B1 Topic 1 – Cheat Sheets
Classification (How Scientists put animals
Kingdoms
into groups)
Key words:
-multicellular – made up of many cells
-unicellular – made up of ONE cell
-Heterotrophic feeders– eating and digesting food
-Autotrophic feeders – using an energy source to make food e.g.
photosynthesis
-Saprophytic feeders – digesting food outside the body and then
absorbing it
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The order of Classification is: Kingdom,
Phylum, Class, Order, Family, Genus
and Species (Remember –
K.P.Crisps.Offer.Fairly.Good.Snacks
There are five kingdoms of organisms:
Animalia, Plantae, Fungi, Protoctista
and Prokaryotae (be careful with
spelling)
Scientists write the Kingdoms in Latin
so it is not translated wrongly – e.g.
French Scientists also use the term
‘Animalia’ when classifying organisms.
Multicellular
Animalia
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Heterotrophic
M.R F.A.B – Mammals, Reptiles, Fish,
Amphibians and Birds
--------------------------------------------------------------Oxygen Absorption methods
Lungs – Mammals, Birds, Reptiles and adult
amphibians
Gills – Fish
Moist skin – young amphibians
--------------------------------------------------------------Reproduction
Viviparous (internal fertilisation/live birth) –
mammals
Oviparous – (external fertilisation/lay eggs) –
Reptiles, Fish, Amphibians, Birds
--------------------------------------------------------------Thermoregulation (how they regulate heat)
Homeotherm (warm blooded) – mammals and
birds
Poikilotherm (cold blooded) – reptiles, fish,
amphibians
Prokaryotae
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Autotrophic
Saprophytic
Complex
structure
Simple
structure
Protoctista
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A few
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Cell wall
Vertebrates (Chordata) and Invertebrates
(non chordata) (back bone and no back
bone)
Fungi
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Unicellular
Nucleus
Viruses – There is no kingdom for viruses as
scientists do not think of them as being alive; they
are not living until they are in a host cell. The virus
doesn’t show all the life process such as growth or
feeding.
Plantae
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Problems with classification
 An axolotl (an amphibian) has gills even when it is an adult
 Sharks are fish but use internal fertilisation and some give
birth to live young.
Species
Definition: When to organisms can interbreed to produce FERTILE
offspring.
 Two organisms with similar characteristics can reproduce
but do not belong to the same species – these are called
HYBRIDS
 E.g. donkey + zebra = Zedonk
 Lion + tiger = Liger
Most hybrids are infertile e.g. zedonk however ligers are fertile
and can reproduce to form liligers
 HYBRIDS DO NOT BELONG TO ANY SPECIES
Naming Species
An organism has two Latin words
E.g. Erithacus rubecula
The first name is the GENUS - Erithacus
The second name is the SPECIES - rubecula
 The system is agreed by scientists all over the word to allow
them to communicate clearly, whatever their language
Variation – Differences in characteristics
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All organisms are adapted to their
surroundings e.g. a dessert fox does
not look the same as an artic fox.
Polar bears have:
 Thick layer of blubber for insulation
 White fur for camouflage
 Thick fur for insulation
 Small ears to stop it losing heat
 Large feet to spread out its weight to
stop it sinking in the snow
Deep-sea Pompeii worms (live in deep-sea
hydrothermal vents, up to 350 degrees):
 The body of the worm is covered in a
thick layer of bacteria that helps
protect it from the heat
 It is adapted to withstand high
pressures
 It has no eyes (as it is dark) but has
sensitive tentacles
Evolution
Organisms generally produce far more
offspring than the environment can support.
Most will die before adulthood because there
are not enough resources for all of them (e.g.
food and space)
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Organisms have different
characteristics and they are in
competition for resources.
The organisms that have the best
suited characteristics for the
environment will survive ‘survival of
the fittest’
The organisms that survive pass on
their genes to their offspring.
The organisms that didn’t survive will
eventually become extinct
Genetic variation – variation caused by information inside cells
(genes)
Environmental variation – differences in characteristics caused b the
environment
Discontinuous variation – e.g. rolling your tongue, blood group and
gender (you can only ever be one) caused by genetic variation
Continuous variation – e.g. height, weight (you can change) caused
by genetic and environmental variation
This graph shows continuous variation – the shape of the graph (bell
shape) is called normal distribution curve.
It shows that most individuals measure within the middle part of the
range in variation and there are fewer individuals within the
measurements at the extremes of the range.
Genes
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DNA is found in the nucleus of a cell.
Lots of DNA makes up a chromosome
There are 23 pairs or 46 chromosomes in the human body
Chromosomes are divided up into genes
Genes carry instructions for out characteristics e.g. eye
colour
Alleles are alternate forms of a gene e.g. blue eyes or
brown eyes
Phenotype – Physical appearance e..g brown eyes or tall
Genotype – Genetic makeup e.g. BB or Bb
Homozygous dominant – BB, TT, RR
Homozygous recessive – bb, tt, rr
Heterozygous – Bb, Tt, Rr
Genetic disorders
Cystic fibrosis (CF) is caused by a recessive allele, cc.
The lungs get clogged with thick mucus which makes it difficult to breathe and causes chest infections. The mucus also blocks tubes to the small intestine
and stops the enzymes that digest food – therefore this can result in weight loss
Sickle cell anaemia
This is also caused by a recessive allele.
People with the disease can become tired and short of breath. Their joints can also become painful as blood cells stick together and block blood vessels