Transcript B1.1 Keeping Healthy - Durrington High School

Bacteria
Weight problems
Antibiotics
B1.1 Keeping Healthy
Diet and exercise
Pathogens and
disease
Immunity
Defence
mechanisms
Diet and exercise
•Carbohydrates
•Proteins
•Fats
•Vitamins
•Minerals
•Water
•Fibre
Metabolic rate:
Rate of chemical
reactions in your
cells
Affected by...
Gender,
proportion of muscle
to fat,
exercise /activity,
genetics
How much energy do you need?
Key words:
•Males need more energy than females
Deficiency diseases
•Growing teenagers need more energy than the elderly
Malnourished
•If you exercise you need to eat more
•Temperature has an effect – hotter then less energy spent warming up
Weight problems
Obesity
• Excess energy is stored as fat
• Some body fat is needed for
cushioning and as an energy store
• Can lead to arthritis, diabetes,
high blood pressure, heart disease
Inheritance:
Affect metabolic rate, risk of heart
disease, muscle:fat, cholesterol
Cholesterol:
Needed for cell membranes and
hormones eating high fat food means
a higher level of harmful cholesterol
and heart disease. This can also be
inherited so levels will be high
regardless of diet
Losing weight (mass)
Take in less energy than you use
• Reduce amount of food
• Increase exercise
Slimming groups provide support
Pathogens and disease
Pathogens: Microorganisms that cause disease
Infectious: the microorganism can be passed on
Semmelweis
Many women used to die after childbirth ‘childbed fever’. He noticed doctors would
go from dead body to baby delivery without washing hands. A doctor had a cut and
died from the same symptoms. He told doctors to wash their hands but they were
angry he was blaming them for deaths – they didn’t know about viruses /bacteria and
thought it was God’s punishment to women
Bacteria:
Single-celled living organisms.
Used in yogurts, medicine
Reproduce asexually
inside the body, produce
toxins and damage cells
Symptoms are your body
responding to this
viruses:
Very small, cause
diseases in every
type of living
organisms
They take over
body cells, damage
and destroy them
Defence mechanisms
•
•
•
•
Droplet infection – mucus
Direct contact – skin barrier
Contaminated food and drink – stomach acid
Break in the skin – scabs
White blood cells of the
immune system
Ingest microorganisms
Produce specific antibodies
Produce antitoxins
Antibiotics
Painkillers relieve symptoms but do not affect the microorganism
Antibiotics work inside the body to kill bacteria that cause diseases by
damaging the bacterial cells – they don’t work on viruses as they live
inside body cells
Some bacteria may mutate by
natural selection
They are antibiotic resistant
The flu virus mutates very
easily so the immune system
wont recognise it
To reduce this we should... Only use antibiotics when
necessary, treat with specific antibiotics, medical staff
wash hands, isolate some patients, clean hospitals
MRSA: a result of natural
selection in hospitals
where many bacteria and
antibiotics used to treat
Growing bacteria
• Microorganisms can be cultured in the lab
• A culture medium (agar) is given containing an
energy source (carbohydrate) and minerals. They are
kept warm and allowed oxygen to grow
Safety:
Bacteria may mutate so
contamination must be
avoided – e.g. From
skin, air, water..
Petri dishes and agar
must be strilised from
an autoclave or using
gamma radiation / UV
Inoculate the plates – sterilise
the loop, dip in suspension, zigzag then incubate
Immunity
• Antigens – unique proteins on a cell surface
• White blood cells produce antibodies to join up with antigens
on a pathogen
• White blood memory cells – immunity
Vaccination – dead or weakened
version of the pathogen
introduced to body so white blood
cells can develop antibodies –
immune
e.g. MMR, tetanus, smallpox wiped
out
Vaccination debate: no medicine is risk
free and some have rare side effects but
it is important to vaccinate to protect the
population from disease
e.g. MMR, Whooping cough – parents
told could be dangerous but the disease
itself poses more risk – brain damage etc
Exam Questions
[6 marks]
Reflex actions
Responding to
change
Homeostasis
B1.2 Coordination and Control
Fertility
Hormones and
plant growth
Hormones and
menstrual cycle
Responding to change
• The nervous system
carries impulses
along neurons
enabling you to
react to your
surroundings and
coordinate your
behaviour.
