Chapter 10: Diesease And Immunity

Question 1

Describe a pathogen

Answer 1

a disease-causing organism

Question 2

Describe a transmissible disease

Answer 2

a disease in which the pathogen can be passed from one host to another

Question 3

How is pathogen transmitted?

Answer 3

• by direct contact, including through blood and other body fluids
• indirectly, including from contaminated surfaces, food, animals and air

Question 4

Use of Skin in body defense

Answer 4

The skin prevents infection from pathogens. If it is cut or grazed, it immediately begins to heal itself, often by forming a scab.

Question 5

Use of a nose in body defense

Answer 5

The nose has internal hairs, which act as a physical barrier to infection.

Question 6

Use of a mucus in body defense

Answer 6

The mucus is produced by goblet cells and traps bacteria, dust, particles; The cilia beat; And push the mucus away from the lungs towards the throat.

Question 7

Use of stomach acid in body defense

Answer 7

It contains hydrochloric acid, it is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water.

Question 8

Use of white blood cells in body defense

Answer 8

White blood cells attack pathogens.

Question 9

Lymphocytes

Answer 9

They recognise proteins on the surface of pathogens called antigens. Lymphocytes detect that both the proteins and pathogens are foreign and produce
antibodies.

Question 10

Phagocytes

Answer 10

They surround pathogens in the blood, bind to them and engulf them.

Question 11

Describe active immunity

Answer 11

defence against a pathogen by antibody production in the body

Question 12

What do pathogens have

Answer 12

each pathogen has its own antigens, which have specific shapes

Question 13

Describe antibodies

Answer 13

proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes

Question 14

How do antibodies bind to the varying shape of antigens?

Answer 14

specific antibodies have complementary shapes which fit specific antigens

Question 15

How is active immunity gained?

Answer 15

after an infection by a pathogen or by vaccination

Question 16

Process of vaccination

Answer 16

(a) weakened pathogens or their antigens are put into the body
(b) the antigens stimulate an immune response by lymphocytes which produce antibodies
(c) memory cells are produced that give long-term immunity

Question 17

Explain the role of vaccination in controlling the spread of diseases

Answer 17

White blood cells make correct antibodies, so that if in future the real microorganisms get into the blood, the antibody is already or very quickly made by the body. This prevents spread of disease.

Question 18

What is passive immunity?

Answer 18

is a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk

Question 19

importance of breast-feeding for the development of passive immunity in infants

Answer 19

When a mother breast-feeds her baby, the milk contains some of the mother’s white blood cells, which produce antibodies -provide baby with protection against infection at a vulnerable time.

Question 20

Are memory cells developed in passive immunity

Answer 20

Memory cells are not produced

Question 21

Hygienic factors that prevent spread of disease

Answer 21

(a) a clean water supply
(b) hygienic food preparation- all milk should be pasteurised, meat thoroughly cooked and at bottom of fridge.
(c) good personal hygiene- Must wash hands before handling food and after going to toilet
(d) waste disposal- should be stored in dustbins or garbage cans. Then get rid off by burning or burying deep
(e) sewage treatment- If disease bacteria get into water supplies used for drinking, hundreds of people can become infected.

Question 22

Describe cholera

Answer 22

a disease caused by a bacterium which is transmitted in contaminated water

Question 23

What does cholera do?

Answer 23

cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ions from the blood