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Diet and Metabolic rate
Carbohydrates – release energy
Fats – keep warm, release energy
Protein – growth, cell repair, cell replacement
Fibre – smooth digestive system
Vitamins and minerals – small amounts to keep healthy

Energy needs vary from person to person
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Energy fuels chemical reactions which are called your metabolism
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g
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g
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 Make you feel ill by damaging cells and producing toxins (poisons)
Viruses
 not cells, much smaller 1/100th the size of a bacterium
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White blood cells:
 Travel around body in blood and patrol for microbes
...
When WBC comes across a foreign antigen they will produce
antibodies to kill pathogen
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Antibodies then produced rapidly and carried round the body to kill all
similar bacteria or viruses
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Fighting disease – Vaccination
Protects from future infections
 When infected with new microorganism it takes white blood cells a few
days to learn how to cope with it
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These carry antigens which stimulate antibodies to be
produced and attack the microorganism
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Pros:
 Controls lots of infectious diseases that were once common
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As fewer people able to spread the disease
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Antibiotics kill the bacteria causing the problem without damaging your
body cells
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Antibiotics DON’T KILL VIRUSES! Because viruses are inside of body cells
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Investigating antibiotics
 Microorganisms grown in a growth medium (agar jelly) which
contains carbohydrates minerals proteins and vitamins
 Inoculating loops are used to transfer microorganisms to jelly
 Paper discs soaked in different types of anti-biotics and placed on the
jelly
Equipment is sterilised to prevent contamination – passing equipment through
a flame
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Fighting Disease – Past and Future
Semmelweis:
Make doctors wash their hands using antiseptic before entering his ward
Cut death rate of puerperal fever from 12% to 2%
Couldn’t prove why so when he left hospitals death rate rose again

Antibiotic resistance is becoming more common

Bacteria
 Can mutate to produce new strains
 New strain could be antibiotic resistant
 Or a new strain which no one would be immune to
Viruses
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Mutate often- hard to create vaccines
Real problem if virus evolved so it was both deadly and infectious
In an event precaution(s) would be took to stop spread
Worst-case scenario is a flu pandemic
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Viruses get inside of your body cells and use the cells machinery to replicate
itself multiple times
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What are antigens?
Antigens are proteins on the surface of all pathogens
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What is the difference between an epidemic and a pandemic?
Big outbreak of disease (epidemic) pandemic is a global spread of a disease
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Why would a course of antibiotics not
be suitable for treatment of flu? (2 marks)
Because flu is a virus and antibiotics can only treat bacterial illnesses
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Describe 3 ways that white blood cells fight pathogens
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Explain what a vaccine involves and how being vaccinated against typhoid can prevent a
person from catching the disease (4 marks)
a dead, weakened or inactive version of typhoid is injected into the body
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When the real pathogen invade the white blood cells can
rapidly mass produce the right antibodies to quickly remove the pathogen preventing you
from feeling ill
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When the impulse reaches the end of the sensory neurone it triggers chemicals
to be released which diffuse across the gap and attach to the relay neurone
this then triggers a new electrical impulse to set off along the relay neurone
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Stimulus detected by receptors, impulses sent along a sensory
2
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When impulse reaches synapse between relay neurone and sensory
neurone chemicals are released
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Synapse between relay and motor neurone the same thing happens,
chemicals are released and cause impulse to be sent along motor
neurone
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Impulses travel along the motor neurone to the effector
6
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Neurones in reflex go through spinal cord or unconscious parts of the
brain – quicker as you don’t need to think about it

Stimulus – recpetor – sensory neurone – relay neurone – motor neurone –
effector – response

Hormones
Chemical messengers sent in the blood
Carried by blood plasma
Only affect particular cells called target cells
Produced by various glands
Travel at the speed of blood
Hormones are chemical messengers, travel in blood to activate target cells

Pituitary gland: produces LH and FSH
Ovaries: produce Oestrogen

Hormones Vs Nerves
Nerves
Very fast
Act for very short time
Act on precise area

Hormones
slower
Act for a long time
Act on a general area

Warm Up and Exam Questions
what are the five sense organs in the human body?
Eyes, ears, nose, skin, tongue
In what form is information transmitted along nerve cells?
electrical impulses
What are the two different types of effectors in the human body
Glands and muscles
What name is given to the connection between two nerve cells?
Synapse
What are Hormones secreted by?
Glands
Give one difference between a nervous response and a hormonal response?
nervous responses are much quicker

1a) reflex action
bi) B
ii) D
c) when the impulse reaches the end of the neurone chemicals are
released which diffuse across the gap and then trigger a new electrical
impulse to be sent in the next neurone (2 marks)
d) give one physiological advantage to the body of these automatic
responses
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Minimise damage to the
body (1 mark)
2) FSH is produced in the pituitary gland it’s carried round the body in the
blood plasma and acts on target cells in this case the ovaries and stimulates
them to produce oestrogen (3 marks)

The Menstrual Cycle
4 Stages
Stage 1: day 1 is when the bleeding starts- uterus lining breaks down for about
four days
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No fertilised egg
is there lining breaks down and cycle starts again

