c3.2 defence against disease

Question 1

pathogen

Answer 1

microscopic entities that causes disease within their hosts

Question 2

virus eg

Answer 2

covid-19

Question 3

bacteria eg

Answer 3

e coli

Question 4

fungi eg

Answer 4

yeast

Question 5

protists

Answer 5

malaria

Question 6

physical barriers against pathogens [2]

Answer 6

1. mucus membranes
2. skin

Question 7

why mucus membranes can defend against pathogens [3]

Answer 7

1. sticky- traps pathogen
2. pH not favourable
3. natural organisms- competitive exclusion by non-harmful microbes

Question 8

lysozyme

Answer 8

enzymes that breaks down pathogens

Question 9

what makes mucus

Answer 9

goblet cells

Question 10

what moves mucus

Answer 10

ciliated cells

Question 11

why skin can defend against pathogens [5]

Answer 11

1. continuous
2. many layers
3. dry
4. pH- not favourable to pathogens
5. natural organisms- competitive exclusion by non-harmful microbes

Question 12

metabolic pathway eg

Answer 12

blood clotting

Question 13

mechanism of blood clotting

Answer 13

1. clotting factors: thrombin
2. fibrinogen (soluble) → fibrin (fibrous)
3. captures erythrocytes
4. clot

Question 14

2 types of immune system

Answer 14

1. innate immune system
2. adaptive immune system

Question 15

innate immune system

Answer 15

• doesnt change
• phagocyte

Question 16

phagocyte

Answer 16

detect anything that might have a foreign antigen

Question 17

phagocytosis

Answer 17

engulfs pathogens then lysozymes in their lysosomes to digest them

Question 18

adaptive immune system

Answer 18

changes overtime depending on the individuals history of exposure to various antigens

Question 19

identify lymphocyte

Answer 19

circle with circle inside

Question 20

identify phagocyte

Answer 20

has ‘c’ shape inside it

Question 21

mechanism of HIV

Answer 21

kill t helper cells → weaken immune system significantly because macrophages are too slow and cant find the pathogen

Question 22

why do memory cells retain the memory

Answer 22

dont die

Question 23

how do memory cells recognise pathogens

Answer 23

bind to receptor, works if the pathogen is slightly different as long as they can still bind

Question 24

amoeboid movement

Answer 24

phagocytes use pseudopods to crawl and chase the pathogen

Question 25

antigen

Answer 25

presented to t helper cells and the b cells (nymphocytes)

Question 26

t cells

Answer 26

find the right b cells and release cytokines

Question 27

how do t cells work

Answer 27

- divide into plasma cells to release antibodies - small percentage turn into memory cells

Question 28

how HIV works

Answer 28

infects t-helper cells and other lymphocytes to cause acquired immunodeficiency syndrome (AIDS)

Question 29

what does retrovirus contain

Answer 29

rna

Question 30

causes of HIV [5]

Answer 30

1. bodily fluids form an infected to uninfected person 2. sex without a condom 3. sharing hypodermic needles 4. transfusion of infected blood 5. childbirth- virus can get through placenta + lots of blood during childbirth

Question 31

how hiv turn into aids

Answer 31

- takes time for t-cell count to decrease 1. t-helper cells gets attacked and starts to die 2. if t-helper cell count too low then AIDS

Question 32

how less t-helper cells lead to lowered immunity

Answer 32

antibodies are unable to be produced → lowered immunity

Question 33

why aids causes people to die

Answer 33

body becomes susceptible to opportunistic infections

Question 34

treatment of hiv

Answer 34

group of antiretroviral drugs- prevents damage to immune system

Question 35

how antibiotics work [3]

Answer 35

1. block the process of bacteria building a cell wall by linking molecules together - bacteria can burst easier 2. affect ribosomes (cell’s protein-building machines) so prevent them from building proteins. proteins do all the cell’s work so a bacterium that cant build proteins cant survive - virus dont have ribosomes, rely on their host’s ribosomes 3. causes dna strands to break and prevent the breaks from being repaired when bacteria begins to copy their dna. without intact dna, bacteria cant live or reproduce

Question 36

why antibiotics dont work against viruses

Answer 36

Viruses do not possess a metabolism (they are not alive) bc they dont have their own metabolic reactions and instead take over the cellular machinery of infected host cells

Question 37

how to treat viruses

Answer 37

Antiviral treatments target features specific to viruses (e.g. viral enzymes like reverse transcriptase or components of the capsid)

Question 38

how do bacteria become drug resistant

Answer 38

can pass resistant gene through plasmids

Question 39

mrsa

Answer 39

- bacteria- staphylococcus aureus - og- mrsa - variation- mssa - result: mssa is killed, mrsa survives, nrsa reproduces so resistant gene proliferates → mrsa population increases → mrsa is a dominant strain → methycillin is no longer effective against infection

Question 40

what do vaccines contain

Answer 40

antigens (weakened/killed pathogens) or nucleic acids (dna/rna)

Question 41

why nucleic acids vers of vaccines are better

Answer 41

faster bc less trials needed

Question 42

antigens in vaccines

Answer 42

sequences that code for the antigens without causing the disease

Question 43

2nd response after the vaccination

Answer 43

create more antibodies in a shorter amount of time

Question 44

zoonoses

Answer 44

infectious disease that can transfer from other species to humans