Stimulus
Change in the
environment
Receptor
E.g. Eyes, skins, found in
sense organs
Sensory neuron
CNS
Brain and spinal cordcoordinates response
Motor neuron
Effector
Muscles (contract) or
glands (secrete)
Reflex actions
• Automatic responses important for survival
• Similar response to a normal conscious
action but involves a relay neuron in the
spinal cord or unconscious area of the brain
• It then travels to the conscious area so you
know about the reflex - after it has
happened
Synapses
Junctions between nerves
Impulses cross the synapses
Chemicals released into the
gap between neurons
Chemicals attach to the
surface of the next neuron
and set up a new electrical
impulse
• Sensory receptor --> sensory
neuron --> CNS --> relay neuron
(spinal cord) --> motor neuron -> effector
27
Hormones and fertility
• Glands secrete hormones which are then carried around in the blood
Menstrual cycle
Brought about by hormones made and released
by pituitary gland and ovaries
Hormones:
FSH
-causes eggs to mature
-Stimulates the ovary to produce oestrogen
Oestrogen
-Causes the lining of the uterus to develop
-Inhibits FSH production
-Stimulates the release of the mature egg
Others: progesterone and LH
28 days: womb lining thickens, Eggs
released from ovary after 14 days ovulation, If not fertilised, the womb
lining and egg come out as a period
Contraception
Inhibits production
of FSH so eggs
don't mature in the
ovaries
Fertility treatments
FSH used to stimulate eggs to mature
and trigger oestrogen production
IVF - eggs collected and fertilised in the
lab then implanted
Advantages - fewer children
(cost), women freedom
Disadvantages - expensive,
multiple births, embryo use
Homeostasis
• Internal environment is maintained by homeostasis
Controlling water and ions
-Water moves in an out of body
cells
-taken in from food and drink
-lost from breathing out, sweat
and urine (salt lost here too)
-Kidneys control this
Controlling temperature
-Core temperature 37C, enzymes
work best
-Sweat to cool down, shiver to
warm up
-Below 35C hypothermia risk
- too high leads to heat stroke /
heat exhaustion enzymes and
cells don’t work properly
Controlling blood glucose
-Kept constant by hormones from pancreas
Hormones and plant growth
• Plants are sensitive, they need to grow the right way..
• Plant roots grow towards moisture and in the direction of
force of gravity
• Plant shoots grow towards light and against the force of
gravity
Phototropism – response of a plant to light
Gravitropism/geotropism – response of a
plant to gravity
Auxin – hormone that controls responses of
roots and shoots
Using plant hormones – used as rooting powder
or high doses as weed killers due to rapid
uncontrolled growth
The opposite
occurs in the roots
Exam Questions
Legal and illegal
drugs
Drugs in sport
Drugs
B1.3 Medicine and Drugs
Cannabis and hard
drugs
How effective are
medicines
Developing new
medicines
Developing new medicines
A good medicine is:
• Effective – prevent / cure a disease / ease symptoms
• Safe – not toxic or unacceptable side effects
• Stable – use the medicine in normal conditions and able to be stored
• Successfully taken into and removed from body
Developing drugs can take 12 years and cost
around £350million
They are tested on cells, tissues and organs
before animal testing and human trials
Placebo – pill that does not contain the drug
Double blind trial – neither doctor or patient
knows who has the real drug
Thalidomide
Used in 1950s as treatment
for morning sickness
Tests on pregnant animals
not carried out until 1968
Affected fetuses – born
with severe limb
deformities
How effective are medicines?
Statins: drugs that lower cholesterol in the blood and stop the
liver producing too much cholesterol. Patients should also
have a healthy diet. This reduces the risk of heart disease
Prescribed and non-prescribed drugs
Prescribed drugs have been tested in double blind trials and
many of the most effective ones come from living organisms.
