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What is Breathing?

Q. What is breathing? Ans. Breathing is an external process, in this process inhale of air and exhale of air. Or  Breathing (or ventilation) is the process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, mostly by bringing in oxygen and flushing out carbon dioxide.   Breathing is also known as external respiration. It is part of respiration but not internal or cellular respiration. The process of breathing does not fill the alveoli with atmospheric air during each inhalation (about 350 ml per breath), but the inhaled air is carefully diluted and thoroughly mixed with a large volume of gas (about 2.5 liters in adult humans) known as the functional residual capacity which remains in the lungs after each exhalation, and whose gaseous composition differs markedly from that of the ambient air . Physiological respiration involves the mechanisms that ensure that the composition of the fu
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what is Binary Fission? How many types of Binary Fission?



                           Asexual reproductions are following types:
A.   Fission
B.   Budding
C.   Spore formation
D.   Fragmentation
E.   Regeneration
F.   Gemmulation
G.   Conidia formation
H.   Zoospores
I.    Vegetative propagation


A.  Fission (Fission=division)
It is type of Asexual reproduction in which a fully-grown parent cell divides into two or more than two daughter cells.
In this, the reproductive unit is whole parental body.
Types of Fission: On the basis of number of off-springs produced, fission reproduction is divides into two categories:  
(a)      Binary Fission
Definition: It is division of adult parental body into two nearly equal daughter cells during favorable condition.
Occurrence: It is the simplest and most common method of asexual reproduction found in protists (Amoeba, Euglena, Paramecium), bacteria, green algal forms (Chlamydomonas) and planarians (flat worms).
Mechanism: In binary fission, nucleus of mother cell first elongate than nucleus divides into two daughter nuclei called karyokinesis is followed by division of cytoplasm called cytokinesis.
Daughter cells feeds, grow and repeat the process. The organism undergoing binary fission are called immortal as after binary fission is left the parental cell so there is no natural death.
                   Types of Binary Fission
On the basis of division of Cytokinesis, the Binary fission divides into following three groups:
(i)    Irregular or simple binary fission:
In this type of fission cytokinesis may take place along any plane but its plane is always perpendicular to that of karyokinesis.



(ii)   Longitudinal binary fission:
In this type of reproduction cytokinesis takes place along longitudinal axis.
E.g. Euglena

(iii)  Transverse binary fission:
In this type of binary fission, cytokinesis occurs along the transverse axis.
E.g. Paramecium



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