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Structural Organisation in Animals: CBSE Class 11 NCERT Solution

Aug 12, 2015 17:42 IST

    Find the CBSE Class 11 Biology NCERT Solution for the Chapter- 7, Structural Organisation in Animals. It has been framed keeping the Students' perspective in mind. This will help the Students with easy and simple understanding of the concept and technique employed in solving as per the CBSE Marking Scheme.

    To get the Complete NCERT Solution, Click Here

    Few Sample Question from this Chapter are given below:

    Q. State the volume of air remaining in the lungs after a normal breathing.

    Ans. The volume of air remaining in the lungs after a normal breathing is called Functional Residual Capacity (FRC). It can be measured as the sum of expiratory reserve volume (ERV) and residual volume (RV). The average value of functional residual capacity of the human lungs is about 2500 – 3000 mL.

    Q. Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?

    Ans. Aalveolar region has characters suitable for the efficient exchange of gases.  The gaseous exchange between the alveoli and the blood capillaries surrounding the alveoli, takes place by the process of diffusion because of pressure or concentration gradient. The highly-permeable and thin membrane of the alveoli is suitable for the diffusion of gases, while other parts of the respiratory system are not structured to serve this purpose. Hence, diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system.

    Q. What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?

    (i) pO2 lesser, pCO2 higher

    (ii) pO2 higher, pCO2 lesser

    (iii) pO2 higher, pCO2 higher

    (iv) pO2 lesser, pCO2 lesser Answer

    Ans. (ii) pO2 higher, pCO2 lesser

    Q. Explain the process of inspiration under normal conditions.

    Ans. Inspiration is the process of drawing air form outside the body into the lungs. It is initiated by the contraction of diaphragm which creates a pressure gradient between the lungs and the atmosphere. This contraction of diaphragm increases the volume of the thoracic chamber in the anteroposterior axis with the simultaneous contraction of external intercostal muscles which lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorso-ventral axis. The overall increase in the thoracic volume results in a similar increase in pulmonary volume. The increase in pulmonary volume decreases the intra-pulmonary pressure to less than the atmospheric pressure. This causes a pressure gradient between the lungs and the atmosphere, which forces the air from outside to move into the lungs. Hence, inspiration takes place.

    Q. How is respiration regulated?

    Ans. It is the respiratory rhythm centre present in the medulla region of the brain which regulates the respiration. The functions of the respiratory rhythm centre are moderated by the  pneumotaxic centre present in the pons. Chemosensitive area which is situated adjacent to the rhythm centre, is highly sensitive to CO2 and H+ concentration. Increase in the concentration of these compounds can activate this chemosensitive area which in turn gives signal to the rhythm centre to change the rate of expiration for the elimination of these compounds.

    The receptors present in the carotid artery and aorta can also detect the levels of carbon dioxide and hydrogen ions in blood. As the level of carbon dioxide increases, these receptors send signals to the rhythm centre to perform the corrective actions.

    Q. What is the effect of pCO2 on oxygen transport?

    Ans. Paitial pressure of carbon dioxide plays a major role in the transport of oxygen. In the alveoli, the low pCO2 and high pO2 favours the formation of haemoglobin. The oxyhaemoglobin then carries the oxygen molecules to the tissues where the high pCO2 and low pO2 favours the dissociation oxyhaemoglobin to release the oxygen at the tissues.

    To get the Complete NCERT Solution, Click Here

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