12.2 Animal And Plant Diseases

Question 1

Ring rot

Answer 1

Bacterial disease of potatoes, tomatoes and aubergines
Caused by gram positive bacterium Clavibacter michiganesis
If a field is infected, cannot be used to grow potatoes again for 2 years

Question 2

TMV

Answer 2

Virus that infects tobacco plants
Damages leaves, flowers and fruits - stunts growth
No cure - can only use resistant crop strains

Question 3

Potato blight

Answer 3

Caused by protocist oomycete
Hyphae penetrates host cells, destroys leaves, tubers and fruit
No cure - can use chemical treatments and resistant strains

Question 4

Black sigatoka

Answer 4

Banana disease caused by fungus Mycosphaerella fijiensis - attacks and destroys leaves
Hyphae penetrates leaves and causes them to turn black
Fungicide can be used to control spread of disease

Question 5

Tuberculosis

Answer 5

Bacterial disease - Mycobacterium tuberculosis and M. bovis
TB damages lung tissue and suppresses the immune system
People with HIV/AIDS are more likely to get TB
Cured with antibiotics and prevented by vaccinations

Question 6

Bacterial meningitis

Answer 6

Bacterial infection of the meninges in the brain - can spread to cause septicaemia
Antibiotics can cure the disease, and vaccines can protect against some forms of meningitis

Question 7

HIV/AIDS

Answer 7

Targets T helper cells in the immune system
Gradually destroys immune system - become open to other infections

Question 8

How does AIDS affect the body?

Answer 8

Retrovirus - RNA is genetic material
Contains reverse transcriptase - transcribes RNA into single strand DNA in the host cell

Question 9

Influenza/flu

Answer 9

Viral infection of the ciliated epithelial cells in the gas exchange system
Kills these cells and leaves them open to secondary infection

Question 10

What causes a flu epidemic or pandemic?

Answer 10

Flu viruses mutate regularly
If there is a major change in the surface of antigens, then there will be a pandemic or epidemic

Question 11

Malaria

Answer 11

Caused by protocista Plasmodium
Vector - Anopheles mosquitoes

Question 12

How does the Plasmodium parasite work?

Answer 12

Has a complex life cycle with two hosts - mosquitoes and people
Reproduce inside female mosquito
Female needs to take blood meals to provide her with protein before she lays her eggs - this is when Plasmodium is passed onto people

Question 13

How does Plasmodium affect the body?

Answer 13

Invades RBCs, liver, and the brain

Question 14

How is the spread of malaria controlled?

Answer 14

No vaccine against it
Destroy anopheles mosquitoes can be destroyed by insecticides and removing stagnant water
Mosquito nets, window and door screens, long sleeved clothing

Question 15

Ring worm

Answer 15

Fungal disease affecting mammals
Causes infectious circular areas of skin
Antifungal creams are used as cures

Question 16

Athlete’s foot

Answer 16

Human fungal disease caused by Tinia Pedia - form of human ring worm that digests the warm, moist skin between the toes
Antifungal creams are an effective cure