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NCERT Exemplar · Class 9 Science Diversity in Living Organisms

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Long Answer Questions 50–57 (part 7 of 7)

  1. Exercise 50

    Write names of few thallophytes. Draw a labelled diagram of Spirogyra.

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    Ulothrix, Spirogyra, Cladophara, Ulva and Chara,
    Thallophytes: Spirogyra, Ulothrix, Cladophora, Ulva, Chara. NCERT_Solution_Class9_Science_Exemplar_Ch7_Q50 Answer: Spirogyra, Ulothrix, Cladophora, Ulva, Chara.

  2. Exercise 51

    Thallophyta, bryophyta and pteridophyta are called as ‘Cryptogams’. Gymnosperms and Angiosperms are called as ‘phanerogams’. Discuss why? Draw one example of Gymnosperm.

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    The Thallophyta, bryophyta and pteridophyta are called as ‘Cryptogams’ because the reproductive organs of these groups are inconspicuous or hidden. Seeds are absent. On the other hand ‘Phanerogams’ include gymnosperms and angiosperms which have well differentiated reproductive tissue and the embryo with stored food. Embryo develops into seed. Cell-wall Chloroplast Pyrenoids Nucleus Cytoplasm Spirogyra Pinus Cycas
    Cryptogams (Gk. krypto, hidden) have inconspicuous, poorly developed reproductive organs and never form seeds; thallophytes, bryophytes and pteridophytes reproduce by spores instead. Phanerogams (Gk. phaneros, visible) have well-developed, visible reproductive organs and always form seeds — gymnosperms as naked seeds on cones, angiosperms as seeds enclosed in a fruit. NCERT_Solution_Class9_Science_Exemplar_Ch7_Q51 Answer: Cryptogams (Thallophyta, Bryophyta, Pteridophyta): hidden reproductive organs, no seeds. Phanerogams (Gymnosperms, Angiosperms): visible reproductive organs, seeds. Example gymnosperm: Pinus.

  3. Exercise 52

    Define the terms and give one example of each
    (a)
    Bilateral symmetry
    (b)
    Coelom
    (c)
    Triploblastic

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    (a)
    The left and right halves of the body have the same design, eg, liver fluke (b) Coelom is the internal body cavity between visceral organs and body wall in which well developed organs can be accommodated, eg. butterfly (c) Animals having three layers of cells from which differentiated tissue can be made are called triploblastic, eg. star fish (c) Asterias (star fish) (b) Butterfly Acetabulum (a) Liverfluke
    (a)
    Bilateral symmetry — the body can be cut by one plane, along the anteroposterior axis, into two identical mirror-image halves, left and right, e.g. cockroach.
    (b)
    Coelom — a body cavity lying between the gut and the body wall, lined by mesoderm on both sides, e.g. earthworm.
    (c)
    Triploblastic — a body built from three germ layers, ectoderm, mesoderm and endoderm, e.g. starfish.
    Answer: (a) cockroach (b) earthworm (c) starfish.

  4. Exercise 53

    You are given leech, Nereis, Scolopendra, prawn and scorpion; and all have segmented body organisation. Will you classify them in one group? If no, give the important characters based on which you will separate these organisms into different groups.

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    All organisms given in the question do not belong to same group. Leech and Nereis belong to phylum annelida because they have metamerically segmented body i.e., body is divided into many segments internally by septa. Body segments are lined up one after the other from head to tail. But Scolopendra, prawn and scorpion belong to phylum arthropoda as these have jointed legs and open circulating system.
    No — segmentation alone does not put them in one group; they split into two phyla. Annelida — leech, Nereis: soft body, thin cuticle, no jointed appendages, closed blood vascular system, true coelom. Arthropoda — Scolopendra, prawn, scorpion: hard chitinous exoskeleton, jointed appendages (legs), open circulatory system (haemolymph in a haemocoel). Answer: No. Annelida (leech, Nereis): no jointed appendages, closed circulation. Arthropoda (Scolopendra, prawn, scorpion): jointed legs, chitinous exoskeleton, open circulation.

