Transpiration is the rate of the water vapour exhalation by the plant cells through its opening pores. The correct blanks are guard cells and closing.
Plant cells have certain specialized cell organelles that help in maintaining the rate of the carbon dioxide and the water content in their cells.
Stomata of the plant cells are specialized organelles that maintain the water and rate of transpiration by the plants. They have guard cells surrounding them that regulates their opening and closing.
The guard cells of the stomata form pores of the stomatal opening. The opening and the closing of the pores are regulated by the bulge and the carbon and the water intake and outtake of the cell is maintained.
Therefore, option A. guard cells and closing are the correct blanks.
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