B1.3 Flashcards
What are drugs?
most are chemical substances that affect the CNS
they cause changes in psychological behaviour
can be addictive
some medically useful (e,g antibiotics such as penicillin) but most harmful
if become addicted, there is a physical need and withdrawal symptoms without
build up tolerance to some so need more for same effect
What are the 4 different types of drug and what effect do they have?
depressants- e.g alcohol
decrease brain activity and slows responses of CNS, causing slow reactions and poor judgement of speed and distance
stimulants- e.g caffeine/nicotine increase brain activity by increasing number of neurotransmitters at some neurone synapses increase speed of reactions make you feel alert and awake often used to treat depression
painkillers e.g morphine
decrease feeling of pain in different ways
e.g blocking nerve impulses in brain
hallucinogens e.g LSD
distort what’s seen and heard by altering pathways nerve impulses usually travel along
What is reaction time and how can it be measured?
the time it takes to respond to a stimulus - normally under 1 second
can be effected by things like drugs
can also be measured
one person holds ruler vertically between thumb and forefinger then let go without warning
second person has to catch ruler as soon as they see it fall and as quickly as possible
reaction time measured by how far down ruler caught - lower down=slower reaction, higher up=faster reaction
What problems can smoking cause
tobacco smoke contains carbon monoxide which combines with haemoglobin in red blood cells and prevents them carrying oxygen. in pregnancy it can deprive foetus of oxygen so the baby will be underweight
contains tar which is a carcinogen, a chemical that can cause cancer. lung cancer more common in smokers- 90% associated with smoking, including passive
contains nicotine which is addictive
What problems can alcohol cause?
short term:
slows reactions
blurred vision
lowers inhibitions
long term:
poisonous- liver usually breaks down alcohol into harmless by-products. too much causes liver cells to die, forming scar tissue which blocks blood flow through liver. called cirrhosis
if liver can’t clean out blood, dangerous substances build up and damage the rest of the body
too much alcohol can also lead to brain damage
What are the benefits of organ transplants?
if organ severely damaged it can be replaced by a donated natural organ
living donors can donate whole or part of an organ e.g one of two kidneys and part of liver
organs from people who have died or are brain dead can also be transplanted
What are the problems with organ transplants
shortage so less likely to get one e.g if unlikely to survive operation
may only be considered if change lifestyle e.g if obese, greater risk of dying so may have to lose weight or people who have damaged liver by drinking too much alcohol have to stop drinking before liver transplant
some people think people who damage own organs don’t deserve transplant as much as those whose organs have been damage through illness/disease
What are infectious diseases?
diseases which can be transmitted from person to person
caused by pathogens- microbes that cause disease
include bacteria, protozoa, fungi and viruses
How are pathogens spread?
water- drinking or bathing in dirty/contaminated
e.g cholera, bacterial infection that causes diarrhoea and dehydration. spread by drinking water contaminated by other sufferers
food- eating contaminated
e.g salmonella, bacteria that causes food poisoning is found in food left too long or not cooked properly
air- carried in air in droplets produced by coughing/sneezing
e.g influenza virus that causes flu
contact- touching contaminated surfaces
e.g athlete’s foot fungus spread by touching same things as infected such as towel
body fluids such as blood (by sharing needles), breast milk and semen (through sex)
e.g HIV virus that causes aids is spread this way and stops immune system working
animal vectors - vectors that carry and spread disease
e.g anophdes mosquito carries protozoa that causes malaria. spreads it by biting and sucking blood of other organisms
house fly - carries bacterium that causes dysentery and spreads it by carrying bacteria onto food
What physical barriers stop pathogens entering the body?
skin- unbroken, barrier against microbes
damaged, blood clots quickly and the seal acts as a barrier to keep out microbes
respiratory system- respiratory tract (nasal passage, trachea and lungs) lined with mucus and cilia
mucus catches dust and bacteria before they reach lungs
cilia pushes gunk-filled mucus away from lungs
What chemical barriers stop pathogens entering the body?
eyes- produce lysozyme chemical in tears which kills bacteria on surface of eye
stomach - hydrochloric acid kills pathogens in things like food
How do plants defend themselves against pathogens?
produce chemicals
some have antibacterial effect that protect the plant against bacteria
What are antiseptics and how are they used?
