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Must to Remember Facts

  • In direct respiration exchange of gases is through body cells directly and blood is not used. It is found in aerobic bacteria, protists, plants, sponges, flatworms, round worms, coelenterates and many arthropods.

  • In indirect respiration exchange of gases takes place through special respiratory organs like skin, gills, buccopharyngeal cavity and lungs.

  • Normal rate of respiration is 12 to 15 times/min.

  • Eupnea is normal regular breathing

  • Hyperpnea is an increase in rate…

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Water as a medium for respiration and adaptation in fishes

Water, as a medium is less suitable for respiration than air because

  • It is about 1000 times denser and therefore more energy is required in passing it over the respiratory surfaces.

  • Any given volume of air contains more oxygen than the same volume of water under the similar conditions.

Fishes are well developed for respiration in water. They are able to utilize upto 80% of oxygen contained in the water passing across the gill.

Factors responsible for the efficiency of fishes …

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