November 27, 2014

IPE Exams - Jr Inter Zoology SA Questions with Answers for AP and Telangana

Q: Define species. Explain various aspects of species.
A: The word species (L. Kind or appearance) was first used by John
Ray. It is the basic unit of classification. A species is an
interbreeding group of similar organisms sharing the common gene pool
and producing fertile offspring. Species is a group of individuals
that are
a. Reproductively isolated from the organisms of other species.
b. Sharing the common ecological niche.
c. Showing similarity in Karyotype.
d. Having structural and functional similarities.
Eg: Apis indica, A.dorsata, A.florea, A.mellifera
Here indica, dorsata, florea and mellifera are different species that
belong to the genus Apis. Sometimes closely related species of same
genus may interbred, but, they produce sterile offspring. Eg: When
female donkey and male horse interbred, a hinny (sterile) is produced.

Q: Describe structure of a multipolar neuron.
A: Neuron is the functional unit of nervous tissue. A multipolar
neuron has a cell body with many dendrites and an axon.
i. Cyton (Cell body, soma or perikaryon) contains nucleus and
cytoplasm. Cytoplasm contains Nissil bodies, neurofibrils, lipofuscin
granules. (A group of cytons in central nervous system is known as
nucleus and in peripheral nervous system as ganglion).

ii. From the periphery of cyton, fine, branched processes are formed
called dendrites. They conduct impulses towards cyton.

iii. From the axon hillock of cyton, a long cylindrical process is
formed, known as axon (nerve fibre). Its plasma membrane is called
axolemma and cytoplasm as axoplasm.
Distally, axon is divided into many branches, known as telodendria
(axon terminals).
Telodendria end with synaptic knobs, which contains synaptic vesicles
that contain neurotransmitters.
Axon transmit impulses away from the cyton. (Group of axons in central
nervous system is called tract and in peripheral nervous system as
nerve).

iv. Interneuronal junction or neuro muscular junction is known as synapse.

v. In myelenated neurons, internode of axon is wrapped by Schwann
cells. Inner part of Schwann cell contains myelin and outer part
contains cytoplasm and nucleus. This outer part is called neurilemma.

vi. In myelenated neuron, the portion of axon that is devoid of myelin
is called node of Ranvier. The part of axon between adjacent nodes is
known as internode.

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