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NCERT Exemplar · Class 9 Science The Fundamental Unit of Life

59 questions · 59 still being checked

Long Answer Questions 53–59 (part 6 of 6)

  1. Exercise 53

    Draw a plant cell and label the parts which
    (a)
    determines the function and development of the cell
    (b)
    packages materials coming from the endoplasmic reticulum
    (c)
    provides resistance to microbes to withstand hypotonic external media
    without bursting
    (d)
    is site for many biochemical reactions necessary to sustain life.
    (e)
    is a fluid contained inside the nucleus

    Matches the book, not yet reviewed

    This working reaches the answer NCERT prints. It has not yet been read through by hand.

    NCERT’s answer
    Hint— (a) Nucleus (b) Golgi apparatus (c) Cell wall (d) Cytoplasm (e) Nucleoplasm. Diagram of the plant cell can be drawn and label it with parts mentioned above
    (a)
    nucleus, (b) Golgi apparatus, (c) cell wall, (d) cytoplasm, (e) nucleoplasm.
    The nucleus directs the cell's activities and development; Golgi vesicles package material arriving from the ER; the cellulose wall keeps the cell from bursting in a hypotonic medium; cytoplasm hosts most metabolic reactions; nucleoplasm is the fluid nuclear sap.
    Answer: (a) nucleus (b) Golgi apparatus (c) cell wall (d) cytoplasm (e) nucleoplasm.

  2. Exercise 54

    Illustrate only a plant cell as seen under electron microscope. How is it different from animal cell?

    Matches the book, not yet reviewed

    This working reaches the answer NCERT prints. It has not yet been read through by hand.

    NCERT’s answer
    Plant cell Plant Cell Animal Cell
    NCERT_Solution_Class9_Science_Exemplar_Ch5_Q54 Unlike an animal cell, this plant cell carries a rigid cell wall outside the plasma membrane, plastids (chloroplasts) for photosynthesis and one large central vacuole occupying most of its volume; an animal cell lacks all three, has only small vacuoles instead, but does carry centrioles, which a plant cell lacks. Answer: Under the electron microscope a plant cell shows a cell wall, plastids and one large central vacuole but no centrioles; an animal cell lacks the first three, has only small vacuoles, and does have centrioles.

  3. Exercise 55

    Draw a neat labelled diagram of an animal cell.

    Not cross-checked

    NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.

    An animal cell has no cell wall or plastids and only small, few vacuoles -- the plasma membrane alone bounds it. NCERT_Solution_Class9_Science_Exemplar_Ch5_Q55 Answer: Labelled diagram: plasma membrane, nucleus, cytoplasm, endoplasmic reticulum, Golgi apparatus, mitochondria, ribosomes, lysosome and centriole.

  4. Exercise 56

    Draw a well labelled diagram of an eukaryotic nucleus. How is it different from nucleoid?

    Not cross-checked

    NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.

    A nucleoid, seen in bacteria, has no surrounding membrane and no nucleolus, and holds a single circular DNA lying free in the cytoplasm, not enclosed by any membrane. Answer: A eukaryotic nucleus is membrane-bound, with a nucleolus; a nucleoid is not, and its DNA lies free in the cytoplasm.

  5. Exercise 57

    Differentiate between rough and smooth endoplasmic reticulum. How is endoplasmic reticulum important for membrane biogenesis?

    Not cross-checked

    NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.

    Rough ER carries ribosomes on its outer surface and makes proteins for export or for other organelles; smooth ER has no ribosomes and makes lipids, including steroids, and helps detoxify drugs.The proteins and lipids synthesised on the ER travel by vesicles to form the membranes of the Golgi apparatus, lysosomes and the plasma membrane itself -- this making of membrane material is called membrane biogenesis. Answer: Rough ER (ribosome-studded, protein synthesis) versus smooth ER (ribosome-free, lipid synthesis); both supply the proteins and lipids that build other organelles' membranes -- membrane biogenesis.

  6. Exercise 58

    In brief state what happens when
    (a)
    dry apricots are left for sometime in pure water and later transferred to
    sugar solution?
    (b)
    a Red Blood Cell is kept in concentrated saline solution?
    (c)
    the Plasma-membrane of a cell breaks down?
    (d)
    rheo leaves are boiled in water first and then a drop of sugar syrup is
    put on it?
    (e)
    golgi apparatus is removed from the cell?

    Check this one against your book

    NCERT’s printed answer for this exercise does not match its own question. This working follows the question as printed.

    (a)
    In pure water:
    \[\text{pure water (hypotonic)} \Rightarrow \text{endosmosis} \Rightarrow \text{cells swell} \]
    In sugar solution:
    \[\text{sugar solution (hypertonic)} \Rightarrow \text{exosmosis} \Rightarrow \text{cells shrink} \]
    (b)
    Concentrated saline is hypertonic to the RBC.
    \[\text{RBC in hypertonic saline} \Rightarrow \text{exosmosis} \Rightarrow \text{cell shrinks (crenation)} \]
    (c)
    The membrane no longer separates cytoplasm from the outside.
    \[\text{membrane breaks} \Rightarrow \text{cytoplasm mixes with surrounding medium} \Rightarrow \text{cell dies} \]
    (d)
    Boiling kills the leaf.
    \[\text{boiling} \Rightarrow \text{membrane not selectively permeable} \Rightarrow \text{no plasmolysis with syrup} \]
    (e)
    Golgi apparatus packages and dispatches cell products, and forms lysosomes.
    \[\text{Golgi apparatus removed} \Rightarrow \text{no packaging/secretion, no lysosome formation} \]
    Answer: (a) swells in water, shrinks in sugar solution (b) shrinks/crenates (c) cytoplasm leaks out, cell dies (d) no plasmolysis (e) no packaging, secretion or lysosome formation.
    NCERT prints: the fifth hint labelled (d) again, repeating the fourth — a misprint: by content it is (e), the same point this solution gives for the Golgi apparatus (no packaging, secretion or lysosome formation).

  7. Exercise 59

    Draw a neat diagram of plant cell and label any three parts which differentiate it from animal cell.

    Not cross-checked

    NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.

    NCERT_Solution_Class9_Science_Exemplar_Ch5_Q59 Cell wall, plastids (chloroplasts) and a large central vacuole are absent in an animal cell. Answer: Cell wall, chloroplasts and a large central vacuole (absent in an animal cell).