Non-prescribed drugs may not have been evaluated the same
way due to expense.
St John’s Wort is a non-prescribed herbal remedy for
depression – it has been found to be an effective medicine and
more effective than placebo
Drugs
Drug: alters the way the body works
Legal: coffee, cigarettes, alcohol
• Millions of people take these so health impact
is much bigger than for illegal drugs
Illegal: cocaine, ecstasy, heroin
• Affect nervous system
Cannabis:
Trigger mental illness
Higher risk of
depression
Gateway drug?
Almost all heroin
users were originally
using cannabis –
people in touch with
drug dealers
Withdrawal symptoms – cravings, aches, sweating etc
Addiction: dependent – cant function without the drug. More and more
is needed for same effects
Addicts may turn to crime to fund drug habits, more likely to get STDs,
mental / physical health problems
Drugs in sport
Random drugs tests. Athletes that are caught are banned. Some medicines
contain banned substances so they need to be careful. Some drugs are found
naturally in the body as levels vary it can be difficult to find cheaters
Sport
Drug type
Why use them?
Problems
Bodybuilding Painkillers
Compete when injured
Exacerbates injury
Archery
Beta blockers
Steady hands
Insomnia, depression
Cycling
Erythropoietin
More RBC - oxygen to legs
Kidney disease
Sprinting
Anabolic steroids Muscle growth
Sexual characteristic change
Ethics:
 People should be able to do what they want with their body regardless of risk
 Only the richest / most sponsored people can cheat
 Desire to win and be the best
 Other athletes are using them
 Claim they didn’t know they were cheating, coaches gave them ‘supplements’
Exam questions
[6 marks]
[4 marks]
Environmental
change
Competition in
animals and plants
Adaptation for survival
Adapt and survive
Adaptation in
plants
Adaptation in
animals
Adapt and survive
Living organisms need to survive and reproduce
• Plants need: light, carbon dioxide, water, oxygen, nutrients
• Animals need: food, water, oxygen
• Microorganisms needs depend - some are light plants, some
like animals and some need no oxygen or light
Extremophiles – organisms adapted to extreme environments.
e.g. Bacteria can live at temperatures as low as -15 or up to 80C as their enzymes
are adapted not to denature.
How do you survive?
• Each fig tree has its own type of pollinating wasp – the fig flowers are adapted to attract
the specific wasp type. The wasps are adapted with specially shaped heads, ovipositors
• Star nose mole reacts and eats prey within 230milliseconds - they are blind and need to
eat their prey as soon as they touch it or it might escape
• Venus fly traps have grow in bogs with little nutrients. Insects are attracted to their smell
and colour, enzymes are digested and nutrients used
Adaptation in animals
Surface area: volume ratio
• Mammals in a cool climate grow to a large size (e.g. Whales)
to keep their ratio as small as possible to maintain body heat
Cold Climates:
 Small surface area e.g.
Ears
 Insulation – blubber
(thick layer of fat under
skin), fur coat
 Fat layer also provides
a food supply during
winter
Dry climates
 Deserts may be hot in day and freezing at night.
 Lack of water
 Often active at night rather than day
Can’t sweat or will lose water
 small – large surface area:volume to lose heat
through skin
Big ears- lose heat
Thin fur, little body fat
Camouflage : Important in predators and prey
Dependent on environment (arctic hares brown in summer and white in winter)
Adaptation in plants
Water taken in through roots
Stoma in leaves allow gases in and out for photosynthesis
and respiration
In dry climates:
– very wide root
systems
– store water in
leaves, stems or
roots
Surface area:volume ratio
Curled leaves – traps layer of
moist air, reduces surface area
Thick cuticle – stops evaporation
Or.. Broad leaves – large surface
area to collect dew
Epiphytes – in rainforests live high above ground and collect
water and nutrients from the air
Competition in animals and plants
Animals
• Food – more likely to be successful
if eat a wide range. Competition
between own species too, better
adapted will survive
• Territory – compete for best
space/ area
• Mate – males fight or display
Success depends on adaptations ...
