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 ...
Multiple fission (Multi=many, fission=division)
Definition: it is type of asexual reproduction
in which the parental body divides into many daughter cells simultaneously
during the unfavorable condition to increase the chances of survival of
daughter cells.
Occurrence: Multiple Fission is found in a
number of organisms e.g. algae among plants, Plasmodium Malarial parasite,
Amoeba, Monocystis.
Mechanism:
o
Multiple
fission occurs when condition not favorable.
o
Under
unfavorable condition mother cell produce a layer called “cyst” (encystation)
and nucleus of parent cell divides by repeated amitosis many times and produce
many daughter nuclei this process is called “karyokinesis” then followed
by division of cytoplasm (cytokinesis).
o
When
favorable condition comes this cyst ruptured, daughter cells comes out and form
individual organism.
o
Some
cytoplasm of the parental body remains unused and is called residual body.
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