B2.2 - How do organisms protect themselves against pathogens

Question 1

Name the 3 types of defence the body has against diseases

Answer 1

Physical
Chemical
Bacterial

Question 2

What is an example of a physical defence mechanism and how it protects the body

Answer 2

Skin in humans, cuticle and cell walls in plants, mucus

Provides a barrier to pathogens

Question 3

What is an example of a Chemical defence mechanism and how it protects the body

Answer 3

Stomach acid, antimicrobial substances, enzymes in tears and saliva

Question 4

What is an example of a Bacterial defence mechanism and how it protects the body

Answer 4

Bacteria on the skin and in the gut

Adapted to living on the body so competes against invading pathogens

Question 5

How does the nose protect us from diseases? Physical defence (2 marks)

Answer 5

nose hair acts as a barrier against pathogens

Nose produces mucus which prevents the pathogens traps the pathogens before they enter the lungs.

Question 6

How does the stomach protect us from diseases? Chemical defence (2 marks)

Answer 6

Stomach acid (Hydrochloric acid) kills pathogens in the stomach.

Question 7

How does the body prevent pathogens from entering cuts on the skin?

Answer 7

Blood clotting prevents the pathogens from entering the cut.

Question 8

What is the function of white blood cells?

Answer 8

To destroy pathogens

Question 9

Give two examples of white blood cells

Answer 9

Phagocytes and lymphocytes

Question 10

When a white blood cell engulfs a pathogen this is called?

Answer 10

phagocytosis

Question 11

What can lymphocytes produce to stop pathogens from making us ill?

Answer 11

antibodies

Question 12

What are antibodies?

Answer 12

Antibodies are molecules that stick to specific pathogens. They disable pathogens

Question 13

How do antibodies disable pathogens?

Answer 13

Pathogens have antigens on their surface. Antibodies with specific shapes bind to the pathogen.

Question 14

What is found on the surface of pathogens?

Answer 14

Antigens

Question 15

Why can you only get chicken pox once?

Answer 15

Your body builds immunity to the pathogen

Question 16

How do we build immunity

Answer 16

The first time we are infected, our white blood cells produce antibodies.

The next time we get infected, some of the white blood cells from before remain and can quickly produce the antibodies faster than last time.
The pathogen is destroyed before it can make us ill.

Question 16

How do we build immunity

Answer 16

The first time we are infected, our white blood cells produce antibodies.

The next time we get infected, some of the white blood cells from before remain and can quickly produce the antibodies faster than last time.
The pathogen is destroyed before it can make us ill.

Greater immune response

Question 17

What is a memory cell?

Answer 17

White blood cells that remain in your bloodstream and produce a quick response if the antigen is encountered again

Question 18

what is a Lymphocyte

Answer 18

White blood cells that attack pathogens by producing antibodies.

Question 19

What is a Phagocyte

Answer 19

White blood cells that engulf harmful microorganisms

Question 20

list 3 ways white blood cells protect us from pathogens

Answer 20

1. produce antibodies
   ( Lymphocyte)
2. Engulf (eat) pathogen
   (Phagocyte)
3. produce antitoxins