P1 567 Infection+ response

Question 1

describe lifestyle factors and consequent non-communicable diseases (4)

Answer 1

• smoking: increased risk of lung disease/ lung cancer/ mouth cancer/ cardiovascular diseases/ birth defects
• poor diet+obesity+lack of exercise: cardiovascular diseases/ type 2 diabetes/ cancers
• drinking excess alcohol: liver disease/ brain damage (reduced brain function)/ birth defects
• exposure to radiation/chemicals: certain cancers due to carcinogens

Question 2

define communicable diseases

Answer 2

• spread between individuals
• caused by pathogens (bacteria/viruses/fungi/protists)
• influenza/ chicken pox/ measles
• opposite are non-communicable diseases (cancer/dementia/diabetes)

Question 3

describe how pathogens/diseases are spread between individuals (3)

Answer 3

• inhalation of droplets in air- coughing/ sneezing
• direct contact- STDs/ touch
• food+water

Question 4

define benign tumours

Answer 4

• growth of abnormal cells contained in one area
• not cancerous- do not invade other parts of the body
• surgically removed

Question 5

define malignant tumours

Answer 5

• spread+invade neighbouring tissues
• if cells get into bloodstream they are carried around the body+ leads to secondary tumours
• cancerous- require prompt medical treatment to prevent spreading

Question 6

describe risk factors for cancer (6)

Answer 6

• smoking
• UV exposure: UV radiation causes skin cancer
• alcohol: bowel/mouth
• obesity
• infections: damage immune system, eg. hepatitis C causes changes in cells
• genetics: mutations in inherited genes

Question 7

name drugs that were traditionally extracted from plants/micro-organisms (3)

Answer 7

• digitalis: originates from foxglove, used in heart to improve circulation
• aspirin: originates from willow, painkiller
• penicillin: originates from penicillium mould, antibiotic

Question 8

state stages of drug development (4)

Answer 8

• pre-clinical trials: new drug tested in labs for toxicity (safe for humans) +efficacy (how well it works) on cells/tissues (sometimes animal)
• 1st clinical trials: low doses tested on human volunteers for toxicity+ side effects
• 2nd clinical trials: tested on patients with the disease- test group is given the drug and control group is given a placebo to see changes- finds dosage
• prescribed to public: findings checked by peer review to approve

Question 9

2 reasons why healthy volunteers are used in 1st clinical trials

Answer 9

• too great a risk for ill patients- safer
• side effects (toxicity) of drug easier to identify- see if patient becomes ill

Question 10

describe double-blind trials

Answer 10

• when the doctors+patients are unaware if the drug is real or a placebo
• prevents bias affecting results of clinical trials

Question 11

describe how pathogenic bacteria works +examples

Answer 11

• reproduce quickly in right conditions (warmth/ moisture/ nutrients) through binary fission
• prokaryotic cells
• release toxins that damage cells+ make people feel ill
• eg. cholera/ dysentry/ tuberculosis/ gonorrhoea

Question 12

describe the disease salmonella (type/spread/symptoms/control)

Answer 12

• bacterial disease
• spread by bacteria ingested in food/ on food prepared in unhygienic conditions
• symptoms: vomiting, fever, cramps, diarrhoea (caused by the toxins the bacteria produces)
• poultry in UK is vaccinated against salmonella to control the spread

Question 13

describe the disease gonorrhoea
(type/spread/symptoms/control)

Answer 13

• bacterial disease
• sexually transmitted (STD)
• symptoms: pain while urinating, yellow/green discharge
• prevented by barrier contraception
• used to be easily treated with antibiotics (penicillin) but bacteria has become drug-resistant

Question 14

describe how pathogenic viruses work

Answer 14

• reproduce by injecting their genes into a host cell+ producing thousands of copies of itself until the cell bursts+ the virus is released into the body
• not living organisms- unable to reproduce on their own
• very small+ hidden inside cells so hard to detect
• eg. flu, common cold, HIV/AIDS
• cannot be treated with antibiotics

Question 15

why can’t viruses be treated with antibiotics

Answer 15

• surrounded by a protective protein coating
• don’t have cell walls that can be attacked by antibiotics (like bacteria)
• difficult to develop drugs that kill viruses without damaging host cells (body tissue)

Question 16

describe the disease measles
(type/spread/symptoms/control)

Answer 16

• viral disease
• spread through droplet inhalation in air from sneezes/coughs of infected people
• symptoms: fever, red skin rash, mouth sores
• most young children vaccinated against it
• can be fatal