Avoiding competition can also lead to
success
Plants
• Light (photosynthesis) smaller
plants may flower earlier in the year
before the bigger plants to get more
light
• Water (photosynthesis) different
types of roots – spread along surface
or deep underground
• Nutrients
• Space (roots and light)
Spreading seeds –
sycamore, dandelion,
Fruits, sticky
Environmental change
• Average temperature, wind, rainfall, light, pH, oxygen levels,
other species, climate will affect where an organism lives
• If any of these change the biodiversity can be affected
• Bioindicators can be used to monitor change – lichen are
sensitive to air pollution
Changing birds of Britain
Bird habitats and migration affected
Dartford warblers are more
common due to increased
temperatures, but less common in
Spain where it is now too warm
Bees
Disease (CCD) affecting honey bees
Bees are important for pollination of
plants – apples, raspberries,
cucumbers etc
Cause unknown – pesticides? Climate?
Exam questions:
[6 marks]
Decay processes
Carbon cycle
B1.5 Energy in biomass
Recycling organic
waste
Pyramids of
biomass
Energy transfers
Pyramids of biomass
• Biomass is the amount of living thing
available to the next level in a food chain
– the mass of material in living
organisms
• It is the total mass without the mass of
water (dry mass in grams)
• Pyramids of biomass show how much
energy is available at levels in a food
chain
Energy transfers
Much of the energy lost in:
•
Movement (muscles
contracting)
•
Heat
•
Keeping a constant body
temperature (energy
needed to keep warm or
cool down)
•
Waste (herbivores can’t
digest all they eat,
excess protein passed
out as urea)
1110 KJ in
heat loss
3060 KJ
in food
1797 KJ in urine
and faeces
Decay processes
Detritus feeders (e.g. Maggots, worms)
start the process by eating dead
animals and producing waste material
Decomposers (microorganisms) digest
everything, using some of the nutrients
to grow and reproduce
They produce waste products – CO2,
water and nutrients
This recycling means the soil contains
mineral ions plants need to grow and
cleans up dead organisms
Conditions for decay:
• Warm
– Chemical reactions in
microorganisms work faster
when warm
– Reactions slow down and stop
if too cold, enzymes denatured
if too hot
• Moist
– Easier to dissolve food,
prevents drying out
• Plenty of oxygen
– Decomposers respire, need
oxygen to release energy
Uses: sewage treatment works,
compost
Carbon cycle
The amount of carbon is fixed
• Photosynthesis: green
plants and algae remove
CO2 from the atmosphere
– passed on when plants
are eaten
Carbon dioxide + water  glucose + oxygen
•
Respiration: living
organisms use oxygen to
break down glucose CO2 is
a waste product.
Decomposers respire too
Glucose + oxygen  carbon dioxide + water
•
Combustion: fossil fuels
contain carbon , when we
burn then CO2 is produced
Fuel + oxygen  carbon dioxide + water
Recycling organic waste
• Organic waste – (e.g. Vegetable peelings) doesn’t rot
easily in landfill, it forms a liquid that can pollute
waterways and methane gas which contributes to
global warming
Making compost:
To speed up the process:
• Mixing regularly helps oxygen get in
• Warmer conditions (up to about 70C)
• Moist conditions
Methods: compost heap, black bag,
compost bin, council composting
Exam questions
[2 marks]
Genetic
engineering
Genetic and
environmental
differences
B1.6 Variation
Inheritance
Types of
reproduction
Cloning plants
Cloning animals
Inheritance
• Genetic information is in the nucleus of cells
• Inside the nucleus are chromosomes made up of DNA – humans have 46
chromosomes (23 pairs)
• Genes are a section of DNA and control enzymes and proteins made in
your body
• Genes are passed on to you in the sex cells (gametes) from your parents –
they come in pairs
Types of reproduction
Sexual reproduction
Asexual reproduction
• Male sex cell and female sex
cell
• Risky as the two have to
meet
• BUT provides genetic
variation important for
survival
• E.g. Mammals, birds
• One parent
• No genetic variation –
clones
• Cells of body reproduce
asexually – divide in two for
growth and repair
• E.g. Bacteria, strawberries
Advantages – allows evolution, variation, increases chances of species survival
