1. Whales look like fishes. They can swim in water like them but they are not fish as they respire with lungs, have four chambered heart, diaphragm, mammary gland, hairs, etc. Whales are viviparous like any other mammal.

    Whales look like fishes. They can swim in water like them but they are not fish as they respire with lungs, have four chambered heart, diaphragm, mammary gland, hairs, etc. Whales are viviparous like any other mammal.

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  2. Flight adaptations of the birds are the following: (1) Forelimbs are modified into wings. (2) Body is covered with exoskeleton of water-proof and light-weight feathers. (3) Long bones of endoskeleton are pneumatic having air cavities. (4) A11 birds are toothless; their jaws are modified into horny bRead more

    Flight adaptations of the birds are the following:
    (1) Forelimbs are modified into wings.
    (2) Body is covered with exoskeleton of water-proof and light-weight feathers.
    (3) Long bones of endoskeleton are pneumatic having air cavities.
    (4) A11 birds are toothless; their jaws are modified into horny beaks.
    (5) Body is streamlined to reduce air resistance during its flight.
    (6) Birds have air sacs helping in double respiration.
    (7) Flights muscles are well developed.
    (8) Tail feathers form a steering apparatus.
    (9) Birds have a acute vision.

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  3. The nature of skin in four classes of tetrapoda are: (i) Class Amphibia - Thin, moist, glandular and respiratory skin. (ii) Class Reptilia - Dry and non-glandular skin with horny scales or scutes. (iii) Class Aves - Dry and non-glandular skin with feathers. (iv) Class Mammalia - Glandular skin withRead more

    The nature of skin in four classes of tetrapoda are:
    (i) Class Amphibia – Thin, moist, glandular and respiratory skin.
    (ii) Class Reptilia – Dry and non-glandular skin with horny scales or scutes.
    (iii) Class Aves – Dry and non-glandular skin with feathers.
    (iv) Class Mammalia – Glandular skin with hairs.

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  4. Notochord is a transient mesodermal rod in the most dorsal portion of the chordate embryo. In other words, notochord is an ensheathed flexible rod of turgid cells located along the back of chordate embryos and some primitive chordates ventral to nerve cord. It provides place for the attachment of muRead more

    Notochord is a transient mesodermal rod in the most dorsal portion of the chordate embryo. In other words, notochord is an ensheathed flexible rod of turgid cells located along the back of chordate embryos and some primitive chordates ventral to nerve cord. It provides place for the attachment of muscles. Notochord has given rise to jointed axial skeleton of vertebral column. Nente cord is a collection of nerve fibres that runs throughout the length of an animal. It is hollow and dorsal in chordates where it gets modified into central nervous system of brain and spinal cord. Nerve cord is solid and ventral in nonchordates.

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  5. (i) Hemichordata - Balanoglossus (ii) Urochordata - Herdmania (ii) Cephalochordata - Amphioxus (Branchiostoma)

    (i) Hemichordata – Balanoglossus (ii) Urochordata – Herdmania
    (ii) Cephalochordata – Amphioxus (Branchiostoma)

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