According to the acid-growth hypothesis, auxin works . dissolving sieve plates, permitting more rapid transport of nutrients. b. dissolving cell membranes temporarily, permitting cells that were on the verge of dividing divide more rapidly. c. changing the ph within the cell, permitting the electron transport chain to operate more efficiently. d. increasing the activity of proton pumps that lower the ph of cell walls, allowing cells to elongate.

The correct answer is D increasing the activity of protons pumps that lowers the pH  of the cell walls allowing cells to elongate.

Explanation:

The plant growth hormone auxin work by increasing the H+ ion concentration thus decreasing the pH of the apoplast.

    The decrease in the pH of the apoplast helps in the cell wall extension that ultimately result in cell growth.

   Auxin hormone exert this effect by increasing the activity of increasing the activity of proton pumps in the apoplastic membrane.

hey bro i looked it up on google the structure of the eye-spot in euglena viridie, e. ehrenbergii, and phacus pyriyorme is not as franzé haa described it. the so-called “crystal body” and “lens bodies” were not found in any of the individuals of the species examined by me. as earlier observers have stated, the eye-spot consists simply of a mass of pigment granules arranged in a single layer, and probably embedded in a protoplasmic framework, but the latter could not be seen, and its presence was only inferred from the fact that the pigment granules must be held together in some way, thd the eye-spot as a whole is capable of expansion, and that the pigment granules can be separated from each other.

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