Experiment No – 10
Symbiotic association in root nodules of leguminous plants ,
Cuscuta on host, lichens.
Aim
To study symbiotic association in root nodules of leguminous plants, Cuscuta on host,
lichens.
Observation
1) Symbiotic association in root nodules of leguminous plants

Root nodules are commonly found in the roots of leguminous plants

They are formed due to association with a nitrogen fixing bacteria,Rhizobium

Rhizobium is gram – ve bacteria

Root nodules contains pink colour leghaemoglobin pigment

It also contains enzyme nitrogenase which helps in the formation of Ammonia
2) Cuscuta on host

Cuscuta commonly called dodder /amberal live as stem ectoparasite on other plants

Stem of Cuscuta is thin and slender shaped without cholorophyll

It winds around the stem of host plant

Stem of cuscuta fixes with the host plant by the special structure called Haustoria

Haustoria direct connection with host plant and withdraw water ,carbohydrates and
other solutes

Cuscuta can weaken or kill host plant and reduce crop yield
3)
Lichens

Lichens are composite organisms representing a symbiotic association between
fungus and algae

The algal component is phycobiont and the fungal component is mycobiont

They grow on land,rocks, tree trunks and walls of houses.

Algae prepares food for fungi and Fungi provides shelter and absorbs minerals,
nutrients and water to algae

Main three different types are crustose, foliose, fructicose
Experiment No – 11
Study of homologous and analogous organs in plants and animals
Aim
Study of homologous and analogous organs in plants and animals
Observation
1) Homologous Organs
The structures of animals and plants under study show homology, i.e. similarity in the
fundamental (basic) structures due to shared or common embryonic origin but all of these
organs/features performs different functions
Homologous Organs in Animals

The structures depict the forelimbs of a man, cheetah, whale and bat in the case of
animals.

The hand of a man, limb of cheetah, flipper of a whale and the wings of a bat have
common set of bones but all of these structures though appears similar but are
involved in different functions like grasping, running, swimming and flying
respectively.
Homologous Organs in Plants

The structures depict Bougainvillea (thorn) and Cucurbita (tendrils) in the case of
plants.

The leaves of the plant Bougainvillea have been modified into the thorns for protection
while leaves in Cucurbita are made into tendrils for providing support in climbers.
2)
Analogous Organs
The structures of animals and plants under study shows analogy, i.e. they perform
similar functions in different organisms but do not share same structure on the basis of
origin.
Analogous Organs in Animals
 The structures depict the wings of a bat and wings of an insect in case of animals.
 The forelimbs of bats, birds and wings of insects are used for flying by these animals
however, they are structurally very different from each other.
Analogous Organs in Plants
 The structures depict Passiflora (stem tendril) and pea (leaflet tendril) in case of plants.
 The Passiflora and pea have leaves modified into tendrils which support the plant
during climbing whereas they do not share any structural similarities.