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Slide 1

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B1:Topic 1 ­
Classification variation
and inheritance
B1: Topic 1 (Flashcards)…read more

Slide 2

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Classification: the process of sorting organisms into groups based on their
Massive variety of organisms in the world, in order to recognise them
Biologists look carefully for similarities and differences.
Organisms are then sorted into groups with similar features or
characteristics. These groups can them be divided into smaller and smaller
groups and so on.
Classification is the division of organisms based on their characteristics.
First divided into Kingdoms
Kingdom Main Characteristics
Animalia (Animals) e.g. Multicellular (many cells); do not have cell walls; do not
mammals, insects, birds have chlorophyll; feed heterotrophically (unable to make
own food, digest internally); complex cell structure with
Plantae (Plants) e.g. trees Multicellular; have cell walls made of cellulose; have
mosses chlorophyll; feed autotrophically (making their own food
using energy source [via photosynthesis]); complex cell
structure with nucleus
Fungi e.g. pin moulds, Multicellular; have cell walls not made of cellulose; do not
mushrooms have chlorophyll; feed satrophically (off dead or decaying
organisms/organic matter, digest externally); complex cell
structure with nucleus
Proctista e.g. amoeba, Mostly unicellular(one celled) ­ a few are multicellular;
algae complex cell structure with nucleus
Prokaryotae Unicellular;
B1: Topic simple cell structure with no nucleus
1 (Flashcards)…read more

Slide 3

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Phyla Genera
KINGDOMS (sing. Classes Orders Families (sing. Species
phylum) genus)
· Animal · Vertebrate · Mammal · Primate · Hominid · Homo · sapiens
^The full classification of humans from kingdom to species.
Genus and species are coined to give each animal their unique
name. For instance, this is how we get the name `Homo sapiens.'
This system of naming is the binomial system. The name is
usually derived from the Latin, the system is effective because it
gives a universal name to each organism to eliminate confusion.
Viruses are not living things so do not have a
kingdom this is because the virus itself does not exhibit the
life processes necessary for scientists to consider it a living
organism. Only when the virus enters and takes over another living
cell can it alter the way that living cell works in order to reproduce
making copies of the virus.
Chordata phylum ­ (chordates) Animals that have a supporting rod that runs
along the length of their body surrounding a hollow nerve tube. All vertebrates
belong to this group because they have a backbone. However some
invertebrates have other means of supporting their bodies.
Vertebrate ­ Animal with a backbone
Invertebrate ­ Animal without a backbone
Classification of vertebrates: 1.)outer covering 2.)oxygen absorption (through lungs, gills or skin)
3.) reproduction (internal or external fertilisation) or whether oviparous (lay eggs) or
viviparous (develop embryos internally) 4.) thermoregulation (temperature regulation)
B1: Topic 1 (Flashcards)
homeotherms maintain constant body temperature, poikilotherms whose body temperature
fluctuates with environment.…read more

Slide 4

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Definition of a species
Species can also be defined as a group of organisms with similar
enough characteristics to interbreed (reproduce with other members
of the same group) to produce fertile offspring (able to reproduce.)
However, two closely related species can often breed to produce
hybrids which share characteristics of both species and are neither
one species or the other. Hybrids are often infertile so are unlikely to
pass on their characteristics through reproduction. The `zedonk' is the
hybrid offspring of a zebra and donkey.
Hybridisation in ducks Complications in classification ^the `zedonk' hybrid foal
Mallard ducks hybridise with other closely related species to produce
fertile hybrid offspring. A hybrid duck has two different species as
parents, yet is still fertile so could be considered a new species. Instead
this produces ducks with a wide range of characteristics.
What's more some species do not need to reproduce to produce offspring so there are further
problems with this definition.
For instance some plants and fungi reproduce asexually producing
individuals from part of adult organisms. It is also the primary form
of reproduction for multicellular organisms like bacteria and
protocists who reproduce by splitting in half. In this method of
reproduction offspring arise from a single parent so no
interbreeding can be seen therefore different species cannot be
B1: Topic 1 (Flashcards)…read more

Slide 5

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Ring species
Sometimes a chain of populations in close proximity to each other with similar
characteristics form a ring species. Neighbouring populations of the same
species have slightly different characteristics but can still interbreed. A ring
species is a ring of overlapping populations of two closely related species where
neighbouring populations can only interbreed but those at two ends of the chain
cannot because their characteristics have become too dissimilar. It is hard to
divide ring species into separate species and classifying between two species is
difficult because of the gradual change seen in characteristics.
Examples are Larus gulls in Northern hemisphere and salamanders on the
South West coast of USA
Larus gulls in the nothern
hemisphere are a ring species
Cannot interbreed
Larus fuscus and Larus
argentus are considered
to be two different
species because they
cannot interbreed.
^Ring species of salamanders
on south west coast USA
B1: Topic 1 (Flashcards)…read more

Slide 6

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Variation is the the differences
between an individuals characteristics
within a species. Variation can make
classification difficult. Variation within
a species can be grouped in two
types: e.g. human height
1.)Continuous variation distribution
curve Examples of
· No distinct categories
· Tends to be quantitative
· Controlled by a lot of genes
· Strongly influenced by the environment
e.g. blood groups *Normal distribution curve ­ A graph of
2.)Discontinuous variation variation for a population with a bell
shaped curve that shows most values in
· Distinct categories the middle of the range and a few
· Tends to be qualitative extreme values. E.g. Human height
· Controlled by a few genes
· Unaffected by the environment
Quantitative data- numerical; can be measured
Genes vs. environment Qualitative data- not numerical; can be observed
Variation is due to two factors: not measured
1.)genetic variation (inheritance) ­ variation due to the genes inherited after
sexual reproduction or genetic mutation, caused by instructions within cells.
2.)environmental variation ­ variation due to the condition in which an
organism has developed. Characteristics obtained this way are acquired.
B1: Topic 1 (Flashcards)…read more

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Excellent Resource! Only issue is that it doesn't have all of B1 in it e.g. it doesn't include topic 3.

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