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SolveItNCERT · CBSE · NEET

NCERT Exemplar · Class 10 Science Life Processes

82 questions · 82 still being checked

Multiple Choice Questions 31–35 (part 4 of 9)

  1. Exercise 31

    Which is the first enzyme to mix with food in the digestive tract?
    (a)
    Pepsin
    (b)
    Cellulase
    (c)
    Amylase
    (d)
    Trypsin

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    NCERT’s answer
    (c)
    (c) Amylase.Saliva, released as food enters the mouth, carries salivary amylase — the first enzyme to act, breaking starch before any other digestive juice is added: \[\text{starch} \xrightarrow{\text{salivary amylase}} \text{maltose} \]

  2. Exercise 32

    Which of the following statement(s) is (are) correct?
    (i)
    Pyruvate can be converted into ethanol and carbon dioxide by yeast
    (ii)
    Fermentation takes place in aerobic bacteria
    (iii)
    Fermentation takes place in mitochondria
    (iv)
    Fermentation is a form of anaerobic respiration
    (a) (i) and (iii)
    (b) (ii) and (iv)
    (c) (i) and (iv)
    (d) (ii) and (iii)

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    NCERT’s answer
    (c)
    (c) (i) and (iv).Yeast ferments pyruvate to ethanol and \(\displaystyle \mathrm{CO_2}\), and fermentation is itself a form of anaerobic respiration: \[\text{pyruvate} \xrightarrow[\text{yeast}]{\text{no } \mathrm{O_2}} \text{ethanol} + \mathrm{CO_2} + \text{energy} \] \[\mathrm{C_6H_{12}O_6} \xrightarrow[\text{yeast}]{\text{no } \mathrm{O_2}} 2\,\mathrm{C_2H_5OH} + 2\,\mathrm{CO_2} \] It runs in the cytoplasm, not mitochondria, and not in aerobic bacteria.

  3. Exercise 33

    Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
    (a)
    conversion of pyruvate to ethanol
    (b)
    conversion of pyruvate to glucose
    (c)
    non conversion of glucose to pyruvate
    (d)
    conversion of pyruvate to lactic acid

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    (d)
    (d) Conversion of pyruvate to lactic acid.Without enough \(\displaystyle \mathrm{O_2}\), muscle cells ferment instead of respiring fully: \[\text{pyruvate} \xrightarrow{\text{lack of } \mathrm{O_2}} \text{lactic acid} + \text{energy} \] \[\mathrm{C_6H_{12}O_6} \xrightarrow{\text{no } \mathrm{O_2}} 2\,\mathrm{C_3H_6O_3} \] The lactic acid build-up causes the cramp.

  4. Exercise 34

    Choose the correct path of urine in our body
    (a)
    kidney → ureter → urethra → urinary bladder
    (b)
    kidney → urinary bladder → urethra → ureter
    (c)
    kidney → ureters → urinary bladder → urethra
    (d)
    urinary bladder → kidney → ureter → urethra

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    NCERT’s answer
    (c)
    (c) kidney → ureters → urinary bladder → urethra.Each kidney drains through its own ureter into the urinary bladder, which stores urine until it is released through the single urethra.

  5. Exercise 35

    During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the
    (a)
    cytoplasm
    (b)
    chloroplast
    (c)
    mitochondria
    (d)
    golgi body

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    NCERT’s answer
    (a)
    (a) Cytoplasm.Lactate dehydrogenase converts pyruvic acid to lactic acid in the cytoplasm during anaerobic breakdown — mitochondria, which need \(\displaystyle \mathrm{O_2}\), are bypassed: \[\text{pyruvic acid} \xrightarrow{\text{no } \mathrm{O_2}} \text{lactic acid} \] \[\mathrm{C_6H_{12}O_6} \xrightarrow{\text{no } \mathrm{O_2}} 2\,\mathrm{C_3H_6O_3} \]