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

---

B1
...






Classification means grouping things by their features
or characteristics

The Five Kingdoms

There is no kingdom for viruses because most scientists
do not think of them as being alive
...

However the actual virus particle does not show other
life processes, such as growth or feeding, like other
organisms
...
2 – Vertebrates and invertebrates




Vertebrates are animals that have a backbone (a series of small bones called vertebrae)
...
Fish have gills to absorb oxygen from
water
...


One thing scientists did agree on
was that platypuses were
vertebrates

We can also divide vertebrates into groups using reproduction
characteristics
...

This is where the adult female released her eggs into the water where
they are fertilized by sperm released by an adult male
...

Another characteristic we can use is whether the vertebrates are
homeotherms
...
Other vertebrates are poilikotherms, which
means that their body temperature varies with the temperature of their
surroundings
...
We may have to look at many characteristics to help
decide in which group to place an organism
...
3 – Species
A species is a group of organisms that can breed with each other and produce fertile offspring
...

 Problem 1 – Some species reproduce asexually from parts of their body or by diving in two
...

 Problem 2 – Some organism from closely related species can interbreed and produce hybrid offspring that are fertile

Difficulties with classification


Mallard ducks can hybridise with other closely related
species to produce fertile hybrid offspring
...




Neighboring populations of the same species may
have slightly different characteristics but still
interbreed
...
The chain often forms a
ring shape and so these organism are called ring
species
...


Naming a species


An organism’s scientific name has two Latin words
(genus and species)
...

Organisms that share the first word in their name are
closely related
...




The binomial system is also useful because organisms
with the same common names may actually be
different species
...
The system is
agreed by scientists all over the world to allow them to
communicate clearly, whatever the language
...
4 – Variation
What is variation?
Differences in characteristics are called variation
...
The variation within a species can make classification difficult
...
To count the species you need to be able
to identify them which can be tricky if species are very similar to one another
...




Biodiversity is important because we obtain many products from living things e
...
foods and medicines
...


B1
...

Organisms from Polar Regions are adapted to living in the cold
...
Hot fluids, at more than 3500C, come out of these vents and cool
quickly
...


Different types of variation





Discontinuous variation in characteristics is usually caused by the instructions within your cells and is called
genetic variation
...
This is called a normal distribution curve
...

Characteristics that show continuous variation are often controlled by both genes and the environment
...
Acquired characteristics are caused by the environment and so cause
environmental variation between organisms
...
7 – Evolution



Organisms generally produce far more offspring than the environment can support
...

The offspring will show variation in their characteristics
...
Individuals that happen to have variations that are better adapted will be more likely to survive
...
Individuals that survive may breed and so may pass
their variations on to their offspring
...
Charles Darwin suggested that if the environment changes,
natural selection will result in characteristics of a species changing gradually from generation to generation
...

Speciation is the formation of new species, such as when populations of a species are separated
geographically and evolve until they are no longer capable of interbreeding
...
8 – Genes




Three main parts of cells are the cell membrane, the
cytoplasm and the nucleus
...
Each
strand forms a structure called a chromosome
...
There are
usually to copies of each type of chromosome
...
g
...
Different forms of the same gene
are called alleles
...
Each copy of a gene may be a different
allele
...
Human body cell nuclei contain 23
pairs of chromosomes, which contain about 23,000
different genes in total
...
Each
different sets of alleles gives each of us slightly
different characteristics
...
Each
chromosomes carries a large number of genes and
each gene does a particular job
...




B1
...
The male gametes are sperm cells in animals and pollen grains in plants
...
Gametes are different to most body cells because they only
have one copy of each chromosome
...
In sexual reproduction two gametes fuse together
...


A recessive characteristic is only seen if both alleles are recessive
...
A
dominant allele is shown by a capital letter
...
The
alleles in an organism are its genotype
...
If both alleles for a gene in an
organism are the same, the organism is homozygous
...


B1
...
The sickle cell is recessive,
so pope who have two copies of the allele suffer
from the disorder
...
Suffers can also have times
when their joints are incredibly painful because
their red blood cells stick together and block blood
vessels
...


Cystic fibrosis


Family pedigree charts


Figure D is a family pedigree chart, showing how
cystic fibrosis is inherited
...


Another genetic disorder caused by a recessive
allele is cystic fibrosis
...
Mucus also blocks some of
the tubes that carry enzymes to the small intestine
to digest food
...

This is called pedigree analysis
...


B1
...
For instance, it
needs enough water for substances to dissolve and
for chemical reactions to take place inside the cells
...
Temperature is also kept constant so that
the enzymes that help reactions to occur can work
quickly
...

The body loses water in breath and sweat
...
It also loses
water in urine, and if the boy contains too much
water the kidneys produce more urine
...
The control of water in the
body is called osmoregulation
...
Blood glucose
regulation is important because if glucose
concentration is too high or low you can get very ill
...
The opposite (vasodilation) happens when the body is hot and needs to lose heat
...
This means as a change to the body happens
in one direction, mechanisms in the body work to make it change in the opposite direction
...


B1
...

Anything your body is sensitive to is
called a stimulus
...
For example your skin
contains certain receptor cells to
detect the stimulus of temperature
change
...
The brain
processes this information and can
send impulses to other organs to
alter the way the body works
...
This transmission of
impulses is called neurotransmission
...
The Dendron has many
branches at the end called
dendrites that receive impulses from
receptor cells or other neurons
...
The
impulse then passes along the axon
to the endings where it passes
across to other neurons
...
14 – Responding to stimuli
Different neurons


The neurons hat receive impulses from
receptor cells are sensory neurons
...
The neurons that take impulses
to effectors are motor neurons
...
Relay neurons are
short neurons that are found in the spinal
cord, where they link motor and sensory
neurons
...




