Diseases

Question 1

How do bacteria cause disease symptoms?

Answer 1

Usually produce toxins

Question 2

How do fungi cause disease symptoms?

Answer 2

Secrete digestive enzymes that digest living cells, allowing the fungus to spread through tissue

Question 3

How do protoctista cause disease symptoms?

Answer 3

Often by consuming cell material of host

Question 4

How do viruses cause disease symptoms?

Answer 4

Insert genetic material into host’s DNA, taking control of cell metabolism

Question 5

What is a communicable disease?

Answer 5

A disease caused by a pathogen, which can be transmitted to another organism

Question 6

What is a pathogen?

Answer 6

A disease causing organism

Question 7

What is potato blight?

Answer 7

A disease caused by a protoctist, where hyphae penetrate cells, destroying leaves, tubers and fruit

Question 8

What is ring rot?

Answer 8

A disease caused by a bacterium, where vascular tissue in leaves and tubers is destroyed

Question 9

What is TMV?

Answer 9

Tobacco Mosaic Virus, a viral disease which causes mosaic patterns of discolouration on leaves, flowers and fruit

Question 10

What is Black Sigatoka?

Answer 10

A fungal disease, where hyphae penetrate and digest cells in leaves, causing them to turn black in colour

Question 11

What is Malaria?

Answer 11

A disease caused by the plasmodium protoctist, which infects erythrocytes and liver cells, causing fever and fatigue

Question 12

What is TB?

Answer 12

Tuberculosis is a bacterial disease which destroys lung tissue, resulting in coughing, fatigue and chest pain

Question 13

What is HIV/AIDS

Answer 13

Human immunodeficiency disease infects t helper cells thereby inhibiting the immune system and leaving the body very vulnerable to other infections

Question 14

What is athlete’s foot?

Answer 14

A fungal disease where skin on people’s feet is digested, causing cracking and itchiness

Question 15

What is callose?

Answer 15

A polysaccharide that is deposited in plant cell walls, plasmodesmata and sieve plates to prevent pathogens being able to spread to other cells within a plant

Question 16

What chemical defences do plants have to prevent disease?

Answer 16

Insect repellants (e.g. citronella), insecticides, antibacterials (glossypol), antifungals (saponins), anti-oomycetes, general toxins (cyanide compounds)

Question 17

Compare the structures of callose and cellulose

Answer 17

Both (largely) linear, both polysaccharides of ß-glucose, callose has 1,3 glycosidic bonds whereas cellulose has 1,4 glycosidic bonds, cellulose has cross links, callose is helical and has some branching

Question 18

What are cytokines?

Answer 18

Cell-signalling molecules that attract phagocytes to sites of infection

Question 19

What do opsonins do?

Answer 19

Bind to pathogens and mark them for phagocytosis (phagocytes have receptors that bind to opsonins)

Question 20

What are primary defences? What are some examples?

Answer 20

Defences that prevent pathogens from entering the body.

Skin, conjunctiva (membrane covering the eye), mucus, ciliated epithelia, acidic conditions in stomach and vagina

Question 21

What are blood clotting systems for?

Answer 21

Repairing primary defences when they get damaged (particularly the skin)

Question 22

What is inflammation and how does it help?

Answer 22

Inflammation is when mast cells release histamine, causing blood vessels to dilate, causing more plasma to move into the tissue fluid and an increase in temperature. This increased temperature slows the rate of pathogen production and the inflammation is thought to help isolate pathogens.

Question 23

How does phagocytosis work?

Answer 23

A phagocyte engulfs a pathogen and encloses it within a membrane. A lysosome fuses with the phagocyte to form a phagolysosome, and releases digestive enzymes with digest the pathogen and destroy it

Question 24

What is the role of t helper cells?

Answer 24

To release cytokines, which stimulate b cells and other t cells and attract phagocytes to sites of infection

Question 25

What is the role of t killer cells?

Answer 25

Release performs which break down/damage membranes of pathogens

Question 26

What is the role of t memory cells?

Answer 26

Recognise antigens from previous infections (known as immunological memory)

Question 27

What is the role of t regulatory cells?

Answer 27

Prevent autoimmune reponses

Question 28

What is the role of plasma cells?

Answer 28

Produce antibodies

Question 29

What is the role of b effector cells?

Answer 29

Divide to form plasma cell clones

Question 30

What is the role of b memory cells?

Answer 30

Remember specific antigen (enabling rapid secondary immune response)

Question 31

What are antigens?

Answer 31

Molecules on cells (or viruses) that the immune system can use to detect infection

Question 32

What is opsonisation?

Answer 32

When antibodies act as opsonins, speeding up phagocytosis

Question 33

What is agglutination?

Answer 33

When antgen-antibody complexes clump together, making the clump too large to enter cells and meaning several pathogens can be engulfed at once

Question 34

What is neutralisation?

Answer 34

When antibodies bind to toxins, rendering them harmless

Question 35

What are autoimmune diseases?

Answer 35

When the immune system malfunctions and stops recognising self antigens. The body’s own cells are attacked by its own immune system

Question 36

When is an animal immune?

Answer 36

When it can be infected by a pathogen without developing any symptoms of the disease

Question 37

What is the principle of vaccination?

Answer 37

To persuade the body to produce antibodies and memory cells against a particular pathogen without the person contracting the disease