Infection and Response Flashcards
what are the three types of viral diseases?
- Measles
- HIV
- TMV
how are measles spread?
through droplets from a sneeze or a cough
what are the symptoms for measles? (2)
- fever
- red skin rash
how can measles be fatal?
- they can cause damage the lungs, leading to pneumonia
- they can cause damage to the brain, causing a brain infection
how is HIV spread? (2)
through direct sexual contact or the exchanging of bodily fluids
what are the symptoms of HIV?
flu-like symptoms for the first few weeks and then the patient won’t experience any symptoms for several years afterwards
which cells does HIV attack?
immune cells
which drug can stop the HIV virus from replication?
- antiretroviral drugs
what is TMV?
tobacco mosaic virus - causes a mosaic pattern on the leaf of the plants
what are the effects of TMV on a plant? (2)
- parts of the plants become discoloured
- the plant can’t carry out photosynthesis, stopping growth
what is one example of a fungal disease?
rose black spot
what is rose black spot?
causes purple/black spots on the leaves
how is rose black spot spread?
in water or by the wind
what are the effects of rose black spot on plants?
- leaves turn yellow and drop off, affecting photosynthesis
how can rose black spot be treated?
using fungicides or stripping the plant of the affected leaves
what are two examples of a bacterial disease?
-salmonella
- gonorrhoea
how is salmonella spread?
ingesting infected food that’s been prepared in unhygienic conditions
what are the symptoms of salmonella? (4)
- fever
- abdominal cramps
- vomiting
- diarrhoea
how has the spread of salmonella been controlled in the uk?
- salmonella is usually found in poultry (chickens)
- in the uk, all chickens are vaccinated against salmonella
how is gonorrhoea spread?
sexual contact
what are the symptoms of gonorrhoea? (2)
- thick yellow/green discharge from the penis or vagina
- pain when urinating
what was used to treat gonorrhoea in the past?
penicillin
why might penicillin not be able to treat gonorrhoea now?
there are some antibiotic resistant strains of bacteria that are now common
how can we stop the spread of gonorrhoea?
- using a condom
- people who have unprotected sex should be tested so it can be dealt with before they pass it on to anyone else
what is one example of a protist disease?
malaria
what is a symptom of malaria?
- repeated bouts of fever
how is malaria spread?
through a mosquito, which acts as a vector that carries the disease from person to person
how can we prevent the spread of malaria?
- finding areas of still water and draining them so that mosquitoes can not breed OR spraying the still water with insecticides to kill the mosquitoes
- sleeping under a mosquito net to prevent them from biting you
what is the job of the non-specific defence system?
to prevent pathogens from entering the body
what are the four main parts of the non-specific defence system?
- Skin
- Nose
- Lungs
- Stomach
how does skin prevent pathogens from entering the body? (2)
- the outer layer of the skin consists of dead cells and is difficult for pathogens to penetrate
- also produces an oily substance called sebum which can kill bacteria
how can the nose help to prevent pathogens from entering the body?
- contains hair and mucus that can trap the pathogen before it enters the breathing system
how can the lungs help to prevent pathogens from entering the body?
- trachea and bronchi are covered with tiny hairs called cilia
- cilia are covered in mucus which can trap pathogens
- the cilia then waft the mucus upwards towards the throat where it’s swallowed into the stomach
how can the stomach prevent pathogens from entering the body?
- contains hydrochloric acid that kills pathogens
what are the two main functions of the immune system?
- destroys pathogens and any toxins they produce
- protects us in case the same type of pathogen invades us again in the future
what are the three functions of a white blood cell?
- Phagocytosis
- Produce Antibodies
- Produce Antitoxins
what is phagocytosis? (3)
- the white blood cell detects chemicals released from the pathogens and moves towards it
- white blood cell ingests the pathogens
- uses enzymes to destroy the pathogens
what do antibodies do in the face of a pathogen?
- they stick to the pathogens, triggering the pathogens to be destroyed
what is the main fact about antibodies?
- they are extremely specific (antibodies that protect against measles won’t protect against any other disease)
what do antitoxins do?
stick to the toxin molecules that bacteria let out, preventing them from damaging cells
how does vaccination work? (4)
- a dead or inactive form of the pathogen is injected into the body
- white blood cells are stimulated to create antibodies against the ‘pathogen’
- the white blood cells divide by mitosis to produce copies of itself
- those copies of the white blood cell can stay in the body for decades and will protect the body if that disease comes back
what do antibiotics do?
kill infective bacteria without harming cells
what is antibiotic resistance?
- where bacteria have evolved over years so that they are no longer killed by the antibiotics
what type of disease can antibiotics not kill?
- a disease caused by a virus
why can antibiotics not kill viruses?
- because viruses need a host cell to reproduce in and so antibiotics can not kill the virus without killing the cell
what was extracted from foxglove?
heart drug digitalis
what was extracted from willow trees?
aspirin
who discovered penicillin?
alexander fleming from the mould penicillium
what about the drug needs to be checked before giving it to humans? (3)
- the toxicity (if it’s safe for humans)
- if the drug is effective
- the best dose
what is preclinical testing carried out on? (3)
- cells
- tissues
- animals
who is clinical testing carried out on?
humans
what happens in the first stage of clinical testing?
very low doses of the drug are given to healthy volunteers
define optimal dose
the best dose to treat the disease with the fewest side effects
what is a placebo?
a tablet or injection with no active drug in it
why will some patients get better with a placebo?
because they think they’re being treated and so believe that they’re getting better
what is a double-blind trial? (3)
- test group receive the active drug
- control group receive a dummy drug which looks exactly like the test drug but has no active ingredient
- neither the patients nor the doctors know which patients took the drug and which took the placebo
- this is to stop bias
what are the four tissues in a plant?
- upper epidermis
- palisade mesophyll (palisade cells)
- spongy mesophyll
- lower epidermis
what is the upper epidermis? (3)
- transparent
- allows light to pass through to the palisade cells so they can undergo photosynthesis
- covered with a layer called the waxy cuticle (reduces the evaporation of water so the leaf won’t dry out)
what are the palisade cells?
- contain chloroplasts for photosynthesis
what is the spongy mesophyll?
- full of air spaces that allow carbon dioxide and oxygen to diffuse throughout the plant
what is the lower epidermis? (3)
- has tiny pores called stomata which allow carbon dioxide to enter the leaf and oxygen to leave
- stomata further help to control the amount of water vapour that can pass out
- guard cells on the side of the stomata
define translocation
the movement of sugars and other molecules through the phloem tissue
what is the transpiration method? (4)
- begins with the evaporation of water from cells inside the leaf
- water diffuses through the spongy mesophyll and out through the stomata
- to replace the water that’s been lost, the xylem transports water into the leaf
- water is also drawn up from the root hair cells, through the xylem vessels to the leaf
the four factors that affect the rate of transpiration?
TEMPERATURE
evaporation is faster when temperatures are higher = transpiration is faster
AIR HUMIDITY
evaporation is faster when the air is dry = transpiration is faster under dry conditions
WINDY CONDITIONS
wind removes water vapour, allowing more water to evaporate = transpiration is faster under windy conditions
LIGHT INTENSITY
high light intensity increases the rate of photosynthesis and then the stomata open and water vapour passes out of the leaf = transpiration rate increases
define what the guard cells do (2)
when light intensity is high (during the day) the guard cells swell and change their shape so the stomata can open and carbon dioxide can diffuse into the leaf for photosynthesis
under hot conditions, the plant closes its stomata to reduce water loss from transpiration