Question 17

describe the disease HIV
(type/spread/symptoms/control)

Answer 17

• viral disease that causes AIDS
• initially causes flu-like symptoms
• virus attacks the immune system until it cannot fight off other infections/cancers
• this can be controlled by antiretroviral drugs +condoms
• spread through the exchange of bodily fluids (often during sex) or sharing of drug needles

Question 18

describe the disease tobacco mosaic virus (TMV)
(type/symptoms)

Answer 18

• viral plant pathogen
• symptoms: mosaic pattern of discolouration on leaves-> limits photosynthesis so affects plant growth

Question 19

describe how pathogenic fungi work

Answer 19

• reproduce in/on dead or living organisms
• can be single-celled (or multi-cellular)
• eg. rose black spot, athlete’s foot, ringworm

Question 20

describe the disease rose black spot
(type/spread/symptoms/control)

Answer 20

• plant fungus/ fungal disease
• symptoms: purple/black spots develop on leaves-> limits photosynthesis so affects plant growth
• fungal spores spread through water+ wind
• treated with fungicides+ by removing/destroying affected leaves

Question 21

describe how pathogenic protists work

Answer 21

• eukaryotic cells
• most protists are not pathogenic
• require a moist environment+ specific temp
• often need a vector to transmit pathogen from one host to the next eg. mosquitos
• eg. malaria

Question 22

describe the disease malaria
(type/spread/symptoms/control/prevention)

Answer 22

• protist disease
• pathogen that causes malaria is transmitted by mosquitos (primary vector)
• symptoms: fever, sweats/chills, headaches, vomiting, diarrhoea
• can be fatal
• spread controlled by insect repellent, sleeping with mosquito nets, removal of stagnant water
• spread prevented by antimalarial drugs, vaccination

Question 23

name human defences preventing pathogens from entering body (7)

Answer 23

• skin: physical barrier, dead cells difficult to penetrate, forms scabs, skin cells produce oils to kill microbes
• hairs+mucus in nose: mucus traps microbes, hairs stop large pathogens from entering the lungs
• hydrochloric acid in stomach: kills microbes that enter body through food/drink
• mucus+cilia in trachea+bronchi: trap microbes to be carried out of body by cilia (tiny hairs)
• blood clotting by platelets: seal wounds to prevent microbes entering body+ reduce risk of infection
• tears: remove unwanted particles
• white blood cells: fight infection

Question 24

describe ways white blood cells fight pathogens inside the body (4)

Answer 24

• phagocytosis: engulf+ digest pathogens
• lymphocytes produce antibodies: specific to the antigen detected to target the pathogen
• lymphocytes produce antitoxins: proteins which neutralise toxins (which make you feel ill) released by pathogens
• memory cells: after recovering from a disease some white blood cells remain, antibodies are produced quicker if you catch the disease again, patient won’t feel ill

Question 25

describe phagocytosis process (4)

Answer 25

* lymphocytes recognise a foreign pathogen due to its different antigens, then create antibodies shaped specifically to the antigens * antibodies attach to antigens of pathogen * antibodies group together in one area to reduce symptoms+ prevent spread of pathogen * phagocyte engulfs the complex

Question 26

describe the process of vaccination

Answer 26

* injecting a small amount of a dead/inactive pathogen into the body * provokes white blood cells to produce antibodies * therefore memory cells are also produced * if the pathogen re-enters the body memory cells will produce the antibodies needed

Question 27

why doesn't vaccination provide full immunity

Answer 27

injected pathogen is inactive so will not reproduce -> less antibodies+ memory cells will be produced than needed for full immunity

Question 28

describe 3 causes of antibiotic resistance

Answer 28

* doctors must not overprescribe antibiotics to patients or prescribe them for viral and non-serious infections * failure to complete a full course of antibiotics - not all bacteria killed * overuse of antibiotics in agriculture

Question 29

describe how antibiotic resistant bacteria are spread

Answer 29

* random mutation of bacteria cells gives resistance * resistant bacteria unable to be destroyed * bacteria reproduce quickly

Question 30

describe the benefit of herd immunity

Answer 30

* majority of the population are vaccinated against a specific pathogen, a few are not vaccinated but well, a few are not vaccinated but are ill+contagious. * **the majority are protected +don't become ill** due to the high level of vaccination * **less chance of non-vaccinated being exposed to pathogen**