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NCERT Exemplar · Class 9 Science The Fundamental Unit of Life

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Multiple Choice Questions 21–29 (part 3 of 6)

  1. Exercise 21

    Lipid molecules in the cell are sythesized by
    (a)
    smooth endoplasmic reticulum
    (b)
    rough endoplasmic reticulum
    (c)
    golgi apparatus
    (d)
    plastids

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    NCERT’s answer
    (a)
    (a) Smooth endoplasmic reticulum — its tubular membranes manufacture lipid (fat) molecules; the rough ER's ribosome-studded membranes make proteins instead.

  2. Exercise 22

    Cell arises from pre-existing cell was stated by
    (a)
    Haeckel
    (b)
    Virchow
    (c)
    Hooke
    (d)
    Schleiden

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    NCERT’s answer
    (b)
    (b) Virchow — he added that every cell arises from a pre-existing cell (omnis cellula e cellula), extending the theory Schleiden and Schwann had proposed.

  3. Exercise 23

    Cell theory was given by
    (a)
    Schleiden and Schwann
    (b)
    Virchow
    (c)
    Hooke
    (d)
    Haeckel

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    (a)
    (a) Schleiden and Schwann — they proposed that all living organisms are made of cells and cell products; Virchow later added that cells arise only from pre-existing cells.

  4. Exercise 24

    The only cell organelle seen in prokaryotic cell is
    (a)
    mitochondria
    (b)
    ribosomes
    (c)
    plastids
    (d)
    lysosomes

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    NCERT’s answer
    (b)
    (b) Ribosomes — prokaryotic cells lack membrane-bound organelles such as mitochondria, plastids and lysosomes, but still carry ribosomes to synthesise protein.

  5. Exercise 25

    Organelle without a cell membrane is
    (a)
    ribosome
    (b)
    golgi apparatus
    (c)
    chloroplast
    (d)
    nucleus
    THE FUNDAMENTAL UNIT OF LIFE

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    NCERT’s answer
    (a)
    (a) ribosome.Ribosomes are granules of RNA and protein with no boundary membrane; golgi apparatus, chloroplast and nucleus are all membrane-bound organelles.

  6. Exercise 26

    1\displaystyle 1 μm is
    (a)
    10−6\displaystyle 10^{-6} m
    (b)
    10−9\displaystyle 10^{-9} m
    (c)
    10−10\displaystyle 10^{-10} m
    (d)
    10−3\displaystyle 10^{-3} m

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    NCERT’s answer
    (a)
    (a) \(\displaystyle 10^{-6}\) m.\[1\ \mu\text{m} = 10^{-6}\ \text{m} \]The SI prefix micro (\(\displaystyle \mu\)) always denotes \(\displaystyle 10^{-6}\) of the base unit.

  7. Exercise 27

    Lysosome arises from
    (a)
    endoplasmic reticulum
    (b)
    golgi apparatus
    (c)
    nucleus
    (d)
    mitochondria

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    NCERT’s answer
    (b)
    (b) golgi apparatus.The golgi apparatus packages digestive enzymes into vesicles that pinch off and mature into lysosomes.

  8. Exercise 28

    Living cells were discovered by
    (a)
    Robert Hooke
    (b)
    Purkinje
    (c)
    Leeuwenhoek
    (d)
    Robert Brown

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    NCERT’s answer
    (c)
    (c) Leeuwenhoek.He first observed living cells in pond water in $\displaystyle 1674$; Robert Hooke's $\displaystyle 1665$ cork sections showed only dead, empty cell walls.

  9. Exercise 29

    Select the odd one out
    (a)
    The movement of water across a semi permeable membrane is affected
    by the amount of substances dissolved in it.
    (b)
    Membranes are made of organic molecules like proteins and lipids
    (c)
    Molecules soluble in organic solvents can easily pass through the
    membrane.
    (d)
    Plasma membranes contain chitin sugar in plants

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    NCERT’s answer
    (d)
    (d) Plasma membranes contain chitin sugar in plants.Membranes are lipid-protein bilayers, not chitin; chitin is a structural sugar of fungal cell walls, and plant cell walls are cellulose, not the plasma membrane.