Answer: Keys are pairs of two contrasting characters. Selection of
one character leads to rejection of another character while identifying a
particular species or genera or family and so on. For example presence or
absence of hair on body can give aclue if an animal belongs to mammalian or
not.
Tuesday 31 January 2012
Question 8. Define the following terms: (a) Phylum (b) Class (c) Family (d) Order (e) Genus
Answer:
(a) Phylum: Phylum comes next to Kingdom in the
taxonomical hierarchy. All broad characteristics of an animal or plant are
defined in a phylum. For example all chordates have a notochord and gill at
some stage of life cycle. Similarly all arthopods have jointed legs made of
chitin.
(b)
Class: A class includes related orders.
Class defines more detailed characters other than broad architecture. For
example all mammals have mammary glands to secrete milk, have hairy body. All
birds or aves have pneumatic bones to assist in flying. The common character
among them is the presence of notochord thereby making them members of the same
phylum.
(c)
Family: Family, has a group of related
genera with still less number of similarities as compared to genus and species.
Families are characterised on the basis of both vegetative and reproductive
features of plant species. Among plants for example, three different genera
Solanum, Petunia and Datura are placed in the family Solanaceae. Among animals
for example, genus Panthera, comprising lion, tiger, leopard is put along with
genus, Felis (cats) in the family Felidae. Similarly, if you observe the
features of a cat and a dog, you will find some similarities and some
differences as well. They are separated into two different families – Felidae
and Cancidae, respectively.
(d)
Order: Order further zeroes down on
characteristics and includes related genus. For example humans and monkeys
belong to the order primates. Both humans and monkeys can use their hands to
manipulate objects and can walk on their hind legs.
(e)
Genus: comprises a group of related
species which has more characters in common in comparison to species of other
genera. We can say that genera are aggregates of closely related species. For
example, potato, tomato and brinjal are three different species but all belong
to the genus Solanum. Lion (Panthera leo), leopard (P. pardus) and tiger (P.
tigris) with several common features, are all species of the genus Panthera.
This genus differs from another genus Felis which includes cats.
Question 7. Can you specify the correct sequence of taxonomic categories? (a) Species , Order, Phylum, Kingdom (b) Genus, Species, Order, Kingdom (c) Species, Genus, Order, Phylum
Answer: As clear from the table in previous answer (a) and (c) is
showing the correct order.
Question 4. What do we learn from identification of individuals and populations?
Answer: In a diverse country like India we can learn following
things from identification of individuals and population:
1.
Native Place.
2.
Mother Tongue
3.
Costumes
4.
Cuisine
3.
Religion
4.
Caste
5.
Socio-economic Background
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