Natural Disease Defenses

Question 1

What physical defences do plants have?

Answer 1

• Bark (lignin)
• Waxy cuticle
• Thorns, spines and hairs
• Shrivelling/folding leaves
• Cellulose cell walls
• Mimicry

Question 2

What chemical defences do plants have?

Answer 2

• Releasing chemicals/hormones signalling other plants to defend themselves
• Histamine
• Toxic chemicals
• releasing hormones that attract predators to pests
• Antibacterial molecules

Question 3

What are human first lines of defence?

Answer 3

Skin
Scabs
Nose hair and mucus
Cilia cells
Eyelashes/tears
Stomach acid

Question 4

What does a non specific defence system mean?

Answer 4

It aims to block/destroy ALL microorganisms

Question 5

How does skin prevent disease?

Answer 5

• Barrier between inside and outside
• Shedding skin
• Sebaceous glands produce anti microbial oils

Question 6

How are scabs formed and how do they prevent disease?

Answer 6

• platelets make fibrin, pulling edges together
• mesh forms trapping RBCs, forming a clot
• dries into a scab
• stops pathogens entering body

Question 7

How do nose hairs and mucus prevent disease?

Answer 7

• nose hair traps larger particles
• mucus traps pathogens

Question 8

How do cilia cells prevent disease?

Answer 8

• hair-like projections waft mucus away
• found in lungs
• goblet cells between them for mucus production

Question 9

How do tears prevent disease?

Answer 9

• high salt concentration dries up pathogens
• lyzosomes break down pathogens
• washes out pathogens

Question 10

How do eyelashes prevent disease?

Answer 10

They trap dirt and pathogens

Question 11

How does stomach acid prevent disease?

Answer 11

• low pH (2) HCl destroys pathogen cell walls, killing them
• stomach lining prevents damage to body

Question 12

What are the 2 main types of WBCs?

Answer 12

Phagocytes and lymphocytes

Question 13

Describe the process of phagocytosis

Answer 13

• phagocytes leave blood through capillary walls and enter tissue that is being attacked
• cell membrane and cytoplasm of phagocyte surround the pathogen
• pathogen is engulfed by phagocytosis
• pathogen is digested by lytic enzymes, useful substances are absorbed and waste is released by exocytosis
• phagocyte continues to engulf more pathogens

Question 14

Define antigens

Answer 14

A substance capable of stimulating an immune response.
Often on the surface of a pathogen but can also be a toxin or chemical

Question 15

Define antibodies

Answer 15

A protective protein produced by immune system in response to presence of antigens
Antibodies recognise and latch onto antigens in order to remove them from body

Question 16

How do lymphocytes destroy pathogens?

Answer 16

• they have antibodies on their surface which vond to specific antigens on surface of pathogens
• when the antigen is detected, vast amounts of copies of antibodies are produced
• antibodies lock onto matching antigens allowing pathogens to be destroyed

Question 17

What adaptations do phagocytes have for their purpose?

Answer 17

Lots of mitochondria for energy for phagocytosis

Lots of ribosomes for lytic enzymes

Question 18

What adaptations do lymphocytes have for their purpose?

Answer 18

Lots of ribosomes for antibody production