Hormones involved in the menstrual cycle
FSH
 Causes egg to mature in the ovaries
 Stimulates ovaries to produce oestrogen
 Produced in the pituitary gland
Oestrogen
 Causes pituitary gland to produce LH
 Inhibits further release of FSH
 Produced in the ovaries
LH
 Stimulates release of an egg
 Produced by pituitary gland

Controlling Fertility
Hormones can reduce fertility
Oestrogen prevents release of egg- taken every day inhibits FSH so egg
production stops and stays stopped
Progesterone- stimulates thick cervical mucus which prevents sperm getting
through and reaching egg
The Pill
 Oestrogen and progesterone
 Pros – 99% effective, reduces risk of some cancers
 Cons- isn’t 100% effective, can cause side effects, doesn’t protect against
STI’s
 Also a progesterone only pill which has fewer side effects but not as
effective
Or increase it
FSH and LH injections to stimulate ovaries to release eggs
 Pros – helps women get pregnant
 Cons – doesn’t always work, too many eggs released causing multiple
pregnancies

IVF- collecting eggs from a woman’s ovaries and fertilising them in a lab using
sperm
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When tiny ball of cells it is transferred
to the womb
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 Pros – give infertile couple a baby
 Cons – strong reaction to hormones, increased risk of cancer, multiple
births

Plant Hormones
Auxin
Controls growth near tips of shoots and roots
responds to light, gravity and moisture
if tip of plant removed no auxin available plant stops growing
Auxin promotes growth in shoots
Shoots grow towards light
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 Gravity moves auxin to lower part of shoot
 Cells grow faster on the lower side bending shoot upwards

Auxin inhibits growth in plant roots
Roots grow towards gravity
 Lower side more auxin
 Cells on top elongate faster root bends downwards
Roots grow towards moisture
 More auxin on side with more moisture
 Side away from moisture grows quicker root bends towards moisture

Plant hormones used in agriculture
Weed killers made from hormones which only affected broad leaved leaves
Rooting powder contains auxin helps plant cuttings grow roots and grow
quicker

Homeostasis
bodily levels need to be controlled:
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Ion content
Sugar content
Water content
Temperature

Ion content is regulated by the kidneys
Blood sugar levels need to be controlled
Water is lost from the body by sweat through the skin via the lungs in breath
and via the kidneys as urine
Cold day no exercise= more urine pale diluted urine
Hot day exercising= less urine dark concentrated urine

Body Temperature is controlled by the brain
Enzymes work best at 37 degrees Celsius

Warm up Questions
Describe what happens at day 1 of the menstrual cycle
the lining of the womb breaks down and bleeding begins
What is phototropism?
phototropism is how plants are sensitive to light and grow towards light
Name the hormone that controls phototropism
auxin
List four things that need to be kept constant in the body
ions, water, temperature, sugar levels
Why is it important that the human body is kept at 37 degrees C?
because enzymes work best at this temperature

Drugs
Drugs change body’s chemistry
can become addicted and get withdrawal symptoms
Medicinal – antibiotics
Recreational – legal or illegal e
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alcohol, nicotine
Performance enhancing – steroids
Performance enhancing drugs have health and ethical problems
Athletes use them to get better at sport
anabolic – increase muscle
stimulants – increase heart rate
steroids cause high blood pressure
some drugs banned by law and sporting bodies
For drugs: Athletes have right to make own decision, drug free sport isn’t fair
anyway as different athletes have better training equipment etc
Against drugs: unfair because people get an advantage through drugs not
training, athletes may not be fully informed about the health risks

Drug claims
Statins:
 Prescribed drugs lower risk of circulatory disease
 Evidence that statins lower blood cholesterol and lower risk of heart
disease
 Research done by government no connection to manufacturers
 Used control groups
Cannabis:
 Illegal drug cause mental health problems
 Results vary open to interpretation
 Not enough definite scientific evidence

Testing Medicinal Drugs
1
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Test on live animals- see how the drug works- see its toxicity- see the
best dosage
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3
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Optimum dose is
found
Patients put into two groups one group given the drug the other a
placebo
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now used to treat leprosy
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Alcohol: nervous system slows reactions, poor coordination, unconsciousness
affect liver and brain, addictive
Costs to the NHS, cause sorrow and anguish to people affected by them

Adaptions
Desert animals adapted to save water and keep cool
they have large s
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a – v ratio reduces heat loss
Well insulated
thick layer of blubber or insulation also acts as an energy store
thick hairy coats keep body heat in
Camouflage
white fur to avoid detection by predators and sneak up on prey
Desert plants adapted for little water
small s
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ratio e
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spines reduce water loss
Water storage tissues
cacti store water in thick stem
Maximising water absorption
cacti have shallow but extensive roots others have deep roots to access
underground water
Some plants and animals are adapted to deter predators
 Armour – thorns, spines tortoise shells etc
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of predators
no
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of competitors
Non-living factors:
change in average temperature
change in average rainfall
change in level of air or water pollution
Population
1
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Population decreases
not enough prey to support predators – predator numbers fall
3
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Energy from the sun is source for nearly all life on earth
2
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Respiration supplies energy for all life processes including movement
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Especially true in
mammals and birds whose bodies are kept at constant temperature
4
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Energy also
wasted in faeces
5
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Explains why there is no many food chains with more than 5 trophic
levels because so much energy is lost there isn’t enough to support any
more organisms

