Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Diet and Exercise
Mineral ions and vitamins are also
important in a healthy diet
...

➔ -too little food = underweight
➔ -too much food = overweight
➔ too little vitamin D = leads to rickets
➔ poor diet = type 2 diabetes
when someone uses more energy than they consume
they will lose body mass

factors affecting health:
inherited factors
cholesterol levels in blood

metabolic rate factors:
➢ age
➢ weight
➢ gender
➢ inherited factors
➢ proportion of muscles to fat
➢ amount of exercise usually stays high for a short
while after)

defending against infection- bacteria
diseases caused by bacteria
main types of pathogen:
bacteria
viruses

bacteria
➔ come in many shapes
and sizes (largest is 10
micrometres long)
➔ living cells
➔ can multiply rapidly
➔ once inside body can
release toxins or poisons
that cause us to feel ill

food
poisoning

cholera
(think of a
collar)

typhoid
(think of a
bow tie)
whooping cough
(think about waiters
coughing over your
food)

defending against infection - viruses
viruses
● many times
smaller than
bacteria
● smallest
organisms
known
● consist of a
fragment of
genetic
material inside
a protective
protein coat
● can only
reproduce
inside host
cells

inside host cells:
1
...
makes
hundreds of
thousands of
copies of itself
3
...
virus passes
through the
bloodstream
and airways

diseases caused by viruses:
➔
➔
➔
➔
➔

MMR - mumps, measles and rubella
influenza
AIDS
colds
chicken pox

defending against infection

white blood cells:
➔ ingest pathogens
and destroy them
➔ produce :
➔ antibodies to
destroy a particular
pathogen
➔ or antitoxins to
counteract toxins
produced by
pathogens

lymphocytes:
➔ a type of white blood
cell
➔ produces specific
antibodies to kill a
particular pathogen
➔ these antibodies have
a protein that has a
chemical fit to a
certain antigen
➔ reproduces quickly &
makes copies of the
antigen

antibodies:
➔ lymphocytes produce
them
➔ they are proteins
➔ can neutralise
pathogens by: 1) bind
to pathogen and
destroy 2) coat
pathogens - clumping
them together so they
are easily ingested by
white blood cells

vaccinations
Vaccination involves putting a
small amount of an inactive
form of a pathogen, or dead
pathogen, into the body
...

if the person gets a live
form of the pathogen, the
white blood cell can
respond in the same way,
as if they had had the
disease before (quicker)
If a large proportion of
the population is
immune to a particular
pathogen, the spread of
that pathogen is greatly
reduced

you are not in danger
of developing the
disease however
some people may
have a mild reaction

Hygiene
a simple way to reduce the risk of infection:
➔ maintain personal hygiene
➔ keep hospitals clean

Ignaz Semmelweiss - 19th Century
● realised the importance of cleanliness in hospitals
● doctors washing their hands was not common
● once the policy of washing hands between
patients was put in place the number of deaths
from infectious diseases was greatly reduced
● however at the time his idea was ignored as
people did not know that pathogens caused
diseases at the time
Ignaz Semmelweiss

Medicine

Some medicines:
★
help to relieve the symptoms of a disease
★ kill the infectious pathogens
...

Since the discovery
of penicillin, many
other antibiotics have
been discovered and
developed
...
These cells
survive and reproduce,
producing even more
bacteria that are not affected
by the antibiotic
...

if people develop MRSA, it will develop
rapidly as there is no effective treatment
to reduce chances:
● avoid unnecessary use of antibiotics
● complete the full course

The main steps in the development of resistance are:
1
...

3
...


The rate of development of resistant strains of bacteria can be slowed down
...


Growing microorganisms in the lab
1878, Robert
Koch discovered
how to grow
bacteria in a petri
dish
...

cholera and TB)

scientists now grow
microorganisms in labs so they
can be investigated

culturing microorganisms: (must have
sterile conditions)
●
●

●

petri dishes, nutrient agar jelly and other culture
media must be sterilized
the inoculating loops used to transfer
microorganisms must be sterilised (usually by
passing the metal loop through a Bunsen burner
flame)
the petri dish lid is usually sealed with sticky tape to
stop air microorganisms getting in and
contaminating the culture

lab safety:
➔ if you cultivated microorganisms close to body
temperature they would grow pathogens that could
harm your health (grow quicker in warm temps)
➔ maximum temperature is 25 degrees
➔ however higher temperatures are used industrially

Nerves and Hormones
receptors
sensitive to light

sensitive to sound
and position of
head

chemicals in food

chemicals in the
air

sensitive to touch,
pressure, pain &
temperature

When a receptor is stimulated it sends a signal along the nerve cells, also called neurons, to the brain
...


Neurones

effector
motor neuron
motor neuron

relay neuron
sensory neurons - carry signals from
receptors to CNS
relay neurons - carry messages from one
part of the CNS to another
motor neurons - carry signals from CNS
to effectors
signals cross synapses using chemicals
...
water content is controlled by: the lungs (as we breathe), skin
(sweating) & urine (produced by kidneys)

internal conditions part 2
ion content of the body:
controlled to protect cells from too much water entering or leaving the cells
...
Controlled by:
● sweating
● shivering
● controlling blood flow to skin

blood sugar levels
controlled to supply cells with a constant supply of energy
...