  5. Exercise 54

    Which organism is more complex and evolved among Bacteria, Mushroom and Mango tree. Give reasons.

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    Hint— Mango tree is more complex and evolved because, it is eukaryotic, autotrophic, terrestrial sporophyte with covered seed. The bacteria is unicellular prokaryote and fungi are the heterotrophic, simple thallophyte with no tissue systems.
    Bacteria — prokaryotic, unicellular: no nucleus, no tissue or organ differentiation. Mushroom — eukaryotic, multicellular (hyphae forming a mycelium), heterotrophic, but still no true tissue or organ differentiation and no vascular tissue. Mango tree — eukaryotic, multicellular, autotrophic, with differentiated tissues and organs (root, stem, leaf, flower) and vascular tissue (xylem, phloem) for conduction, plus sexual reproduction through flowers, fruit and seeds. Answer: Mango tree — eukaryotic, autotrophic, with differentiated tissues, organs and a vascular system, and sexual reproduction via flowers, fruit and seeds.

  6. Exercise 55

    Differentiate between flying lizard and bird. Draw the diagram.

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    Flying lizard belongs to group reptiles and characterised as cold blooded,body covered with scales and having three chambered heart, while birds belong to group aves and have characteristics of being warm blooded, having feather covered body, forelimbs modified as wings and having four chambered heart.
    A flying lizard is a reptile (genus Draco); a bird belongs to class Aves. Gliding organ: a lateral fold of skin, the patagium, stretched over elongated ribs, used only to glide downward between trees. A bird's forelimbs are modified into true wings covered with feathers and moved by strong pectoral muscles for powered flight. Skin is dry and scaly in the lizard, feathered in the bird. The lizard is cold-blooded (poikilothermous); the bird is warm-blooded (homeothermous). The lizard's egg is soft-shelled; the bird's is hard-shelled. NCERT_Solution_Class9_Science_Exemplar_Ch7_Q55 Answer: The lizard glides on a rib-supported skin fold; the bird flies using feathered wings powered by pectoral muscles.

  7. Exercise 56

    List out some common features in cat, rat and bat.

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    Bat, rat and cat belong to class mammalia and have following common features (a) All have notochord at some stage of life cycle. (b) All are warm blooded. (c) All have four chambered heart. (d) All have skin covered with hair and with sweat and oil glands.
    Cat, rat and bat are all mammals (class Mammalia), so they share: a warm-blooded body with hair covering the skin; a notochord at some stage of life; young that develop inside the mother and are born alive (viviparous), then fed on milk from mammary glands; skin bearing sweat and oil glands; a four-chambered heart with a muscular diaphragm separating the thoracic and abdominal cavities; an external ear (pinna); and heterodont teeth, the type pattern differing by species. Answer: Shared mammalian features — hair, a notochord stage, viviparity and mammary glands, sweat and oil glands, a four-chambered heart and diaphragm, pinnae, and heterodont teeth.

  8. Exercise 57

    Why do we keep both snake and turtle in the same class?

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    Hint— Because both are ($\displaystyle 1$) cold blooded ($\displaystyle 2$) have scales ($\displaystyle 3$) breathe through lungs ($\displaystyle 4$) have three chambered heart, and ($\displaystyle 5$) they lay eggs with tough covering. Flying lizard (Draco) Pigeon
    Snake and turtle are both placed in class Reptilia because they share the class's defining features despite very different body forms: dry, scaly skin with no mucus glands; lungs used for respiration throughout life; a three-chambered heart (two atria, one ventricle); a cold-blooded (poikilothermous) body whose temperature varies with the surroundings; and eggs with a leathery or calcareous shell, laid on land, with no larval stage. Answer: Both show Reptilia's shared traits — scaly skin, lung breathing, a three-chambered heart, cold-bloodedness and shelled eggs — so classification rests on these features, not outward shape.