Decay
Elements are cycled back to the start of the food chain by decay
1
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Plants take carbon oxygen hydrogen nitrogen from air and soil
and turn them into complex compounds e
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carbohydrates, proteins
and fats which are passed up the food chain
3
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Microorganism digesting material is decay
5
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All important elements are recycled
7
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Compost bin
 Waste made into compost
 Compost is decayed remains of animal and plant matter
 It recycles nutrients back into the soil

The Carbon cycle
1
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Carbon dioxide removed by plants
2
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When plants and animals die detritus feeders and microorganisms feed
on remains when these organisms respire carbon dioxide is returned
4
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Fossil fuels are burnt which releases carbon into the atmosphere

Warm up Questions
what is a trophic level
the energy stage on a pyramid of biomass or a feeding level in a food chain
what is biomass
the mass of the living material in a trophic level
why do most food chains have no more than 5 trophic levels?
because there is not enough energy to support it as so much gets lost at each
trophic level
What is a stable community
a stable community is when the material taken out of the soil is balanced by
those that are put back in
name two types of organisms that remove carbon dioxide from the
atmosphere using photosynthesis
green plants and algae
name the process that releases carbon dioxide from fossil fuels
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Most cells have nucleus where genetic material is stored as
chromosomes
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Human cell contains 23 pairs of chromosomes
3
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Different genes control the development of
different characteristics
4
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there can be different versions of the same gene giving different
versions of the same characteristic e
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eye colour these are called
Alleles
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DNA is coiled up to form the arms of the chromosome

Sexual Reproduction
Produces genetically different cells
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Genetic information from two organisms is combined
Mother and father produce gametes
Each gamete contains 23 chromosomes
Egg and sperm fuse together to form a cell with the full number of
chromosomes

Sexual reproduction involves the fusion of
male and female gametes
Because there are two parents the offspring
contain a mixture of their parents’ genes

Asexual Reproduction
Produces genetically identical cells
Ordinary cell can make a new cell by dividing
Asexual reproduction one parent there is no fusion of
gametes, no mixing of chromosomes and no genetic
variation
Offspring are genetically identical to the parent they are
clones

1
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Each chromosome splits down the middle to form two identical sets of
half chromosomes
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The DNA replicates itself to form two identical cells with a complete set
of x-shaped chromosomes

Warm up Questions
A pair of identical twins have green eyes
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Twin
B weighs half a stone more than Twin A
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2
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4
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Quick and cheap

Tissue culture:
1
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Grow into new plants which are clones
3
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2
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4
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6
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Hundreds of ideal offspring produced every year

Adult cell cloning
1
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3
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Taking unfertilised egg cell and removing the genetic material
Complete set of chromosomes from adult body cell inserted into cell
Egg cell stimulated with an electric shock making it divide
Ball of cells – implanted into surrogate mother to grow into clone of
original adult body cell

Issues surrounding cloning
1
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3
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5
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Useful gene cut from organism’s chromosomes using enzymes
2
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Chromosome put back into organism
Used to make bacteria produce human insulin
Genes can be transferred into animals and plants
GM crops: modified to be resistant to virus’s herbicides and insects
Sheep: engineered to produce substances like drugs in their milk which can be
used to treat illnesses
Genetic disorders: scientists trying to treat disorders by inserting working
genes into sufferers
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Increase yield of crops
2
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Al ready being grown elsewhere in the world without any problems
Cons:
1
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Not convinced GM crops are safe
3
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few cells are taken and grown in a growth medium using hormones they grow
into new plants that are clones of the parent plant
Other than tissue culture name another way plant clones are produced
cuttings
Give an advantage of cloning using cow embryo transplantation
100s of ideal offspring can be produced each year
What is a reduced gene pool?
when there are fewer alleles in a population
Name one useful product genetically modified bacteria produce
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Species with similar characteristics have similar genes evolutionary trees
show common ancestors and relationships between organisms
Ecological relationships
 Organisms in same environment look similar suggesting they compete
for food
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Individuals within species show variation difference in genes by sexual
reproduction and mutations (change in DNA)
2
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Genes responsible for useful characteristic is passed on
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Over time useful characteristic will accumulate in population
Evolution occurs due to mutations
Mutation – change in DNA
Most of the time there is no effect
Not everyone agreed with Darwin
 Went against religious beliefs
 Couldn’t provide good explanation for how useful characteristics
appeared and how it was passed on
 Wasn’t enough evidence to convince other scientists
Lamarck:
“if a characteristic was used a lot by an organism then it would become more
developed
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Natural selection is a
process that explains how this happens by mutations

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