Defences against disease

Question 1

Name physical defences of plants

Answer 1

Bark, waxy cuticle in leaves, thorns and hairs

Question 2

Describe physical defences of plants

Answer 2

poisons to deter herbivores and antibacterial chemicals

Question 3

Name physical barriers to infection in the human body

Answer 3

skin, hair in ears and nose, formation of scabs, mucus and cilia

Question 4

How to mucus and cilia work to prevent disease?

Answer 4

Mucus is a sticky substance which traps pathogens. Cilia are hairlike structures on cells which beat to waft mucus and trapped pathogens out of the airways

Question 5

Name chemical defences to infection in the human body

Answer 5

Stomach acid and lysozymes (enzymes in tears)

Question 6

How does the immune system recognise pathogens in the body?

Answer 6

Using antigens

Question 7

What is an antigen?

Answer 7

protein on the surface of a pathogen, identifying it as an invader

Question 8

What do phagocytes do?

Answer 8

engulf invading pathogens

Question 9

What do lymphocytes do?

Answer 9

recognise pathogens and produce antibodies

Question 10

What is an antibody?

Answer 10

Y-shaped protein produced by a lymphocyte. Antibodies bind to antigens on pathogens, helping to destroy them

Question 11

What is a memory lymphocyte?

Answer 11

a lymphocyte which stays in the blood after an infection and produces antibodies if the same pathogen infects again.

Question 12

What is the primary response?

Answer 12

The first time a pathogen is encountered by the body

Question 13

What is the secondary response?

Answer 13

When a pathogen is encountered which has infected the body before

Question 14

Why is the primary response slow?

Answer 14

Because the correct antibody needs to be made which has a matching shape to the antigen on the pathogen

Question 15

Why is the secondary response fast?

Answer 15

Because memory lymphocytes recognise the antigen on the pathogen and produce antibodies quickly

Question 16

What is inside a vaccination?

Answer 16

Dead or weakened form of the pathogen

Question 17

Why do vaccinations work?

Answer 17

Body will fight the pathogen and produce memory lymphocytes capable of producing the correct antibodies should the pathogen invade again

Question 18

What is herd immunity?

Answer 18

When enough of a population have been immunised against a disease, those not immunised will be less likely to come into contact with the disease so will be protected.

Question 19

What does it mean if someone is immune to a disease?

Answer 19

They have memory lymphocytes capable of producing antibodies to fight the disease. They will not become ill with that disease.

Question 20

What are the advantages of vaccination and immunisation?

Answer 20

Individuals will not become ill with or possibly die from a disease. Herd immunity can stop spread of disease and other people becoming ill. Using a vaccine is cheaper than treating someone with the disease