Disadvantages – need to find a partner, waste energy. Waste in producing
gametes, slower
Genetic and environmental differences
Nature – genetic variety
• E.g. Eye colour, gender, shape of nose
Nurture – environmental variety
• E.g. Scars, accents, drinking when pregnant
Combined causes of variety
• E.g. Height, weight
Investigating variety: scientists study twins adopted by
different families compared to identical twins brought up
together and non-identical twins
Plant cloning
Cuttings
Tissue culture
•
•
•
•
•
•
•
Remove a small section of the plant
New roots and shoot will form to give
you a new plant
Rooting powders and moisture will
help the process
Quick and cheap
Genetically identical plants
Used commercially for orchids and
fruit trees
•
•
•
Expensive but allows thousands
of new pants from tiny piece of
plant
Use plant hormones to make a
small group of cells produce a
big mass of identical plant cells
Using hormones these can then
forma new plant
This guarantees all plants will
have the desired characteristics
Animal cloning
Embryo cloning
• Best cow given fertility hormones to
produce lots of eggs and fertilise
from best bull
• Divide each embryo into individual
cells - Each cell grows into an
identical embryo in the lab
• Transfer embryos into surrogate
mothers - Identical cloned calves
born
Advantages: high quality
embryos taken to poor
places and produce lots
of milk / meat.
Can make lots of identical
copies of genetically
modified embryos that
produce genetically
useful compounds
Adult cell cloning
•
•
Advantages: Save animals from
extinction, Bring back prized animals,
Clone genetically engineered, medically
useful animals (e.g. Those with useful
proteins in their milk)
Disadvantages: Could lead to cloning
humans – ethics? Abuse of science –
cloning for organs, Reduces variety –
species less able to adapt if there is a
change (usually some of the species will survive
and reproduce but not if we are all clones)
Genetic engineering
• Changing the genetic
material of an organism
• A gene is taken from one
organism and transferred
into the genetic material of
a different organism
Genetic engineering – insulin
Human engineering:
Genetic diseases can be very serious
It might become possible to insert
‘healthy’ genes into the affected
cells using genetic engineering
Exam questions
[6 marks]
Theories of
Evolution
Classification and
evolution
B1.7 Evolution
Accepting Darwin’s
ideas
Natural Selection
Theories of Evolution
All species of living things alive today have evolved from the
first simple life forms
Jean-Baptiste Lamarck was a French biologist
His idea was that every animal evolved from primitive worms - The change was caused by
the inheritance of acquired characteristics
Problems: No evidence - People
didn’t like to think they
descended from worms People could see clearly that
changes were not passed onto
their children (e.g. Big muscles)
Accepting Darwin’s Ideas
Darwin travelled the Galapagos Islands and noticed animals were adapted
to their surroundings – his theory is that all living organisms have evolved
from simpler life forms. This process has come about by natural selection
Building up the evidence:
• Animal and plant specimens
• Breeding experiments with
pigeons
• Studied barnacles
• Network of friends also
interested (scientists,
pigeon breeders)
Why did people object?
Religious – god made the world
Not enough evidence
No way to explain inheritance –
genetics not known about
Natural Selection
1.
2.
3.
4.
Variation
Competition
Survival of the fittest
Reproduction
Darwin’s finches
Examples of evolution:
Peppered moth,
Antibiotic resistance in bacteria,
Warfarin resistance in rats
Mutations: New forms of genes resulting from changes to existing genes – random –
mistakes made when DNA is copied in cell division. Mutations introduce more variety.
May have no effect or harmful but if better suited to the environment and more likely to
survive and reproduce
Classification and Evolution
Species: A group of similar organisms that are capable of
interbreeding to produce fertile offspring
Evolutionary tree
DNA evidence used to
decide which species
an animal belongs to
and work out
evolutionary
relationships
Exam questions: