1. The body segmentation first appeared in the phylum, Annelida (annulus meaning little ring). For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-4/

    The body segmentation first appeared in the phylum, Annelida (annulus meaning little ring).

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  2. The numbers of eggs produced by an oviparous mother will be more than the young ones produced by a viviparous mother. This is because in oviparous animals, the development of young ones takes place outside the mother’s body. Their eggs are more prone to environmental conditions and predators. TherefRead more

    The numbers of eggs produced by an oviparous mother will be more than the young ones produced by a viviparous mother. This is because in oviparous animals, the development of young ones takes place outside the mother’s body. Their eggs are more prone to environmental conditions and predators. Therefore, to overcome the loss, more eggs are produced by mothers so that even under harsh environmental conditions, some eggs might be able to survive and produce young ones. On the other hand, in viviparous organisms, the development of young ones takes place in safe conditions inside the body of the mother. They are less exposed to environmental conditions and predators. Therefore, there are more chances of their survival and hence, less number of young ones is produced compared to the number of eggs.

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  3. Birds have undergone many structural adaptations to suit their aerial life. Some of these adaptations are as follows. 1.Streamlined body for rapid and smooth movement. 2.Covering of feathers for insulation. 3.Forelimbs modified into wings and hind limbs used for walking, perching, and swimming 4.PreRead more

    Birds have undergone many structural adaptations to suit their aerial life. Some of these adaptations are as follows.
    1.Streamlined body for rapid and smooth movement.
    2.Covering of feathers for insulation.
    3.Forelimbs modified into wings and hind limbs used for walking, perching, and swimming
    4.Presence of pneumatic bones to reduce weight
    5. Presence of additional air sacs to supplement respiration

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  4. Gas bladder or air bladder is a gas filled sac present in fishes. It helps in maintaining buoyancy. Thus, it helps fishes to ascend or descend and stay in the water current.   For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-4/

    Gas bladder or air bladder is a gas filled sac present in fishes. It helps in maintaining buoyancy. Thus, it helps fishes to ascend or descend and stay in the water current.

     

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  5. The characteristic features of the phylum, Chordata, include the presence of a notochord and paired pharyngeal gill slits. In sub-phylum Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. Thus, it can be said that all vertebrates are choRead more

    The characteristic features of the phylum, Chordata, include the presence of a notochord and paired pharyngeal gill slits. In sub-phylum Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. Thus, it can be said that all vertebrates are chordates but all chordates are not vertebrates.

     

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