chemicals that destroy or stop bacteria growing
used outside the body to help clean wounds and surfaces
prevent instead or treat infection
found in many household products e.g bathroom cleaner
used in hospitals and surgeries to try and prevent spread of infections like MRSA
What are antibiotics and how are they used?
drugs used inside the body, taken as pill or injected
treat patients already infected with bacteria or fungi
don’t destroy virus e.g cold and flu
two types- antibacterials and antifungals
What is the difference between antibacterials and antifungals?
antibacterials e.g penicillin
treat bacterial infections by killing bacteria or stopping it growing
bacteria can become resistant to certain antibacterials so they won’t work
antifungals e.g nystatin
treat fungal infections by killing fungi or stopping them growing
How do bacteria become resistant to antibiotics?
can mutate, which can cause them to become resistant to an antibiotic
if infection, some bacteria may be resistant to antibiotcs so only non-resistant strains killed. resistant survive and reproduce so population increases and can cause infection
misuse- e.g doctors overprescribing or patients not finishing a course
this causes increased rate of development of resistant strains. antibiotics no longer used to treat mild infection, only more serious
What practical investigates antibiotics and antiseptics?
pour hot sterilised agar jelly into sterile petri dish
when jelly cooled and set, transfer bacteria to culture medium
3 paper discs- one soaked in antibiotic 1, one in antibiotic 2 and a control soaked in water
place discs onto jelly and label, then tape lid onto dish and leave for 24 hours at 25 degrees
anywhere bacteria can’t grow is inhibition zone, larger=more effective antibiotic
none around control- show antibiotic stops bacteria growing not paper discs
controls: temperature, size of disc, concentration of antibiotic
same experiment can investigate antiseptics
How is energy lost through a food chain?
to stay alive e.g respiration, movement, excretion
lost to surroundings as heat
doesn’t disappear just can’t be used by next animal in food chain
food chain’sonly 5 trophic levels as not enough energy left to support more
What are pyramids of biomass?
pyramids to show the amount of energy at each stage of food chain
each time you go up a trophic level, mass or organisms goes down as most biomass is lost so doesn’t become biomass in next level
What is parasitism?
What are some examples of a parasitic relationship?
relationship where parasite lives on/in a host and take what they need to survive, often harming host
fleas- live in fur/ bedding of animals and feed by sucking their blood, reproduce quickly
headlice- live on human scalp and suck blood for food, making the host itch
tapeworms- attach to intestinal wall of host and absorb nutrients from them, causing malnutrition
mistletoe- grows on trees and plants and absprbs water and nutrients from them, can reduce host’s growth
What is mutualism ?
What are some examples of a mutualistic relationship?
relationship where both organisms benefit
oxpeckers and buffalo- birds live on back of buffalo and eat pests as well as alerting animals to predators by hissing
cleaner fish eat dead skin and parasites from larger fish, cleaner fish get food and aren’t eaten by bigger fish
nitrogen-fixing bacteria and legumes. plants carry bacteria in root nodules. bacteria get supply of sugar and plants get nitrates for photosynthesis
chemosynthetic bacteria live in giant tube worms or gills of molluscs. worms supply bacteria with chemicals from sea and the bacteria turn it into food for both through
chemosynthesis
How does a larger population have a larger impact on the environment?
larger population due to modern medicine and farming.
raw materials such as non-renewable energy sources used up more rapidly
more waste produced
more pollutants produced e.g phosphates, nitrates and sulphur dioxide
Why do plants need fertilisers?
What happens if too much?
without them, crops wouldn’t grow as well and food yields would be down
if too much is applied and it rains soon after, nitrates will leach into the rivers and cause Eutrophication
excess nitrates leach into river, causing rapid growth of algae. the algae use up all the light on the surface
some plants die as they can’t photosynthesise due to competition for light
microbe numbers increase as they feed on the dead matter
as the microbes respire they use up all the oxygen, fish and other aquatic life due to lack of oxygen
the result is a stagnant, deoxygenated river/lake
What practical shows the effect of pollutants on plant growth?
one jam jar with cotton wool soaked in water and another soaked in the pollutant e,g nitrate
both contain 20 cress seeds on the cotton wool
after 5-7 days, measure the length of shoots and work out the average for each jar
the results depend on the pollutant used e.g nitrate causes increased plant growth compared to control
controls: temperature, amount of light, volume of solution, number of seeds, type of seed
ensures the effect on plant growth inly due to pollutant
same experiment can be used to show effect of pollutant on seed germination
