To Study Homology and Analogy with the help of Models, Charts and Specimens- Lab Experiment Video Lecture - Class 10

homology and analogy of plants and
animals the central idea of biological
evolution is that all life on Earth
shares a common ancestor there is much
evidence for the theory of evolution
homologous and analogous organs in
animals and plants are considered to be
major evidence in favor of the theory of
evolution some traits in different
organisms are similar because they
inherited them from a common ancestor
and some similarities evolved in other
ways these are called homologies and
analogies we will look at the different
characteristics and identify the
homologous and analogous organs in the
plants and animals we have selected
homology homology is similarity in
structure among different organisms
which is inherited from a common
ancestor those similar in structure the
function of the structure is different
in different organisms homology in
animals in animals all the structures
are similar they have different
functions in different animals for
example the four limbs of some animals
have a similar set of bones because they
derived from a common ancestor depending
on lifestyle these bones have different
shapes and will perform different
functions for example let's look at
organs such as bats wing wing of birds
seals flipper for limp of horse and the
human arm we can observe that although
the shape and size of the bones are not
similar there is still a similarity in
their structure they have the same set
of bones humerus radius and ulna carpals
and metacarpals
humans use the hand for grasping and
doing work seals use flippers for
swimming and bats and birds use their
wings for flight the horse uses its four
limbs for running homology in plants in
plants as well as animals we can also
observe homologous structure in some
plants like pea and Barbary the leaves
show a different function and shape from
the leaves we normally see the tendrils
of the pea plant and spines of Barbary
plant are homologous organs showing
different functions the tendril of a pea
is a modified leaf and is used for
providing mechanical support for the
plant in the case of barberry
the leaves are modified into spines and
are meant for protection
the tendril of a pea and spine of
barberry originated from leaves so they
are homologous organs in plants but have
different functions analogy analogy is a
similarity in function in different
organisms due to evolution that is
species may also have similar traits
even though they are not related to each
other this usually results because the
species live in similar environments
fill similar ecological roles and
through natural selection the same type
of structure is favored in different
ancestors the structures in this case
are known as analogue structures analogy
in animals
an example of an analogue straight in an
animal would be the wings of insects
feathers of birds and wings of bats
which have common functions but
different origins
the wings of an insect originated from
the inner or outer surface of the
insects body feathers of birds
originated from the four limbs and wings
of bats originated from both the four
limp and membranous skin of the abdomen
analogy implants take a look at the
leaves of opuntia and people plant in
the open shell the stem is modified into
a broad succulent leaf like structure
which will perform photosynthesis in the
same way as leaves the people leaf is a
normal leaf which will also perform
photosynthesis so both the punchy and
people leaves perform the common
function of photosynthesis but have
different structures therefore they are
analogous organs in plants in the case
of potato and sweet potato we can
observe that they have similar
characteristics but different origins
the potato is a modified underground
stem which is meant for storage of food
it has eyes which represent nodes sweet
potato is a modified underground root
which is also meant for storage of food
it has root hairs here are the mean
points you should know about homologous
and analogue structures
you