●

hormones reach their
target organs by
travelling via the
bloodstream from their
glands

Hormones in the Menstrual Cycle

oestrogen levels

FSH
secreted by the pituitary
gland
...

sometimes twins/triplets can be concepted because
treatment can boost the production of mature eggs
(can increases the risk of complications in
pregnancy and childbirth, and may lead to premature
or underweight babies)

IVF

●

can have
bad side
effects changes in
weight,
mood and
blood
pressure

●

ethical
issues

●

●

allow couples to
choose when to
start and stop
having children
modern birth
control has less
estrogen so
side effects are
minimal

●

●

●

If a couple are having difficulty conceiving a child
because the quantity or quality of the man’s sperm is
poor then IVF can be used
As FSH can also be used to encourage the
production of several mature eggs at once, it is used
as part of IVF to increase the number of eggs
available for fertilisation
...

shoots and roots respond
differently to high
concentrations of auxins:
➔ shoots grow more
➔ roots grow less

weed killers:
Selective weed killers work on some plants but not others
...
Selective weed killers contain growth hormone
that cause the weeds to grow too quickly and then die
...


rooting powder:
Rooting powder contains growth hormones to make stem cuttings quickly develop
roots

phototropisms & gravitropism
In a shoot, the shaded side contains more auxin
...


Auxins have the opposite effect on root cells
...
This causes the root to bend away from the light
...
In a root placed horizontally, the bottom side contains more auxin than the top side
...

In a shoot placed horizontally, the bottom side contains more auxin than the top side
...


developing new drugs
New medical drugs have to be tested to ensure that they work, and are safe,
before they can be prescribed
...

2
...


The drugs are tested using human cells grown in the laboratory
...
A typical test involves giving a known amount of the substance to the
animals, then monitoring them carefully for any side-effects
...
Very low doses of the drug
are given to begin with
...


double blind trials
designed to minimise the placebo effect:
some patients are given a drug, others a
placebo
...


it caused damage to the arms
and legs of unborn babies,
leading to them being
incompletely formed
...
Others are
legally available on prescription or even in some
medicines available from the pharmacy
...
They may also damage the
athlete’s body
...
We compete with
animals and plants all over
the world
...


Cold Climates
●

●
●

●
●

a white appearance as
camouflage from prey on the
snow and ice
thick layers of fat and fur for
insulation against the cold
a small surface area to
volume ratio, to minimise
heat loss
a greasy coat that sheds
water after swimming
large furry feet to distribute
their load and increase grip
on the ice
...


survival in the desert
...


spines instead of leaves
...
The
spines also protect the cacti
from animals that might eat
them
...
Growing
predator numbers will
eventually reduce the food
supply to the point where it can
no longer sustain the predator
population, and the number of
predators will go down
...
This causes
acid rain
...
This makes
lichens natural indicators
of air pollution
...

In places where no
lichens are growing, it
is often a sign that
the air is heavily
polluted with sulfur
dioxide
...
The
depth of the rain
should be measured
daily and at the same
time of day
...
The
carbon becomes part of complex molecules
such as proteins, fats and carbohydrates in the
plants and algae

returning carbon to atmosphere
Organisms return carbon dioxide to the
atmosphere by respiration
...
Plants, algae and
microorganisms do too
...
For
example, identical twins inherit
exactly the same genetic
information from their parents
...


Reproduction
sexual reproduction

cloning plants - tissue culture

asexual reproduction

cloning - cuttings
The simplest way to clone a plant
involves taking a cutting
...
Plant
hormones are often used to encourage
new roots to develop
...

After a few weeks, new roots develop
and a new plant is produced
...


cloning in animals
Embryo transplants
● A developing embryo is
removed from a pregnant
animal (at an early stage)
before the embryo’s cells
have had time to become
specialised
...

● the offspring are identical to
each other and genetically
related to the original
pregnant animal
...


adult cell cloning

Genetic Engineering

Genetic modification works in animals, plants and microorganisms
...
Some GM crops are resistant to certain herbicides
(weed killers) while others are resistant to insect pests
...
GM crops generally have
increased yields, useful for feeding
a growing population
...

However, some people are excited
by the almost limitless possibilities
of genetic modification, while others
believe the process is unethical and
should be banned
...


Evolution
Darwin’s Theory

Lamarck’s Theory

He studied variation in plants and animals
during a five-year voyage around the
world in the 19th century
...


1
...
The reasons for skepticism

by an organism

include:

becomes bigger and

Darwin’s theory conflicted with

stronger, and one

religious views that God had

that is not used

made all the animals and plants

●

eventually disappears

on Earth

2
...


theory was published to discover
how inheritance and variation
worked

Lamarck's theory cannot account
for all the observations made about
life on Earth
...

On the other hand, Darwin's theory
can account for the continued
presence of simple organisms
...

The key points are that:
●

individuals in a species show a wide
range of variation

●

this variation is because of
differences in their genes

●

individuals with characteristics most
suited to the environment are more
likely to survive and reproduce

●

the genes that allow these
individuals to be successful are

In this evolutionary tree,
species A and B share a
common ancestor
...
All seven species
share a common ancestor,
probably from the distant
past
...

Individuals that are poorly adapted to their
environment are less likely to survive and
reproduce
...
Given enough time, a species
will gradually evolve
...
For example, if the Earth
had been hotter, colder, bigger or
smaller, our bodies would have
changed to suit those conditions
...
Moths with a mutant

viruses reproduce very rapidly
...
This gave

evolve in a relatively short time
...
coli
...
(natural selection)

can be damaged or changed when it
reproduces
...


bark with soot
...
The black variety now had the advantage and were

the bacterial cell
...
Over time, black peppered

resistance to an antibiotic
...


antibiotic is present, the resistant bacteria
have an advantage over bacteria that are
not resistant
...




---