving the pathogens of host tissue, nutrients and energy.

Question 47

What are reinforce cell walls

Answer 47

The invasion of pathogens stimulates the release of compounds callose and lignin. These molecules are deposited between the cell surface membrane and cell wall. It forms a matrix shape and antimicrobial compounds that kill the pathogens can be deposited in this shape.

Question 48

What can callose be deposited

Answer 48

in the plasmosdesmata reducing the size of channels that connect neighbouring plant cells. it can also be deposited in the sieve pores preventing phloem sap from being transported.