Many neurons have a fatty layer
surrounding the axon
...
It helps to insulate the
neuron from surrounding tissue
...

Impulses are transmitted
across the gaps by
chemical substances called
neurotransmitters
...

However, having synapses is
useful because the
chemicals are only released
from the axon endings
...


The reflex arc


If you pick up a very hot
object you immediately
respond my dropping it
...
Reflex actions are
responses that are
automatic, extremely quick
and protect the body
...

Reflex arcs bypass the parts
of the brain involved in
conscious thought so are
quicker than coordinated
responses
...
15+16 Hormones + Diabetes
Hormones


Hormones are produced and released by endocrine
glands
...
An organ that
responds to a certain hormone is a target organ
...
After a meal the concentration
of glucose in your blood goes up
...
Insulin affects certain cells, which then
take glucose out of blood and convert it into
glycogen
...

This is when the pancreas does not produce insulin, so
when blood glucose concentration rises, the body is
unable to correct them
...

Insulin must be injected into the subcutaneous fat
layer beneath the skin, as fat easily absorbs the insulin
...


Type 2 Diabetes








This usually occur when the cells in a person’s body
respond less well to insulin – the cells become resistant
to it
...

You are classed as obese if you have a BMI of over 30
...

BMI= weight / height2

B1
...
If it’s caused by light is
called phototropism
...
Plant roots are negatively
phototropic
...


Hormones and phototropism


Auxins are also found in root tips, where they have the
opposite effect to that in shoots
...
It helps the plant roots to anchor the
plant in place and reach moisture underground
...
Once this is completed, the seed
releases a plant hormones called gibberellins
...


Artificial auxin is used because it only makes plants
with broad leaves grow out of control and i
...
Plants
with narrow leaves are unaffected
...


Rooting powder


Positive phototropism is caused by plant hormones
called auxins
...

Shoots grow towards the light
...

Large numbers of the same plant can be produced
quickly using cuttings, compared to growing from
seed
...
The flower are sprayed with the hormones
that causes the fruit to develop but not to grow seeds
...


Fruit ripening


Plant hormones naturally control the ripening of fruits
...

E
...
Fruit trees are sprayed with hormones to stop the
fruit falling off
...


B1
...
Some of these coordinate how we behave and respond to stimuli
...
Any chemical substance that changes the way in which he body works, is called a drug
...
This speeds up reaction times
...
Some are medicines – to limit
damage caused by diseases or injuries
...

Some illegal drugs are used in carefully controlled conditions in hospitals
Most drugs can be addictive which means that people become dependent on the drug and feel that they cannot
function properly without it
...
22+23 – Damage caused by smoking
and effects of alcohol
Damage caused by tar


Tobacco smoke contains many chemical
substances
...
These can cause cancers, which
develop most often in the lungs and mouth
...
It is found in tobacco smoke
...
It
also makes blood vessels narrower
...
If the heart gets too little
oxygen it may cause a heart attack
...


Short term effects of alcohol




It slows down activity in the brain and nervous
system
It reduces negative feelings
It lowers inhabitations

Long term effects of alcohol





Drinking frequently can damage all organs
Cirrhosis of the liver
Damage to the brain
Addiction

The cost to society



Over 9000 deaths can be directly related to alcohol
5% of money spent on health in the UK each year is
used to treat people who have been drinking
excessively

B1
...


Difficult decisions


Doctors use a scientific criteria to make decisions based on the likelihood of success
...


Other ethical issues


Some donors would like to choose who should or shouldn’t get their organs
...


B1
...
There are millions of species of
microorganisms, some which live on or in our bodies
...

Many pathogen are bacteria, such as those that cause cholera, food poisoning etc
...

Sometimes through direct contact
between people and sometimes
carried by vectors
...
26 – Antiseptics and antibodies
Defense against invasion


Resistance

Animals including humans, have many different ways
to protect themselves against invasion by
pathogens
...
We also have
chemical defenses that help to kill pathogens before
they can harm us
...

Chemical substances that kill microorganisms outside
the body are called antiseptics
...
They
use chemical substances that are antibacterial to
prevent pathogens from causing damage
...
Antibiotics
are chemical substances that kill or prevent the
growth of bacteria and some fungi but not human
cells
...
This
means that resitant bacteria all of those different
types will be left behind when the antibiotic
treatment stops
...
28 – Interdependence and food webs



All organisms need food
...

Food chains show us what eats what
...
Food chains from a habitat can be joined together into a food web, which shows the feeding relationships
between the different organisms
...


B1
...
People need food and fresh water to survive
...
Crops often grow better with fertiliser added to the
soil
...
Everything that we use every day requires
resources, including fossil fuels to generate electricity to make them
...
Sulfur dioxide gas is released from burning fossil fuels and pollutes the air if the
concentration is high
...
This is called eutrophication
...
32 - Pollution indicators
Air pollution indicators


The more pollution we cause, the more harm there is to habitats
...
We call them indicator species
...




Recycling is the process of taking materials out of waste before disposal and converting them into new products that
we can use
...
33+34 – The carbon and nitrogen
cycle
The carbon cycle

The nitrogen cycle





The movement of carbon through dead and living
organisms and the atmosphere is shown in the
carbon cycle and is an example of natural recycling



Nitrogen is essential for the formation of amino
acids in proteins
...

There's lot of nitrogen in air – about 78% of the air is
nitrogen
...

Only nitrates are useful to plants, so we are
dependent on other processes to convert nitrogen to
nitrates in the soil

---