C3.2 Defence against disease

Question 1

pathogen

Answer 1

any microorganism that causes disease in another organism

Question 2

disease

Answer 2

illness or disorder of the body or mind that leads to poor health

Question 3

virus

Answer 3

pathogenic, can only exist by living inside the living cell of another organism

Question 4

communicable diseases

Answer 4

infectious diseases (transfer from a diseased host to a healthy organism)

Question 5

NOS: observations lead to important progress (cholera)

Answer 5

John wick in London was cautious enough to link past experiences to a cholera outbreak. He mapped all infected, and closed the water pump nearest, stopping the outbreak of Vibio cholerae, evidence incorporated into the ‘germ’ theory

Question 6

Skin

Answer 6

largest organ of the body, covered in microorganisms.
- tough physical barrier preventing pathogens from entering
- skin sealed through blot clots
- chemical protection from sebum (maintains low skin pH, inhibits growth of microorganisms)

Question 7

Mucous membrane

Answer 7

found lining vulnerable areas where pathogens can enter
- airways, reproductive, digestive
- goblet cells, produce mucous containing glycoproteins
- microorganisms trapped by mucous
- swept along cilia of the ciliated epithelium
- swallowed and destroyed by stomach acid or expelled
- contains lysozyme enzymes which have antibacterial properties

Question 8

Platelets

Answer 8

skin is cut = microorganisms can get in
- to minimise blood loss and unwanted microorganisms, blood starts to clot
- in response to blood vessel damage, platelets create temporary plug
- release chemicals called clotting factors that trigger chemical cascade

Question 9

platelets

Answer 9

cellular fragments that make up one component of the blood

Question 10

BLOOD CLOTTING PROCESS

Answer 10

1. clotting factors stimulate the release of enzyme thrombin
2. thrombin catalyses the conversion of soluble protein fibrinogen to insoluble fibrin
3. fibrin creates mesh, traps more platelets. Small initial stimulus amplified to produce large amount of fibrin
4. exposure to air hardens mesh creating scab

Question 11

Innate immune system

Answer 11

non-specific
- recognise and respond to any item that is ‘non-self’ cause displaying as non-self antigens
- self antigens: individual’s own cells
- does not change over lifetime

Question 12

antigen

Answer 12

molecule that can trigger an immune response

Question 13

phagocytes

Answer 13

type of white blood cell which carries out a non specific immune response ingests and breaks down pathogens through phagocytosis

Question 14

adaptive immune system

Answer 14

specific presence of non-self antigens
- a sequence of events occur that leads to antibody production and memory cells
- encounters same thing: process occurs much quicker and produces many antibodies, pathogen destroyed before any symptoms occur
- changes over course of life, develops with age
vaccinations: introduces new pathogens, speeds up immune response to next exposure

Question 15

lymphocytes

Answer 15

responsible for antibody production

Question 16

erythrocytes

Answer 16

red blood cells

Question 17

infection control by phagocytes

Answer 17

innate immune system
phagocytes engulf pathogens via endocytosis
enzyme lysosome destrtoy pathogen

Question 17

leukocytes

Answer 17

white blood cells

Question 18

lymphocytes: adaptive immunity system

Answer 18

found in lymph nodes and circulating the blood
produce antibodies (y-shaped proteins)
antibodies bind to antigens on pathogens and
- tag for destruction
- prevent it from binding with other host cells

Question 19

antibodies are specific

Answer 19

specific to antigens, so we need many different types of lymphocytes to make different antibodies

Question 20

ACTIVSTION OF B-LYMPHOCYTES BY HELPER T-LYMPHOCYTES

Answer 20

1. Pathogens are engulfed by macrophages
2. antigen presentation on outside of macrophage
3. T-lymphocyte bind the antigen and become activated
4. Activated T-cell binds to a specific lymphocyte (B-cell)
5. B-cell activation
6. Activated B-cell clones itself (mitosis)
7. differentiate into plasma cells or memory cells
   - grow
   - produce organelles for antibody production (RER, golgi apparatus)
8. Antibody production

Question 21

B-lymphocytes

Answer 21

make proteins called antibodies to fight pathogens

Question 22

T-lymphocytes

Answer 22

protect by destroying harmful pathogens and sending signals to control immune system’s response to threat

Question 23

Immunity

Answer 23

B-cells that differentiate into memory cells remain in blood
produce rapid response if pathogen detected again
Immunity: either antibodies or memory cells to fight pathogen

Question 24

Transmission of HIV in body fluids

Answer 24

HIV: human immunodeficiency virus
virus persists in the blood/body fluids of an infected person
(unprotected sex, sharing needles, transfusion of blood)

Question 25

Infection of lymphocytes by HIV with AIDS as a consequence

Answer 25

HIV destroys helper T-cells
Loss of ability to produce antibodies, vulnerability increases
AIDS: acquired immunodeficiency syndrome
most die from opportunistic infections
antiretroviral drugs prevent immune system damage

Question 26

Antibiotics - chemicals that block processes occurring in bacteria

Answer 26

antibiotics: chemicals that disrupt prokaryotic metabolism
do not affect human cells or virus
some organisms naturally produce antibiotics to eliminate competition (fungi)
Antibiotics taken for bacterial infections

Question 27

Evolution of antibiotic resistance

Answer 27

Resistance is caused by mutation and at random
resistant bacteria doesnt do anything until antibiotic applied
antibiotics kill competitors (non-resistant bacteria)
resistant bacteria becomes dominant
resistance passed down to offspring or other species

Question 28

prevention of resistance

Answer 28

only take antibiotics when needed
restrict use of antibiotics for farm animal growth
develop new types of antibiotics

Question 29

Zoonoses

Answer 29

Pathogens that can be transmitted from other species to human
tuberculosis: bacteria passed from cattle by unpasteurised infected milk or cough from cows
rabies: virus from dogs passed via bites/scratches
japanese encephalitis: virus from pigs or birds passed by mosquito bites
COVID 19: evidence virus passed from bats to humans

Question 30

Vaccines and immunization

Answer 30

vaccines initiate an adaptive immune response to generate antibodies and/or memory cells with the symptoms of infection
vaccines contain antigens or nucleic acids with sequences that code for antigens

Question 31

herd immunity

Answer 31

when enough of the population has immunity (infection or vaccine) the pathogen declines
important cause not everyone can vaccinate