higher secondary - first year - botany - Textbooks Online

3. During day and night take in O 2
and release CO 2
i.e only respiration takes
place and there is no photosynthesis.
4. Holozoic mode of nutrition since no chlorophylls present and hence they
are heterotrophs.
5. Growth is limited in animals. Growth stops after attaining a particular size
and age.
6. Excretory system and nervous system are well developed.
7. Reserve food material is glycogen.
8. Lacks cell wall. They have small vacuoles. Centrosomes are present.
Cells do not have inorganic crystals.
9. Animals do not depend on any external agents for sexual reproduction.
Regeneration of body parts and asexual reproduction is found only in lower
organisms.
Limitations of Two Kingdom System of Classification
The two kingdom system
of Classification proposed by
Linnaeus has been in use for a
long time. But later it proved
to be inadequate and
unsatisfactory in view of new
information and discoveries
about the lower forms of
organisms. The following are
the shortcomings of the two
kingdom system of
classification.
1. Certain organisms
share the characteristics
of both plants and
animals. eg. Euglena
Plantae
Pteridophtes
Spermatophytes
Bryophytes
and Sponges. In
Euglena, some species
have chlorophyll and are autotrophic like plants. However like animals
they are dependent on an external supply of vitamins B, and B 12
which they
cannot synthesize themselves. A few species of Euglena lack chloroplasts
and are therefore colourless and non-photosynthetic (heterotrophic). They
have a saprotropic mode of nutrition, carrying out extra-cellular digestion.
4
j j
j
j
Fungi
j
j
Bacteria
Algae
j
I n v e r t e b r a t e s
Chordates
Fig: 1.1. Diagrammatic representation of
Two Kingdom System
j
j
Animalia
j
j